Glossary of technical terms for the use of metallurgical engineers Terms starting with alphabet ‘T’
Glossary of technical terms for the use of metallurgical engineers
Terms starting with alphabet ‘T’
Taber abraser – It is a specialized piece of equipment that which uses rotating abrasive wheels to abrade a material sample under controlled conditions.
Taber abraser index – It is a measurement used to quantify a material’s resistance to abrasion, which is the wear and tear caused by friction, rubbing, or scraping. It essentially determines how well a material can withstand surface degradation over time. The index is calculated by measuring the rate of material loss (weight loss) or changes in appearance (like scratches, haze, or gloss reduction) after a certain number of abrasion cycles using the Taber abraser.
Table – When data are split into categories, tables provide a way of summary. A simple table gives the frequency, or the percentage, in each category. There are as many cells in the table, as there are categories, plus the last cell, which is called the margin. Tables can summarize data for two or more factors (category variables), and an example is shown below. The contents of a table can be the frequencies (or percentages) at each combination of the factor levels. Alternatively, they can be summary values of a numeric variable, for each category.
Table-top foundation – It allows for ducts, piping, and ancillary items to be located below the equipment. Elevated support is common for large turbine-driven equipment such as electric generators. Table-top structures are considered to be flexible, hence their response to dynamic loads can be quite complex.
Table-top with isolator foundation – It is used for high vibrating equipments like pumps, blowers, and fans etc. Table-top structures are considered to be flexible, hence their response to dynamic loads can be quite complex. Springs and dampers located at the top of supporting columns are sometimes used to minimize the response to dynamic loading. The effectiveness of isolators depends on the equipment speed and frequency.
Tabs – It means extra lengths of composite or other material at the ends of a tensile sample to promote failure away from the grips
Tabular dimensioning – It is a method where dimensions (like size and location) are listed in a table, instead of directly on a drawing. This approach is particularly useful for parts which vary in dimensions but share the same features or geometry. Instead of individual dimensions, letters or symbols represent features, and their corresponding values are found in the table. Tabular dimensions are also referred to as tabled dimensions. Tabular dimensioning allows for a more concise and organized way to represent dimensions.
Tachometer – It is an instrument which measures rotational speed (or angular velocity). It is a small generator which is normally used as a speed sensing device.
Tachometer generator – It is a generator, mechanically coupled to a rotating machine whose function is to generate a voltage, the magnitude or frequency of which is used either to determine the speed of rotation of the common shaft or to supply a signal to a control circuit to provide speed regulation.
Tack – It is the property of a polymer or compound which causes two layers to stick together on application of mild pressure. It is the stickiness of an adhesive or filament-reinforced resin prepreg material. Tacky polymers or compounds do not necessarily stick to other surfaces.
Tacker – It is a non-standard term for a tack welder.
Tacking – It means making of tack welds.
Tack range – It is the period of time in which an adhesive remains in the tacky-dry condition after application to the adherend, and under specified conditions of temperature and humidity.
Tack weld – It is a weld made to hold parts of a weldment in proper alignment until the final welds are made.
Taconite – Taconite ore contains low-grade iron in fine specks and bands. It is a highly abrasive iron ore. It is a natural mineral. It is an extremely hard and flinty which contains around 17 % to 30 % iron. The iron in taconite occurs principally as magnetite and hematite and finely dispersed with silica in sedimentary deposits. The mining of taconite, a tough and abrasive low-grade ore (ranging from 40 % to 60 % silica and 17 % to 30 % iron), is especially difficult because of the extreme hardness of the ore. Because of this hardness, additional drilling, blasting, crushing, and grinding are frequently needed to extract the ore.
Tafel line, Tafel slope, Tafel diagram – When an electrode is polarized, it frequently yields a current / potential relationship over a region which can be approximated by E = +/- B log(i/io), where ‘E’ is the change in open-circuit potential, ‘i’ is the current density, and ‘B’ and ‘io’ are constants. The constant ‘B’ is also known as the Tafel slope. If this behaviour is observed, a plot on semi-logarithmic coordinates is known as the Tafel line and the overall diagram is termed a Tafel diagram.
Taguchi analysis – It is also known as the Taguchi method. It is a statistical design of experiments (DOE) approach developed by Genichi Taguchi to optimize products and processes. It focuses on reducing variability and improving robustness by identifying key factors which influence product performance and making the process less sensitive to ‘noise’ factors.
Taguchi method – It is a quality engineering approach developed by Genichi Taguchi which focuses on designing quality into products and services from the start. It uses statistical design of experiments to optimize processes and reduce variation, aiming to make products more robust and less susceptible to defects. The method involves identifying key factors, designing experiments, running tests, analyzing results, and confirming improvements.
Tail end – It is the point of loading in any conveyor system where materials are introduced for transport.
Tailings – It is the discarded portion of a crushed ore, separated during concentration. It is residual material left over from the processing of ore. It is the Material rejected from a mill after most of the recoverable valuable minerals have been extracted.
Tailings-pond – It is a low-lying depression which is used to confine tailings, the main function of which is to allow enough time for heavy metals to settle out or for cyanide to be destroyed before water is discharged into the local water-shed.
Tail mark – It is a small repeating raised or depressed area caused by the opposite condition on a roll. The repeat distance is a function of the offending roll diameter. It is greatly enlarged roll mark with a very shallow height or depth.
Tailored blanks – It is a section of sheet or strip which is cut-to-length and trimmed to match specifications for the manufacturer’s stamping design for a particular part. Since excess steel is cut away (to save shipping costs), all that remains for the stamper is to impart the three-dimensional shape with a die press.
Tail pulley – It is a pulley system positioned at the tail end of a conveyor system, facilitating the return of the conveyor belt.
Tail-spend – It refers to ad hoc spending and uncategorized supplier purchases which are low in volume, frequency or value.
Tail water – It is the runoff of water from the lower end of a land area.
Tainter gate – It is a type of radial arm floodgate used in dams and canal locks to control water flow A side view of a Tainter gate resembles a slice of pie with the curved part of the piece facing the source or upper pool of water and the tip pointing toward the destination or lower pool. The curved face or skin-plate of the gate takes the form of a wedge section of cylinder. The straight sides of the pie shape, the trunnion arms, extend back from each end of the cylinder section and meet at a trunnion which serves as a pivot point when the gate rotates.
Take-up – It is a mechanical structure designed to adjust the length of belts and chains, compensating for factors such as shrinkage, stretch, and wear, ensuring optimal tension.
Take-up pulley – It is a pulley which can move in order to maintain relatively constant tension.
Take-up travel – It is the distance the take-up can move during the belt operation.
Talent – It is the composite state made up of several elements. People are called talented when they possess or acquire (i) skills, knowledge, intelligence, and experience, (ii) ability to learn and grow, (iii) judgment, attitude, and character, and (iv) perseverance and self-motivation. Talent is a set of unique abilities possessed by individuals. There are two types of talent normally found in the organization. These are uni-dimensional and multi-dimensional. Both types of talent have the same objective, however, with different perspectives.
Talent management – It is the science of using strategic human resource planning to improve organizational values and to make it possible for the organizations to achieve their goal and objectives. Everything done to recruit, retain, develop, reward and make people perform forms a part of talent management as well as strategic workforce planning. A talent management strategy is needed to link to the organizational strategy for its appropriate functioning. The objective of talent management is to create a high performance, sustainable organization which meets its strategic and operational goals and objectives. Talent management is the processes of ensuring that talented people are attracted, retained, motivated, and developed in line with the needs of the organization. It is a set of activities taken with regards to personnel with outstanding talents, to ensure their development and increase their operational efficiency, while simultaneously achieving the organizational goal and objectives.
Tally sheet – It is also known as a check sheet. It is a simple tool for collecting data by recording the frequency of events or occurrences. It uses tally marks to represent each count, making it a quick and efficient method for data collection. Tally sheets are useful for organizing data and can be a precursor to creating more detailed statistical visualizations like bar charts or frequency tables.
Talus – It is a heap of broken, coarse rock found at the base of a cliff or mountain.
Tandem die – It is a progressive die consisting of two or more parts in a single holder. It is used with a separate lower die to perform more than one operation (such as piercing and blanking) on a part in two or more stations.
Tandem drawing – It is also called multi-stage drawing. It is a process where wire or tube is drawn through a series of dies in a single pass to achieve the desired shape, size, and accuracy.
Tandem mill – It is a multi-stand continuous rolling mill consisting of three or more stands arranged so that the rolling stock being processed travels in a straight line from stand to stand. Rolling stock is fed into the tandem mill from an entry end and progressively reduced in thickness by a preset percentage in each stand to achieve the final desired thickness as the material exits the last stand. In continuous rolling, the different stands are synchronized so that the rolling stock can be rolled in all stands simultaneously. Modern cold rolling mills are continuous tandem mills.
Tandem scanner – It is an assembly of two different types of scanning together in one system for true confocal point scanning.
Tandem scanning microscopy – It is a specialized imaging technique which allows for the observation of microscopic structures, both at and deep within the surface of intact objects, without the need for sectioning. This method, also known as tandem scanning confocal microscopy (TSCM), provides high-resolution images while maintaining the integrity of the sample.
Tandem seal – It is a multiple-seal arrangement consisting of two seals mounted one after the other, with the faces of the seal heads oriented in the same direction.
Tandem welding – Compared to a conventional gas metal arc welding (GMAW) system, tandem welding uses two in line wires, one behind the other. The welding wires are fed simultaneously and melted using independent contact tips mounted in the same torch. The result is excellent weld quality with little spatter and up to three times the deposition rates and travel speeds of conventional systems. The process has ideal characteristics for automated applications.
Tangent – It is a straight line or plane which touches a curve or curved surface at a point, but if extended does not cross it at that point. In a conveyor system, tangent is the straight segment following a curved conveyor, providing a transition between curved and straight sections.
Tangent bending – It means the forming of one or more identical bends having parallel axes by wiping sheet metal around one or more radius dies in a single operation. The sheet, which can have side flanges, is clamped against the radius die and then made to conform to the radius die by pressure from a rocker-plate die which moves along the periphery of the radius die.
Tangential feed – In it the die, either cylindrical or flat, moves past the work-piece on a path which brings the pitch line of the thread form tangent to the work surface.
Tangential feeding attachments – These attachments have essentially the same capabilities as radial feeding attachments. Some advantage is gained with tangential attachments since the adjustments and control for a given size of work are made within the attachment rather than by the travel of the machine slide. With a two-roll tangential attachment, no radial movement occurs between the roll spindles during rolling, and rolling pressures are higher than in radial-infeed rolling.
Tangential flow filtration (TFF) – It is also known as cross-flow filtration. It is the feed solution flows parallel to the membrane surface, rather than being pushed through it directly. This continuous, tangential flow helps prevent membrane fouling and provides efficient separation, concentration, and purification of biomolecules and particles.
Tangential internal residual stresses – These are also known as hoop stresses. These stresses are internal stresses within a material, specifically in cylindrical structures like pipes, which exist even when no external forces are applied. These stresses act tangentially, or circumferentially, around the cylinder, trying to separate the wall in the circumferential direction. They are a result of internal pressure or other factors which cause the material to deform and retain internal stresses.
Tangential rolling – It is done in lathes or automatic bar machines equipped with one-roll or two-roll attachments mounted on a cross slide of the machine. The rolls are rotated by their contact with the rotating work. Two-roll attachments are the most common for tangential rolling. They are available in different sizes. Each size has a capacity for a range of work diameters. Capacity up to a work diameter of 65 millimeters is commonly available, and larger sizes are obtainable for special applications.
Tangential thread rolling – It is similar to infeed rolling except that the dies (rolls) are fed past the blank on a path parallel to the radial path at a distance such that when the axis of the roll is opposite the axis of the blank the pitch line of the thread form is tangent with the surface of the blank. The operating principle of this process is that as the rolls advance, they reach maximum penetration when the centre-line of the rolls is directly opposite the centre-line of the work. The total depth of penetration is determined by the quantity the rolls are offset in relation to the work. As in radial-infeed rolling, only a slight axial movement occurs between the rolls and the work.
Tangent modulus – It is the slope of the line at a predefined point on a static stress-strain curve, expressed in force per unit area per unit strain. This is the tangent modulus at that point in shear, tension, or compression, as the case can be.
Tangible asset – It is a physical asset, meaning it has a real form and can be touched and seen. Examples include land, buildings, machinery, vehicles, inventory, and cash. In organizations, tangible assets are valued for their monetary worth and their ability to be used to create products or provide services.
Tank – It is typically a container or reservoir which is designed to store or transport liquids or gases. These tanks can be used for several applications, including static storage, transportation, and process engineering. It is also a large receptacle constructed in a furnace for melting the batch. Tanks replaced pots in larger glass factories in the 19th century.
Tank chain – It refers to the continuous track system used on tanks and other tracked vehicles. These chains are typically made of steel plates (with or without rubber pads) and act as the treads for the vehicle. Instead of wheels, tanks use these tracks to provide traction and distribute the vehicle’s weight over a larger area, reducing pressure on the ground.
Tanker – It is a ship or a motor vehicle designed to carry liquids or gases on roads. Road tanker is also called tank truck. Several variants exist because of the wide variety of liquids which can be transported. Tank trucks tend to be large. They can be insulated or non-insulated, pressurized or non-pressurized, and designed for single or multiple loads (frequently by means of internal divisions in their tank). Some are semi-trailer trucks. They are difficult to drive and highly susceptible to rollover because of their high center of gravity, and potentially the free surface effect of liquids sloshing in a partially filled tank.
Tank wagons – These are wagons designed to carry liquid consignment like petroleum products.
Tantalum (Ta) – It is a chemical element with atomic number 73. It is a very hard, ductile, lustrous, blue-gray transition metal which is highly corrosion-resistant. It is part of the refractory metals group, which are widely used as components of strong high-melting-point alloys. It is a group 5 element, along with vanadium and niobium, and it always occurs in geologic sources together with the chemically similar niobium, mainly in the mineral groups namely tantalite, columbite, and coltan. The chemical inertness and very high melting point of tantalum make it valuable for laboratory and industrial equipment such as reaction vessels and vacuum furnaces. It is used in tantalum capacitors for electronic equipment such as computers. It is being investigated for use as a material for high-quality super-conducting resonators in quantum processors.
Tap – It is a cylindrical or conical thread-cutting tool with one or more cutting elements having threads of a desired form on the periphery. By a combination of rotary and axial motions, the leading end cuts an internal thread, the tool deriving its principal support from the thread being produced. Tap is also a connection to a winding at some point between the ends. It is used to adjust voltage.
Tap changer – It is a mechanism in transformers which allows for variable turn ratios to be selected in distinct steps. This is done by connecting to a number of access points, known as taps along either the primary or secondary windings. Tap changers exist in two primary types, namely (i) no-load tap changers (NLTC), which is to be de-energized before the turn ratio is adjusted, and (ii) on-load tap changers (OLTC), which can adjust their turn ratio during operation. The tap selection on any tap changer may be made through an automatic system, as is frequently the case for on-load tap changers, or a manual tap changer, which is more common for no-load tap changers. Automatic tap changers can be placed on a lower or higher voltage winding, but for high-power generation and transmission applications, automatic tap changers are often placed on the higher voltage (lower current) transformer winding for easy access and to minimize the current load during operation.
Tap density – It is the apparent density of a powder, obtained when the volume receptacle is tapped or vibrated during loading under specified conditions.
Tap drill – It is a drill bit specifically chosen for its size to create a hole which is to be subsequently tapped. It is designed to create a hole which allows the tap to cut a thread of a particular size and depth. The tap drill is used to prepare the hole, while the tap then cuts the internal thread.
Tape – It is a strip of cloth, paper, or plastic with an adhesive surface, used for sealing, binding, or attaching items together. It is also a narrow plastic strip covered with a magnetic substance, and is used to record sounds, pictures, and computer information. In case of composites, tape is the unidirectional prepreg fabricated in widths up to 305 millimeters for carbon and 75 millimeters for boron. Woven broad goods carbon and glass tapes up to 1,250 millimeters or 1,500 millimeters wide are available commercially.
Tape automated bonding (TAB) – It is a manufacturing process which is used to connect bare integrated circuits (ICs) to a flexible circuit board (FPC) or printed circuit board (PCB). It involves attaching the integrated circuits to fine conductors in a polyamide or polyimide film, providing a direct connection to external circuits. This method is frequently used for high-volume production and allows for a more compact and flexible design compared to traditional wire bonding.
Taper – It refers to something gradually becoming narrower or thinner, or to the gradual decrease of something, like a quantity or force.
Taper angle – It refers to the gradual reduction in diameter, width, or thickness of a long, narrow structure as it extends from one end to the other. This creates a conical or wedge-like shape. The angle is measured between the centre-line of the structure and one of its sloped sides.
Tapered land bearing – It is a thrust bearing containing pads of fixed taper.
Tapered roller – It is a specialized conical conveyor roller designed for curved sections, featuring end and intermediate diameters proportional to their distance from the curve’s centre.
Tapered roller bearings – It is a tapered version of a roller bearing and is used for combined axial and radial loads. This type of bearing is designed to handle large radial and thrust loads. Because of their load versatility, they are found in car hubs due to the extreme amount of both radial and thrust loads that car wheels are expected to carry. They are commonly found in heavy industrial, truck and wheel applications with combined radial and axial loads. Some examples are manual transmissions, gearboxes, power generation and other process equipment.
Tape replica method (fax-film) – It is a method of producing a replica by pressing the softened surface of tape or plastic sheet material onto the surface to be replicated.
Taper section – It is a section cut obliquely (acute angle) through a surface and prepared metallographically. The angle is frequently chosen to increase the vertical magnification of surface features by a factor of 5 or 10. Taper sectioning is normally carried out for micro-structural examination of coated metal samples.
Tape wrapped – Fabric tape is heated and wrapped onto a rotating mandrel and subsequently cooled to firm the surface for the next tape layer application.
Tap hole – In blast furnace, tap hole also known as iron notch. It is used for tapping the hot metal from the furnace. It is located slightly above the floor of the hearth. Tap hole is an essential part of the blast furnace. Large blast furnaces normally have 2 to 4 tap holes. Tap hole is normally exposed to an extremely dynamic environment with high temperature and pressure, frequent drilling and plugging, substantial chemical attack, and flow induced shear.
Tap hole drill – Tap hole drill is a high-capacity drill hammers to ensure effective drilling of the tap hole for the opening of the blast furnace tapping. The tap hole drills can have electro-mechanical, pneumatic, hydro-pneumatic, or hydraulic drive. Taphole drills are to combine maximum flexibility with well proven high-capacity drill hammers to ensure effective drilling. These drills are to provide (i) reliable opening of any taphole without delays, (ii) smooth taphole channel for less taphole wear (iii) minimize oxygen lancing for increased operator safety and prevention of damages to taphole structure, (iv) high reverse impact energy for safe withdrawal of stuck drill bar, (v) reduced equipment maintenance cost and prolonged hammer lifetime. Further they are to accomplish a maximum protection of the critical taphole area, in order to (i) maximize the lifetime of the taphole, (ii) reduce the number of taphole repairs, and (iii) increase availability of the blast furnace.
Tap hole mass – It is a prepared ready to use refractory product, made of a bond of aggregates, additives, and plasticizers. It is used to close the tap hole of a blast furnace after tapping so that no material can leak out, and to keep it plugged until the tap hole is opened for next tapping. It is applied to ensure periodical and stable tapping from the blast furnace and also to protect the inner surface of tap hole bricks. Its functions are (i) to enable smooth operation of the tap hole, (ii) to maintain constant tap hole length, (iii) to control the liquid flow out of the blast furnace, and (iv) to ensure separation of hot metal and slag. Blast furnace tap hole mass is normally developed and designed to suit the operating parameters of the blast furnace and to maintain stable tapping time and tap hole depth even under severe operational conditions with high productivity coefficients (ton per cubic meter per day) or high hot metal temperatures.
Tap-hole mix – It is specially designed plastic refractory, supplied ready for use, made up of aggregate, bond and liquid which, after firing, form a carbon bond. This material is specially designed to fill blast furnace tap-holes.
Tapping – It means producing internal threads with a cylindrical cutting tool having two or more peripheral cutting elements shaped to cut threads of the desired size and form. By a combination of rotary and axial motion, the leading end of the tap cuts the thread while the tap is supported mainly by the thread it produces. It also means the opening the outlet of a melting furnace to remove molten metal. It is also removing of molten metal from a furnace.
Tapping cycle, blast furnace – Tapping cycle begins as the tap hole is drilled open and is terminated by plugging the taphole with the taphole mass when the furnace gas bursts out. At the end of the tapping, the gas-slag interface tilts down towards the taphole and a considerable amount of slag remains above the taphole level. The iron phase can be drained from levels below the taphole because of the large pressure gradient that develops near the taphole in the viscous slag phase. The average slag-iron interface is therefore lower than the taphole level. Depending on a number of factors, such as liquid production rates, hearth volume and tapping strategies, the initial stage of a tapping cycle varies and can be categorized into three patterns. The ‘iron first’ pattern occurs if the slag-iron interface is above the taphole level when the taphole is drilled open. The tapping cycle starts with an outflow of iron only, and slag starts flowing later when the slag-iron interface has descended to the taphole. After this, iron and slag are drained simultaneously until the end of the tapping. The time elapsed from the start of the tapping until slag enters the runner is called the slag delay. The ‘simultaneous’ pattern appears if the slag-iron interface lies in, or at a finite depth below the taphole when the tapping commences. The high-pressure gradient in the slag phase can promote iron flow, or even drags iron up from below the taphole. As a result, iron and slag are drained together during the whole period of tapping. The ‘slag first type’ pattern is opposite to the iron first pattern. In this pattern slag flows out initially and iron after a delay. This is since the slag-iron interface is far below the taphole as the tapping begins, and the phenomena can be observed in larger furnaces with multiple tapholes. The pressure gradient caused by the viscous slag is initially inadequate to lift iron up.
Tap-to-tap time – It refers to the duration between the end of one heat (batch) of molten steel being tapped from a furnace and the beginning of the next heat being tapped. It essentially measures the cycle time of a steelmaking operation from the end of one tapping to the start of the next.
Tar – It is a thick, sticky, dark brown or black liquid mainly composed of hydro-carbons and other organic compounds. It is a byproduct of the destructive distillation of organic materials like wood, coal, peat, and even some fossil fuels.
Tar acids – These are phenolic compounds which are extracted from tar, particularly coal tar. These compounds react with caustic soda to form water-soluble salts. They are a group of chemicals, including phenol, cresols, and xylenols, obtained during the distillation of coal tar.
Tar bearing basic ramming mix – It is a tar bearing refractory which has suitable properties to permit ramming into place to form a monolithic structure.
Tar bearing basic refractories – These are refractories consisting principally of basic grains to which tar has been added during manufacture.
Tar bonded blast furnace tap-hole mass – It is normally thermoplastic, hard (frequently needing pre-heating of the tap hole mass in the mud gun barrel by gas heaters or hot water / steam to become pliable, and slower curing (2 hours cast time is deemed insufficient for full curing and sintering, although only 20 minutes to 30 minutes is frequently encountered in practice). The latter necessitates the mud gun to remain in position for an extended time after plugging to avoid subsequent unintended tap hole self-opening. Unlike resin binders, tar bonded tap hole mass is reported to have an advantage of forming a transition free union with carbon-based refractory resulting in a monolithic tap hole lining and improved adhesiveness under high temperature conditions.
Tar bonded dolomite refractories – These are a type of basic refractory material used in high-temperature applications like steelmaking. These refractories are mainly composed of sintered dolomite and are bonded using tar to improve their strength and durability.
Tar distillation plant – The design and composition of a tar distillation plant is dependent on the type of the tar to be distilled and the compounds which are to be extracted. Hence, the design and composition of a tar distillation plant differs from location to location. A typical tar distillation plant consists of several sections namely (i) tar distillation section, (ii) caustic washing section, (iii) de-oiling section, (iv) springing section, and (v) recasting section.
Tar distillation process – Fractional distillation process is used for the distillation of coal tar. Fractional distillation of tar refers to the process by which components in a chemical mixture are separated by taking advantage of the difference in their boiling points. Distillation of coal tar is carried out mainly to produce benzoles, naphtha, creosotes, naphthalene, anthracene, carbolic and cresylic acids, pyridine and pitch. The purpose of tar distillation is to (i) dehydrate the tar in the dehydration column, (ii) remove the pitch from dehydrated tar in pitch column and (iii) separate tar oils in fractionating column. Since the quality of the coal tar is dependent on the coal carbonizing process and since there are large numbers of chemical compounds available in coal tar, the design and composition of the tar distillation plant varies with the type of tar and the compounds which are required to be distilled. Hence, it is very rare that the two tar distillation plants are exactly similar.
Tare weight – It is the weight of the empty vehicle itself. It is also known as the unladen weight. This weight is crucial for accurately calculating the net weight of the cargo, which is the weight of the goods loaded into the vehicle.
Tar oil – It is a type of oil, such as creosote, which can be derived from coal or wood distillation. It is used as a preservative for timber, but its use has been restricted because of its carcinogenic potential.
Target – It is a value which reflects a desirable outcome. In case of X-ray, it is that part of an X-ray tube where the electrons strike and from which X-rays are emitted.
Target population – It refers to the entire group of individuals or objects which a study is interested in. It is the specific group about which information is being gathered or inferences are being made.
Tarnish – It is the dulling, staining, or discolouration of metals because of the superficial corrosion. It is the surface discolouration of a metal caused by formation of a thin film. The thin layer of corrosion which forms on the surface of copper, brass, aluminum, magnesium, and other soft metals or alloys as their outermost layer undergoes a chemical reaction with the surrounding air, frequently but not necessarily involving atmospheric oxygen. Tarnish normally appears as a dull grey, black, or sometimes iridescent film or coating on the metal. It is a self-limiting surface phenomenon, as the tarnished top layers of the metal protect underlying layers from reacting.
Tatara system – It is a traditional Japanese method of iron and steel making. It involves using a special type of furnace (made of clay and sand) to smelt iron sand with charcoal, producing a unique type of steel called tamahagane. This steel is then used to create traditional Japanese swords.
Taxonomy – It refers to a hierarchical classification system which organizes and defines the relationships between data, people, and processes within a supply chain. It helps standardize terminology and provide a unified view of the supply chain, making it easier to manage and analyze.
Taylor/von Mises criterion – It defines a minimum number of independent slip systems needed for a material to deform uniformly without failure at grain boundaries. Specifically, it states that at least five independent slip systems must be active for uniform, homogenous deformation in poly-crystalline materials.
Taylor vortices – In a journal bearing, these are the vortices formed in a liquid occupying the annular space between two concentric cylinders.
TBCCO (Tl-Ba-Ca-Cu-O) – It stands for thallium-barium-calcium-copper oxide. It is a family of high-temperature super-conductors with the general chemical formula TlmBa2Can−1CunO2n+m+2. TBCCO materials have high critical temperatures and are known for their good transport critical current densities and low microwave surface resistance, making them suitable for several applications.
T-beam – It is also called tee beam. It is used in construction. It is a load-bearing structure of reinforced concrete, wood or metal, with a capital T-shaped cross section. The top of the T-shaped cross section serves as a flange or compression member in resisting compressive stresses. The web (vertical section) of the beam below the compression flange serves to resist shear stress. When used for highway bridges the beam incorporates reinforcing bars in the bottom of the beam to resist the tensile stresses which occur during bending. The T-beam has a big disadvantage compared to an I-beam (with I-shape) since it has no bottom flange with which to deal with tensile forces, applicable for steel section. One way to make a T-beam more efficient structurally is to use an inverted T-beam with a floor slab or bridge deck joining the tops of the beams. Done properly, the slab acts as the compression flange.
T-distribution – It is a statistical distribution describing the means of samples taken from a population with an unknown variance. It is the distribution of values with particular degrees of freedom of difference between sample and population mean divided by the standard error of mean. It is a population distribution which is symmetric and resembles the normal distribution except that it shows more dispersion. Some sample statistics have a ‘t’ sampling distribution.
Team – It consists of a number of people (normally small in number) with different backgrounds, skills, and knowledge and drawn from different departments of the organization, who work together on a specific and defined task. There is normally a team leader. The team leader is often permanently appointed for the duration of the team’s assignment. But leadership at any one-time places itself according to the logic of the work and the specific stage in its progress. There are no superiors and subordinates and there are only senior team members and junior team members.
Team working – It means a group of people working together toward achieving a desired goal. Team working is the ability of the employees to work together toward a common vision, the ability to direct individual accomplishment toward the organizational objectives. It is the fuel which allows the employees to achieve exceptional results. Team working takes place when two or more persons, who are interdependent in executing a set of activities, interact face-to-face and interact frequently with each other, make differential contributions, and strive to achieve a common goal in respect of a core task.
Teapot ladle – It is a ladle in which, by means of an external spout, metal is removed from the bottom rather than the top of the ladle.
Tear – It is a defect, particularly in materials like non-woven fabrics or in metal casting. It refers to a localized damage caused by force or stress, resulting in a separation or splitting of the material. In non-woven materials, this can be due to fibres sliding and separating under tension. In casting, it is frequently associated with hot tearing, where cracks form during cooling because of the stress and shrinkage.
Tear burr – It is the burr formed by the sides of a cutter as the cutter tears a chip from the work-piece. It is also a ragged form of the Poisson burr caused by a built-up edge on the cutting tool.
Tearing – It is the act of breaking apart a material by force, without the aid of a cutting tool. A tear in a piece of paper, fabric, or some other similar object may be the result of the intentional effort with one’s bare hands, or be accidental. Unlike a cut, which is normally on a straight or patterned line controlled by a tool such as scissors, a tear is normally uneven and, for the most part, unplanned. An exception is a tear along a perforated line, which has been previously partially cut, so the effort of tearing probably produce a straight line. Materials vary in their susceptibility to tearing. Some materials can be quite resistant to tearing when they are in their full form, but when a small cut or tear is made, the material becomes compromised, and the effort needed to continue tearing along that line becomes less. In deep drawing process, tearing occurs near the base of the drawn cup and results from high stresses in the vertical wall which cause thinning and failure of the metal at that location.
Tearing fracture – It is the micro-scale ductile fracture created by micro-void coalescence. Frequently, it results in a dull / matte flat fracture surface on a macro-scale plane perpendicular to a tensile stress in axial or bending loading but can also apply to ductile fracture in mode II or mode III loading.
Tearing topography surface – It is a non-conventional fractographic mode. This fracture occurs in a variety of alloy systems, including steels, aluminum, titanium, and nickel alloys, and under a variety of fracture conditions, such as overload, hydrogen embrittlement, and fatigue. The tearing topography surface is a new fracture topography undoubtedly associated with (or linked to) hydrogen embrittlement (HE), hydrogen degradation (HD), and hydrogen-assisted micro-damage (HAMD) at the micro-scale in pearlitic steel produced by the combined action of mechanical stress-strain fields and chemical / environmental effects (in particular, hydrogen effects in pearlite). There is clear experimental evidence of the association between the tearing topography surface region and the hydrogen damage in pearlite, at the macro-, micro- and nano scales, i.e., considering the three levels of hydrogen-assisted damage in the pearlitic material: macro-damage, micro-damage and nano-damage. Tearing topography surface fractures can be because of the closely spaced micro-void nucleation and limited growth before coalescence, resulting in extremely shallow dimples. However, this hypothesis does not appear to be probable, since tearing topography surface is frequently observed along with well-developed dimples in alloys having relatively uniform carbide dispersions, and since tearing topography surface is observed under varying stress states.
Tear resistance – It is also known as tear strength. It measures a material’s ability to resist tearing or cuts, especially when under tension. It is essentially how much force is needed to create or continue a tear in a material. It is a useful engineering measurement for a wide variety of materials by many different test methods. This property is crucial for determining the suitability of materials like fabrics, rubbers, and plastics in several applications.
Tear ridges – These are thin ridges observed in what used to be called quasi-cleavage fracture. In some cases, the ridges are wide enough to show dimpled rupture on the ridge.
Tear, speed – It is a series of surface cracks perpendicular to the extruding direction. Speed tearing normally occurs in corner radii or extremities of a section and is caused by localized high temperature.
Tear testing – It is a method used to determine the force needed to propagate a tear through a material, like fabric or plastic. It measures the material’s resistance to tearing once a tear has begun.
Technical audit – Technical audit is an audit which is performed by an auditor who is a technical person with an in-depth knowledge of the subject matter. The technical audit a systematic, documented verification process of objectively obtaining and evaluating the audit evidence, in conformance with the audit criteria and followed by communication of the results for the people who have initiated the audit with some purpose. In technical audit, the technical aspects of every system, equipment, process, stores and inventories, spare parts, administration, commercial activities and all the inputs are studied without any prejudices. Technical audit is conducted against an objective which is generally of technical nature and consists of the verification, monitoring and analysis of the available data and submission of technical report containing recommendations. The technical audit is normally associated with examination, verification, and evaluation, assessment, and check activities. For the technical audit, the auditor is required to have the knowledge of the auditing process, technology, design and engineering, relevant standards and regulatory norms, and latest developments in the fields for which the audit is being conducted. Technical audit is frequently used to identify deficiencies, areas for improvement, and potential risks, ultimately aiming to ensure quality, manage risks, and enhance transparency.
Technical characteristics – It refers to specific qualities or features of a product, system, or process which relate to its functionality, performance, and technical aspects. These characteristics define how something is built, what it can do, and how well it does it. They are frequently used in technical specifications and documentation to ensure clarity and consistency.
Technical cost model (TCM) – It is a structured approach to estimating and analyzing the production cost of a product or service, considering various technical factors and their impact on cost. It is used to understand how different aspects of the production process, like materials, methods, and scale, affect the overall cost, allowing for informed decisions on design, research, and production scale-up.
Technical details – These refer to specific, frequently complex information related to a particular field or subject, especially one involving science, technology, or industry. These details delve into the specifics of how things work, the components involved, and the intricacies of processes or systems. They are frequently presented in technical documentation, specifications, or reports.
Technical drawings – These are also known as ‘engineering drawings’. They are means of communications and convey technical information of plant and equipment. These are drawings intended to convey information for construction, operation or maintenance of a system or equipment. They describe three-dimensional objects through the medium of two-dimensional paper. The process of producing technical drawings, and the skill of producing those, is often referred to as ‘drafting’. Technical drawings are normally accepted as legal document and is frequently being used for regulatory approvals.
Technical instructions – These are detailed, written communications which guide users on how to operate, maintain, or repair a specific equipment or system. They provide step-by-step explanations and can include warnings or safety precautions to prevent misuse or damage.
Technical literature – It refers to written materials which provide information about specific technical fields, including documents designed to inform and guide users or experts in a particular area. It is characterized by clarity, precision, and a focus on practical application and instruction. Technical literature includes research articles and papers, manuals, conference proceedings, books, patents, and technical reports related to a specific technical field or topic.
Technical model – It is a representation of a system, process, or entity which focuses on its technical aspects, such as components, functions, and interactions. It is used to understand, design, and analyze the technical aspects, frequently employing mathematical, logical, or physical representations.
Technical person – Technical person normally refers to someone with specialized knowledge, skills, and expertise in a particular field, frequently related to technology, engineering, or a specific craft. They are able to understand and apply technical details, principles, and methods in their work.
Technical process – It is a sequence of actions or steps undertaken to achieve a specific outcome, frequently involving tools, equipment, or specialized knowledge. It is a systematic approach to transforming inputs (like raw materials) into outputs (like a product).
Technical procedures – These are detailed, step-by-step instructions for performing a specific task or process, typically related to the operation, maintenance, or testing of systems or components. They are designed for ensuring consistency, minimize errors, and improve quality, frequently documented in written form as standard operating procedures (SOPs).
Technical publications – These are documents which provide detailed, accurate, and clear information about technical products, processes, or systems. They serve as guides for users, technicians, and engineers, ensuring proper operation, maintenance, and repair. These publications are crucial for understanding complex technical concepts and procedures, and they frequently include manuals, training materials, catalogs, and specifications.
Technical skills – These are specialized abilities and knowledge needed to perform specific tasks or use specific tools, equipment, or software. They are frequently learned through training or education and are essential for several jobs, particularly in fields like technology, engineering, and manufacturing. These skills are typically measurable and can be demonstrated through proficiency in using specific technologies or tools.
Technical specification – It is that part of the tender documents which provides to the bidder technical details of the materials, plant and equipment, services, or site activities. It becomes contract technical specification after incorporating the changes agreed with the bidder during the tender negotiations. It sets out precisely what characteristics are needed from the materials, plant and equipment, services, or site activities being sought by the purchasing organization. Technical specification is a comprehensive document which clearly, accurately and completely describes in detail what the purchasing organization wants successful bidder to supply. Technical specification has five mandatory requirements mainly (i) title of the specification, (ii) scope, (iii) statement of requirements, (iv) requirement for quality assurance, and (v) delivery schedule or implementation schedule.
Technical standard – It is an established norm or requirement for a repeatable technical task, especially when written in a formal document that establishes uniform criteria, methods, processes, and practices. A technical standard can be developed privately or unilaterally by edict, or by groups such as trade associations, industry standards organizations, or governments, frequently as per the formal consensus of experts in the discipline.
Technical tools – These tools refer to instruments or equipment, frequently electronic or digital, used to perform specific tasks or accomplish goals. They encompass a wide range of devices and software, from computers and smartphones to online platforms and applications, that facilitate various aspects of life, work, and learning. In essence, tech tools are instruments or pieces of equipment that leverage technology to aid in specific tasks or work.
Technical training – It is a structured program designed to teach individuals the specific skills and knowledge needed to perform tasks related to particular technologies, tools, or methods. It focuses on ‘hard skills’ or vocational training, enabling employees to operate, maintain, or implement systems and processes effectively.
Technician – Technician is a worker proficient in the skills of a field of technology. It can also refer to a person who is an expert in the practical or technical aspects of a science.
Technique – It is a way of accomplishing a task. It defines how the work is to be performed.
Techno-economic analysis (TEA) – It is also called techno-economic assessment. It is a method used to evaluate the economic performance of a technology by analyzing its technical and financial aspects. It assesses the overall value of a technology, allowing analysts to weigh costs against benefits, and ultimately determine its economic viability. T Techno-economic analyses are crucial for making informed decisions about new technologies, processes, or projects, helping to identify potential risks and optimize processes for greater efficiency and profitability.
Technological development – It is also called technological change. It is the overall process of invention, innovation and diffusion of technology or processes. In essence, technological development covers the invention of technologies (including processes) and their commercialization or release as open source through research and development (producing emerging technologies), the continual improvement of technologies (in which they often become less expensive), and the diffusion of technologies throughout industry or society (which sometimes involves disruption and convergence). In short, technological change is based on both better and more technology.
Technological equipment – It encompasses devices and systems developed using scientific knowledge for practical applications. It includes process equipments, computers, peripherals, networking gear, and telecommunications devices. Essentially, it’s any equipment or software related to information technology that enables processing, storage, and transmission of information.
Technological hazard – It is a hazard originating from technological or industrial conditions, including accidents, dangerous procedures, infrastructure failures or specific human activities, which can cause loss of life, injury, illness or other health impacts, property damage, loss of livelihoods and services, social and economic disruption or environmental damage is known as technological hazard. Examples of technological hazards include industrial pollution, nuclear radiation, toxic wastes, dam failures, transport accidents, factory explosions, fires and chemical spills etc. Technological hazards can also arise directly as a result of the impacts of a natural hazard event.
Technological potential – It is the quantity by which it is possible to reduce greenhouse gas emissions or improve energy efficiency by implementing a technology or practice which has already been demonstrated is known as technological potential.
Technological upgradation – It refers to the process of replacing or updating existing technology with newer, more advanced versions to improve performance, security, and functionality. This can involve upgrading hardware, software, or the entire system.
Technologists – Technologists are persons who uses their expertise to manage technology and solve technical problems. Technologist is a broad term, as it covers a wide range of roles across several industries, but they normally connect people and systems using their expertise and technology tools.
Technology – It is the science of technical processes which is a wide, though related, body of knowledge. Technology embraces the chemical, mechanical, electrical, and physical sciences as they are applied to society, the environment, and otherwise human endeavours. Technology refers to both the application of knowledge for achieving practical goals in a reproducible way, and the products and tools resulting from such efforts. It is a piece of equipment or a technique for performing a particular activity is known as technology. The adverse impacts of hazards cannot be frequently prevented fully but their scale or severity can be substantially lessened by several strategies and actions.
Technology additionality – If the technology used for the project activity is to be the best available for the circumstances of the host party, then it is known as technology additionality.
Technology development – It encompasses the advancement and improvement of existing technologies, or the creation of entirely new ones through research and innovation. It involves the process of applying scientific knowledge to practical ends, frequently resulting in new products, processes, or systems.
Technology transfer – It is the dissemination of knowledge leading to the successful implementation of the results of research and development. It consists of the broad set of processes which cover the exchange of knowledge, money, and goods among different stakeholders that lead to the spreading of technology for adapting to or mitigating climate change is known as technology transfer. Technology transfer outputs from a research project, such as prototypes, software, devices, specifications designs, processes, or practices, etc. are either expendable or frequently have only temporary and limited utility. As a generic concept, the term is used to encompass both diffusion of technologies and technological cooperation across and within countries.
Tecnored process – This process is based upon a low-pressure moving bed reduction furnace which reduces cold bonded, carbon bearing, self-fluxing, and self-reducing pellets. Reduction is carried out in a short height shaft furnace of distinct design at typical reduction temperatures. The process produces hot metal (liquid iron). Tecnored technology has been conceived and developed to be a ‘coke-less’ ironmaking process, thus avoiding the investment and operation of environmentally harmful coke ovens besides significantly reducing green-house gas emissions in the production of hot metal. Tecnored process uses a combination of hot and cold blast and requires no additional oxygen. It eliminates the need for coke plants, sinter plants, and tonnage oxygen plants. Hence, the process has much lower operating and investment costs than those of traditional ironmaking routes. Tecnored process is flexible with regard to the type of iron bearing and carbon bearing raw materials which it can process. The ability of the process to smelt either pellets or briquettes, or even mixed charges of both, provides means of using a wide range of alternative feed materials. The process has got good productivity and high energy efficiency. Tecnored process is also being claimed to be suitable for producing ferro-alloys such as ferro manganese.
Tedlar – It is the trade name for poly-vinyl-fluoride (PVF) used as a waterproof film on some composites.
Tee, fitting – A tee is used to either combine or split a fluid flow. Most common are equal tees which have the same body and branch diameter but there is also a wide range of reducing tees where either the branch or the body is of a different diameter relative to each other. A swept tee is where the branch enters the body at an arc and is used to minimize the frictional losses and promote flow in the system. Wye (Y) pipe tee fittings are with three openings and are used to create branch lines. A wye tee is where the branch is stabbed into the body at an angle usually 45 degrees and is usually used where the branch is a smaller diameter than the main pipe. Wye tees are similar to tees except that the branch line is angled to reduce friction and turbulence that could hamper the flow.
Tee joint – It is also known as a T-joint. It is a type of welding joint where two pieces of metal are joined at a right angle, forming a T-shape. Essentially, one piece of metal is welded to the centre of the flat surface of another piece, resulting in a structure which resembles the letter ‘T’. This type of joint is normally used in welding applications like structural steel, equipment manufacturing, and tubing.
Tee joint, fillet weld – It is a type of weld used to join two pieces of metal that intersect at a 90-degree angle, forming a ‘T’ shape. The weld is applied along the edges where the two pieces meet, creating a triangular weld cross-section. This type of weld is considered a fillet weld, which is a weld with a triangular cross-section and is used to join plates or components at an angle.
Tee joint, groove weld – It is a type of weld used to join two pieces of material together where they intersect at a 90-degree angle, creating a ‘T’ shape. Specifically, it involves preparing the joint with a groove weld, a method where a cut or depression is made into the material before welding to ensure a strong and robust connection.
Teeming – It means pouring molten metal from a ladle into ingot moulds. The term applies particularly to the specific operation of pouring either iron or steel into ingot moulds.
Tee section – It is also called T-beam or T-bar. It is a structural beam with a T-shaped cross-section.
Tee splitting – It is also known as T-splitting. It is a process where a wide flange beam is divided down the web to create two T-shaped beams. This process is used to produce structural tees, which are then used in several applications such as roof trusses and shipbuilding.
Teflon – It a tough synthetic resin made by polymerizing tetra-fluoro-ethylene. It is a high-performance polymer with excellent non-stick, low-friction, and heat-resistant properties.
Telecommunication – It is the field which deals with transmission of information over distances longer than can be covered by an unaided human.
Telegraph – It is a system for transmitting text messages, by wire or other means.
Telegrapher’s equations – These are coupled linear partial differential equations which relate the voltage and current on a transmission line.
Telephone balance unit – It is a balun, a transformer used to convert between balanced and unbalanced lines, as used in telephone circuits.
Telephone line – It is outside plant that connects a central office to subscriber equipment.
Telephone – It is the transmission of voice by electrical means.
Telescopic crane – A telescopic crane has a boom which consists of a number of tubes fitted one inside the other. A hydraulic or other powered mechanism extends or retracts the tubes to increase or decrease the total length of the boom. These types of booms are frequently being used for short term construction projects, rescue jobs, lifting boats in and out of the water, etc. The relative compactness of telescopic booms makes them adaptable for many mobile applications. However, it is to be noted that while telescopic cranes are not automatically mobile cranes, many of them are. These are frequently truck-mounted.
Telescoping – It describes the movement of one part sliding out from another, lengthening an object from its rest state. In modern equipment this can be achieved by a hydraulics, but pulleys are normally used for simpler designs. It also means lateral stacking, mainly in one direction, of wraps in a coil so that the edges of the coil are conical rather than flat. Improper alignment of rolls over which the metal passes before rewinding is a typical cause.
Television – It is the transmission of moving images by electrical means.
Tellegen’s theorem – It is a theorem relating to branch currents in an electrical network.
Telluride – It is a chemical compound consisting of the element tellurium and another element, frequently gold or silver.
Tellurium (Te) – It is a chemical element with atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulphur, all three of which are chalcogens. It is occasionally found in its native form as elemental crystals. Tellurium is far more common in the Universe as a whole than on Earth. Its extreme rarity in the earth’s crust, comparable to that of platinum, is due partly to its formation of a volatile hydride which caused tellurium to be lost to space as a gas during the hot nebular formation of earth.
Tempcore process – Tempcore process for the production of reinforcement bar (rebar) is a patented process in which the hot rolled bar is intensively surface quenched by water, immediately as the bar emerges from the last hot rolling stand of the rolling mill and during the subsequent air cooling the quenched outer layer is tempered by the dissipation of retained heat from the core. Tempcore process is able to produce high strength weldable steel rebars with low carbon and low manganese contents without any addition of costly micro-alloying elements such as vanadium or niobium. Since the same billet composition can be used for different steel grades and diameters, a significant rationalization can be done in the plant. The water quenching and self-tempering treatment is applied directly in line after the finishing stand without any reduction of rolling speed or loss of productivity. By a judicious combination of Tempcore treatment and micro-alloying chemistry, new higher grades (yield strength higher than 700 megapascals MPa and tensile strength higher than 800 megapascals) can be produced, especially for large diameter rebars (up to 75 millimeters). Tempcore process for the production of rebars has three stages. These stages of the Tempcore process are (i) quenching of the surface layer, (ii) self-tempering of the martensite, and (iii) transformation of the core. The process, properly applied, leads to an increase of the yield strength of rebars and this increase depends on the cooling intensity.
Temper – In heat treatment, it is reheating of hardened steel or hardened cast iron to some temperature below the eutectoid temperature for the purpose of decreasing hardness and increasing toughness. The process is also sometimes applied to normalized steel. In tool steels, the term temper is sometimes used, but inadvisedly, to denote the carbon content. In non-ferrous alloys and in some ferrous alloys (steels which cannot be hardened by heat treatment), the hardness and strength produced by mechanical or thermal treatment, or both, and characterized by a certain structure, mechanical properties, or reduction in area during cold working. It also means to moisten green sand for casting moulds with water. In refractories, temper means to bring a refractory mixture to a usable state by mixing with a liquid. In case of cold rolling, cold rolled strip can be produced in various conditions such as skin rolled, quarter hard, half hard, and full hard depending on how much cold work has been performed. This cold working (hardness) is frequently called temper, although this has nothing to do with heat treatment temper. Quarter hard sheets can be bent (perpendicular to the direction of rolling) on itself without fracturing. Half hard sheets can be bent 90-degree while full hard can be bent 45-degree. Hence, these materials can be used for in applications involving high amounts of bending and deformation, without fracturing. In casting, temper is to moisten green sand for casting molds with water.
Temperate climates – These climates of earth occur in the middle latitudes (around 23.5 degrees to 66.5 degrees north /south of the equator), which span between the tropics and the polar regions of earth. These zones normally have wider temperature ranges throughout the year and more distinct seasonal changes compared to tropical climates, where such variations are frequently small. They normally differ only in the amount of precipitation. In temperate climates, not only do latitudinal positions influence temperature changes, but different sea currents, prevailing wind direction, continentality (how large a landmass is) and altitude also shape temperate climates.
Temperature – It is a physical quantity which quantitatively expresses the attribute of hotness or coldness. Temperature is measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making up a substance. Temperature is a fundamental physical concept which consists of the three basic quantities of mechanics namely (i) mass, (ii) length, and (iii) time. Temperature is an expression which denotes a physical condition of matter. Yet, the idea of temperature is a relative one, arrived at by a number of conflicting theories. Classic kinetic theory depicts heat as a form of energy associated with the activity of the molecules of a substance. These minute particles of all matter are assumed to be in continuous motion which is sensed as heat. Temperature is a measure of this heat. To standardize on the temperature of objects under varying conditions, several scales have been devised. The SI (International System of Units) unit for temperature is the kelvin.
Temperature codes – In hazardous location motors, the temperature code is assigned to group together flammable liquids, vapours, dusts, and flyings into groups with similar flashpoints.
Temperature coefficient – It describes the relative change of a physical property which is associated with a given change in temperature. For a property ‘R’ which changes when the temperature changes by ‘dT’, the temperature coefficient ‘a’ is defined by the equation dR/R = a x dT’. Here ‘a’ has the dimension of an inverse temperature and can be expressed e.g., in 1/K.
Temperature-composition phase diagram – It is a visual representation showing the different phases (solid, liquid, and gas) present in a material system under various temperature and composition conditions. It essentially maps out which phases are stable and in what proportions at different points along a temperature and composition axis.
Temperature control – It is the systematic monitoring and regulation of equipment component temperatures, particularly crucial in environments with extreme temperatures which can impact overall performance.
Temperature gradient – It is the rate of change in temperature over a distance. It describes how much the temperature changes per unit of distance in a particular direction. Essentially, it is a measure of the steepness of the temperature variation in a given space, e.g., a steeper gradient means the temperature changes rapidly over a short distance, while a shallower gradient indicates a gradual change over a larger distance.
Temperature, ignition – In hazardous location motors, it is the temperature at which once attained will cause an explosion to occur in the volatile environment.
Temperature influence, measuring instruments – Since temperature influences several properties of a material, it also affects the proper operation of measuring instruments. Very high or very low temperatures can damage or even destroy parts of the measuring instrument. In particular, plastic parts and sealing materials age much faster under the influence of constant high or low temperatures. For example, if the temperature is too low, they lose their elasticity. To ensure proper function of the pressure measuring instruments, some producers specify temperature ranges in their data sheets for the pressure medium, ambient conditions and during storage. Other producers define an operating temperature range which includes both the medium and ambient temperature range. The measuring instrument is not damaged provided the specifications are adhered to. The data specified in the data sheets regarding the measuring accuracy, on the other hand, are only valid for the temperature-compensated range which is significantly smaller and are also be specified in the data sheets.
Temperature inversion – It is also known as a thermal inversion. It is a meteorological phenomenon where air temperature increases with height instead of decreasing, as typically observed in the troposphere. This means a layer of cooler air near the surface is overlain by a layer of warmer air above.
Temperature measuring devices – There are several methods of measuring temperature which can be categorized as (i) expansion of a material to give visual indication, pressure, or dimensional change, (ii) electrical resistance change, (iii) semiconductor characteristic change, (iv) voltage generated by dissimilar metals, and (v) radiated energy.
Temperature profile – It refers to the distribution of temperature across a system or object. It shows how the temperature varies at different points or depths within the system or object.
Temperature range – It refers to the difference between the highest and lowest temperature values within a specified period, such as a day, a week, a month, or a year. It can also refer to the range of temperatures within which something is expected to function properly, like the operating temperature range of a device.
Temperature rise – It is the measurable rise above the ambient temperature at which the fully loaded motor operates. This temperature rise is the result of the heat losses in the stator winding, core, and rotor. On most motors, manufacturers have replaced the Rise rating on the motor nameplate with a listing of the Ambient temperature rating, insulation class and service factor.
Temperature sampling system – The disposable thermocouple for temperature measurement is an integral part of tracking progress throughout the heat. Expendable probes are also used for tracking bath carbon content and dissolved oxygen levels in the steel. Disposable probes are typically mounted in cardboard sleeves that slide on to a steel probe(pole) which has internal electrical contacts. The disposable probe transmits an electrical signal to the steel pole, which in turn transmits the signal to an electronic unit for interpretation. Almost all probes rely on an accurate temperature measurement to precisely calculate carbon or oxygen levels.
Temperature scales – The most common scales are the Celsius scale with the unit symbol deg C (formerly called centigrade), the Fahrenheit scale (deg F), and the Kelvin scale (K), with the third being used predominantly for scientific purposes. The kelvin is one of the seven base units in the International System of Units (SI). Absolute zero, i.e., zero kelvin or -273.15 deg C, is the lowest point in the thermodynamic temperature scale. Experimentally, it can be approached very closely but not actually reached, as recognized in the third law of thermodynamics. It is impossible to extract energy as heat from a body at that temperature.
Temperature sensor – It is a device which detects and measures the temperature of an object or environment and converts it into a readable signal, often electrical. It can be used in several applications, from measuring the temperature of air or liquids to monitoring the heat conditions of machinery.
Temperature swing adsorption (TSA) – It is a process which is used to separate components of a gas mixture by utilizing changes in temperature to control adsorption and desorption. It involves adsorbing specific gases onto a solid material at a lower temperature and then desorbing them by heating the adsorbent bed. This cyclical process allows for efficient separation and purification of gases.
Temperature transmitter – It is an electrical instrument which interfaces with the temperature sensor to isolate, amplify, filter noise, and convert the signal from the sensor to send it to the control device. Its primary function is to measure and alert temperature changes. It is a device that converts a temperature sensor’s output signal into a standardized and more robust electrical signal, typically a 4-20 mA or 0-10 V signal. This conversion allows for accurate and reliable temperature measurement over long distances, even in noisy environments.
Temperature, ultimate – It is the highest temperature of any spot to which a specific class of insulating materials can be continuously subjected without marked decrease in the system’s designed life.
Temper brittleness – It is also called temper embrittlement. It is the brittleness of low-alloy steels caused by holding within or cooling slowly through a temperature range (normally 300 deg C to 600 deg C) just below the transformation range. Brittleness is the result of the segregation at grain boundaries of impurities such as arsenic, antimony, phosphorus, and tin. It is normally manifested as an upward shift in ductile-to-brittle transition temperature. Temper brittleness can be reversed by retempering above the critical temperature range, then cooling rapidly.
Temper carbon – It is the clusters of finely divided graphite, such as that found in malleable iron, which are formed as a result of decomposition of cementite, e.g., by heating white cast iron above the ferrite-austenite transformation temperatures and holding at these temperatures for a considerable period of time. It is also known as annealing carbon.
Temper colour – It is a thin, tightly adhering oxide skin (only a few molecules thick) which forms when steel is tempered at a low temperature, or for a short time, in air or a mildly oxidizing atmosphere. The colour, which ranges from straw to blue depending on the thickness of the oxide skin, varies with both tempering time and temperature.
Temper designation – It is a system of letters and numbers used to indicate the specific heat treatment or cold working processes an alloy has undergone to achieve desired properties. It follows the alloy designation, separated by a dash, and provides information about the material’s strength, hardness, and ductility.
Tempered layer – It is a surface or sub-surface layer in a steel sample which has been tempered by heating during some stage of the metallographic preparation sequence (normally grinding). When observed in a section after etching, the layer appears darker than the base material.
Tempered martensite – It is the decomposition products which result from heating martensite below the ferrite-austenite transformation temperature. Under the optical microscope, darkening of the martensite needles is observed in the initial stages of tempering. Prolonged tempering at high temperatures produces spheroidized carbides in a matrix of ferrite. At the higher resolution of the electron microscope, the initial stage of tempering is observed to result in a structure containing a precipitate of fine iron carbide particles. At around 260 deg C, a transition occurs to a structure of larger and elongated cementite particles in a ferrite matrix. With further tempering at higher temperatures, the cementite particles become spheroidal, decreased in number, and increased in size.
Tempered martensite embrittlement – It is the embrittlement of high-strength alloy steels caused by tempering in the temperature range of 205 deg C to 370 deg C. It is also called 350 deg C embrittlement. Tempered martensite embrittlement is thought to result from the combined effects of cementite precipitation on prior austenite grain boundaries or inter-lath boundaries and the segregation of impurities at prior austenite grain boundaries. It differs from temper embrittlement in the strength of the material and the temperature exposure range. In temper embrittlement, the steel is normally tempered at a relatively high temperature, producing lower strength and hardness, and embrittlement occurs upon slow cooling after tempering and during service at temperatures within the embrittlement range. In tempered martensite embrittlement, the steel is tempered within the embrittlement range, and service exposure is normally at room temperature.
Tempered refractory castable – It is a refractory castable to which liquid has been added and sufficiently mixed to produce the desired consistency for placement.
Tempered steel – It is the steel which has undergone a heat treatment process for its hardening to improve its toughness and resilience. It involves reheating the steel to a specific temperature range below its critical point and then cooling it gradually. This process modifies the steel’s internal structure, making it less brittle and more resistant to cracking while maintaining a degree of hardness.
Temper embrittlement – It is the embrittlement of low-alloy steels caused by holding within or cooling slowly through a temperature range (normally 300 deg C to 600 deg C) just below the transformation range. Embrittlement is the result of the segregation at grain boundaries of impurities such as arsenic, antimony, phosphorus, and tin. It is normally manifested as an upward shift in ductile-to-brittle transition temperature. Temper embrittlement can be reversed by retempering above the critical temperature range, then cooling rapidly.
Tempering – In case of glass, tempering is a process where glass is heated to a high temperature and then rapidly cooled to increase its strength and safety characteristics. This process creates compressive stress on the surface of the glass, making it stronger and more resistant to impact and thermal shock. In refractories, tempering means heating of a pitch bonded refractory to a relatively low temperature (up to 800 deg C).
Tempering, steel – It is the process of reheating hardened (martensitic) or normalized steels to some temperature below the A1 temperature. The rate of cooling is not important except for some steels which are susceptible to temper brittleness. As the tempering temperature is increased, the martensite of the hardened steel passes through stages of tempered martensite and is gradually changed into a structure consisting of spheroids of cementite in a matrix of ferrite (formerly termed as sorbite). These changes are accompanied by a decreasing hardness and increasing toughness. The tempering temperature depends upon the desired properties and the purpose for which the steel is to be used. If substantial hardness is essential, then the tempering temperature is to be low. On the other hand, if substantial toughness is needed, then the tempering temperature is to be high. Proper tempering of hardened steel needs a certain amount of time. At any selected tempering temperature, the hardness drops rapidly at first, gradually decreasing more slowly as the time is prolonged. Short tempering periods are normally undesirable and are to be avoided. Good practice needs at least 30 minutes (or preferably, 1 to 2 hours) at tempering temperature for any hardened steel.
Temper mill – It is also known as skin-pass mill. It is a type of cold-rolling mill used to achieve the desired surface finish, flatness, and mechanical properties in metal strip production. It is typically the final process in a cold-rolling sequence, applied after annealing and other processing steps. It is a process which serves to attain the correct yield points and the desired surface characteristics such as roughness and flatness. Temper mill can be single stand temper mill or DCR temper mill. DCR stands for ‘double cold reduction’. This two-stand facility combines thickness reduction in the first stand with skin passing in the second stand. It is also possible to use both stands for skin passing.
Temper rolling – It is the light cold rolling of sheet steel to improve flatness, to minimize the formation of stretcher strains, and to get a specified hardness or temper. Temper rolling does impart a small amount of cold reduction, typically in the range of 0.25 % to 1.0 %. Temper rolling results in a surface which is smooth and the yield point phenomenon (excessive stretching and wrinkling in subsequent operations) is eliminated. This makes the steel more ductile for further forming and stretching operations. After temper rolling the cold rolled sheet is oiled with rust preventive oil.
Template – It is also called templet. It is a gauge or pattern made in a die department, normally from sheet steel. It is used to check dimensions on forgings and as an aid in sinking die impressions in order to correct dimensions. In composites, it is a pattern which is used as a guide for cutting and laying plies.
Temporal scale – Climate can vary on a large range of scales, which can range from seasonal to geological (up to hundreds of millions of years) is known as temporal scale.
Temporary bracing – It is the metal which is attached to a fabrication prior to galvanizing in order to provide added support so that the steel does not change shape during heating and cooling. Temporary bracing is removed after galvanizing.
Temporary hardness – It is also known as carbonate hardness. It is caused by the presence of dissolved bi-carbonates of calcium and magnesium [Ca(HCO3)2 and Mg(HCO3)2] or carbonate of iron (FeCO3). Temporary hardness is mostly destroyed by mere boiling of water. During boiling, the bi-carbonates are decomposed and form insoluble precipitates. Carbonates and hydroxides can be removed by filtration, while carbon di-oxide (CO2) escapes out. The chemical equations are Ca(HCO3)2 = CaCO3 (insoluble) + H2O + CO2, and Mg(HCO3)2 = Mg(OH)2 (insoluble) + 2CO2. Maintenance is always a concern with equipment when hard water containing temporary hardness is present because of its scale forming potential, especially when water is heated as in the case of water-cooling system.
Temporary load – It is also known as a live load or imposed load. It is a load which is not constant and can vary over time because of the occupancy and use of a structure. These loads are dynamic and not fixed, unlike dead loads.
Tenacity – It is the term which is normally used in yarn manufacture and textile engineering to denote the strength of a yarn or of a filament of a given size. Numerically, it is the grams of breaking force per denier unit of yarn or filament size. Grams per denier is expressed as gpd.
Tender – It is a formal offer or bid submitted by a supplier to provide goods or services at a specified price. It is a structured process where organizations invite potential providers to compete for a contract, ensuring fairness and transparency in the procurement process.
Tender documents – These are prepared for the purpose of procuring materials, production unit, services, or site activities. They are used for calling the bids. A tender document normally consists of three parts, namely (i) notice inviting tender, (ii) commercial specification, and (iii) technical specification.
Tender enquiry (TE) – It is also known as a ‘request for tender’ (RFT). It is a formal invitation issued by a buyer to potential suppliers to submit bids for supplying goods or services. It outlines the requirements, conditions, and process for the tendering process.
Tendering process -It is a purchase or procurement process. It is a formal invitation for suppliers to submit bids or proposals for providing specific goods, services, or construction projects at a specified price within a defined timeframe. It is a structured process designed to ensure fair and competitive procurement.
TENORM – It is abbreviation for ‘technically-enhanced naturally-occurring radioactive materials’. These are naturally-occurring radioactive materials which have been concentrated or exposed by human activities.
Tensegrity – It is a structural system where isolated compression elements (like struts) are balanced by a continuous network of tension elements (like cables or wires). This creates a stable, floating structure where the compression elements appear to float within the tension network. The term ‘tensegrity’ has been coined by combining tension and integrity.
Tensile burr – It is the burr produced in blanking or piercing operations in which the slug separates from the stock as a result of tensile stresses.
Tensile compliance – It is the reciprocal of Young’s modulus.
Tensile force – It is known as tension which is the pulling or stretching force transmitted axially along an object such as a string, rope, chain, rod, truss member, or other object, so as to stretch or pull apart the object. In terms of force, it is the opposite of compression. It can also be described as the action-reaction pair of forces acting at each end of an object.
Tensile hoop stress – It is the stress induced within the walls of a circular or cylindrical object, like a pipe or pressure vessel, because of the internal pressure. It acts tangentially to the circumference, attempting to pull the wall apart in a circular direction. In essence, it is the stress which ‘hoops’ around the object, like the tension in a barrel hoop.
Tensile member – It is the fabric, cord and / or metal reinforcing section of a belt, as distinguished from the rubber cover.
Tensile modulus – It is also called Young’s modulus or the Young-modulus. It is a mechanical property of solid materials that measures the tensile or compressive stiffness when the force is applied lengthwise. It is the modulus of elasticity for tension or axial compression. It is defined as the ratio of the stress (force per unit area) applied to the object and the resulting axial strain (displacement or deformation) in the linear elastic region of the material.
Tensile-plus-compressive burr – It is the burr produced in blanking or piercing operations in which the slug separates from the stock in a stress field which is initially tensile, but changes to compressive at actual separation. This burr is normally associated with small die clearances and short die life.
Tensile strength (TS) – In tensile testing, it is the ratio of maximum load to original cross-sectional area. It is also called ultimate tensile strength (UTS). It is the maximum stress which a material can withstand while being stretched or pulled before breaking. In brittle materials, the tensile strength is close to the yield point, whereas in ductile materials, the ultimate tensile strength can be higher. The tensile strength is normally found by performing a tensile test and recording the engineering stress against strain. The highest point of the stress–strain curve is the ultimate tensile strength and has units of stress. In case of ceramic fibres, tensile strength also known as parting strength is the maximum tensile force which a coherent ceramic fibre product can withstand before it fails.
Tensile stress – It is a stress which causes two parts of an elastic body, on either side of a typical stress plane, to pull apart.
Tensile structure – It is a construction of elements carrying only tension and no compression or bending. The term tensile is not to be confused with tensegrity, which is a structural form with both tension and compression elements. Tensile structures are the most common type of thin-shell structures. Majority of the tensile structures are supported by some form of compression or bending elements, such as masts (as in The O2, formerly the Millennium dome), compression rings or beams.
Tensile test – A tensile test is a destructive mechanical test which is used to measure a material’s strength and how much it can be stretched before breaking. It involves applying a controlled tensile (pulling) force to a sample and observing its behaviour under stress and strain until it fractures. The test results provide valuable information about a material’s tensile strength, yield strength, and ductility.
Tensile testing – It is also known as tension testing, It is a fundamental engineering test in which a sample is subjected to a controlled tension until failure. Properties which are directly measured through a tensile test are ultimate tensile strength, breaking strength, maximum elongation and reduction in area. From these measurements the other properties which can be determined are: Young’s modulus, Poisson’s ratio, yield strength, and strain-hardening characteristics, Uniaxial tensile testing is normally used for getting the mechanical characteristics of isotropic materials. Some materials use biaxial tensile testing. The main difference between these testing machines being how load is applied on the materials.
Tensile yield strength – It is the point at which a material, under tensile stress, begins to deform permanently. It is essentially the maximum stress a material can withstand before it starts to change shape permanently and does not return to its original form if the load is removed.
Tension – It is the force or load which produces elongation. Tension (as a transmitted force, as an action-reaction pair of forces, or as a restoring force) is measured in newtons in the International System of Units.
Tension control by torque (TCT) – In a hot strip mill, tension control using torque-based methods aims to manage the tensile stress within the strip as it passes through successive rolling stands. This is crucial for achieving desired strip dimensions, flatness, and preventing damage. The process involves using the torque output of the rolling stands to infer or directly control the strip tension, frequently in conjunction with looper angle adjustments.
Tension / extension springs – These springs are designed to operate with a tension load and hence the spring stretches as the load is applied to it.
Tension force – It is defined as the force acting through a rope, cable or string when it is pulled tightly from both sides.
Tensioning – It is the process of adjusting belt tension to maintain proper operation, preventing issues like slipping or excessive wear, and ensuring optimal conveyor performance.
Tension leveller – It is an equipment which corrects the shape of metal strips by applying tension while passing them over rollers. This process, known as tension levelling, helps to achieve desired flatness, reduce internal stresses, and improve the overall shape of the strip.
Tension linkage chains – These are chains designed to transmit a load or force, frequently for moving objects or holding them in place. They are used in several applications, including elevators and other mechanical systems. A key characteristic of these chains is that they can be used to move a load slowly or intermittently over a distance, or to reliably hold a load in position.
Tension member – It is a structural element designed to carry loads primarily through tensile forces, meaning it is subjected to stretching rather than compression or bending. These members are integral components in engineering and architectural structures, such as trusses, bridges, towers, and suspension systems, where they provide stability, distribute loads, and resist deformation. Typically made from high-strength materials like steel, wire ropes, or composites, tension members are valued for their efficiency in transferring forces along their length while maintaining lightweight and durable construction. Their design and performance are crucial in ensuring the safety and functionality of structures subjected to dynamic and static loads.
Tension reel – It is also known as a coiler or winder. It is a type of reel used in industrial processes, particularly in steel and metalworking, to wind or collect material into coils. It is frequently found at the end of a production line, where it tightly winds a strip or plate of material into a coil, while also maintaining the needed tension during the process.
Tension scratch – It is a short longitudinal indentation parallel to the rolling direction.
Tension testing – It is a method of determining the behaviour of materials subjected to uniaxial loading, which tends to stretch the material. A longitudinal ample of known length and diameter is gripped at both ends and stretched at a slow, controlled rate until rupture occurs. It is also known as tensile testing.
Tenth-scale vessel – It is a filament-wound material test vessel based on a one-tenth sub-scale of the prototype.
Tephroite – It is a manganese silicate mineral, chemically represented as Mn2SiO4, and is part of the olivine group. It is characterized by its orthorhombic crystal structure and frequently found in iron-manganese ore deposits, skarns, and metamorphosed manganese-rich sediments. Its typical colour is ash gray.
Terawatt (TW) – It is one trillion ‘watts’.
Terpolymer – It is a polymeric system which contains three monomeric units.
Terminal blocks or strips – These are accessories available to titan frame motors which fits into the conduit box and provides a means to group terminating leads from accessories separately from the main leads.
Terminal erosion rate – It is the final steady-state erosion rate which is reached (or appears to be approached asymptotically) after the erosion rate has declined from its maximum value. This occurs in some, but not all, cavitation and liquid impingement tests.
Terminal period – In cavitation and liquid impingement erosion, it is a stage following the deceleration period, during which the erosion rate has leveled off and remains approximately constant (sometimes with superimposed fluctuations) at a value substantially lower than the maximum rate attained earlier.
Terminal phase – In an alloy phase diagram, a terminal phase is a solid solution which occurs near the pure component end of the diagram. These phases are based on the crystal structure of one of the pure elements and can dissolve a certain amount of the other element. They are distinguished from intermediate phases, which form between the pure elements and have their own distinct crystal structures.
Terminal solid solution – In a multi-component system, it is a solid phase of limited composition range which includes the composition of one of the components of the system.
Terminal velocity – It is the maximum velocity (speed) attainable by an object as it falls through a fluid (air is the most common example). It occurs when the sum of the drag force (Fd) and the buoyancy is equal to the downward force of gravity (Fg) acting on the object. Since the net force on the object is zero, the object has zero acceleration.
Ternary alloy – It is an alloy which contains three principal elements.
Ternary compound – It is a chemical compound containing three different elements.
Ternary molybdenum chalcogenides (Chevrel phases) – This name stands for a vast class of materials, whose general formula is MxMo6X8, where ‘M’ is a cation and ‘X’ a chalcogen (sulphur, selenium, or tellurium). There are also some compounds in which molybdenum is partially substituted by rhenium (Re), ruthenium (Ru), or rhodium (Rh). The great flexibility of this structure (where both ‘M’ and ‘X’ can vary) originated the diversity of both the chemical and physical properties observed namely super-conductivity, catalysis, ion conduction, and so on. In super-conductivity alone, several compounds show exciting characteristics such as re-entrant super-conductivity, interplay with magnetic order, double domain super-conductivity, Jaccarino-Peter effect, and high critical fields. The main applications of the ternary molybdenum chalcogenides appear to use the latter property.
Ternary system – It is the complete series of compositions produced by mixing three components in all proportions.
Terne – It is an alloy of lead containing 3 % to 15 % tin. It is used as a hot dip coating for steel sheet or plate. The term long terne is used to describe terne-coated sheet, whereas short terne is used for terne-coated plate. Terne coatings, which are smooth and dull in appearance (terne means dull or tarnished in French), give the steel better corrosion resistance and improve its ability to be formed, soldered, or painted.
Terne coating – It is a process where a mild steel sheet or strip is coated with a lead-tin alloy (typically 8 % to 20 % tin). This coating provides a layer of protection against corrosion and improves the material’s durability, making it suitable for applications like roofing, gasoline tanks, and other outdoor-exposed items.
Terpene – It is a class of naturally occurring unsaturated hydrocarbons with carbon skeletons derived from one or more units of isoprene (C5H8). Terpenes are frequently sub-classified as per the total number of carbon atoms they contain, e.g., the C5 hemiterpenes, C10 monoterpenes, and C20 diterpenes etc.
Terpolymer – It is a copolymer made from three different monomers.
Terracing – It refers to the creation of level platforms or stepped slopes to manage soil erosion and facilitate mining operations. These terraces are typically built on sloping terrain to create stable, level areas for mining activities like equipment movement, storage, and ore processing.
Tertiary air – It is the air for combustion which is supplied to the furnace to supplement the primary and secondary air.
Tertiary amines – These include triethanolamine (TEA) and methyl-diethanolamine (MDEA). Tertiary amines react more slowly with carbon di-oxide (CO2) than primary and secondary amines thus require higher circulation rate of liquid to remove carbon di-oxide compared to primary and secondary amines. This can be improved through the use of promoters. A major advantage of tertiary amines is their lower heat requirements for carbon di-oxide liberation from the carbon di-oxide containing solvent. Tertiary amines show a lower tendency to form degradation products in use than primary and secondary amines, and are more easily regenerated. In addition, tertiary amines have lower corrosion rates compared to primary and secondary amines. The main drawback is its reaction rate is too slow.
Tertiary creep – It is the final stage of creep deformation, characterized by a rapidly increasing strain rate leading to material failure. It occurs when the material’s cross-sectional area effectively reduces because of the necking or the formation of internal voids. This stage is frequently associated with the growth of microscopic internal pores and tears, which eventually cause fracture.
Tertiary crusher – It is a piece of equipment used in the third stage of crushing, after primary and secondary crushing. It is designed to reduce the size of materials further, typically to a finer product like sand or dust.
Tertiary waste-water treatment – Tertiary treatment process is used as a final cleaning process to improve the quality of the waste-water. For the removal of nutrient (nitrogen and phosphorus), removal of toxin [pesticides, volatile organic compound and metals], and for the polishing of the effluent like biological oxygen demand and total suspended solids, the tertiary treatment processes are used. These processes are the extension of conventional secondary biological treatment process for the further stabilization of the substances which demands oxygen in the wastewater, and also to remove the nitrogen and phosphorus. Tertiary treatment process consist of selected biological, physical, and chemical separation processes to remove organic and inorganic substances which resist conventional treatment practices. Tertiary treatment process consists of flocculation basins, clarifiers, filters, and chlorine basins or ozone or ultraviolet radiation processes. Tertiary techniques can also involve the application of waste-water to land to allow the growth of plants to remove plant nutrients. The physical and chemical separation techniques like activated carbon adsorption, flocculation or precipitation are the process involved in the tertiary treatments. The most common tertiary treatment applications are filtration and disinfection and where applicable ammonia and phosphorous removal. Ammonia is toxic to fish and phosphorous causes algal blooms.
Tesla – It is the SI (International System of Units) unit of magnetic flux density.
Tesla coil – It is a kind of resonant transformer capable of very high voltages. It is almost identical to an Oudin coil except that it has separately wound primary and secondary.
Test – It a procedure intended to establish the quality, performance, or reliability of something, especially before it is taken into widespread use.
Test bars – These bars are used in several fields to assess materials, tools, and systems. They can be used to verify the accuracy of machine tools, measure the rigidity of equipment, test the strength of steel bars, or measure the properties of clay like porosity and shrinkage.
Test campaign – In case of a new process development, it refers to a controlled experiment, frequently a small-scale trial, used to gather data and insights before a full-scale implementation of the process. It helps assess the viability, effectiveness, and potential impact of a new process. It also refers to a controlled marketing initiative designed to evaluate the effectiveness of a product, service, or marketing campaign before it is fully launched. It involves limited testing in specific markets or with a small group to gather data, identify potential issues, and make adjustments before a wider release.
Test, complete Initial – It is a motor test which consists of full load heat run, percent slip, no load current, full load current, locked rotor current, locked rotor torque, breakdown torque (calculated), efficiency and power factor at 100 %, 75 % and 50 % full load, winding resistance, high potential, and bearing inspection. Complete initial tests are performed on a dynamometer.
Test configuration – It defines the specific environment and parameters under which a test is to be executed. It essentially outlines the conditions, including hardware, software, network, and other relevant settings, which the test is to be run within. This setup ensures that tests are performed under controlled and reproducible conditions, which is crucial for identifying and replicating issues.
Testing – It offers a host of invaluable information, allowing a person to gain critical data on the material, work out process variables, and develop a recipe for process scale-up.
Testing, adjusting and balancing (TAB) – In heating, ventilation, and air conditioning (HVAC), testing, adjusting and balancing (TAB) are the three major steps which are used to achieve proper operation of heating, ventilation, and air conditioning systems.
Testing equipment – It refers to the instruments, tools, and machinery used to perform tests, measurements, and evaluations on products, materials, or systems. Testing equipment helps ensure that items meet specified requirements and standards.
Testing machine – It is a piece of equipment which is used to evaluate the physical properties of materials or structural elements by applying controlled forces or conditions and measuring their responses. This helps determine characteristics like strength, flexibility, and durability. These machines are crucial in materials science, engineering, and quality control.
Testing methods – These refer to the procedures or approaches which are used to evaluate a system, product, or service to determine if it meets specified requirements or performs as expected. These methods can be used in various fields, including science, engineering, and software development.
Testing procedures – These are a detailed, step-by-step guide outlining how to evaluate a product, system, or service to ensure it meets specific requirements and standards. These procedures define the process for identifying characteristics or problems and frequently involve a series of programmed tests or actions.
Testing sample – It refers to a smaller group or subset selected from a larger population or set of items for the purpose of testing and evaluating their characteristics or properties. This sample is intended to represent the larger population or set and is used to gather information and make inferences about the entire group.
Testing standards – These standards provide a defined set of procedures, guidelines, and criteria for conducting tests on different materials, products, or systems. These standards ensure consistency and reliability in testing, allowing for meaningful comparisons of results between different laboratories and industries. These standards cover aspects like testing equipment, conditions, and parameters to be measured.
Test, noise – It is a motor test of the sound levels produced by the motor at certain distances. All sound tests are performed at no load in a free field. Noise tests are carried out as per standards.
Test of hypothesis – It is a statistical test of the plausibility of the null hypothesis in a study.
Test programme planning – All significant testing programme programs begin with preparation of a detailed test plan document. A test plan specifies material properties to be evaluated, selects test methods, eliminates options offered by standard test methods by selecting specific sample and test configurations, and defines success criteria. It is prepared by the contractor, approved by the certifying agency, and is the focal point for understanding between the contractor and certifying agency. A clearly written, well-prepared test plan is also a primary management tool used to define the scope of the work, degree of success, and progress toward completion.
Test, short commercial – It is a motor test conforming to standards consisting of no-load current, locked rotor current, winding resistance, high potential, and bearing inspection.
Test, spray – It is a test of the motor stator on sealed, form wound stators only. The stator is sprayed with water and then measured for seepage in the winding.
Test statistic – It is a sample statistic measuring the discrepancy between what is observed in the sample, as opposed to what one expects to observe if the null hypothesis is true. A test statistic is a quantity calculated from the sample of data. It is used in hypothesis testing, where its value dictates whether the null hypothesis is to be rejected or not. The choice of a test statistic depends on the assumed model and the hypothesis being tested.
Test, vibration – It is a test of the motor when operating to ensure the vibration does not exceed certain levels.
Tetra-chloro-ethylene – It is also known as per-chloro-ethylene (PCE). It is a chlorinated hydrocarbon solvent, primarily used in dry cleaning and as a degreasing agent. It is a colourless, non-flammable liquid with a sweet, ether-like odour. Tetra-chloro-ethylene is a volatile substance, meaning it evaporates easily into the air.
Tetra-fluoro-ethylene (TFE) – It also known as tetra-fluoro-ethene, is a fluoro-carbon gas with the chemical formula C2F4. It is a colourless, odourless gas which is flammable and readily used to produce several fluoro-polymers, most notably poly-tetra-fluoro-ethylene (PTFE), better known as Teflon.
Tetragonal – It means having three mutually perpendicular axes, two equal in length and unequal to the third axis.
Tetragonal crystal structure – It is characterized by having three mutually perpendicular axes, two of which are equal in length, and the third axis is either longer or shorter than the other two. This system is defined by the relationship ‘a’ equal to ‘b’ not equal to ‘c’, where ‘a’ and ‘b’ represent the equal axes and ‘c’ represents the unique axis, with all angles (alpha, beta, and gamma) equal to 90-degree.
Tetragonal martensite – It is a form of martensite, a hard and brittle phase of steel, characterized by a body-centered tetragonal (BCT) crystal structure. This structure results from the rapid cooling (quenching) of austenite, where carbon atoms are trapped in the iron lattice, preventing them from diffusing. The body-centered tetragonal structure is a non-equilibrium phase and is responsible for the high hardness and brittleness of martensite.
Tetragonal zirconia polycrystal (TZP) – It is a ceramic material with a tetragonal crystal structure, typically containing zirconia (ZrO2) and a stabilizer like yttria (Y2O3). Tetragonal zirconia polycrystal is known for its high fracture toughness and strength at room temperature, making it a popular choice for several applications.
Tetrathionic acid – It is a sulphur oxoacid, specifically a sulphuric acid dimer, with the chemical formula H2S4O6. It is a conjugate acid of tetrathionate and is formed through disulphide linkages.
Tetrode – It is an electron device, nearly always a vacuum tube, with four internal active electrodes.
Tex – It is a unit for expressing linear density equal to the mass or weight in grams of 1,000 meters of filament, fibre, yarn, or other type of textile strand.
Textile conveyor belts – These are conveyor belts with one or more layers of textile, normally EP (polyester / polyamide) or PP (polyamide / polyamide).
Textile fibres – These are fibres or filaments which can be processed into yarn or made into a fabric by interlacing in a variety of methods, including weaving, knitting, and braiding.
Textile oil – It is an oil which is used to lubricate thread or yarn to prevent breakage during spinning and weaving. It is also an oil acceptable for direct contact with fibres during textile production.
Texture – In a polycrystalline aggregate, it is the state of distribution of crystal orientations. In the normal sense, it is synonymous with preferred orientation, in which the distribution is not random. It is not to be confused with surface texture. In refractories, texture is the relationship between the shapes and sizes of the grains and pores in a coherent refractory.
Textured structure – It refers to a surface or material which has a distinct physical feel and appearance, characterized by variations in its surface characteristics. This can be a result of roughness, or the presence of bumps, grooves, or other features which create a sense of depth or dimension.
Texture evolution models – These models are basically of two main categories namely (i) those principally for the prediction of deformation textures or (ii) those predicting recrystallization / transformation textures. Powerful computers availability these days have speeded the development of such modeling techniques. Models for the depiction of deformation texture is more advanced compared to the models for predicting recrystallization / transformation textures. Deformation texture modeling is based on the slip and twinning processes and the associated crystal rotations to predict anisotropic plastic flow and texture evolution. Models of this kind include lower bound and upper bound methods in which either stress or strain compatibility is enforced among the grains in a polycrystalline aggregate, respectively. Upper bound models in several cases provide reasonable estimates of deformation texture evolution.
Tg – It is the glass transition temperature.
Theoretical air – It is the quantity of air needed for perfect combustion.
Theoretical density – It is the maximum possible density of a material, calculated based on its atomic structure and assuming no defects or voids. It is essentially the ratio of the mass of the atoms within a unit cell to the volume of that unit cell.
Theoretical draft – It is the draft which is available at the base of a stack if there is no friction or acceleration losses in the stack.
Theoretical flame temperature – It is the temperature which is attained by the products of combustion provided the entire chemical energy of the fuel, the sensible heat content of the fuel, and combustion above the datum temperature are transferred to the products of combustion. This assumes no heat loss to the surroundings and no dissociation.
Theoretical stress concentration factor -It is a multiplying factor for applied stress which allows for the presence of a structural discontinuity such as a notch or hole. It equals the ratio of the greatest stress in the region of the discontinuity to the nominal stress for the entire section.
Theoretical throat – It is the distance from the beginning of the joint root perpendicular to the hypotenuse of the largest right angle triangle which can be inscribed within the cross section of a fillet weld. This dimension is based on the assumption that the root opening is equal to zero.
Theoretical yield – It refers to the maximum quantity of product which can be produced from a given quantity of reactant, assuming the reaction proceeds to completion with 100 % efficiency and no losses. It is a calculation based on the stoichiometry of the balanced chemical equation and represents the ideal outcome.
Therm – It is a unit of heat applied especially to gas. One therm is equal to 25,210 kilo-calories.
Thermal activation – It is a process where a system overcomes an energy barrier, allowing a reaction or process to proceed, by increasing the temperature and providing more thermal energy. This increase in temperature shifts the distribution of particle energies, causing more particles to possess enough energy to overcome the activation energy barrier and facilitate the reaction.
Thermal agglomeration – It is a process where particles are combined and bonded together using heat. It involves heating particles to cause them to melt, soften, or undergo sintering, resulting in the formation of larger, stable agglomerates or granules. This process is normally used to create larger, denser particles from smaller ones, frequently in applications like powder metallurgy, ceramics, and the solidification of powdered materials.
Thermal aging – It is the exposure of a material or component to a given thermal condition or a programmed series of conditions for prescribed periods of time.
Thermal analysis – It is a method for determining transformations in a metal by noting the temperatures at which thermal arrests occur. These arrests are manifested by changes in slope of the plotted or mechanically traced heating and cooling curves. When such data are secured under nearly equilibrium conditions of heating and cooling, the method is normally used for determining certain critical temperatures needed for the construction of phase diagrams.
Thermal barrier coating (TBC) – It is a thick (125 micrometers to 250 micrometers) insulating layer, designed to reduce the temperature at the metal interface. A plasma sprayed layer of yttria-stabilized zirconia is frequently used.
Thermal breakage – In case of thermal breakage, the barrel is broken showing radial oriented fracture lines whose origin is at or near to the axis of the barrel. The fracture is perpendicular to the roll axis and normally occurs close to the centre of the barrel length. The thermal breakage is related to the maximum difference of temperature between surface and axis of the roll barrel. Three factors important for thermal breakage are (i) thermal gradient, (ii) residual stresses, and (iii) strength and integrity of core material.
Thermal coal – It is a type of bituminous coal which is used to provide heat energy in combustion in various types of furnaces via the pulverized fuel method because of its high calorific value (CV). It is also sometimes called as non-coking coal, steam coal, or boiler coal. It includes all those bituminous coals which are not included under coking coal category. It is characterized by higher volatile matter (VM) than anthracite (more than 10 %) and lower carbon (C) content (less than 90 % fixed C). Its gross CV is higher than 5,700 kilocalories per kilogram on an ash‐free but moist basis. The maximum use of thermal coal is for the generation of steam in the boilers for the purpose of generation of electricity. Thermal coal is also used in some of the processes for ironmaking especially in the production of direct reduced iron (DRI) and in the smelting reduction processes for the production of hot metal (HM).
Thermal conduction – It is the diffusion of thermal energy (heat) within one material or between materials in contact. The higher temperature object has molecules with more kinetic energy. Collisions between molecules distributes this kinetic energy until an object has the same kinetic energy through-out.
Thermal conductivity (k) – It is defined as the quantity of heat which flows through a unit area in direction normal to the surface area in a defined time with a known temperature gradient under steady state conditions. It is a property which relates the rate of heat loss per unit area of a material to its rate of change of temperature. Essentially, it is a value which accounts for any property of the material which can change the way it conducts heat. Heat spontaneously flows along a temperature gradient (i.e., from a hotter body to a colder body). As an example, heat is conducted from the hot-plate of an electric stove to the bottom of a saucepan in contact with it. In the absence of an opposing external driving energy source, within a body or between bodies, temperature differences decay over time, and thermal equilibrium is approached, temperature becoming more uniform. In refractories, thermal conductivity is the quantity of heat transmitted through a refractory in unit time divided by unit cross-sectional area and unit temperature gradient along the direction of heat flow. It indicates general heat flow characteristics of the refractory and depends upon the chemical and mineralogical compositions as well as the application temperature. The unit of the thermal conductivity of refractories is watts of heat flow per meter of material thickness per Kelvin of temperature difference (W/K.m). In addition to the temperature, the co-efficient of thermal conductivity depends also on the composition of raw materials, the mineralogical structure of the brick mix, true porosity and pore size, firing temperature and grading. Hence the absolute values of the thermal conductivity vary widely for the different types of the refractories.
Thermal contraction – It is negative thermal expansion. Substances normally contract with decreasing temperature, with rare exceptions within limited temperature ranges.
Thermal control – It is the process of managing and regulating the temperature of an object, space, or system to maintain it within a desired range. It involves using a combination of techniques, such as sensors, controllers, actuators, and materials, to monitor and adjust temperature levels. This is crucial for preventing overheating, which can lead to system failures, reduced efficiency, or even permanent damage.
Thermal coupling – in its broader sense, it refers to unwanted heat transfer between objects or systems which is ideally be thermally isolated. In the context of temperature sensing, a thermocouple is a device which uses this principle to measure temperature. It consists of two dissimilar metals joined at a junction, and the voltage generated across the junction because of a temperature difference is used to determine the temperature.
Thermal creep – It refers to the phenomenon where a material deforms (changes shape) under a constant stress at high temperatures. This deformation happens over time, and the rate of deformation is affected by the material’s properties and the applied stress and temperature.
Thermal cutting – It is a group of cutting processes which melts the metal (material) to be cut. Thermal cutting processes differ from mechanical cutting (machining) in that the cutting action is initiated either by chemical reaction (oxidation) or melting (heat from arc). All cutting processes result in the severing or removal of metals.
Thermal decomposition – It is also called thermolysis. It is a chemical decomposition of a substance caused by heat. It is the decomposition of a compound into its elemental species at high temperatures. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is normally endothermic as heat is needed to break chemical bonds in the compound undergoing decomposition. If decomposition is sufficiently exothermic, a positive feedback loop is created producing thermal runaway and possibly an explosion or other chemical reaction. Thermal decomposition is a chemical reaction where heat is a reactant. Since heat is a reactant, these reactions are endothermic meaning that the reaction requires thermal energy to break the chemical bonds in the molecule. Thermal decomposition is also a process whereby fine solid particles can be produced from a gaseous compound.
Thermal dewatering – Thermal dewatering of the lignite coal simulates the coal forming process under high temperature and high pressure to reduce the moisture content. It upgrades the lignite coal to a coal which is similar to bituminous coal. Process parameters are temperature in the range of 280 deg C to 350 deg C, pressure in the range of 1 megapascal to 130 megapascal. It is a non‐evaporative drying method where the moisture in lignite extracted in liquid form. In addition to the drying, thermal dewatering also reduces the hydroscopic nature of the coal while increasing its calorific value. Some inorganic and organic matter is also removed during this process. The technological requirements are high and are difficult to realize in a large-scale plant.
Thermal diffusivity – It is the thermal conductivity divided by density and specific heat capacity at constant pressure. It is a measure of the rate of heat transfer inside a material and has SI (International System of Units) unit of square meter per second. It is an intensive property. In case of refractories, thermal diffusivity is the thermal conductivity of a refractory divided by its heat capacity per unit volume.
Thermal efficiency – It is the efficiency of a boiler, based on the ratio of heat absorbed to total heat input. This does not include heat loss from the boiler shell.
Thermal electromotive force – It is the electromotive force generated in a circuit containing two dissimilar metals when one junction is at a temperature different from that of the other.
Thermal embrittlement – It is the inter-granular fracture of maraging steels with decreased toughness resulting from improper processing after hot working. Thermal embrittlement occurs upon heating above 1,100 deg C and then slow cooling through the temperature range of 980 deg C to 815 deg C, and has been attributed to precipitation of titanium carbides and titanium carbo-nitrides at austenite grain boundaries during cooling through the critical temperature range.
Thermal emittance – It is the ratio of the radiant heat flux emitted by a sample to that emitted by a black-body radiator at the same temperature.
Thermal endurance – It is the time at a selected temperature for a material or system of materials to deteriorate to some pre-determined level of electrical, mechanical, or chemical performance under prescribed conditions of test.
Thermal energy – This term is frequently used ambiguously in physics and engineering. It can denote several different physical concepts, including (i) internal energy which means the energy contained within a body of matter or radiation, excluding the potential energy of the whole system, (ii) heat energy, which is the energy in transfer between a system and its surroundings by mechanisms other than thermo-dynamic work and transfer of matter, an (iii) the characteristic energy kBT associated with a single microscopic degree of freedom, where ‘T’ denotes temperature and ‘kB’ denotes the Boltzmann constant. The term ‘thermal energy’ is best avoided because of its ambiguity. Instead, the more precise terms such as ‘internal energy’ and ‘heat’ are used to avoid confusion.
Thermal energy method (TEM) – The process deburrs components by igniting a volatile gas mixture within a pressurized chamber containing the work piece gear. This creates a combustion heat wave that almost instantaneously reaches temperatures up to 3,500 deg C which is then subsequently only sustained for a few milliseconds.
Thermal equilibrium – It takes place when there is no net flow of thermal energy between the materials when they are connected by a path permeable to heat. Thermal equilibrium obeys the zeroth law of thermo-dynamics. A system is said to be in thermal equilibrium with itself if the temperature within the system is spatially uniform and temporally constant.
Thermal etching – It is heating a sample (normally a ceramic) in air, vacuum, or inert gases in order to delineate the grain structure. It is used mainly in high-temperature microscopy.
Thermal expansion – It is the tendency of matter to increase in length, area, or volume, changing its size and density, in response to an increase in temperature (normally excluding phase transitions). In refractories, thermal expansion means the reversible change in size of materials because of temperature changes.
Thermal expansion coefficient – It is the linear thermal expansion coefficient is used to determine the rate at which a material (e.g., the steel cord tensile member in a conveyor belt) expands as a function of temperature. This can be of importance for environments with extremely changing low and high temperatures.
Thermal expansion moulding – It is a process in which elastomeric tooling details are constrained within a rigid frame to generate consolidation pressure by thermal expansion during the curing cycle of the autoclave moulding process.
Thermal expansion under load (creep) – It is a time dependent property which determines the deformation in a given time and at a given temperature by a refractory under stress. Refractory material must maintain dimensional stability under extreme temperatures (including repeated thermal cycling) and constant corrosion from hot liquid and gases. In the creep test, sample 50 millimeters diameter and 50 millimeters height with an internal bore for the measuring rod is heated at constant rate and under a given load (nirmally at 0.2 newtons per square millimeters). After the required temperature is reached, the samples is held for 10 hours to 50 hours. The compression of the samles, after maximum expansion has been attained, is given in relation to the test time as a measure of creep at a specified test temperature.
Thermal fatigue – It is the fracture resulting from the presence of temperature gradients which vary with time in such a manner as to produce cyclic stresses in a structure.
Thermal gradient – It refers to the rate of change of temperature over a distance. It describes how temperature varies in different locations within a system, whether it’s a building, a circuit, or the earth’s crust. Essentially, it is the temperature difference divided by the distance between two points. Thermal gradients are a necessary condition for heat flow to occur between two points. Heat flows from hotter areas to colder areas.
Thermal inspection – It is a non-destructive test method in which heat-sensing devices are used to measure temperature variations in components, structures, systems, or physical processes. The basic principle of thermal inspection involves the measurement or mapping of surface temperatures when heat flows from, to, or through a test object. Temperature differentials on a surface, or changes in surface temperature with time, are related to heat flow patterns and can be used to detect flaws or to determine the heat transfer characteristics of a test body. Thermal methods can be useful in the detection of sub-surface flaws or voids, provided the depth of the flaw is not large compared to its diameter. Thermal inspection becomes less effective in the detection of sub-surface flaws as the thickness of an object increases, since the possible depth of the defects increases.
Thermal inspection techniques – Considerable effort has already been expended to extend the application of thermal or infra-red cameras to the inspection of billet at rolling temperatures. Several techniques utilizing emitted radiation and / or superimposed reflected radiation in different combinations have been used and include colour synthesis. The ultimate aim is to allow control of hot rectification processes on-line before further processing without cooling. The results of these developments have been varied but the overriding feature has always been that the defects are to be quite large to ensure detection and this feature makes these techniques inappropriate. Recently a more refined thermal inspection system has become available and is marketed by Elkem under the name of Thermomatic. This system has been developed for billet inspection and contains a means of inducing thermal energy into the billet surface in a controlled way. The surface is then viewed with a sensitive infra-red camera and the thermal images are correlated to allow identification of longitudinal seams. The range of billet temperature is, however, strictly limited and the system is insensitive to defects with transverse orientations. This obviously limits its application for continuous cast billet.
Thermal loads – Changing temperatures of equipments and their foundations cause expansions and contractions, and distortions, causing the different parts to try to slide on the support surfaces. The magnitude of the resulting frictional forces depends on the magnitude of the temperature change, the location of the supports, and on the condition of the support surfaces. The thermal forces do not impose a net force on the foundation to be resisted by soil or piles since the forces on any surface are balanced by equal and opposite forces on other support surfaces. Thermal forces, however, can govern the design of the grout system, pedestals, and hold downs. Calculation of the exact thermal loading is very difficult since it depends on a number of factors, including distance between anchor points, magnitude of temperature change, the material and condition of the sliding surface, and the magnitude of the vertical load on each sole-plate. Lacking a rigorous analysis, the magnitude of the frictional load can be calculated as ‘Force = (friction coefficient) x (load acting through sole-plate)’.
Thermally induced embrittlement (TIE) – It is the severe loss of ductility or toughness or both, of a material, normally a metal or alloy. Several forms of embrittlement can lead to brittle fracture. Several forms of thermally induced embrittlement can occur during thermal treatment or high temperature service. Some of these forms of embrittlement, which affect steels, include blue brittleness, 475- deg C embrittlement, quench-age embrittlement, sigma-phase embrittlement, strain-age embrittlement, temper embrittlement, tempered martensite embrittlement, and thermal embrittlement.
Thermally induced porosity (TIP) – It refers to the formation of pores or voids within a material as a result of heating or thermal treatments, typically because of the expansion of trapped gases or the coalescence of pre-existing pores. These pores can significantly impact a material’s mechanical properties, particularly its resistance to fatigue and crack initiation.
Thermal mass flow meters for gases – The most commonly used flow meters for gases measure the operating volume flow. This needs additional measurements of pressure and temperature to calculate the mass flow rate. These corrective measures add cost and increase the complexity of the measurements. In addition, they decrease the measuring system accuracy. The thermal mass flow measurement for gases, on the contrary, provides mass flow rate in kilograms per hour directly without any additional measurements or calculations. Using the normal density of the gas, the normal volume flow rate can be calculated, e.g., in N cubic meter/hour. There are two industrial methods used for thermal gas mass flow rate measurement, hot film anemometers and calorimetric or capillary meters.
Thermal mechanical dewatering process – Thermal mechanical dewatering process of the lignite coal consists of the combined action of temperature and mechanical force. Moisture of the coal is extracted in liquid form. The investigation work on the thermal mechanical dewatering is being carried out in several countries. The process results into good drying with the removal rate of moisture higher than 60 %. The tendency of spontaneous ignition and the hygroscopic nature of the coal are reduced. Technological requirements consisting of a temperature lower than 200 deg C and a pressure of less than 0.2 megapascals can be easily realized. Some inorganic matter is removed together with the moisture of the coal.
Thermal-mechanical treatment (TMT) – It is also known as thermo-mechanical processing. It is a metallurgical process which combines thermal and mechanical treatments to achieve specific material properties, particularly in steel. This process involves heating and cooling steel while simultaneously deforming it, typically through rolling or other mechanical processes. The objective is to refine the micro-structure of the steel, leading to improved strength, ductility, and other desirable properties.
Thermal neutron activation analysis (TNAA) – It is a technique which is used to identify and quantify elements by exposing a sample to thermal neutrons, converting stable isotopes into radioactive isotopes, and measuring the emitted radiation. It is a powerful analytical tool for multi-element analysis, widely used in several fields.
Thermal noise – It is the electrical noise produced in a resistor by thermally generated currents. These currents average zero, but produce electrical power having a non-zero average, which can affect instrument response. It is also known as Johnson noise.
Thermal oxidation – It is a process where a material, particularly silicon, is heated in an oxygen-containing environment to form a layer of oxide, typically silicon – (SiO2). This process is widely used in semi-conductor manufacturing for several applications like isolating devices, creating gate oxides in transistors, and forming masks for doping.
Thermal pollution – Thermal pollution can occur when water is used as a coolant near a power or industrial plant and then is returned to the aquatic environment at a higher temperature than it was originally. As a result of hot water discharge, the temperature of water body increases. Thermal pollution can lead to a decrease in the dissolved oxygen level in the water while also increasing the biological demand of aquatic organisms for oxygen. This affects adversely the aquatic life. This alters the spectrum of organisms, which can adopt to live at that temperature and dissolved oxygen level. When organic matter is also present, the bacterial action increases due to rise in temperature; hence, resulting in rapid decrease of dissolved oxygen. The discharge of hot water leads to the thermal stratification in the water body, where hot water will remain on the top. Thermal pollution, unlike chemical pollution, results in a change in the physical properties of water. A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers.
Thermal process – It involves the addition or subtraction of heat from a substance to alter its physical or chemical properties. It can be used for various purposes like heating, cooling, melting, drying, or even changing the chemical composition of a material. Thermal processes are noncatalytic processes which decompose, rearrange, or combine hydrocarbon molecules by the application of heat.
Thermal profile – It is a complex set of time-temperature data typically associated with the measurement of thermal temperatures in an oven. The thermal profile is frequently measured along a variety of dimensions such as slope, soak, time above liquidus (TAL), and peak. A thermal profile can be ranked on how it fits in a process window (the specification or tolerance limit). Raw temperature values are normalized in terms of a percentage relative to both the process mean and the window limits. The centre of the process window is defined as zero, and the extreme edges of the process window are +/- 99 %. A ‘process window index’ (PWI) higher than or equal to 100% indicates the profile is outside of the process limitations. A ‘process window index’ of 99 % indicates that the profile is within process limitations, but runs at the edge of the process window, e.g., if the process mean is set at 200 deg C with the process window calibrated at 180 deg C and 220 deg C respectively, then a measured value of 188 deg C translates to a process window index of −60 %. The method is used in a variety of industrial and laboratory processes.
Thermal protection system (TPS) – It is a specialized form of shielding designed to protect spacecraft, hypersonic vehicles, and other objects from extreme heat during atmospheric re-entry or in high-temperature environments. These systems are crucial for maintaining structural integrity and acceptable internal temperatures.
Thermal protector – It is a protective device for assembly as an integral part of the machine and which, when properly applied, protects the machine against dangerous overheating because of the overload and, in a motor, failure to start. It is especially important for motors which start automatically, are located remotely, unattended or out-of-sight of operator.
Thermal protector, winding-Therma-Sentry – It is complete thermal protection system for windings, protecting the motor from running overloads. It also protects the motor from abnormally high ambient temperatures, voltage unbalance, high or low voltage, ventilation failure and single phasing. It consists of three thermistors, solid state control for mounting in the customer supplied panel, with 3 amperes control circuit capacity.
Thermal protector, winding-thermistors – It is a non-linear resistance temperature detector made from semi-conductor material. There are two general types, positive temperature coefficient (PTC) which has a resistance that increases with increasing temperature, and negative temperature coefficient (NTC) which has a resistance that decreases with increasing temperature.
Thermal protector, winding-thermocouples – It is a pair of two dissimilar materials which generates a minute voltage in proportion to its temperature. Such devices can be used as a signal source in indicating instruments and control equipment.
Thermal protector, winding-thermostats – These are snap action, bi-metallic, temperature actuate switches installed in the connection end-turns of the motor winding. Their purpose is to activate a warning device or shutdown the motor upon excessive winding temperatures.
Thermal protector, winding-winding resistance temperature detectors – These are precision, wire-wound resistors with a known temperature-resistance characteristic. Recognized for their accuracy, the resistance temperature detectors resistance increases with temperature rise in a known and highly repeatable manner.
Thermal radiation – It is electro-magnetic radiation emitted by the thermal motion of particles in matter. All matter with a temperature higher than absolute zero emits thermal radiation. The emission of energy arises from a combination of electronic, molecular, and lattice oscillations in a material. Kinetic energy is converted to electro-magnetism because of the charge-acceleration or dipole oscillation. At room temperature, majority of the emission is in the infrared (IR) spectrum, though above around 525 deg C enough of it becomes visible for the matter to visibly glow. This visible glow is called incandescence. Thermal radiation is one of the fundamental mechanisms of heat transfer, along with conduction and convection. The main method by which the Sun transfers heat to the earth is thermal radiation.
Thermal reduction – It refers to the process of heating a metal oxide to extract the metal from it. This process is driven by the heat energy, causing the metal oxide to decompose and release the metal in its elemental form.
Thermal shield – It is located either within a reactor pressure vessel or between the vessel and the biological shield. The thermal shield is comprised of several layers of high-density material. Its function is to reduce radiation heating in the vessel and the biological shield.
Thermal shock – It is the development of a steep temperature gradient and accompanying high stresses within a material or structure. It is a cycle of temperature swings which result in failure of metal because of the expansion and contraction.
Thermal shock resistance – It is the resistance of a refractory to damage caused by abrupt temperature changes. In thermal shock resistance testing, test pieces are cooled abruptly from 950 deg C to room temperature by air blowing.
Thermal shock testing – It means assessing the effects on a material of rapid temperature change. In glass, the shock can derive from the external surface of glass expanding or contracting more rapidly than the interior surface as a result of heating or cooling. Any such difference can lead to cracking or shattering.
Thermal spalling – It is caused by the stresses resulting from unequal rates of expansion or contraction between different parts of the brick and is normally associated with the rapid changes in temperature. Refractories bricks with the highest resistance to thermal spalling are those having the lowest average rate of thermal expansion, high tensile strength, and a texture conducive of flexibility and relief of stress. These compositions also do not show a high rate of thermal expansion through narrow temperature ranges. Other factors being equal, temperature gradients and stresses which cause spalling are least destructive in brick having the highest thermal conductivities. A refractory of a given mineral composition normally has maximum resistance to spalling when the ratio of strength to modulus of elasticity is a maximum.
Thermal spray coatings – These are surface coatings engineered to provide wear-resistant, erosion-resistant, abrasion-resistant, and corrosion-resistant coatings for original equipment manufacturer and for the repair and upgrading of in-service equipment. In general, these coatings can be applied to a range of substrate materials, including metals, ceramics, plastics, and polymer composites. Thermal spray technology evolved and developed within the welding field because of similarities in the electrical and combustion equipment and the feedstock materials used in thermal spray with those used in welding and brazing. Accordingly, thermal spraying is classified as an allied welding process. Thermal spray is a generic term for a group of processes in which metallic, ceramic, cermet, and some polymeric materials in the form of powder, wire, or rod are fed to a torch or gun with which they are heated to near or somewhat above their melting point. The resulting molten or nearly molten droplets of material are accelerated in a gas stream and projected against the surface to be coated (i.e., the substrate). On impact, the droplets flow into thin lamellar particles adhering to the surface, overlapping and inter-locking as they solidify. The total coating thickness is normally generated in multiple passes of the coating device. A variant of plasma spraying uses a transferred arc to heat the surface being coated. It is considered by some to be a welding process akin to hard facing rather than a true thermal spray process, since the surface of the substrate becomes momentarily molten immediately beneath the torch. A major advantage of the thermal spray processes is the extremely wide variety of materials which can be used to make a coating. Virtually any material which melts without decomposing can be used. A second major advantage is the ability of most of the thermal spray processes to apply a coating to a substrate without significantly heating it. Hence, materials with very high melting points can be applied to finally machined, fully heat-treated parts without changing the properties of the part and without thermal distortion of the part. A third advantage is the ability, in most cases, to strip and recoat worn or damaged coatings without changing the properties or dimensions of the part. A major disadvantage is the line-of-sight nature of these deposition processes. They can only coat what the torch or gun can ‘see’. Of course, there are also size limitations prohibiting the coating of small, deep cavities into which a torch or gun does not fit.
Thermal spraying – It is a group of coating or welding processes in which finely divided metallic or non-metallic materials are deposited in a molten or semi-molten condition to form a coating. The surfacing material can be in the form of powder, rod, or wire.
Thermal spraying gun – It is a device for heating, feeding, and directing the flow of a surfacing material.
Thermal spray powder – It is a metal, carbide, or ceramic powder mixture designed for use with hard facing and thermal spraying operations.
Thermal stress cracking – It is the crazing and cracking of some thermoplastic resins, resulting from over-exposure to high temperatures.
Thermal stresses – These are the stresses in a material resulting from non-uniform temperature distribution.
Thermal stresses, refractories – Refractories are required to protect the furnace shell from the high temperatures existing in the furnace for meeting the requirements of the technological process being carried in the furnace. Thermal stresses develop because of the two different temperatures existing on the hot and the cold side of the refractories. The important properties of the refractories for meeting the thermal stresses which the refractories are to face during service are pyrometric cone equivalent, refractoriness under load, thermal expansion under load (creep), hot modulus of rupture, thermal expansion, reheat change (after-shrinkage and after-expansion), and thermal shock resistance.
Thermal taper – It is the thermal distortion of the bearing surfaces. Thermal distortion can form a wedge shape.
Thermal treatment – It is a process which involves converting a precursor material into a catalytic material through a solid-state reaction at high temperatures in the presence of air or a specific gas environment.
Thermal wear – It is the removal of material because of the softening, melting, or evaporation during sliding or rolling. Thermal shock and high-temperature erosion can be included in the general description of thermal wear. Wear by diffusion of separate atoms from one body to the other, at high temperatures, is also sometimes denoted as thermal wear.
Thermal wedge – It is the increase in pressure because of the expansion of the lubricant, e.g., in a parallel thrust bearing. Thermal distortion of the bearing surfaces can also form a wedge shape. This is referred to as thermal taper.
Thermex process – It is a process which is used in the manufacture of reinforcement bar. The reinforcement bars produced by the process are known as TMX bars. Thermex quenching and self-tempering (QST) technology imparts a short, intensive but very precise in line quenching of the rolled bar resulting in a hardened periphery through a proprietary system. On further cooling of the bar in atmosphere, a thermal exchange (thermex) occurs between the core and the cooled martensite surface outside. The resultant reinforcement bar structure is a distinct tempered martensite at periphery and a fine-grained ferrite-pearlite structure in the central zone. This process improves the strength, ductility, and resistance to fire and earthquakes of the reinforcement bars.
Thermionic cathode gun – It is an electron gun which derives its electrons from a heated filament, which can also serve as the cathode. It is also termed hot cathode gun.
Thermionic emission – It is the emission of electrons from a hot surface. The Edison effect has been an early example of description of this phenomenon.
Thermionic generation – Thermionic devices operate similar to thermo-electric devices. However, whereas thermoelectric devices operate according to the Seebeck effect, thermionic devices operate via thermionic emission. In these systems, a temperature difference drives the flow of electrons through a vacuum from a metal to a metal oxide surface. One key disadvantage of this technology is that it is limited to applications with high plying electricity to dissimilar semiconductors. Thermo-electric technology has existed for temperatures above 1,000 deg C. However, some development has enabled their use at around 100 deg C to 300 deg C range.
Thermistor – It is a temperature sensitive resistor with a large, somewhat variable, temperature coefficient of resistance. Thermistor is a resistance thermometer, or a resistor whose resistance is dependent on temperature. The term is a combination of ‘thermal’ and ‘resistor’. It is made of metallic oxides, pressed into a bead, disk, or cylindrical shape and then encapsulated with an impermeable material such as epoxy or glass. Thermistors have some disadvantages. These are (i) it is a very non-linear device and reasonable accuracy is obtained only over narrow spans, (ii) it is quite small and shows errors due to self-heating, and (iii) exposure to high temperature causes a dramatic and permanent shift in its output characteristics. Majority of the applications of the thermistor are in commercial and laboratory applications. Few are used in industrial process control. Thermistors are designated by their resistance at 25 deg C with the most common value being 2,252 ohms. The vessel in which the thermit reaction takes place.
Thermit mixture – It is a mixture of metal oxide and finely divided aluminum with the addition of alloying metals as needed.
Thermit mould – It is a mould which is formed around the workpieces to receive the molten metal.
Thermit reactions – These are strongly exothermic self-propagating chemical reactions such as that where finely divided aluminum reacts with a metal oxide. A mixture of aluminum and iron oxide produces sufficient heat to weld steel, the filler metal being produced in the reaction.
Thermit welding (TW) – It is also called thermite welding. It is a fusion welding process in which two metals become bonded after being heated by superheated metal which has experienced an alumino-thermic reaction. Presently, thermite welding is widely used in the field welding of track, where its portability and versatility are strong assets. The alumino-thermic reaction which occurs in thermite welding of rails follows the equation Fe2O3 + 2Al = 2Fe + Al2O3 + 850 kilo-joules heat and the typical reaction which occurs in the welding of copper conductors to steel rails is 3Cu2O + 2Al = 6Cu + Al2O3 +1,060 kilo-joules heat. This exothermic reaction is extremely violent if only the metal oxide and aluminum reducing agent are used. Pellets of ferroalloy are added to cool this reaction from a typical temperature of 3,090 deg C to 2,480 deg C. These additions also are used to produce the desired chemistry. The amount of added alloy is very critical, because larger amounts cool the reaction to temperatures below 2,040 deg C, at which point the slag / metal separation can be incomplete.
Thermo-chemical machining – It is the removal of work-piece material (normally only burrs and fins) by exposure to hot fuel gases which are formed by igniting an explosive, combustible mixture of natural gas and oxygen. It is also known as the thermal energy method.
Thermo-chemical processing – It is a method that uses heat to drive chemical reactions, converting materials like biomass into energy and chemical products. It is a crucial aspect of thermochemistry, which studies the relationship between heat and chemical reactions.
Thermo-chemical treatment – It is the heat treatment for steels carried out in a medium suitably chosen to produce a change in the chemical composition of the object by exchange with the medium.
Thermo-chemistry – It is the study of the absorption or release of heat during a chemical reaction.
Thermo-compression bonding – It is a non-standard term for hot pressure welding.
Thermocouple – A thermocouple is an assembly of two wires of unlike metals joined at one end designated the hot end. At the other end, referred to as the cold junction, the open circuit voltage is measured. Called the Seebeck voltage, this voltage known as electro-motive force (EMF) depends on the difference in temperature between the hot and the cold junction and the Seebeck coefficient of the two metals. There is a relationship between temperature and output signal. For most industrial applications, the thermocouple has been the popular choice over the years for a variety of reasons. Thermocouples are relatively inexpensive and can be produced in a variety of sizes. They can be of rugged construction, can cover a wide temperature range from 260 deg C to 2,760 deg C, and are available in both standard and premium grade models.
Thermocouple gauge – It is a temperature sensor, specifically designed to measure the temperature of a hot junction formed by two dissimilar metals. This temperature measurement is then indirectly used to determine the pressure, especially in low-pressure (vacuum) environments, based on the principle of thermal conductivity.
Thermodynamic equilibrium – It is a state where a system’s properties, like temperature and pressure, remain constant over time and can only be changed by external factors. In essence, it is a state of balance within the system, with no net change in its macroscopic properties.
Thermodynamics – It is the science which studies energy and its transformations, focusing on the relationship between heat, work, and the properties of systems in equilibrium. It describes the state and changes in the state of physical systems, particularly concerning energy and its interactions. Essentially, it is the study of how energy flows, transfers, and is converted within a system.
Thermodynamic stability – It is the condition of a system being in its lowest energy state with its environment (equilibrium).
Thermoelastic effect – It describes the change in temperature of a material that occurs when it is deformed elastically, either by stretching or compressing. This effect is a consequence of the coupling between the elastic field (stress and strain) and the temperature field within the material. In essence, compressed regions tend to heat up, while extended regions tend to cool down
Thermoelastic instability (TEI) – It is a phenomenon in sliding systems where frictional heating and resulting thermal expansion has led to a localized concentration of contact pressure and temperature, potentially causing hot spots and eventual failure. This localized concentration occurs because the thermal expansion disrupts the initially uniform contact pressure distribution, leading to a feedback loop where more heat is generated in certain areas, further increasing the pressure and temperature. Thermoelastic instability is the sharp variations in local surface temperatures with the passing of asperities leading to stationary or slowly moving hot spots of significant magnitude.
Thermoelectric effect – It means that the conversion between heat flow and current flow, and the reverse.
Thermoelectric fan (TEF) – It is also sometimes called a thermoelectric generator fan. It is a fan which generates its own power by converting heat into electricity using thermoelectric effect. This process, based on the Seebeck effect, converts temperature differences into voltage, which then powers a small motor that drives the fan blades. Essentially, the thermoelectric fan uses a heat source, like a stove or heater, to power itself.
Thermoelectric generation – Thermoelectric (TE) materials are semiconductor solids which allow direct generation of electricity when subject to a temperature differential. This technology is based on a phenomenon known as the Seebeck effect which states that when two different semiconductor materials are subject to a heat source and heat sink, a voltage is created between the two semi-conductors. Conversely, thermoelectric materials can also be used for cooling or heating by applying electricity to dissimilar semiconductors. Thermoelectric technology has existed for a long time (the thermoelectric effect was first discovered in 1821), but has seen limited use due to low efficiencies and high cost. Majority of the thermoelectric generation systems in use have efficiencies in the range of 2 % to 5 %. These have mainly been used to power instruments on spacecraft or in very remote locations. However, recent advances in the nano-technology have enabled advanced thermoelectric materials which can achieve conversion efficiencies 15 % or higher.
Thermo-forming – It is a manufacturing process where a plastic sheet is heated to a pliable forming temperature, formed to a specific shape in a mould, and trimmed to create a usable product. The sheet, or ‘film’ when referring to thinner gauges and certain material types, is heated in an oven to a high-enough temperature which permits it to be stretched into or onto a mould and cooled to a finished shape. Its simplified version is vacuum forming.
Thermo-galvanic corrosion – It is the corrosion resulting from an electro-chemical cell caused by a thermal gradient.
Thermo-gravimetric analysis (TGA) – It is a thermal analysis technique which measures the mass of a sample as it is heated or cooled in a controlled atmosphere. By monitoring the weight change over a range of temperatures, thermo-gravimetric analysis provides insights into the material’s thermal properties, including its decomposition temperature, thermal stability, and volatile content. It is a test procedure which is used to determine the thermal stability or composition of a material. Two modes are possible namely determining the change of weight of a sample while changing temperature at a given rate and the change of weight of a sample with time at a fixed temperature.
Thermo-luminescent dosimeter (TLD) – It is a device which measures radiation exposure by detecting the light emitted when a crystal is heated. These crystals, like calcium fluoride or lithium fluoride, have been exposed to ionizing radiation, trapping electrons in their lattice structure. When heated, these electrons release their stored energy as light, and the intensity of this light is proportional to the initial radiation dose.
Thermo-mechanical-control process (TMCP) – It is a technology for steel production. It is a steel property control technology which has been developed to meet the requirements of higher strength and toughness. Steel grades produced utilizing the thermo-mechanical-control process technology are called thermo-mechanical-control process steels. Thermo-mechanical-control process is used to produce high performance steels which have excellent properties, such as high strength, excellent toughness, and excellent weldability. These steel properties are achieved by controlling the micro-structure of steel through maximizing of grain refinement. Thermo-mechanical-control process steels are normally low carbon and low alloy steels. These steels are sometimes micro-alloyed. The special characteristics of thermo-mechanical-control process technology include (i) low temperature heating of the steel, (ii) a reduction under high pressure in temperature range below re-austenitization temperature, (iii) when necessary, austenitic and ferrite duplex area rolled, and (iv) accelerated cooling after rolling. Thermo-mechanical-control process is normally used to achieve excellent properties for steel products such as high strength, excellent toughness along with excellent weldability through maximizing of grain refinement. These steels have almost same formability and weldability compared with mild steels. The superior mechanical properties introduced to the steel through this processing route are virtually equivalent to those achieved by heat treating conventionally rolled or forged steel and hence thermo-mechanical-control process is used as a substitute for heat treatments which need additional material handling and furnace facilities.
Thermo-mechanical fatigue (TMF) = It refers to the process of fatigue damage under simultaneous changes in temperature and mechanical strain. Fatigue damage at high temperatures develops as a result of inelastic deformation where the strains are non-recoverable. Hence, thermo-mechanical fatigue damage is complex, as it can accumulate over a range of temperatures and strains under both steady-state and / or transient conditions. Thermo-mechanical fatigue is also frequently a low-cycle fatigue issue, since relatively infrequent transients (compared to steady-state exposures) can contribute to the accumulation of thermo-mechanical fatigue damage in different kinds of equipment, such as jet engines, land-based turbines for power generation, and pressure vessels.
Thermo-mechanical fatigue, in-phase – It refers to a specific loading condition where the maximum temperature and maximum mechanical strain occur simultaneously. This means that as the temperature rises, the material experiences a tensile strain, and as the temperature decreases, the material experiences a compressive strain. In contrast, ‘out-of-phase’ loading would have the maximum temperature occurring when the material is under maximum compressive strain.
Thermo-mechanical fatigue, out-of-phase (OP) loading – It refers to a condition where the material experiences maximum compressive stress when it is at its highest temperature, and maximum tensile stress when at its lowest temperature. This is the opposite of in-phase loading, where the maximum temperature and stress coincide.
Thermo mechanical processing – It is technique designed to improve the mechanical properties by controlling the hot-deformation process. Thermo mechanical processing is the sophisticated combination of well-defined deformation operations and well-defined heat treatment in a single production stage to control the microstructure of the material being formed. It produces materials with the desired external qualities (dimensions, shape and surface quality) and acceptable mechanical properties. The process is normally considered as the final stage in the production of steels.
Thermo mechanical treated (TMT) steel reinforcement bars – These are also called quenched and self-tempered (QST) steel reinforcement bars. Quenching and self-tempering treatment of the steel reinforcement bars is a heat treatment process in which hot steel bars coming out of last rolling mill stand are rapidly quenched with water. Rapid quenching provides intensive cooling of surface resulting in the steel bars having hardened surface because of the martensitic structure with hot core. The steel reinforcement bars are then allowed to cool in ambient conditions. During the course of such cooling, the heat released from core tempers the hardened martensitic structure of the surface while core is turned into a ferrite-pearlite structure. This quenching and self-tempering process hence changes the structure of material to a composite structure of ductile ferrite-pearlite composition in core and tough surface rim of tempered martensite providing an optimum combination of high strength, ductility, bendability and other desirable properties. The steel reinforcement bars can be produced with yield strength of 415 mega-pascals (MPa), 500 MPa, and 550 MPa and even higher. Quenching and tempering treatment can also be given to steel reinforcement bars having composition strengthened with micro-alloying.
Thermo-mechanical working – It is a general term covering a variety of metal-forming processes combining controlled thermal and deformation treatments to get synergistic effects, such as improvement in strength without loss of toughness.
Thermometers – These are instruments which measure temperature. These are calibrated in different temperature scales which historically have relied on different reference points and thermometric substances for definition.
Thermo photo voltaic generator Thermo photo voltaic generators can be used to convert radiant energy into electricity. This technology involves a heat source, an emitter, a radiation filter, and a photo-voltaic (PV) cell (like those used in solar panels). As the emitter is heated, it emits electro-magnetic radiation. The photo-voltaic cell converts this radiation to electrical energy. The filter is used to pass radiation at wave-lengths which match the photo-voltaic cell, while reflecting remaining energy back to the emitter. This technology can potentially enable new methods for waste heat recovery. A small number of prototype systems have been built for small burner applications and in a helicopter gas turbine.
Thermo-physical properties – These properties are characteristics of a substance which are affected by temperature and pressure, and describe how a material responds to changes in heat and temperature. These properties (e.g., thermal conductivity and specific heat) are crucial for understanding and predicting the behaviour of materials in several applications, particularly in areas like energy storage and heat transfer. Thermophysical properties are dynamic in nature and can change as the temperature and pressure of a material change.
Thermo-plastic – it is also called thermo-softening plastic. It is a plastic polymer material which becomes pliable or mouldable at a certain high temperature and solidifies upon cooling. Majority of thermo-plastics have a high molecular weight. The polymer chains associate by inter-molecular forces, which weaken rapidly with increased temperature, yielding a viscous liquid. In this state, thermo-plastics can be reshaped, and are typically used to produce parts by several polymer processing techniques such as injection moulding, compression moulding, calendering, and extrusion. Thermo-plastics differ from thermo-setting polymers (or thermo-sets), which form irreversible chemical bonds during the curing process. Thermo-setting polymers do not melt when heated, but typically decompose and do not reform upon cooling.
Thermo-plastic polyesters – It is a class of thermo-plastic polymers in which the repeating units are joined by ester groups. The two important types are (i) polyethylene terephthalate (PET), which is widely used as film, fibre, and soda bottles; and (2) polybutylene terephthalate (PBT), which is mainly a moulding compound.
Thermo-reactive deposition / diffusion process (TRD) – It is a method of coating steels with a hard, wear-resistant layer of carbides, nitrides, or carbo-nitrides. In the thermo-reactive deposition / diffusion process, the carbon and nitrogen in the steel substrate diffuse into a deposited layer with a carbide-forming or nitride-forming element such as vanadium, niobium, tantalum, chromium, molybdenum, or tungsten. The diffused carbon or nitrogen reacts with the carbide-forming and nitride-forming elements in the deposited coating so as to form a dense and metallurgically bonded carbide or nitride coating at the substrate surface.
Thermo-set – It is a resin which is cured, set, or hardened, normally by heating, into a permanent shape. The polymerization reaction is an irreversible reaction known as cross linking. Once set, a thermo-setting plastic cannot be remelted, although majority of them soften with the application of heat.
Thermo-setting – It indicates the capability of being changed into a substantially infusible or insoluble product when cured under application of heat or chemical means.
Thermosetting polyesters – These are a class of resins produced by dissolving unsaturated, normally linear, alkyd resins in a vinyl-type active monomer such as styrene, methyl styrene, or diallyl phthalate. Cure is affected through vinyl polymerization using peroxide catalysts and promoters or heat to accelerate the reaction. The two important commercial types are (i) liquid resins which are cross-linked with styrene and used either as impregnants for glass or carbon-fibre reinforcements in laminates, filament-wound structures, and other built-up constructions, or as binders for chopped-fibre reinforcements in moulding compounds, such as sheet moulding compound (SMC), bulk moulding compound (BMC), and thick moulding compound (TMC), and (ii) liquid or solid resins cross-linked with other esters in chopped-fibre and mineral-filled moulding compounds, e.g., alkyd and diallyl phthalate.
Thermo-setting polymers – It also called thermo-sets or thermo-setting plastics. These are a type of polymer which undergoes an irreversible hardening process when heated, forming a permanent, rigid structure. This hardening, also known as curing, results from extensive cross-linking between polymer chains, creating a strong, three-dimensional network. Once cured, they cannot be softened or reshaped by heat, making them infusible and insoluble.
Thermostat – It is a temperature sensing switch. It is a device which regulates temperature by automatically switching a heating or cooling system on or off to maintain a desired temperature. It acts as a control system, sensing temperature and adjusting the heat or cool to reach a set point.
Thermostatic steam trap – It is operated by changes in fluid temperature. The temperature of saturated steam is determined by its pressure. In the steam space, steam gives up its enthalpy of evaporation (heat), producing condensate at steam temperature. As a result of any further heat loss, the temperature of the condensate falls. A thermostatic trap passes condensate when this lower temperature is sensed. As steam reaches the trap, the temperature increases and the trap closes.
Thermo-technical stresses – Properties related to thermo-technical stresses are important for the heat flux calculations as well as the calculations for the stored heat. The important refractory properties for the thermo-technical stresses are thermal conductivity, specific heat, bulk density, melting point, and thermal capacity, and temperature conductivity.
Theta method – It is a univariate time series forecasting technique that decomposes data into two ‘theta lines’, representing long-term and short-term behaviour. It modifies the local curvature of the time series by applying a ‘theta’ coefficient to the second differences of the data. This allows for highlighting or deflating the long-term trend while maintaining the mean and slope of the original data.
Thevenin’s theorem – It states that ‘any linear electrical network containing only voltage sources, current sources and resistances can be replaced at terminals A–B by an equivalent combination of a voltage source Vth in a series connection with a resistance Rth’. The equivalent voltage Vth is the voltage obtained at terminals A–B of the network with terminals A–B open circuited. The equivalent resistance Rth is the resistance which the circuit between terminals A and B has if all ideal voltage sources in the circuit have been replaced by a short circuit and all ideal current sources have been replaced by an open circuit (i.e., the sources are set to provide zero voltages and currents). If terminals A and B are connected to one another (short), then the current flowing from A and B is to be Vth/RthVthRth as per the Thevenin equivalent circuit. This means that Rth can alternatively be calculated as Vth divided by the short-circuit current between A and B when they are connected together. In circuit theory terms, the theorem allows any one-port network to be reduced to a single voltage source and a single impedance. The theorem also applies to frequency domain alternating current (AC) circuits consisting of reactive (inductive and capacitive) and resistive impedances. It means the theorem applies for alternating current in an exactly same way to direct current except that resistances are generalized to impedances.
Thick adherend test – It is a test method for film adhesives using thick metallic adherends which allows the true shear stress, strain, and modulus of the adhesive to be determined for stress analysis of bonded joints.
Thickener – It is a large, round tank used in milling operations to separate solids from liquids, clear fluid overflows from the tank, and rock particles sink to the bottom. Thickener is also a substance which increases the viscosity (or thickness) of a liquid or solution without significantly altering other properties. This can be applied to several fields. In lubricating grease, thickener is responsible for the thickness of the lubrication film on the working surfaces of the friction joints. The function of the thickener is to provide the gel-like network structure. Generally, the soap thickener is a metallic salt of a long-chain fatty acid, e.g. lithium 12-hydroxy stearate. The soap thickener form interlocked fibres in grease. Thickener can be any material which, in combination with the base oil, produces the solid to semi-fluid structure. Simply put, a grease thickener in combination with the base oil acts much the same way as a sponge holding water. Principal thickeners used in greases include lithium, aluminum, and calcium soaps, clay, and polyurea either alone or in combination. Lithium soap is the most common thickener in use today. Incorporating polymers into the grease can further enhance the properties of the grease such as consistency, shear stability, water resistance, adhesion, tackiness, and soap yield. Polymers such as poly-ethylene, poly-propylene, poly-iso-butylene, halogenated poly-ethylene, poly-methacrylate, and poly-urea are reported to improve the properties of greases.
Thick-film circuit – It is a circuit which is fabricated by the deposition of materials having between 5 micrometers and 20 micrometers thickness, such as screen-printed cermet pastes on a ceramic substrate, which are fired in a kiln to create permanent conductive patterns.
Thick-film lubrication – It is a condition of lubrication in which the film thickness of the lubricant is appreciably higher than that needed to cover the surface asperities when subjected to the operating load, so that the effect of the surface asperities is not noticeable. It is also known as full-film lubrication.
Thick moulding compound – It is a type of thermoset polymer material used in moulding processes, similar to bulk moulding compound (BMC) or sheet moulding compound (SMC), but frequently used in applications needing thicker parts or parts with specific mechanical properties. These compounds are typically ready-to-mould, glass-fibre reinforced mixtures of resin, fillers, and additives.
Thickness – It refers to the distance between two opposite surfaces of an object or material. It is frequently the smallest of three dimensions (length, width, and thickness) and can be expressed in several units like millimeters or inches.
Thickness and profile gauge – This gauge is based on X-ray technology and is aimed at measuring the thickness in the centre-line of the work-piece. The gauge is rarely mounted on a moving carriage and can measure the whole thickness profile along the width of the coil. Normally one thickness / profile measurement system is installed at the end of the last stand in the hot strip mill.
Thickness gauge – It is a device used to measure the thickness of a material or object. It is normally used in several industries, particularly in manufacturing and engineering, to ensure that materials meet specific thickness requirements and standards. These gauges can be used to measure the thickness of several materials, including steel plates, films, papers, metal foils, and coatings.
Thickness tolerance – It defines the acceptable range of variation in the thickness of a material or product, relative to its nominal (target) thickness. It is a crucial aspect of manufacturing, ensuring that parts and materials meet specifications and function correctly.
Thief – It is a racking-device or non-functional pattern area used in the electroplating process to provide a more uniform current density on plated parts. Thieves absorb the unevenly distributed current on irregularly shaped parts, thereby ensuring that the parts receive an electro-plated coating of uniform thickness.
Thimble – It is a single metal fitting with grooves, often used to cover the eye of a wire rope.
Thin film – It is a layer of materials ranging from fractions of a nano–meter (mono-layer) to several micro-meters in thickness. The controlled synthesis of materials as thin films (a process referred to as deposition) is a fundamental step in several applications. A familiar example is the household mirror, which typically has a thin metal coating on the back of a sheet of glass to form a reflective interface. The process of silvering has been once commonly used to produce mirrors, while more recently the metal layer is deposited using techniques such as sputtering. Advances in thin film deposition techniques during the 20th century have enabled a wide range of technological break-throughs in areas such as magnetic recording media, electronic semiconductor devices, integrated passive devices, light-emitting diodes, optical coatings (such as antireflective coatings), hard coatings on cutting tools, and for both energy generation (e.g., thin-film solar cells) and storage (thin-film batteries. A stack of thin films is called a multilayer. In addition to their applied interest, thin films play an important role in the development and study of materials with new and unique properties. Examples include multiferroic materials, and superlattices which allow the study of quantum phenomena.
Thin-film circuit – It is a circuit fabricated by the deposition of material several thousand angstroms thick (such as a circuit fabricated by vapour deposition).
Thin-film lubrication – It is a condition of lubrication in which the film thickness of the lubricant is such that the friction and wear between the surfaces is determined by the properties of the surfaces as well as the viscosity of the lubricant. Under thin-film conditions, the coefficient of friction is frequently 10 times to 100 times higher than under thick-film conditions and wear is no longer negligible.
Thin-film photo-voltaic (PV) cell – It is also known as a thin-film solar cell. It is a type of solar cell where one or more thin layers of photo-voltaic material are deposited onto a substrate like glass, plastic, or metal. These layers are typically a few nano-meters to microns thick, much thinner than the wafers used in traditional crystalline silicon solar cells. Thin-film photo-voltaic cells are a cost-effective alternative to silicon-based solar cells, offering advantages like flexibility and potentially lower material usage. Thin-film solar cells are commercially used in several technologies, including cadmium telluride (CdTe), copper indium gallium diselenide (CIGS), and amorphous thin-film silicon (a-Si, TF-Si).
Thin-film solar panels – These are a type of solar panel which utilizes very thin layers of photo-voltaic materials, typically just a few micro-meters thick, deposited onto a substrate like glass, plastic, or metal. These panels are lighter, more flexible, and normally cheaper than traditional crystalline silicon solar panels.
Thin-film thermocouple (TFTC) – It is a type of temperature sensor which that utilizes the Seebeck effect to measure temperature. It consists of two thin films of different materials, typically metals, deposited on a substrate. When these materials are connected at one point and subjected to a temperature difference, a voltage is generated, which is directly proportional to the temperature difference.
Thin film transistor (TFT) – It is a type of field-effect transistor (FET) where the active semi-conductor layer is a thin film, typically deposited onto a substrate like glass. These transistors are normally used in liquid crystal displays (LCDs) and other flat-panel displays, acting as on / off switches for individual pixels.
Thin layer activation (TLA) – It is a nuclear technique which is used to measure material wear, corrosion, or erosion. It involves irradiating a material with high-energy ions, creating a thin radioactive layer. Changes in radioactivity after the material is subjected to degradation are monitored to quantify the material loss.
Thin-layer chromatography – It is a chromatography technique which separates components in non-volatile mixtures. It is performed on a thin-layer chromatography plate made up of a non-reactive solid coated with a thin layer of adsorbent material. This is called the stationary phase.
Thin section – It refers to a structural element (like a beam, column, or plate) with a high ratio of length to thickness, making its cross-section relatively thin compared to other elements. This distinction is important in structural design since thin sections are more prone to buckling and instability under compressive loads. Thin sections are thin enough to buckle locally before reaching their yield stress, meaning they are not strong enough to fully resist bending or compressive forces. In optical mineralogy and petrography, a thin section is a thin slice of a rock or mineral sample, prepared in a laboratory, for use with a polarizing petrographic microscope, electron microscope and electron microprobe. A thin sliver of rock is cut from the sample with a diamond saw and ground optically flat.
Thin-shell structures – These are also called plate and shell structures. These are lightweight constructions using shell elements. These elements, typically curved, are assembled to make large structures. Typical applications include aircraft fuselages, boat hulls, and the roofs of large buildings.
Thin slab casting and rolling (TSCR) mill – This is used for the production of hot strips. Liquid steel is cast in thin slabs (thickness 50 millimeters to 80 millimeters) which are rolled in finishing mill of hot strip mill after temperature equalization in a furnace. Originally, thin slab casting and rolling technology has been developed with the primary goal of reducing the investment and production costs but today it has become one of the most promising production routes to maintain steel as a leading material in technological application and it is being considered as the technology which has reached a high degree of maturity. Casting speed of 6 meters per minute for slab thickness of 50 millimeters / 55 millimeters is quite common these days. Initially, only commercial quality plain carbon steels were being cast through thin slab casting route. But presently most of the steel grades including low, medium and high carbon steels, HSLA (high strength low alloy) steel grades, line pipe steel grades, and steel grades for automotive application including IF (interstitial free) grades can be cast through thin slab casting route. In fact, this technology has brought paradigm shift in steel technology of casting and rolling. The thin slab casting and rolling technology has been made possible because of the several improvements in casting and rolling processes which include (i) design of the mould, (ii) hydraulic mould oscillations, (iii) use of electromagnetic brakes (EMBR), (iv) use of high pressure descaler and roller side guide (edger) in the mill, (v) dynamic liquid core reduction (LCR), (vi) mould powder quality, and redesigned submerged entry nozzle (SEN), and (vii) water spray cooling. The major advantages of thin slab casting and rolling technology over thick slab casting and hot rolling include (i) reduction in capital cost, (ii) reduction in manpower, (iii) reduction in required floor space, (iv) improvement in the yield of finish product from liquid steel, (v) reduction in the specific fuel consumption, and (vi) reduction in the specific power consumption.
Thin-wall casting – It is a term used to define a casting which has the minimum wall thickness to satisfy its service function.
Thin-wall tube – It is a cylindrical tube with a wall thickness which is relatively small compared to its diameter and length. This means the difference between the outer and inner diameters is much smaller than in a thicker-walled tube. The wall thickness is frequently defined as less than 6 % of the diameter.
Thiol – It consists of any of a class of organo-sulphur compounds consisting of a sulphur atom attached to a hydrogen atom and any other organic substituent, with the general formula R–SH. Thiols are the sulphur analogues of alcohols.
Third angle projection – It is an orthographic projection method where the object is visualized in the third quadrant, meaning it is placed below the horizontal plane and behind the vertical plane. In this system, the projection planes are positioned between the object and the observer, and the planes are assumed to be transparent.
Third law of thermodynamics – It states that the entropy of a system approaches a constant value when its temperature approaches absolute zero, since its atoms stop moving. However, heat transfer between the system and its surroundings prevent the system from ever reaching absolute zero.
Third quartile – It is the value in a distribution such that 75 % of cases have lower values.
Third-party logistics (3PL) – It involves outsourcing logistics functions like warehousing, transportation, and order fulfillment to specialized organizations. This allows the organization to focus on core competencies while external providers manage the complexities of moving goods and managing inventory.
Third-party risk management (TPRM) – It the process of identifying, assessing, and mitigating risks associated with external partners, suppliers, vendors, and other entities involved in the organizations supply chain. This includes evaluating risks like cyber-security breaches, operational disruptions, financial instability, and compliance issues which can arise from third-party relationships.
Third rail – It is an energized conductor in the track bed, using a sliding contact to transfer power to an electric train.
Thixocasting – It is a semi-solid metal casting process which utilizes a partially molten alloy, achieving near-net shape parts with improved mechanical properties and dimensional accuracy. It involves pre-casting a billet with a globular microstructure through stirring the melt, reheating it to the semi-solid temperature, and then pressing it into a die cavity to form the desired component.
Thixotropic – It is concerning materials which are gel-like at rest but fluid when agitated. These materials are having high static shear strength and low dynamic shear strength at the same time. It also means to lose viscosity under stress.
Thixotropic fluid – It is a fluid which takes a finite time to attain equilibrium viscosity when introduced to a steep change in shear rate. Some thixotropic fluids return to a gel state almost instantly, and are called pseudoplastic fluids. Others take much longer and can become nearly solid. Several gels and colloids are thixotropic materials, showing a stable form at rest but becoming fluid when agitated. Thixotropy arises because particles or structured solutes need time to organize.
Thixotropic hardening – When a material is disturbed upon remoulding, it can lose part or all of its strength. As time passes, the structural arrangement of the material particles is restored to a stable form and the material regains hardness under constant volume and water content. The process is known as thixotropic hardening.
Thixotropic material – It is a viscous fluid which appears more solid at rest but becomes more liquid when agitated or subjected to shear stress. This property is reversible, meaning the material returns to its original, more viscous state when the external force is removed.
Thixotropy – It is the property of recovering consistency after a decrease as a result of shearing. It is a time-dependent shear thinning property. Certain gels or fluids which are thick or viscous under static conditions flow (become thinner, less viscous) over time when shaken, agitated, shear-stressed, or otherwise stressed (time-dependent viscosity). They then take a fixed time to return to a more viscous state. Some non-Newtonian pseudo-plastic fluids show a time-dependent change in viscosity. The longer the fluid undergoes shear stress, the lower is its viscosity. Thixotropic age hardening is a more prolonged process than the instantaneous increase in apparent viscosity as shear rate decreases, which is found in non-Newtonian fluids.
Thoria (thorium di-oxide) – It is a crystalline solid frequently white or yellow in colour. It is a by-product of lanthanide and uranium production. Thoria particles, when dispersed within a metal alloy, act as obstacles to dislocation movement (a process that leads to plastic deformation), making the metal harder and stronger, especially at high temperatures.
Thoria dispersed alloy – It refers to a type of material where small particles of thorium di-oxide (ThO2), also known as thoria, are uniformly dispersed within a matrix material. This dispersion of thoria particles is a key technique used to strengthen and improve the properties of several materials, especially at high temperatures.
Thorium (Th) – It is a chemical element with atomic number 90. It is a weakly radio-active light silver metal which tarnishes olive grey when it is exposed to air, forming thorium dioxide. It is moderately soft, malleable, and has a high melting point. It is an electro-positive actinide whose chemistry is dominated by the +4 -oxidation state. It is quite reactive and can ignite in air when finely divided. All known thorium isotopes are unstable. The most stable isotope, 232Th, has a half-life of 14.05 billion years, or about the age of the universe. It decays very slowly through alpha decay, starting a decay chain named the thorium series which ends at stable 208Pb (lead). Thorium is an element similar to uranium which is being considered as the basis of an alternative fuel cycle. Thorium is globally more abundant than uranium, but there are a range of technical and commercial factors which need to be addressed to bring it to full scale operation.
Thread – It is a fine, tightly twisted strand, normally made from yarn. It is distinct from yarn, which is a single, continuous strand. Threads are designed for strength and durability, and their smoothness and fineness make them suitable for several applications. It is also a helical ridge or groove, a spiraling ramp, which is cut into the external or internal surface of a cylindrical shaft. This helical shape allows for the transmission of rotational movement or the secure fastening of components. Threads are normally used in screws, bolts, nuts, and pipes. These threads allow a fastener, like a screw or bolt, to engage with a corresponding nut. In computer science, a thread is typically the smallest set or sequence of instructions that a computer can manage and execute. It is the basic unit of processor (central processing pnit, CPU) utilization.
Thread count – It is the number of yarns (threads) per unit length in either the lengthwise (warp) or crosswise (fill or weft) direction of woven fabrics.
Thread crest – It is the surface of the thread which joins the flanks of the thread and is farthest from the cylinder from which the thread projects. In other words, it is the peak of the thread.
Threaded fastener – It is a fixture which uses a spiraling ramp edged out of a cylindrical shaft to join two or more pieces of material together. A thread or spiral ramp converts rotational force (or torque) in a linear joint capable of maintaining tension on multiple bounded materials.
Threaded flange – It is either threaded or screwed type. The flange is similar to a slip-on flange, but has internal threads. It is normally used to connect other threaded components in low pressure and non-critical applications. This type of flange is not used where temperature or stress is very high. The threaded or screwed flanges are used on pipelines where welding cannot be carried out.
Thread grinding – It is thread cutting by use of suitably formed grinding wheel.
Threading – It is producing external threads on a cylindrical surface.
Threading and knurling – It consists of a method of surface roughening in which spiral threads are prepared, followed by upsetting with a knurling tool.
Thread length – It is the length of the threaded portion of the fastener. In all the commercial fasteners, threaded length is a function of fastener diameter.
Thread rolling – It is the production of threads by rolling the piece between two grooved die plates, one of which is in motion, or between rotating grooved circular rolls. The process is different from metal cutting, grinding, and chasing since it does not remove any metal from the work-piece. Instead, thread rolling uses hardened steel dies to displace and mould ductile metals. It is also known as roll threading.
Thread rolling mills – These mills are used for threading of rods or pipes. Rolled threads are produced in a single pass at speeds far in excess of those used to cut threads. Dies are pressed against the surface of cylindrical blank. As the blank rolls against the in-feeding die faces, the material is displaced to form the roots of the thread, and the displaced material flows radially outward to form the thread’s crest. A blank is fed between two grooved die plates to form the threads. The thread is formed by the axial flow of material in the work piece. The grain structure of the material is not cut, but is distorted to follow the thread form. The resultant thread is very much stronger than a cut thread. It has a greater resistance to mechanical stress and an increase in fatigue strength. Also, the surface is burnished and work hardened.
Thread root – It is the surface of the thread which joins the flanks of adjacent threads and is immediately adjacent to the cylinder from which the thread projects. In other words, it is the valley of the thread.
Thread speed – It is a fixed low speed, normally adjustable, supplied to provide a convenient method for loading and threading machines. It can also be called a preset speed.
Threshold limit values – It is the airborne concentrations of a biological, chemical, or physical agent to which, it is believed that nearly all workers can be exposed without experiencing any harmful effects. Because of individual susceptibility or through aggravation of a pre-existing condition, a small percentage of workers can experience discomfort or even develop an occupational or work-related disease from exposure at concentrations or levels below the threshold limit value.
Threat assessment – It is the process of analyzing the security risks to nuclear facilities and material on a national and international basis.
Threatened species – Threatened species are those species (including animals, plants, fungi, etc.) which are vulnerable to endangerment in the near future.
Three-dimensional (3D) object – It is a solid entity with three dimensions namely length, width, and height. These objects occupy space and have volume. Examples of three dimensional objects include cubes, spheres, cones, and cylinders.
Three-dimensional space – It is a mathematical space in which three values are needed to determine the position of a point. Very frequently, it is the three-dimensional Euclidean space, i.e., the Euclidean space of dimension three, which models physical space.
Three-high rolling mill – These mills have the roll configuration in which there are three horizontally mounted rolls. Rolls in the mills with this configuration rotate permanently only in one direction. These mills make it possible rolling with increased number of grooves than in case of two-high mill stands. The work piece is rolled in one direction between the bottom and intermediate roll and then in the opposite direction between the intermediate and top roll. The fix-fitted intermediate roll is directly driven. The bottom and top roll are driven via the gearbox and they are normally adjustable. This roll configuration is used for the rolling of the shaped rolled products in grooved rolls. The drive of these mills normally includes a fly wheel.
Three-high mill roll configuration – In this type of roll configuration, there are three horizontally mounted rolls. Rolls in the mills with this configuration rotate permanently only in one direction. These mills make it possible rolling with increased number of grooves than in case of two-high mill stands. The rolled stock is rolled in one direction between the bottom and intermediate roll and then in the opposite direction between the intermediate and top roll. The fix-fitted intermediate roll is directly driven. The bottom and top roll are driven via the gearbox and they are normally adjustable. This roll configuration is used for the rolling of the shaped rolled products in grooved rolls.
Three-phase alternating current (AC) railway electrification – It is the application of three-phase power to railways.
Three-phase diagram – It is a graphical representation which shows the relationships between different phases of a material (solid, liquid, and gas) under varying conditions of pressure and temperature. It helps visualize the stability of each phase and the transitions between them, including the triple point where all three phases can coexist in equilibrium.
Three-phase electric power – It is abbreviated as 3-phi. It is a common type of alternating current (AC) used in electricity generation, transmission, and distribution. It is a type of poly-phase system using three wires (or four including an optional neutral return wire) and is the most common method used by electrical grids worldwide to transfer power. In three-phase power, the voltage on each wire is 120-degree phase shifted relative to each of the other wires. Since it is an alternating current system, it allows the voltages to be easily stepped-up using transformers to high voltage for transmission and back down for distribution, giving high efficiency. A three-wire three-phase circuit is normally more economical than an equivalent two-wire single-phase circuit at the same line-to-ground voltage since it uses less conductor material to transmit a given quantity of electrical power. Three-phase power is mainly used directly to power large induction motors, other electric motors and other heavy loads. Small loads frequently use only a two-wire single-phase circuit, which can be derived from a three-phase system.
Three-phase transformer connections – Three-phase power is attainable with one three-phase transformer, which is constructed with three single-phase units enclosed in the same tank or three separate single-phase transformers. The methods of connecting windings are the same, whether using the one three-phase transformer or three separate single-phase transformers.
Three-point bending – It is the bending of a piece of metal or a structural member in which the object is placed across two supports and force is applied between and in opposition to them.
Three-roll forming – It is a process for forming plate, sheet, bars, beams, angles, or pipe into various shapes by passing the work metal between three properly spaced rolls.
Three-way match – It is a validation process which compares a supplier’s invoice against the purchase order and the goods receipt note of the organization to ensure accuracy and prevent fraudulent transactions. It involves matching three key documents: the purchase order, the goods receipt (or delivery receipt), and the supplier’s invoice. This process is crucial for accounts payable (AP) to verify that the organization is only paying for goods or services which have been actually ordered and received, helping to reduce errors, improve cash flow, and strengthen supplier relationships.
Three-quarters hard – It is a temper of no-ferrous alloys and some ferrous alloys characterized by tensile strength and hardness around midway between those of half hard and full hard tempers.
Threshold – It is the value of an indicator which reflects a problem condition.
Threshold effect – It describes a phenomenon where a specific level or point is to be reached before a considerable change or action takes place. It is like a ‘tipping point’ where incremental actions do not produce measurable results until a certain threshold is crossed.
Threshold galling stress (TGS) – It is the stress level where galling, a type of severe adhesive wear, is likely to occur between two sliding surfaces. It is the point beyond which surfaces are more prone to seizing and transferring material, leading to damage and reduced component life-span. Essentially, Threshold galling stress is the stress at which galling is triggered in a sliding contact.
Threshold, instrument – If the input to an instrument is gradually increased from zero, the input has to reach a certain minimum level before the change in the instrument output reading is of a large enough magnitude to be detectable. This minimum level of input is known as the threshold of the instrument. Manufacturers vary in the way they specify threshold for instruments. Some give absolute values, whereas others give threshold as a percentage of full-scale readings.
Threshold level value (TLV) – It is a defined point or limit, either in a physical or numerical sense, where a change or transition from one state to another occurs. In simpler terms, it is a benchmark or boundary which dictates when a specific action, event, or effect is triggered.
Threshold stress – It is the stress for stress-corrosion cracking. The critical gross section stress at the onset of stress-corrosion cracking under specified conditions.
Threshold stress for stress-corrosion cracking – It is an experimentally determined critical gross-section stress below which stress-corrosion cracking does not occur under specified test conditions.
Throat – It is the portion of the blast furnace above the stack. The furnace throat is exposed to descending burden as well as ascending gases. It is also exposed to water when the top sprays are required for top temperature control. The operating condition in this area subjects throat to a range of wear mechanism which includes abrasion, impact erosion, temperature fluctuations, and high temperatures.
Throat of a fillet weld – It is the minimum distance minus any convexity between the weld root and the face of a fillet weld.
Throat of a groove weld – It is a non-standard term for groove weld size.
Throttling – It is a process of controlling or limiting the flow of something (e.g., fluid, energy, information, or data). In thermodynamics, throttling refers to a sudden decrease in pressure of a fluid without a change in its enthalpy. This process is frequently irreversible and can be achieved by using a valve or constriction.
Throttling valve – It is a type of valve which is used to control the flow of fluid by regulating the pressure and flow rate. It does this by introducing a flow restriction, which creates a pressure drop across the valve. This pressure drop allows for precise control over the fluid’s flow, making throttling valves essential in several applications.
Through-feed rolling – It is a thread rolling process where the work-piece (like a screw or rod) is fed axially through the thread rolling dies as the threads are formed. This method is typically used when the thread length exceeds the maximum width of the dies or when continuous rolling of long threaded bars is needed.
Through-hardened steels – These are those steels which have been heat-treated to increase hardness uniformly throughout their entire cross-section, from the surface to the core. This is achieved by heating the steel above its transformation temperature and then rapidly cooling it (quenching).
Through-hardening – It is a heat treatment process where a steel alloy is heated above its transformation temperature and then rapidly cooled (quenched) to achieve a uniform hardness throughout the material, rather than just on the surface. This process, also known as ‘quench and temper’ or ‘neutral hardening’, increases the strength and wear resistance of the steel.
Throughput – It is the quantitative measure embodying the seamless flow of products or inventory processed through the intricate veins of a process or system, encapsulating its efficiency and productivity.
Through-thickness compression – It refers to the compression force applied perpendicular to the plane of a material or structure, specifically in the direction of its thickness. It is also known as flat wise compression or z-direction compression. This type of compression is important in several fields, including composite materials and sheet metal forming, as it can affect the material’s strength and behaviour.
Through-transmission ultrasonic testing – It is a method of non-destructive testing where a transmitter sends ultrasound waves through a material, and a separate receiver on the opposite side detects the quantity of sound which reaches it. Imperfections or defects within the material reduce the quantity of sound transmitted, allowing for their detection.
Throw – It is the distance from the centre-line of the crankshaft or main shaft to the centre-line of the crankpin or eccentric in crack or eccentric presses. It is equal to one-half of the stroke.
Throw-away products – These are small, inexpensive products which are designed without any consideration of repair.
Throwing power – It is the relationship between the current density at a point on a surface and its distance from the counter electrode. The higher the ratio of the surface resistivity shown by the electrode reaction to the volume resistivity of the electrolyte, the better is the throwing power of the process. It is also the ability of a plating solution to produce a uniform metal distribution on an irregularly shaped cathode.
Thrust – It is a reaction force described quantitatively by Newton’s third law. When a system expels or accelerates mass in one direction, the accelerated mass causes a force of equal magnitude but opposite direction to be applied to that system. The force applied on a surface in a direction perpendicular or normal to the surface is also called thrust. Force, and hence thrust, is measured using the International System of Units (SI) in newtons (N), and represents the quantity needed to accelerate 1 kilogram of mass at the rate of 1 meter per second per second.
Thrust bearing – It is also known as collar bearing. In this bearing supporting pressure is parallel to the axis of the shaft having end thrust. Thrust bearing are used in bevel mountings, propeller drives, turbines, etc. In this bearing the shaft, unlike foot strep bearing passes through and beyond the bearing.
Thrust rollers – In a rotary kiln, thrust rollers prevent the drum from drifting or moving horizontally by pushing against the riding rings.
Thrust washer test – This test specifically uses a thrust washer sample configuration. It is a method to determine the wear rate and coefficient of friction of self-lubricated materials in rubbing contact. This test typically involves a testing machine where a rotating sample, frequently a disc, contacts a stationary thrust washer, while controlled pressure and speed conditions are applied. The test measures the friction force and tracks wear under these conditions.
Thumbnail – It is a feature frequently noted at the crack initiation site which has a crescent shape similar to a human thumbnail. If it is discoloured in comparison to the rest of the fracture surface, it can be an indication which it pre-existed in service conditions.
Thumb rule – It is also called rule of thumb. It refers to an approximate method for doing something, based on practical experience rather than theory. It is a heuristic guideline that provides simplified advice or some basic rule-set regarding a particular subject or course of action. It is a general principle that gives practical instructions for accomplishing or approaching a certain task. This usage of the term can be traced back to very early period and has been associated with several trades where quantities have been measured by comparison to the width or length of a thumb.
Thunderstorm – It is also known as an electrical storm, a lightning storm, thundershower or simply a storm. It is a form of weather characterized by the presence of lightning and its acoustic effect on the earth’s atmosphere known as thunder.
Thyristor – It is a four-layer semi-conductor device which stands off applied voltage until triggered.
Thyristor drive – It is a variable speed drive, normally with direct current motors, using thyristors as the switching elements.
Tidal power – It is the extraction of useful energy, normally as electric power, from the tidal rise and fall of water.
Tide marks – These are macroscopic (visible) progression marks on a fracture surface which indicate successive positions of the advancing crack front. The classic appearance is of irregular elliptical or semi-elliptical rings radiating outward from one or more origins. After some growth, the curvature can be lost or reversed as affected by component geometry. Curvature is an indication of the stress field and is also affected by biaxial loading conditions and the shape of the remaining uncracked ligament. Tide marks (also known as clamshell marks, beach marks, or arrest marks) are typically found on service fractures where the part is loaded randomly, intermittently, or with periodic variations in mean stress, alternating stress, or environmental conditions. It is not to be confused with striation (a micro-scale feature) and monotonic crack arrest lines (which are macro-scale and form by a different mechanism). Tide marks formed during intermittent loading are formed by crevice corrosion. In steels, this causes the progression mark to have a dark or black appearance.
Tie bar – It is a bar-shaped connection added to a casting to prevent distortion caused by uneven contraction between two separated members of the casting.
Tie, cavity wall – The tie in a cavity wall is a component which are used to tie the internal and external walls or leaves (constructed of bricks or cement blocks) together, making the two parts to act as a homogeneous unit. It is placed in the cavity wall during construction and spans the cavity. The ends of the tie are designed to lock into the mortar. Also incorporated into the design of the tie is means of preventing water transfer from the outer to the inner leaves. In flat ties, this can be a twist. In wire ties, this can be corrugations formed in the wire or again a twist.
Tie gum – It is a thin sheet of unvulcanized rubber inserted between plies in vulcanized repairs of splices.
Tier – It is one of a series of rows placed one above another.
Tie plate – It is also known as a base plate or sole plate. It is a steel plate used in railway tracks to connect the rail to the cross-ties (or sleepers). It increases the bearing area, helps maintain the rail’s gauge (width), and protects the ties from wear and tear.
Tiger stripes – It is the continuous bright lines on sheet or strip in the rolling direction.
TIG welding – It is the tungsten inert-gas welding. The preferred term is gas tungsten arc welding.
Tight – It means free from leaks as per the given specification.
Tikhonov method – It is also known as Tikhonov regularization or ridge regression. It is a technique used to solve ill-posed problems, particularly in inverse problems, by adding a regularization term to the original problem. This term helps stabilize the solution by controlling the influence of noise in the data. It essentially introduces a trade-off between fitting the data and reducing a norm of the solution.
Tile – It is a preformed refractory, normally applied to shapes other than standard brick.
Tilt – In electron microscopy, it is the angle of the sample relative to the axis of the electron beam. At zero tilt the sample is perpendicular to the beam axis.
Tilt boundary – It is a sub-grain boundary consisting of an array of edge dislocations.
Tilt cylinder – It refers to a hydraulic cylinder that is used to move the furnace’s tilting mechanism, allowing it to be tilted or rotated for several purposes, such as emptying molten materials.
Tilt furnace – It is a furnace which has been used for the infiltration of copper into porous sintered tungsten for heavy duty contacts. The furnace is tilted to one position for the separate sintering of the tungsten and melting of the copper, then tilted to the opposite position to let the melt run to and contact or infiltrate, respectively, the tungsten pieces.
Tilting-pad bearing – It is a pad bearing in which the pads are free to take up a position at an angle to the opposing surface as per to the hydrodynamic pressure distribution over its surface.
Tilting furnace – It is a type of industrial furnace, normally used in the metal casting industry, designed with a tilting mechanism to facilitate the easy and precise pouring of molten metal into moulds / ladles. This allows for consistent pouring and minimizes defects in the finished products.
Tilting runner – Tilting runner is essential equipment for the cast house for the reliable and safe teeming of hot metal. It is normally positioned between two hot metal tracks. The runner is first tilted to fill the hot metal ladle on one track and then tilted back to fill the ladle on the other track.
Tilting or lifting tables – In large 3-high stand, the rolling stock is required to be mechanically lifted from the pass line of the middle and bottom rolls to the higher pass line of middle and top rolls. To achieve this, the tables on either or both sides of the stand can be designed to either tilt or lift.
Tilt mould – It is a casting mould, normally a book (permanent) mould, which rotates from a horizontal to a vertical position during pouring, which reduces agitation and hence the formation and entrapment of oxides.
Tilt mould ingot – It is an ingot made in a tilt mould.
Timber – It is wood or firewood of growing trees. Wood which has been processed into planks and beams is referred to as timber. Some timbers are harder, or softer, than others.
Timber piles – These piles are made from tree trunks after proper trimming. The timber used is to be straight, sound, and free from defects. Steel shoes are provided to prevent damage during driving. For avoiding damage to the top of the pile, a metal bond or a cap is provided. Splicing of timber piles is done using pipe sleeve or metal straps and bolts. The length of the pipe sleeve is to be at least five times the diameter of the pile. Timber piles below the water table have normally long life. However, above the water table, these are attacked by insects. The life of the timber piles can be increased by applying preservatives such as creosote oil.
Time – It is a basic, limited, and dynamic resource. The concept of time is complex and hence there is no single, universally accepted definition of time. The passage of time affects everyone and everything. Further, time is indispensable and irreplaceable resource of accomplishment. It is the most precious asset. It cannot be saved, nor it can be recovered once lost. Everything people have to do needs time, and the better they use their time, the more they accomplish, and the greater is their rewards.
Time above liquidus (TAL) – In the context of reflow soldering, it refers to the duration during which the solder alloy remains in a liquid state above its melting point (liquidus temperature). This liquid phase is crucial for proper wetting and bonding between components and the printed circuit board (PCB).
Time delay – It is a time interval which is purposely introduced in the performance of a function.
Time-invariant system – It is a system whose characteristics do not vary significantly with time.
Time management – It is the act or process of planning and exercising of conscious control over the amount of time spent on specific activities, especially to increase effectiveness, efficiency, and productivity as well as for carrying out the activities effortlessly in a natural way. It can be aided by a range of skills, tools, and techniques when accomplishing specific tasks, projects and complying of goals within the due date. It is also essential for the maximization of health and personal effectiveness. More effective use of time depends upon people’s decision to manage time, instead of letting the time to manage them. This perspective is the first step for gaining control of the time. Time management in the work-place is very important since it makes the employees’ life easier which is more effective for the organization. Employees for carrying out their activities need to manage time. They have to manage time to keep up with the time, to renew policies and strategies and to implement them in the organization. The process of time management is a very complex task and is necessary for the development of the employees and the organization. If the employees have good time management skills then they are more productive and this makes the organization more efficient and productive. Hence, the organization is required to train the employees to be more effective in time management. By practicing time management in the workplace, employees are able to set priorities for their daily work and they can carry on with their duties by doing the assigned tasks in order of their importance.
Time management matrix – It classifies the activities into four categories namely (i) urgent, (ii) not urgent, (iii) important, and (iv) not important. Urgent activities cannot wait and have to be dealt with at once, e.g. answering the phone which is ringing. Urgent activities put pressure on the employees to take immediate action. The category of importance is connected with results. If an activity is important for the employees, then completing it contributes to increased self-esteem and becomes a priority. Employees react to urgent matters. More initiative and involvement is needed to deal with the matters which are important but not urgent. The time management matrix is composed of four quadrants. These activities of quadrant 1 concern those matters which are both important and urgent, the consequences of which are of vital significance, and which are to be dealt with at once. Some employees tend to spend a lot of time dealing with matters which are urgent but not important (quadrant 3). The employee feels that these items belong to quadrant 1. The employees react to those urgent matters which they also consider important. Quite often, the urgency of these matters is based on other people’s priorities and expectations. In general, the employees who spend practically all their time in quadrants 3 and 4 are irresponsible. Such behaviour can even lead to getting rebukes from seniors at work. The heart of the effective self-management is at quadrant 2. Here belong matters which are not urgent but important. These include building meaningful relationships, long-term planning, physical activity, and preventing undesirable situations etc. These are the things which the employees are supposed to do but hardly ever find time to do.
Time of flight (ToF) – It refers to the time it takes for a wave (like sound or light) to travel from a source to an object (or defect) and back to a detector. This measurement is used to determine the distance to the object or defect. In simpler terms: Imagine shining a light and seeing it reflected back. The time it takes for the light to go and return tells a person how far away the reflector is. This is the basic principle of time of flight.
Time order of production – Although the statistical description and the interpretation of data are useful, they ignore a crucial characteristic of the data, i.e., the time order of production. To properly indicate statistical control or lack of it, the statistical model is to be considered as it evolves over time of production, i.e., the time order evolution of the process. If the process mean and variation stay constant over time, and the process is said to be in statistical control. If a process mean shift occurs at a certain time, the process is said to have gone out of control. A process can be subject to several types of disturbances (special causes) which can produce a variety of unstable behaviours with respect to either its mean level or the level of variability or both.
Time quenching – It is a quench in which the cooling rate of the part being quenched is to be changed abruptly at some time during the cooling cycle.
Time series – It is a series of measurements of a variable over time, normally at regular intervals. It is a set of ordered observations on a quantitative characteristic of an individual or collective phenomenon taken at different points of time. Although it is not a requirement, it is common for these points to be equidistant in time.
Time sharing – It is a system whereby multiple human users of a computer can proceed as if they had sole use, while the computer processes each user’s software in round-robin fashion.
Time-temperature profile (TTP) – It is a graphical representation which shows how temperature changes over time, typically in a process like heating, cooling, or a chemical reaction. It is a visual record of the thermal history of a material or system, highlighting important parameters like temperature, time, and slope.
Time-temperature curve – It is a curve produced by plotting time against temperature.
Time-temperature-transformation (TTT) diagram – It is also known as isothermal transformation diagram, sigmoidal diagram, C-curve, or S-curve of the steel. It shows the time needed for austenite to begin to transform, to proceed halfway, and to be completely transformed at any constant temperature in the range covered by the curves. Time-temperature-transformation diagram of a steel can be regarded as a kind of map which charts the transformation of austenite as a function of temperature and time and permits approximation of how the steel responds to any mode of cooling from the austenitic state. These are plots of temperature against time (normally on a logarithmic scale). Time-temperature-transformation visually represents the kinetics of phase transformations in a material, specifically steel alloys, under isothermal conditions (constant temperature). It plots the temperature against the logarithm of time, indicating when different transformations start and end. These diagrams are crucial for understanding the micro-structure of materials and how it is influenced by heat treatment. Time-temperature-transformation diagrams are generated from percentage transformation against time measurements, and are useful for understanding the transformations of an alloy steel at higher temperatures. Time-temperature-transformation diagrams are accurate only for phase transformations in which temperature of the steel is held constant through-out the duration of the reactions, which means these reactions are isothermal. This is why a time-temperature-transformation diagram is also called isothermal (constant temperature) transformation diagram. When steel in the austenitic state is held at any constant temperature lower than the minimum at which its austenite is stable, it transforms with time. The course of isothermal transformation can be represented by plotting percentage of austenite transformed against corresponding elapsed time at constant temperature. For a given steel austenitized in a particular way, information given by a series of such curves, each determined at a different constant temperature, can be summarized in a single diagram.
Time to failure (TTF) – It refers to the length of time a product or system operates before experiencing a failure or error. It is a key metric for reliability analysis, and when averaged across multiple instances, it is known as Mean time to failure (MTTF).
Time-varying covariates – These are explanatory variables whose values can change at different occasions of measurement for the same subject.
Tin (Sn) – It is a chemical element having atomic number 50. It is a silvery-coloured metal. Tin is soft enough to be cut with little force, and a bar of tin can be bent by hand with little effort. When bent, the so-called ‘tin cry’ can be heard as a result of twinning in tin crystals. Tin is a post-transition metal in group 14 of the periodic table of elements. It is obtained mainly from the mineral cassiterite, which contains stannic oxide, SnO2. Tin shows a chemical similarity to both of its neighbours in group 14, germanium and lead, and has two main oxidation states, +2 and the slightly more stable +4. Tin is produced from both primary and secondary sources. Secondary tin is produced from recycled materials.
Tin alloy – It is defined as a mixture of tin with other metals such as copper and antimony. These alloys, like bronze and pewter, are used for several applications because of the tin’s corrosion resistance and low melting point, with added metals providing structural strength.
Tin alloy plating – It consists of electro-deposition of tin alloys which is used to protect steel against corrosion or wear, to impart resistance to etching, and to facilitate soldering. Four types of tin alloys are available in commercial processes. The first is tin lead. It is the most commonly used of these processes because of its simplicity and low cost. It is especially popular in the electronics industry because of its excellent solderability, resistance to tin whisker growth, and resistance to tin pest (formation of a gray powder on the surface, also called tin disease). These properties make it a valuable coating for integrated-circuit leads, surface-mount (small outline transistor) components, and circuit board connections. The second is tin-bismuth. Tin-bismuth processes have been developed in recent years as a substitute for tin-lead. Bismuth as an alloying agent prevents the whiskering and tin pest which can occur in tin coatings. The third is tin-nickel which is used for corrosion-resistant coatings, especially in seawater environments. It has an attractive chrome like appearance and high lubricity when plated over bright nickel. The fourth is tin-zinc. It provides outstanding corrosion protection, comparable to cadmium, and is a possible replacement for cadmium at a lower cost.
Tin coatings – These are applied to steel sheet by electrolytic deposition or by immersion in a molten bath of tin (hot dip process). Hot dip tin coatings provide a non-toxic, protective, and decorative coating for food handling, packaging, and dairy equipment, and they facilitate the soldering of components used in electronic and electrical equipment. In many places, hot dip tin coating has been replaced by electrolytic tin coating. Electrolytic tin coated steel sheet is used where solderability, appearance, or corrosion resistance under certain conditions is important, as in electronic equipment, food handling and processing equipment, and laboratory clamps. It is normally produced with a matte finish formed by applying the coating to base steel sheet called black plate, which has a dull surface texture, and by leaving the coating unmelted. It can also be produced with a bright finish by applying the coating to base steel having a smooth surface texture and then melting the coating.
Tin free steel (TFS) – It is an electrolytic chromium plated steel consisting of a thin layer of chromium and a layer of chromium oxide deposited on a cold rolled sheet steel base (black plate) which gives it a beautiful, lustrous metallic finish on both sides. It is also known as electrolytic chromium coated steel (ECCS). Chromium coating has primarily been developed as an economical and high-quality alternative to the tinplate. Tin free steel excels tinplate in paintability, paint adhesion, and economy. It offers outstanding corrosion resistance, lacquer adhesion, and printability. The layer of chromium protects tin free steel against corrosion. It is an economical and high-quality replacement for tinplate. Its appearance is less attractive (lower brightness) than tinplate. The absence of tin makes tin free steel non appropriate for acidic food (pH less than 4) because of lower corrosion resistance. Tin free steel FS is not used without any biological protection for food products. This protection is frequently given through lacquer. Tin free steel is excellent for lacquer adhesion and is always required to be lacquered on both the surfaces before use.
Tin mill – It consist of continuous tin-plating facility to produce tin mill steel sheet to be used in food and beverage cans and other containers.
Tinning – It is the coating of metal with a very thin layer of molten solder or brazing filler metal.
Tinning process – There are two processes for the tinning of the black plates namely (i) hot dip tinning process and (ii) electroplating process. Hot dip tinning process is the process of immersing the steel black plate into a bath of pure molten tin at a temperature greater than 232 deg C. The coating produced consists of a very thin intermetallic layer which first forms at the interface of the base material and the tin (e.g. when dipping the black plate, an iron / tin alloy is formed) followed by a layer of pure tin. In electroplating, the item to be coated is placed into a vessel containing a solution of one or more tin salts. The item is connected to an electrical circuit, forming the cathode (negative) of the circuit while an electrode typically of the same metal to be plated forms the anode (positive). When an electric current is passed through the circuit, metal ions in the solution are attracted to the item. For producing a smooth, shiny surface, the electroplated sheet is then briefly heated above the melting point of tin. Presently, tinplate is virtually produced only by the electroplating of tin on to the steel base by a continuous process.
Tin ore – Cassiterite, a naturally occurring oxide of tin, is by far the most economically important tin mineral. The bulk of the world’s tin ore is obtained from low-grade placer deposits of cassiterite derived from primary ore bodies or from veins associated with granites or rocks of granitic composition. Primary ore deposits can contain very low percentages of tin (e.g., 0.01 %), and hence large quantities of soil or rock are to be worked to provide recoverable quantities of tin minerals. Unlike ores of other metals, cassiterite is very resistant to chemical and mechanical weathering, but extended erosion of primary lodes by air and water has resulted in deposition of the ore as eluvial and alluvial deposits.
Tin pest – It is a polymorphic modification of tin which causes it to crumble into a powder known as gray tin. It is normally accepted that the maximum rate of transformation occurs at about -40 deg C, but transformation can occur at as high as about 13 deg C.
Tinplate – It is a thin steel sheet coated with tin (Sn) metal. The thin steel sheet on which tin coating is done is known as black plate. Low carbon steel with carbon well below 0.1 % is normally used for tinplate production. Tin coating is applied either by hot dipping or electrolytic coating process. Both processes produce coatings which have characteristics of their own. Hot dip tin coating has advantages in being metallurgically bonded to base steel and of producing a smooth bright surface. Electrolytic coating process is able to produce a uniform coating of controlled thickness. Tin has several properties which make it suitable for use as a coating on steel. It has a good resistance to corrosion in a wide range of environments and in particular retains its appearance and surface properties extremely well in indoor atmosphere. It is easily soldered and the good corrosion resistance ensures effective retention of solderability. It is safe in contact with foods, neither producing risks to health nor impairing flavours. The softness of the metal, although disadvantageous for some uses of coatings, has merit for others, facilitating cold working, giving easy running threads on fasteners, and helping to seal joints.
Tin plating – It is a plating process whereby the molecules from the positively charged tin anode attach to the negatively charged sheet steel. The thickness of the coating is readily controlled through regulation of the voltage and speed of the sheet through the plating area.
Tint etching – It is the immersing of metallographic samples in specially formulated chemical etchants in order to produce a stable film on the sample surface. When viewed under an optical microscope, these surface films produce colours which correspond to the different phases in the alloy. It is also known as colour etching.
Tinting – It is the colouration of a metal surface through thermal oxidation by heating to reveal details of structure.
Tin tossing – It is the oxidizing of impurities in molten tin by pouring it from one vessel to another in air, forming a dross which is mechanically separable.
Tip of pile – It is the first part of the pile to enter the ground.
Tipping point – It refers to the critical threshold in a system’s state beyond which a significant, often unstoppable change or effect occurs. This point marks a transition from one stable state to another, indicating a fundamental shift in the system’s behavior or characteristics.
Tire tracks – These consist of a microscale fractographic feature found especially for cyclic loading conditions in which particulate debris is caught between the two fracture surfaces and causes subsequent imprinting of the surface as the particle(s) moves across the surface.
Titan horizontal motors – These machines are normally used in severe duty environments for pumps, compressors, fans, blowers and other material processing applications.
Titania (TiO2) – It is known as titanium di-oxide or titanium (IV) oxide. It is a naturally occurring oxide of titanium, and a common white pigment. Titania is a white powder which is insoluble in water. It is found in minerals like rutile, anatase, and ilmenite. Titania has several applications.
Titanium (Ti) – It is a chemical element having atomic number 22. It is found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver colour, low density, and high strength, resistant to corrosion in sea water, aqua regia, and chlorine. Titanium can be alloyed with iron, aluminum, vanadium, and molybdenum, among other elements. The resulting titanium alloys are strong, lightweight, and versatile, with applications including aerospace, military, industrial processes, automotive, and consumer electronics etc. The two most useful properties of the metal are corrosion resistance and strength-to-density ratio, the highest of any metallic element. In its unalloyed condition, titanium is as strong as some steels, but less dense. There are two allotropic forms and five naturally occurring isotopes of this element. Titanium forms stable compounds with oxygen, carbon, nitrogen, and sulphur at temperatures of steelmaking. It is sometimes used in steelmaking because of its property for fixing of these elements in order to reduce their harmful effects. Ti is also used for the purpose of grain refining in many steels. In many respects, functions of titanium are similar to the addition of both aluminum and niobium. Titanium is more expensive than aluminum, hence it is rarely used as a deoxidizer.
Titanium aluminide alloys – These alloys are based on the face centered tetragonal (fct) gamma phase (TiAl) represent another type of aluminide material for which significant progress has been made toward commercialization. The gamma titanium aluminide alloys have a number of applications as lightweight replacements for super alloys in the hot section of airplane engines and as thermal protection systems in hypersonic vehicles.
Titanium carbide (TiC) – It is a very hard, heat-resistant ceramic materials of the composition TiC used in cermets and tungsten carbide cutting tools. Chemical vapour deposited titanium carbide coatings are also used to extend the life of cemented carbide cutting tools.
Titanium matrix composite (TMC) – It is a material where a titanium alloy acts as the matrix, or continuous phase, and is reinforced with other materials like fibres or particles, typically ceramics. These reinforcements are designed to improve the material’s strength, stiffness, and / or other desired properties.
Titanium nitride (TiN) – It is a hard, high-melting-point ceramic (2,950 deg C) of the composition TiN which is used in cermets and as a coating material for cemented carbide cutting tools.
Titanium powder metallurgy (P/M) – It offers the possibility of creating net shape or near net shape parts without the material loss and cost associated with having to machine intricate components from wrought billet. Powders can be produced by the blended elemental technique or by pre-alloying and then consolidated by metal injection mouldimg, hot isostatic pressing, direct powder rolling or laser engineered net shaping. Titanium powder is used in aerospace, 3-D printing, powder metallurgy, and surface coatings because of its strength, low weight, and corrosion resistance. It also plays a vital role in energy generation and as a catalyst in chemical processes.
Title block – In a technical drawing, it is a standardized area which contains essential information about the drawing. The title block includes (i) title of the drawing, (ii) type of drawing, (iii) drawing number and revision number, (iv) date of the preparation, (v) scale of the drawing, (vi) measurement unit, (vii) name of the organization who prepared the drawing, (viii) name of persons who prepared and approved the drawing, and (ix) any other information which is needed for the drawing identification. The title block helps in easy identification, organization, and retrieval of drawings.
Titration – It is also known as titrimetry and volumetric analysis. It is a common laboratory method of quantitative chemical analysis to determine the concentration of an identified analyte (a substance to be analyzed). A reagent, termed the titrant or titrator, is prepared as a standard solution of known concentration and volume. The titrant reacts with a solution of analyte (which can also be termed the titrand) to determine the analyte’s concentration. The volume of titrant which reacted with the analyte is termed the titration volume.
T-joint – It is a joint between two members located approximately at right angles to each other in the form of a ‘T’.
T-L orientation, T-S orientation – A three-letter identification system is used to identify the longitudinal (L), transverse (T), and short transverse (S) direction of the applied stress normal to the plane on which the crack propagates and the direction of crack growth. It is used for both prismatic and cylindrical sections. For example, a T-L orientation indicates a stress in the wide transverse direction, and crack propagation is in the longitudinal (or rolling) direction.
TNT – It is abbreviation for tri-nitro-toluene.
Toe – It is also known as tracking. In automotive engineering, toe is the symmetric angle which each wheel makes with the longitudinal axis of the vehicle, as a function of static geometry, and kinematic and compliant effects. This can be contrasted with steer, which is the antisymmetric angle, i.e., both wheels point to the left or right, in parallel (roughly). Negative toe, or toe out, is the front of the wheel pointing away from the centre-line of the vehicle. Positive toe, or toe in, is the front of the wheel pointing towards the centre-line of the vehicle. In welding, toe refers to the junction where the weld face meets the parent metal (the material being welded). It is a critical area since it is a point of stress concentration, making it a potential starting point for cracks like fatigue cracks or cold cracks. To minimize these issues, welds need to have smooth, rounded toes which blend into the parent metal surface.
Toe angle – It refers to the angle of the wheels when viewed from above, specifically concerning their alignment with the vehicle’s longitudinal axis. It essentially describes whether the front edges of the tyres are pointing inwards (toe-in), outwards (toe-out), or are parallel to each other (zero toe).
Toe crack – It is a crack in the base metal at the toe of a weld.
Toggle press – It is a mechanical press in which the slide is actuated by one or more toggle links or mechanisms. In toggle draw presses, the blank holder force is taken on the rocker shaft bearings in the press frame, so that the crank-shaft bearings sustain only the drawing load.
Toggle switch – It is a switch which has an operating lever that can be pushed up and down or left and right to switch an electrical circuit.
Tolerable risk – It refers to the level of risk which an organization deems acceptable after considering the potential benefits and risks associated with an activity or decision. It is a risk which, while not desirable, is deemed acceptable in the given context because of the benefits derived from accepting it. This concept is frequently used in risk management to determine the point where further mitigation measures are not considered cost-effective or necessary.
Tolerance – Tolerance is an allowance, given as a permissible range, in the nominal dimension or value specification of a manufactured item. The purpose of a tolerance is to specify the allowed leeway for imperfections in the production of the part or component. The tolerance can be specified as a factor or percentage of the nominal value, or a maximum deviation from a nominal value, or an explicit range of allowed values, or be specified by a note or published standard with this information, or be implied by the numeric accuracy of the nominal value. Tolerance can be symmetrical, as in 40 millimetres +/- 0.1 millimetres, or asymmetrical, such as 40 millimetres + 0.2 millimetres / – 0.1 millimetres. In metrology, tolerance is the limits of the range of values (the uncertainty) which apply to a properly functioning measuring instrument. In statistics, tolerance refers to a measure of the acceptable range of variation or error within a system, process, or data. It can be used in different contexts, including tolerance intervals, tolerance analysis, and statistical tolerance analysis.
Tolerance analysis – It is an engineering design methodology which aims to absorb as much variation as possible without affecting the function of the product. It does this through the optimal selection of datums, feature controls, assembly methods, and assembly sequence. It differs from the conventional practice of assigning tolerances to drawings prior to release in that it is more systematic and more global in outlook and employs three-dimensional tolerance analysis computer-aided engineering (CAE) tools.
Tolerance design – It is the third stage of robust design, as defined by Genichi Taguchi, in which it is decided how much performance levels of certain parameters has to be increased to meet the quality characteristic. The quality loss function is used to find the majority of the cost-effective way of determining which tolerances have to be tightened and which can be left as is or opened up, in order to reduce cost.
Tolerance design stage of the design process – It concentrates on the selection of allowable tolerances for the important design parameters. The loss function concept of quality is used to provide a basis for striking the proper economic balance in the selection of design.
Tolerance limits – It is the extreme values (upper and lower) which define the range of permissible variation in size or other quality characteristic of a part.
Tolerance stack-up – It is the situation with a sub-assembly of several parts by which all parts are within the tolerance specification, but the cumulative effect of the tolerance of each part results in a critical dimension of the assembly being out-of-tolerance.
Toluene – It is also known as toluol. It is an aromatic hydrocarbon with the chemical formula of C7H8. It is a colourless, water-insoluble liquid with a sweet pungent smell associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a CH3 group attached to a phenyl group. As such, its IUPAC systematic name is methylbenzene. Toluene reacts as a normal aromatic hydrocarbon in electrophilic aromatic substitution. Since the methyl group has higher electron-releasing properties than a hydrogen atom in the same position, toluene is more reactive than benzene toward electrophiles. It undergoes sulphonation to give p-toluene-sulphonic acid, and chlorination by chlorine (Cl2) in the presence of ferric chloride (FeCl3) to give ortho and para isomers of chlorotoluene. Molar mass of toluene is 92 grams per mol. The density of toluene at 20 deg C is 0.87 grams per cubic centimeters. Its freezing point is -95 deg C and boiling point is 111 deg C. Its solubility in water at 20 deg C is 0.52 grams per litre. The vapour pressure of toluene is 0.029 kilograms per second centimeter, Its viscosity at 20 deg C is 0.59 centipoise. It is a highly flammable liquid. Its flash point is 6 deg C. The explosive limit of toluene is in the range of 1.1 % to 7.1 %.
Ton – It is any of several units of measure of mass, volume or force. It has a long history and has acquired several meanings and uses. As a metric unit, it is sometimes spelled as tonne. As a unit of mass, ton means 1,000 kilograms or 1 megagram.
Toner – It is a powder mixture used in laser printers and photocopiers to form the text and images on paper.
Tons-per-vertical-metre -It is a common unit used to describe the quantity of ore in a deposit. In it, ore length is multiplied by the width and divided by the appropriate rock factor to give the quantity of ore for each vertical metre of depth.
Tongue – It is a micro-scale fractographic feature created in materials that mechanically twin. The feature is created when a propagating cleavage crack (e.g., of the {1,0,0} family in body-centered cubic material) deviates onto the composition plane (K1 plane) ({1,1,2}) in steel.
Tongue and groove facing – This type of flange facing has fully confined gasket. Groove is normally not over 1.5 millimeters wider than tongue. Gasket dimensions match tongue dimensions. The flange is less subject to erosive and corrosive contact with the vessel. Since the tongue is more likely to get damaged than the groove, it is normally attached to the part which can be easily removed from the vessel.
Tongue and groove joints – These consist of mating joint elements with a long, shaped-or profiled-protrusion, known as a ‘tongue’, along one or more edges of one element, and a similarly long, shaped- or profiled-groove along one or more edges of the mating element.
Tongue-hold – It is the portion of a forging billet, normally on one end, which is gripped by the operator’s tongues. It is removed from the part at the end of the forging operation. It is common to drop hammer and press-type forging.
Tons of force – It refers to the force exerted by a ton of mass because of the gravity. Specifically, it is the force needed to keep a ton-weight object at rest or to accelerate it to a certain velocity. There are different types of ‘tons’ including short tons, long tons, and metric tons, each with a different mass equivalent.
Tool design – It involves creating and developing the tools used to shape raw materials into finished products, ensuring accuracy, efficiency, and quality during the production process. This includes designing molds, dies, fixtures, and other aids for various manufacturing operations like moulding, machining, and assembly.
Tooling – It is a generic term applying to die assemblies and related items used for forming and forging metals.
Tooling marks – These are indications imparted to the surface of the forged part from dies containing surface imperfections or dies on which some repair work has been done. These marks are normally slight rises or depressions in the metal.
Tooling pad – A lug or boss added to a forging so that on-centre machining and forming can be performed with one setup or checking. This lug is finally machined or cut away. In the context of sheet metalworking and press brake operations, tooling pad refers to a specific type of tool used to bend, shape, or form metal sheets. It is typically a component of the press brake tooling, which includes a punch and die. Tooling pads are used in conjunction with punches to create specific shapes and angles in the metal.
Tooling plate – It is a cast or rolled product of rectangular cross section over 6 millimeters or higher in thickness and with edges either as-cast, sheared, or sawed, with internal stress levels controlled to achieve maximum stability for machining purposes in tool and jig applications.
Tooling resin – It consists of resins which have applications as tooling aids, core boxes, prototypes, hammer forms, stretch forms, foundry patterns, and so on. Epoxy and silicone are common examples.
Tools – Tools refer to instruments, devices, or techniques used to facilitate design, analysis, construction, or manufacturing processes. These can be physical tools like hand tools or machine tools, or they can be software or methods used in engineering disciplines.
Tool side – It is the side of the part which is cured against the tool (mould or mandrel).
Tool steel – It consists of any of a class of carbon and alloy steels normally used for making tools. Tool steels are characterized by high hardness and resistance to abrasion, frequently accompanied by high toughness and resistance to softening at high temperature. These attributes are normally achieved with high carbon and alloy contents. Tool steels are well suited for making of tools. The suitability is because of their distinctive hardness, resistance to abrasion, ability to hold a cutting edge and resistance to deformation at higher temperatures (red hardness). Tool steels are normally used after heat treatment. Tool steels are having carbon content in the range of 0.7 % to 1.4 % and need care and fully controlled condition during its production. The manganese content is kept low to avoid cracking during water quenching.
Tool wear rate (TWR) – It is a measure of how quickly a cutting tool is losing material during a machining process. It is essentially the volumetric quantity of tool material removed per unit time. This wear is a gradual process, leading to changes in the tool’s shape and potentially affecting its performance and life.
Tooth – It is a projection on a multipoint tool (such as on a saw, milling cutter, or file) designed to produce cutting. It is a projection on the periphery of a wheel or segment thereof (e.g., as on a gear, spline, or sprocket) designed to engage another mechanism and thereby transmit force or motion, or both. A similar projection on a flat member such as a rack.
Tooth point – It is the chamfered cutting edge of a face milling blade, to which a flat is sometimes added to produce a shaving effect and to improve finish.
Top-and-bottom process – It is a process for separating copper and nickel, in which their molten sulphides are separated into two liquid layers by the addition of sodium sulphide. The lower layer holds majority of the nickel.
Topaz – It is a silicate mineral made of aluminum and fluorine with the chemical formula Al2SiO4(F, OH)2. It is typically valued as a gemstone. It is a crystalline mineral which naturally forms in a variety of colors, most commonly yellow, brown, orange, or pink, though it can also be blue, green, or even colourless.
Top charging equipment – It refers to the equipment which is used to charge raw materials (like iron ore, coke, and flux) into the blast furnace at the top. This equipment is crucial for maintaining consistent burden profile and ensuring the proper distribution of materials for efficient smelting.
Top coat – It is normally the final paint film applied to a surface.
Top cover – It is the material carrying side of a conveyor belt. It is normally thicker than the bottom cover.
Top dead centre – It is a position in the cycle of a piston engine wherein the piston is at the topmost point in its stroke.
Top gas – It is the gas which comes out at the top of a blast furnace. The gas is cleaned in the dust catcher and the gas cleaning plant to remove dust from the gas.
Top gas recycling-blast furnace process – Top gas recycling’ (TGR) technology is mainly based on lowering the usage of fossil carbon (coke and coal) with the re-usage of the reducing agents (carbon mono-oxide and hydrogen). In top gas recycling-blast furnace, oxygen is blown into the blast furnace instead of hot air to eliminate nitrogen in the top blast furnace gas. Part of the top blast furnace gas containing carbon mono-oxide and hydrogen is utilized again as the reducing agent in the blast furnace. Carbon di-oxide from the blast furnace top gas is captured and then stored. Several recycling processes have been suggested, evaluated or practically applied for different objectives. These processes are distinguished by (i) with or without carbon di-oxide removal, (ii) with or without preheating, and (iii) the position of injection. The concept of the top gas recycling-blast furnace involves several technologies which include (i) injection of reducing top blast furnace gas components carbon mono-oxide and hydrogen in the shaft and hearth tuyeres, (ii) lowering the consumption of fossil carbon input because of the lower coke rate, (iii) usage of pure oxygen gas instead of hot blast air at the hearth tuyere (removal of nitrogen from the process), and (iv) recovery of pure carbon di-oxide from the top blast furnace gas for underground storage.
Top of a dam – It is the elevation of the uppermost surface of a dam, normally the roadway or walkway or the non-overflow section of the dam.
Topography – It is the study of the forms and features of land surfaces. Topography of an area can refer to the landforms and features themselves, or a description or depiction in maps. Topography is concerned with local detail in general, including not only relief, but also natural, artificial, and cultural features such as roads, land boundaries, and buildings. Topographic maps record not just elevation contours, but also roads, populated places, structures, land boundaries, and so on.
Topography of surface – It is made up of a combination of three features, namely (i) surface roughness which refers to the high-frequency irregularities on the surface caused by the interaction of the material microstructure and the cutting tool action, (ii) surface waviness which refers to the medium-frequency irregularities on the surface on which the surface roughness is superimposed (These forms can be caused by the instability of the cutting tool and errors in the machine tool guideway), (iii) surface form which is the general shape of the surface, neglecting roughness and waviness, which are caused principally by errors in the machine tool guideway, and deformations because of the stress patterns in the component.
Topologically close-packed (TCP) phases – These are also known as Frank-Kasper phases. These are a type of intermetallic compound with complex crystal structures characterized by high coordination numbers and unique physical properties. These phases are known for their dense atomic arrangements and frequently found in alloys containing refractory elements like chromium, molybdenum, tungsten, and rhenium.
Topology – It is the shape of an electrical network, independent of its size or values. Topology is also the branch of mathematics concerned with the properties of a geometric object which are preserved under continuous deformations, such as stretching, twisting, crumpling, and bending; that is, without closing holes, opening holes, tearing, gluing, or passing through itself.
Topology optimization – It is a mathematical method which optimizes material layout within a given design space, for a given set of loads, boundary conditions and constraints with the goal of maximizing the performance of the system. Topology optimization is different from shape optimization and sizing optimization in the sense that the design can attain any shape within the design space, instead of dealing with predefined configurations. The conventional topology optimization formulation uses a finite element method (FEM) to evaluate the design performance. The design is optimized using either gradient-based mathematical programming techniques such as the optimality criteria algorithm and the method of moving asymptotes or non-gradient-based algorithms such as genetic algorithms. Topology optimization has a wide range of applications in aerospace, mechanical, bio-chemical and civil engineering. Presently, engineers mostly use topology optimization at the concept level of a design process.
Top pressure – It is the pressure which is maintained at the top of the blast furnace.
Top pressure recovery turbine (TRT) – It is a mechanism which utilizes the blast furnace gas heat and pressure energy to drive a turbine. The work generated by the turbine is transferred to a generator and converted to electric power. Top pressure recovery turbine generates power by exploiting a known property of all gases which is the expansion of gas volume with the reduction of its pressure. The system comprises dust collecting equipment, a gas turbine, and a generator. Top pressure recovery turbine is basically an energy saving measure at the blast furnace which utilizes the waste pressure energy of the BF top gas to generate electric power.
Top roll balancing cylinder – It is a hydraulic or pneumatic device which used to balance the top roll (also known as the work roll) by adjusting its position and pressure against the bottom roll. This is crucial for maintaining consistent material thickness, shape, and quality during rolling.
Top surface control, tundish – Directing too much flow towards the top surface generates surface defects, due to transients, turbulence at the meniscus, and inclusion problems from slag entrainment. However, decreasing surface flows too much can also generate problems. These include surface defects due to the meniscus region becoming too stagnant, and a higher fraction of incoming inclusion particles being sent deep before they can be removed into the slag. Hence, a balance is to be found in order to optimize the flow parameters to avoid defects.
Top view – In technical drawings, a top view represents the perspective of an object as seen from directly above. It provides a two-dimensional representation of the object, showing its layout and features from a high vantage point. The top view of an object shows the width and depth dimensions. This view is crucial for understanding dimensions, spatial relationships, and the overall design of an object, according to engineering resources.
TORBAR averaging pitot tube – The TORBAR is an improvement on round sensor designs because of the unique profiled flats which are positioned around the downstream hole, in order to define the separation-point at which the flow lines separate as the measuring medium passes around the outer pitot tube. This feature creates a stable pressure area at the downstream pressure sensing hole thereby maintaining a more constant flow coefficient at high flow velocities enabling a very wide range of flow measurement (turn down ratio). TORBAR flow meters have been successfully used on a large variety of flow applications. These flow meters are suitable for gases, liquids and steam. Some of the many typical applications include water, natural gas, flue gas, nitrogen, combustion gases, ventilation air, sea water, cooling water, crude oil, and saturated and superheated steam. The versatility of TORBAR flow meters makes them ideal for flue stack flow rate measurement. Possible pipe diameters range from 15 millimeters up to 8 meters. TORBAR averaging pitot tubes are available in a variety of designs to suit the application.
Torch – It is a tool used to cut metal by applying a high-temperature flame. It heats the metal to its melting point, and a stream of oxygen blows away the molten metal, allowing for controlled cutting. The preferred terms cutting torch (arc), cutting torch (oxyfuel gas), welding torch (arc), and welding torch (oxyfuel gas).
Torch brazing – It is a brazing process in which the heat needed is furnished by a fuel gas flame. It utilizes a fuel gas flame as the heat source for the brazing process. The fuel gas is mixed with either air or oxygen to produce a flame, which is applied to the work-piece until the assembly reaches the proper brazing temperature. Then, preplaced filler metal is melted or hand-fed wire can be introduced. Torch brazing is used with several base metals and on several different sizes of assemblies. The process offers several advantages.
Torch soldering – It is a soldering process in which the heat required is furnished by a fuel gas flame. It utilizes a fuel gas flame as the heat source in the soldering process. The fuel gas is mixed with either air or oxygen to produce the flame, which is applied to the materials to be soldered until the assembly reaches the proper soldering temperature. Solder filler metal, which melts at temperatures below 450 deg C, is added to the assembly to bond it. Successful torch soldering is accomplished when parts are clean and fit together closely, and when oxides are not excessive. Torch soldering is used in several industries which utilize a variety of base metals. It is very frequently used to produce a leak-tight assembly with some degree of mechanical strength. This process does have several advantages when compared with other metal-joining methods.
Torch tip – It is that part of an oxy-fuel gas cutting / welding torch from which the gases are issued.
Torn surface – It is a deep longitudinal rub mark resulting from abrasion by extrusion or drawing tools.
Toroidal field – It is a magnetic field that is ring or donut-shaped, with no radial component. It is essentially a field which loops around a central axis, like the magnetic field produced by a current-carrying toroid.
Toroidal inductors and transformers – These consist of magnetic coils wound around a ring of ferromagnetic material.
Torpedo ladle – It is having a shape of a torpedo. The closed shape of the torpedo ladle helps in the preservation of heat during the transport of the hot metal. It is essentially a large, cylindrical ladle mounted on a railcar frame. The car’s design, particularly its shape and lining, minimizes heat loss during transport and allows for controlled pouring. Bricks demonstrating refractoriness, resistance to thermal shock and volume stability are used to line the ladle zones. A wide range of refractories bricks are used for the lining of torpedo ladles. This wide range includes fire clay bricks (alumina content 37 %), high alumina bricks (alumina content ranging from 66 % to 86 %), and alumina silicon carbide bricks. When using alumina silicon carbide bricks, it is necessary to use a layer of insulation bricks for preserving heat since the heat conductivity of silicon carbide is higher than other refractories. The lining is normally done with zonal concept with slag line refractories, impact pad refractories and roof refractories are selected to suit the parameters existing in these areas. Also, the lining of the torpedo ladles consists of permanent lining and the wear lining. Castables are utilized in the spout, floor surround and as repair masses. Chemically bonded refractory castables show strength and density combined with volume stability from ambient to high temperatures. Monolithics used for lining include mortar, gunning mix and joint mix.
Torpedo ladle car – It is a specialized railroad car on which torpedo ladle is mounted. Torpedo ladle is used to transport molten iron or steel from the blast furnace to the steelmaking facility. Torpedo ladle cars move along the railways with the help of traction railway equipment. These cars move normally individually or sometimes in a formation of two ladle cars.
Torpex – It is a high explosive, a type of torpedo explosive, used in mines and is 50 % more powerful than TNT (tri-nitro-toluene). It is a mixture of RDX (cyclonite), TNT, and aluminum powder. The specific composition can vary, but a common formulation is 42 % RDX, 40 % TNT, and 18 % aluminum powder.
Torque – It is the rotational analogue of linear force. It is also referred to as the moment of force (also abbreviated to moment). Just as a linear force is a push or a pull applied to a body, a torque can be thought of as a twist applied to an object with respect to a chosen point, e.g., driving a screw uses torque to force it into an object, which is applied by the screw-driver rotating around its axis to the drives on the head. In a conveyor system, torque is the vigilant act of inspecting and sustaining the rotational force within the drive components, including motors and gear-boxes, orchestrating a harmonious symphony of efficient power transmission.
Torque, breakdown – It is the maximum torque the motor develops with rated voltage applied at rated frequency without an abrupt drop in speed. It is normally expressed as a percentage of full-load torque.
Torque-coil magnetometer – It is a magnetometer which depends for its operation on the torque developed by a known current in a coil that can turn in the field to be measured.
Torque, constant – It is an application which needs the same torque at all operating speeds. Horsepower varies directly with the speed. Examples of constant torque applications include conveyors, hoists, and positive displacement pumps.
Torque control – It means that the motor torque is regulated instead of motor speed.
Torque controller (TC) – The torque controller controls the torque generated by the two reels in a hot strip mill. These controllers receive a torque reference which is produced by the ‘tension control by torque (TCT) controller which aims at keeping constant the strip coiling / uncoiling tensions.
Torque, full-load – It is the torque which is necessary to produce its rated horsepower at full-load speed.
Torque, locked-rotor – It is the torque which the motor develops at rest (for all angular positions of the rotor) with rated voltage and frequency applied.
Torque, locked rotor or starting torque – It is the maximum torque produced at initial start.
Torque, pull-up – It is the minimum torque developed during the period of acceleration from locked-rotor to the speed at which breakdown torque occurs. For motors which do not have a definite breakdown torque, pull-up torque is the minimum torque developed up to the rated full-load speed. It is normally expressed as percentage of full-load torque.
Torque, variable – It is an application in which the torque needed varies as the square of its speed. Horsepower requirements increase as the cube of the speed. Examples include centrifugal pumps and blowers, turbine pumps, and fans.
Torr – It is a unit for measuring pressure, equivalent to 133.322 pascal (Pa) or 0.0013158 atmosphere.
Torricelli’s equation – Torricelli’s equation, or Torricelli’s formula, is an equation to find the final velocity of an object moving with a constant acceleration along an axis (e.g., the x axis) without having a known time interval. The equation itself is Vf square = Vi square + 2a delta-x, where ‘Vf’ is the object’s final velocity along the x-axis on which the acceleration is constant, ‘Vi’ is the object’s initial velocity along the x-axis, ‘a’ is the object’s acceleration along the x-axis, which is given as a constant, and delta-x is the object’s change in position along the x axis, also called displacement. This equation is valid along any axis on which the acceleration is constant.
Torsilastic spring – It is a cylindrical rubber spring consisting of an inner shaft, an outer shell, and a solid layer of rubber of substantial thickness between, and adhered to the shaft and shell.
Torsion – It is a twisting deformation of a solid or tubular body about an axis in which lines which are initially parallel to the axis become helices. It is a twisting action resulting in shear stresses and strains.
Torsional breakage of driven roll necks – This happens mostly during the rolling accidents. Fatigue torsional failure of the roll necks is observed very rarely.
Torsional moment – In a body being twisted, it is the algebraic sum of the couples or the moments of the external forces about the axis of twist, or both.
Torsional stress – It is the shear stress on a transverse cross section resulting from a twisting action.
Torsional vibration – It is the angular vibration of an object (normally a shaft) along its axis of rotation. Torsional vibration is frequently a concern in power transmission systems using rotating shafts or couplings, where it can cause failures if not controlled. A second effect of torsional vibrations applies to passenger cars. Torsional vibrations can lead to seat vibrations or noise at certain speeds. Both reduce the comfort.
Torsion beam suspension – It is also called twist-beam rear suspension, torsion-beam axle, deformable torsion beam, or compound crank. It is a type of automobile suspension based on a large H-shaped or C-shaped member. The front of the ‘H’ attaches to the body through rubber bushings, and the rear of the ‘H’ carries each stub-axle assembly, on each side of the car. The cross beam of the ‘H’ holds the two trailing arms together, and provides the roll stiffness of the suspension, by twisting as the two trailing arms move vertically, relative to each other.
Torsion spring – It is a spring which works by twisting its end along its axis, i.e., a flexible elastic object which stores mechanical energy when it is twisted. When it is twisted, it exerts a torque in the opposite direction, proportional to the amount (angle) it is twisted. There are several types of torsion springs such as torsion bar, torsion fibre, helical torsion spring, and spiral wound torsion spring.
Torsion test – It is a test in which a sample is twisted axially for a given number of revolutions. It can be conducted to destruction or to demonstrate that the material can withstand a specific quantity of twisting.
TOS-EL – It is the abbreviation for ‘top of support-elevation’.
Total air – it is the total quantity of air supplied to the fuel and products of combustion. Percent total air is the ratio of total air to theoretical air, expressed as percent. \Total bell height – It is the vertical distance between the upper termination of the throat section and the bottom of the large bell when closed.
Total base number (TBN) – It is a measurement which indicates the quantity of alkaline (basic) additives in a lubricant, specifically in engine oil. It essentially measures the oil’s ability to neutralize acidic contaminants which can build up because of the combustion byproducts or other sources. A higher total base number value means the oil has a higher capacity to neutralize acids, protecting the engine from corrosion.
Total carbon – It is the sum of the free carbon and combined carbon (including carbon in solution) in a ferrous alloy.
Total cost – It refers to the sum of all expenses an organization incurs to produce a specific output level. It encompasses both fixed costs, which remain constant regardless of production levels, and variable costs, which change with production.
Total cyanide – It is the cyanide content of an electro-plating bath (including both simple and complex ions).
Total dissolved solids (TDS) – It is a measure of the concentration of dissolved matter in water. Total dissolved solids measurements are frequently used to estimate a water body’s salinity, which can affect the distribution of aquatic organisms. Calcium, magnesium, sodium, potassium, bi-carbonate, sulphate, chloride, and silica are typical dissolved solids.
Total elongation – It is the total quantity of permanent extension of a test piece broken in a tensile test normally expressed as a percentage over a fixed gauge length.
Total-extension-under-load yield strength – It is the stress at which a material shows a specified deviation from proportionality of stress and strain.
Total flow – It is the volume of the fluid flowing over a period of time.
Total harmonic distortion (THD) – It is a measure of the magnitude of harmonically-related frequency components a signal processing stage adds.
Total height of furnace – It is the vertical distance between the centre-line of the tap hole and the intersection of the large bell hopper or hopper extension with the gas seal.
Total indicator reading (TIR) – It is a measurement in manufacturing and engineering which quantifies the difference between the maximum and minimum readings of an indicator when it is run along the surface of a part during rotation. Essentially, it is a measure of how much a part deviates from a perfectly round or flat surface.
Total indicator variation – It is the difference between the maximum and minimum indicator readings during a checking cycle.
Total involvement of employees – It is one of the principles of total quality management. All the organizational processes are to be operated at their highest quality level to get high performance of the organization. Hence, quality is not just the responsibility of management or quality control personnel. Neither can it be delegated to certain functions. For the quality efforts in the organization, it is necessary to involve every employee at every level, and every function of the organization. This is because improving of quality is the job of everyone in the organization. Employees at all the levels are the essence of the organization and their full involvement is necessary to enable their abilities to be used for achieving the quality improvement objectives of the organization. In the organization, the unrecognized quality experts are those personnel who do the work at the workplace. They are best equipped to solve the quality related issues. In the organization, if the ideas and advice from these unrecognized quality experts are ignored, then the organization is doing a big mistake since it is ignoring the total involvement of the employees.
Total load – It normally refers to the sum of all forces, weights, or demands applied to a system or component. This can include things like the combined weight of objects on a structure, the total electrical power being consumed by appliances, or the total quantity of data being transmitted across a network. In a conveyor system, total load is the judiciously managed and distributed weight harmonizing across the entire length of the conveyor system, ensuring equilibrium and structural soundness.
Totally enclosed air over (TEAO) motors – These are dust-tight fan and blower duty motors which are designed for shaft mounted fans or belt driven fans. The motors are to be mounted within the airflow of the fan.
Totally enclosed air to air cooled machine – It is a totally enclosed machine which is cooled by circulating the internal air through a heat exchanger which, in turn, is cooled by circulating external air. It is provided with an air-to-air heat exchanger for cooling the internal air, a fan or fans, integral with the rotor shaft or separate, for circulating the internal air and a separate fan for circulating the external air.
Totally enclosed fan cooled (TEFC) motors – These motors prevent the free exchange of air between the inside and outside of the frame, but does not make the frame completely air tight. A fan is attached to the shaft and pushes air over the frame during its operation to help in the cooling process. In these motors, the ribbed frame is designed to increase the surface area for cooling purposes. The totally enclosed fan cooled style enclosure is the most versatile of all. It is used on pumps, fans, compressors, general industrial belt drive, and direct connected equipment.
Totally enclosed fan cooled guarded machine – It is a totally enclosed fan cooled machine in which all openings giving direct access to the fan are limited in size by the design of the structural parts or by screens, grilles, expanded metal, etc. to prevent accidental contact with a cylindrical rod 2 millimeters in diameter, and a probe is not to contact the blades, spokes or other irregular surfaces of the fan.
Totally enclosed machine (motor) – A totally enclosed machine is one so enclosed as to prevent the free exchange of air between the inside and the outside of the case, but not sufficiently enclosed to be termed airtight.
Totally enclosed non-ventilated (TENV) motors – These motors are similar to a totally enclosed fan cooled motor, but these motors have no cooling fan and relies on conventional cooling. The motors have no vent openings, are tightly enclosed to prevent the free exchange of air, but the motors are not airtight. These motors are suitable for uses which are exposed to dirt or dampness, but not very moist or hazardous (explosive) locations.
Totally enclosed wash down (TEWD) motors – These motors are designed to withstand high pressure wash-downs or other high humidity or wet environments. Available on totally enclosed air over, totally enclosed fan cooled, and totally enclosed non-ventilated enclosures, these motors are totally enclosed, hostile, and severe environment motors. These are designed for use in extremely moist or chemical environments, but not for hazardous locations.
Totally enclosed water-cooled machine – It is a totally enclosed machine which is cooled by circulating water, the water or water conductors coming in direct contact with the machine parts.
Total maximum daily load (TMDL) – It is the quantity, or load, of a specific pollutant which a water-body can assimilate and still meet the water quality standard for its designated use. For impaired waters, the total maximum daily load reduces the overall load by allocating the load among present pollutant loads (from point and non-point sources), background or natural loads, a margin of safety, and sometimes an allocation for future growth.
Total mineral resource – It include (i) a concentration (or occurrence) of material of intrinsic economic interest, (ii) reasonable prospects for eventual economic extraction, and (iii) location, grade, quantity, geological characteristic known, estimated or interpreted from specific geological evidence and knowledge.
Total nitrogen – It is the sum of the concentrations of all nitrogen forms in water, including ammonia (NH3), ammonium ion (NH4+), nitrite (NO2), and nitrate (NO3), as well as dissolved and particulate organic nitrogen expressed as elemental nitrogen. Measuring total nitrogen is important for several applications.
Total petroleum hydro-carbons (TPH) – These hydro-carbons refer to a large group of chemical compounds, mainly consisting of hydro-carbons, which originate from crude oil or petroleum products. It is a measurable quantity of these petroleum-based hydro-carbons found in environmental media, such as soil, water, or air.
Total pressure – It is the sum of the static and velocity pressures.
Total productive maintenance (TPM) – It is an important strategic tool for an organization. It is an approach for increasing the organizational effectiveness, as well as the performance of its equipment during its use in operations, by enlisting the full participation and interest of all of its employees. Total productive maintenance is a deliberate strategy aimed at production performance improvement which deals with the organizational infrastructure integrity and the efficient utilization of the resources through continual employee participation and empowerment in production, maintenance, and different other organizational activities. The main goal of total productive maintenance is to reduce waste in different activities, lowering total costs by increasing productivity, and producing high-quality products. Total productive maintenance seeks to maximize equipment effectiveness throughout the life-time of the production equipment. It aims at improving existing plant equipment conditions and increase the knowledge and skills of front-line personnel on the production floor. It strives to maintain the equipment in optimum condition in order to prevent unexpected break-down, speed losses, and quality defects. Total productive maintenance initiatives in production help in streamlining the manufacturing and other organizational functions, and garnering sustained profits. It is adopted, in order to strengthen the manufacturing performance of the organization and to achieve a world-class performance level.
Total quality management (TQM) – It is an organization-wide effort to ‘install and make a permanent climate where employees continuously improve their ability to provide on-demand products and services which customers find of particular value. ‘Total’ emphasizes which departments in addition to production (e.g., sales and marketing, accounting and finance, engineering and design) are obligated to improve their operations, ‘management’ emphasizes which executives are obligated to actively manage quality through funding, training, staffing, and goal setting. While there is no widely agreed-upon approach, total quality management efforts typically draw heavily on the previously developed tools and techniques of quality control.
Total solids concentration – It is the weight of dissolved and suspended impurities in a unit weight of boiler water, normally expressed in parts per million (ppm).
Total suspended particulate matter (TSPM) – It refers to the mass concentration of all solid and liquid airborne particles in the air, including dust, soot, smoke, and liquid droplets. These particles are suspended and can remain airborne for a long time, posing potential health risks.
Total suspended solids (TSS) – It is a measurement of the quantity of matter suspended, but not dissolved, in a unit of water. Suspended solids include a wide variety of materials such as silt, decaying plant matter, industrial wastes, and sewage.
Total transmittance – It is the ratio of the radiant energy leaving one side of a region between two parallel planes to the radiant energy entering from the opposite side.
Total vacuum – It is zero pressure or lack of pressure, as generally experienced in outer space.
Total volume of the furnace – It is the furnace volume between a horizontal plane at the centre-line of the tap hole and the bottom of the closed large bell.
Touch-screen – It is a type of display which can detect touch input from a user. It consists of both an input device (a touch panel) and an output device (a visual display). The touch panel is typically layered on the top of the electronic visual display of a device. Touch-screens are normally found in smartphones, tablets, laptops, and other electronic devices. The display is frequently a liquid crystal display (LCD).
Touch up – It is performing of the finishing work after galvanizing in order to meet standards or specifications, or coating areas of steel which have been exposed due to post galvanizing fabrication, installation, or extremely rough handling.
Toughening – It is a special process of solidification of a glass sheet in order to make it particularly resistant to breakages. The process can be physical (thermal) or chemical. In the former, the glass sheet is heated to a temperature just below its softening point and then immediately cooled by special jets of cold-air. These harden the surface of the glass, giving the inside more time to cool. This allows the external layer to crystallize into a wider lattice while the inside solidifies with higher compression than in the crystal lattice. The result is a sheet of glass which is two or three times stronger than untempered glass and which, upon breakage, shatters into tiny pieces with blunt edges (the most common applications are for automotive glass). The chemical process, on the other hand, is based on the so-called ion-stuffing technique. Different chemical elements possess different ionic radii and therefore different densities. Hence, if glass containing sodium is cooled slowly in a salt bath of molten potassium, the sodium ions migrate from the glass to the salt, while the potassium ions move to the surface of the glass where, because of their wider radium, they create a denser and hence stronger surface layer (of no less than 0.1 millimeters). Glass sheets which have been chemically tempered are five to eight times stronger than those which have not undergone any tempering process.
Toughness – It is the ability of a material to absorb energy and deform plastically before fracturing. Toughness is proportional to the area under the stress-strain curve from the origin to the breaking point. In metals, toughness is usually measured by the energy absorbed in a notch impact test.
Tough pitch copper – It is an obsolete term for copper which has been cast with a deliberate oxygen addition (typically 0.01 % to 0.05 %) to improve electrical conductivity. The metal can have first been either the electrolytically or fire refined.
Tow – It is an untwisted bundle of continuous filaments, normally referring to man-made fibres, particularly carbon and graphite, but also fibre-glass and aramid. A tow designated as 140 K has 140,000 filaments.
Tow conveyor – This conveyor consists of a single strand endless chain which tows floor / track mounted trucks, dollies or cars on which the materials are placed. Tow conveyors are normally used for handling of unit loads like boxes, barrels, crates, cartons, in the warehouse, in assembly lines and for intra-plant movement. Though the tow conveyors follow a fixed path, the carts can be detached easily from the conveyor and moved to other points. Tow conveyors are classified into three groups namely (i) overhead tow conveyor, (ii) flush-floor tow conveyor, and (iii) under floor tow conveyor.
Tower crane – The tower crane is a modern form of balance crane. It is normally fixed to the ground on a concrete and sometimes attached to the sides of structures as well. Tower cranes frequently give the best combination of height and lifting capacity and are used in the construction of tall buildings and tall industrial structures. This crane frequently gives the best combination of height and lifting capacity. The base of the crane is attached to a mast which gives the crane its height. Further the mast is attached to the slewing unit (gear and motor) which allows the crane to rotate. On top of the slewing unit there are three main parts which are namely (i) the long horizontal jib (working arm), (ii) shorter counter jib, and (iii) the operator’s cabin. Tower crane can also be self-erecting type. Self-erecting type tower crane is also called self-assembling or ‘kangaroo’ crane. It lifts itself off the ground using jacks, allowing the next section of the tower to be inserted at ground level or lifted into place by the partially erected crane itself. The crane can thus be assembled without outside help, or can grow together with the building or structure it is erecting.
Tower furnaces – These furnaces conserve floor space by running long strip or strand materials vertically on tall furnaces for drying, coating, curing, or heat treating (especially annealing). In some cases, the load is protected by a special atmosphere, and heated with radiant tubes or by electrical means.
Tow-preg – It is a tow of fibres which has been pre-impregnated with a resin and is typically used in either filament winding or fibre placement operations.
Toxicity – It refers to a material’s ability to release chemicals which harms living organisms, either directly or indirectly by inhibiting metabolic pathways. It is essentially the degree to which a substance is poisonous or harmful. The severity of toxicity depends on the chemical’s dose and potency, as well as the number of cells or organisms affected.
Toxic materials – These materials are substances that can cause harm or damage to living organisms, including humans, when they enter the body or are exposed to. These materials can be poisonous, carcinogenic, or otherwise harmful. They can enter the body through several routes, including inhalation, ingestion, or skin contact.
Toxics release inventory (TRI) – It is an environmental protection programme which tracks the releases and waste management of certain toxic chemicals. It aims to provide the public with information on chemical releases and pollution prevention activities, allowing them to make informed decisions and track industry progress in reducing waste.
Toxic substance – It is a harmful or poisonous substance which can cause acute or chronic effects to a person.
Toxins – These materials refer to substances which are hazardous to human health and the environment and are produced or released by industrial processes. These substances can be chemical or physical hazards, impacting different aspects of human well-being and the environment.
Toyota diffusion (TD) process – It is a method for forming a hard, wear-resistant layer of carbides on the surface of a carbon-containing material, typically steel, using a salt bath. This process utilizes a high-temperature salt bath containing carbide-forming elements (like vanadium, niobium, or chromium) to diffuse these elements into the surface of the substrate, creating a layer of carbides.
Toyota production system (TPS) – It is frequently called lean manufacturing or Just-In-Time (JIT). It is a production philosophy and management system developed by Toyota. Its core principles focus on eliminating waste, maximizing efficiency, and delivering products with the highest quality, at the lowest cost, and in the shortest lead time.
T-peel strength – It is the average load per unit width of adhesive bond line needed to produce progressive separation of two bonded, flexible adherends, under standard test conditions.
TPI – It is the abbreviation for turns per inch. It is a measure of the quantity of twist produced in a yarn, tow, or roving during its processing history. It is also the lead rate of a hoop layer at a specified band width.
Traceability – It is the property of the result of a measurement or the value of a standard whereby it can be related to stated references, usually national or international standards, through an unbroken chain of comparisons all is having stated uncertainties. The concept is often expressed by the adjective traceable. The unbroken chain of comparisons is called a traceability chain. Even though the ISO (International Organization for Standardization) has published (and accepted) the definition listed above, many people have attempted to make this term more meaningful. They feel that the definition is to introduce the aspect of evidence being presented on a continuing basis, to overcome the idea that if valid traceability is achieved, it could last forever. A definition similar to the following one would meet that requirement. Traceability is a characteristic of a calibration or a measurement. A traceable measurement or calibration is achieved only when each instrument and standard, in a hierarchy stretching back to the national (or international) standard was itself properly calibrated and the results properly documented including statements of uncertainty on a continuing basis. The documentation must provide the information needed to show that all the calibrations in the chain of calibrations were appropriately performed.
Trace element – It is an element in a sample which has an average concentration of less than 100 parts per million atoms or less than 100 micro-grams per gram.
Tracer – It is a substance which follows (‘traces’) a physiologic or bio-chemical process. It is a chemical or thermodynamic property of the flow which is conserved during advection. Tracers are materials which are used as markers to show the location of a substance or to follow the pathway of a substance in a chemical reaction or physical process. In composites, tracer is a fibre, tow, or yarn added to a prepreg for verifying fibre alignment and, in the case of woven materials, for distinguishing warp fibres from fill fibres.
Tracer gas– It is a substance which is used to track the movement of fluids, especially air or gas, in a system. It is injected into the fluid and its subsequent behaviour (diffusion, dispersion, velocity) is monitored to understand the flow characteristics of the system. Tracer gases are normally used in leak detection, ventilation studies, and other applications where understanding fluid flow is crucial.
Tracer milling – It is the duplication of a three-dimensional form by means of a cutter controlled by a tracer that is directed by a master form.
Tracing – It refers to the process of copying an existing image or design by drawing over its lines, frequently using a transparent sheet of paper placed on top of the original. It is a method used to reproduce images or transfer them to another surface, and can also be a technique for learning and practicing drawing skills.
Track – It refers to the entire structure upon which trains travel. It is more than just the rails themselves. It encompasses the rails, fasteners, sleepers (or ties), ballast (or slab track), and the underlying subgrade. It is also the mark made by a seal on the surface with which it mates.
Track and trace – It refers to a system which allows the organization to monitor the movement and status of goods throughout the entire supply chain, from raw materials to the end consumer. This involves collecting and analyzing data at several points in the supply chain to gain visibility into the flow of products.
Track gauge – It is the spacing of the two parallel rails on a railway track.
Tracking – It is a term which refers to all actions aimed at following and measuring indicators used to quantify the behaviour of certain variables over time. In the context of marketing, tracking is a technique which makes it possible to evaluate the effectiveness of a specific campaign using several tools. In essence, tracking is a way to evaluate the performance of ongoing activity. In a conveyor system, tracking is the artful operation guiding the conveyor belt along a pre-determined path, akin to a navigator steering a vessel through precise waters.
Tracking pattern – It is the path a seal ring makes when in rubbing contact with the mating ring or seal plate.
Track monitoring – It refers to the periodic measurement of track parameters like gauge, unevenness, alignment, cross level, and twist to assess and maintain the condition of the track. Track parameters themselves describe the relative geometry of the two rails in a three-dimensional system of coordinates. Unevenness, for example, is measured as the undulation of the rail top table, typically measured as the mid-chord offset between two points on the rail.
Track ropes – Track ropes (full locked ropes) have to act as rails for the rollers of cabins or other loads in aerial ropeways and cable cranes. In contrast to running ropes, track ropes do not take on the curvature of the rollers. Under the roller force, a so called free bending radius of the rope occurs. This radius increases (and the bending stresses decrease) with the tensile force and decreases with the roller force.
Traction – In rolling contacts, it is the tangential stress transmitted across the interface. The traction, in general, varies from point to point over the contact area. More generally, traction can denote the force per unit area of contact. In railways, traction refers to the force which propels a train or locomotive, allowing it to move along the track. It is essentially the driving force, achieved through the interaction between the locomotive’s wheels and the rails, and can be generated by electric motors, diesel engines, or steam engines. In the context of electric traction, it describes the systems and processes involved in using electricity to power trains.
Traction battery – It is a battery used to store energy for propelling a wheeled electric vehicle.
Traction current – It is the power supply for wheeled electric vehicles.
Traction motor – It is an electric motor for a wheeled vehicle.
Traction substation – It is a substation which supplies current to a railway, subway or similar electric wheeled transit.
Tractive effort – It refers to the force needed to pull a train or locomotive forward, overcoming resistance from factors like friction, air resistance, and grades.
Tractive force – It is the integral of the tangential surface stress over the area of contact.
Tractor – It is an engineering vehicle which is specifically designed to deliver a high tractive effort (or torque) at slow speeds, for the purposes of hauling a trailer or machinery such as that used in mining or construction.
Trade association – It is an organization founded and funded by the organizations within a specific industry to promote their common interests. Trade associations frequently act as a collective voice, advocating for policies and regulations which benefit their members, and provide resources and support to improve operational practices and stay updated on industry trends.
Trademark – It is a form of intellectual property which consists of a word, phrase, symbol, design, or a combination that identifies a product or service from a particular source and distinguishes it from others.
Trade name – It is the name used by an organization, frequently different from its legal name, to identify its products or services in the market. It is also known as a brand name.
Trade-off – It is a situation normally found in design where more than one functional characteristic of the design is of value to the user. Frequently, it is found that these characteristics oppose one another, and a compromise is to be achieved, e.g., with several materials, increasing the strength reduces fracture toughness, and a trade-off is to be reached. Trade-off studies are best done after gathering data from a sensitivity analysis.
Trade unions – These are independent, membership-based establishments of the employees that represent and negotiate on their behalf. They function in the organization with their presence registered with the management. They give advice when their members have problems at work, represent members in discussions with the management, and help improve wages and working conditions through negotiations. Trade unions also make sure that the statutory requirements are met. Other functions carried out by trade unions are to arrange education and learning opportunities for the employees, promote equal opportunities at work, fight against discrimination and help to ensure a healthy and safe working environment. Several unions also provide services for their members, such as welfare benefits, personal legal help and financial services.
Trading – It is the action or activity of buying and selling goods and services.
Traditional methods – These methods refer to practices, customs, or ways of doing things which have been used for a long time, frequently passed down through generations. They are typically characterized by adherence to established norms and a lack of significant change over time.
Traffic cop – It is a sophisticated sentinel device standing guard, poised to intercept and prevent the undesired impact of cartons as they elegantly make their entrance onto the conveyor stage.
Traffic mark – It is abrasion which results from relative movement between contacting metal surfaces during handling and transit. A dark colour from the abrasively produced aluminum oxide normally is observed. A mirror image of a traffic mark is observed on the adjacent contacting surface.
Traffic marks – Traffic marks are also known as fretting or traffic abrasion. It refers to the dark, abrasive marks which appear on aluminum surfaces because of rubbing or relative movement between contacting metal surfaces. This occurs during handling, transportation, or even in storage. The dark colour is typically caused by the abrasive action producing a dark layer of aluminum oxide.
Trailer – It refers to a vehicle without its own engine which is pulled by another vehicle.
Training and development process – it is any activity which improves upon skills, knowledge and behaviour through both formal and informal training. It enables the organization to adapt to changes which meet the requirements of the customers. It also improves employees’ skills and boosts their morale, thereby making them efficient, reducing waste and operations and increasing productivity. In addition, training and development process brings about reduction in employee turnover and results in minimal supervision. Still, it shortens the time for learning for the new employees, reduces learning costs, and motivates employees to be loyal to the organization.
Training idlers – These idlers are mounted on a mechanical device, actuated by the belt moving against it to make the belt run straight. Training idlers are the guardians of alignment and functionality, ensuring the harmonious centering of the conveyor belt through their diligent oversight and meticulous training.
Trajectory – It is also called also flight path. It is the path which an object with mass in motion follows through space as a function of time. In classical mechanics, a trajectory is defined by Hamiltonian mechanics through canonical coordinates. Hence, a complete trajectory is defined by position and momentum, simultaneously. The mass can be a projectile or a satellite. For example, it can be an orbit, the path of a planet, asteroid, or comet as it travels around a central mass.
Tram – It is a vehicle to haul cars of ore or waste in a mine.
Tramp alloys – These are residual alloying elements which are introduced into steel when unidentified alloy steel is present in the scrap charge to a steelmaking furnace.
Tramp element – It is the contaminant in the components of a furnace charge, or in the molten metal or castings, whose presence is thought to be either unimportant or undesirable to the quality of the casting. It is also called trace element.
Trans-actinides – These are also called super-heavy elements. In the periodic table, these are the set of chemical elements with an atomic number higher than 103, i.e., those heavier than the actinides. The trans-actinides are a subset of the trans-uranic elements.
Transaction costs – These are the expenses incurred during an economic exchange, such as buying or selling a good or service, beyond the price of the item itself. They represent the costs associated with facilitating the exchange, including finding a buyer or seller, negotiating the price, and enforcing the agreement.
Trans-admittance – It is the alternating current (AC) equivalent of trans-conductance.
Trans-boundary pollution – It is pollution which originates in one country but causes environmental damage in another country by crossing borders through air or water pathways. It essentially means pollution which does not stay within the borders of the country where it is generated, but instead spreads to other countries, potentially causing harm to their environments.
Transceiver – It is an apparatus which combines a receiver and transmitter.
Trans-conductance – It is also infrequently called mutual conductance. It is the electrical characteristic relating the current through the output of a device to the voltage across the input of a device. Conductance is the reciprocal of resistance.
Trans-crystalline – It refers to something which is situated within or passing through the crystals of a substance. It is frequently used to describe fractures or cracks which traverse individual crystals, as opposed to following boundaries between them. For example, in the context of corrosion, transcrystalline corrosion is defined as a type of cracking which occurs through the crystal lattice of a material.
Trans-crystalline cracking – It is the cracking or fracturing which occurs through or across a crystal. It is also termed intracrystalline cracking.
Transducer – It is a device which converts energy from one form to another. Normally, a transducer converts a signal in one form of energy to a signal in another form of energy. Transducers are frequently used the boundaries of automation, measurement, and control systems, where electrical signals are converted to and from other physical quantities (energy, force, torque, light, motion, position, etc.). There are two types of transducers namely (i) mechanical transducers which convert physical quantities into mechanical outputs or vice versa, and (ii) electrical transducers which convert physical quantities into electrical outputs or signals.
Transduction – It is the process of converting one form of energy to another form.
Transfer – In tribology, it is the process by which material from one sliding surface becomes attached to another surface, possibly as the result of interfacial adhesion. Transfer is normally associated with adhesion, but the possibility of mechanical inter-locking adherence, without adhesive bonding, exists in certain occurrences. Material can also back transfer to the surface from which it came.
Transfer efficiency – In powder coating, it is the rate at which a powder is deposited on a target per unit of time divided by the gun output.
Transference – It is the movement of ions through the electrolyte associated with the passage of the electric current. It is also called transport or migration.
Transfer facilities – These consist of transportation-related facilities such as loading docks, parking areas, storage areas, or other similar areas where shipments of hazardous waste are temporarily held during the normal course of transportation.
Transfer function – It is the mathematical relation between input and output. It is normally expressed in terms of frequency or complex frequency (s-domain).
Transfer ladle – It is a ladle which can be supported on a monorail or carried in a shank and used to transfer metal from the melting furnace to the holding furnace or from the furnace to the pouring ladles.
Transfer moulding – It is a process for forming and vulcanizing rubber articles by forcing a pre-determined quantity of compound into a closed heated cavity from a heated chamber integral with the mould. In composites, transfer moulding is a method of moulding thermosetting materials in which the plastic is first softened by heat and pressure in a transfer chamber and then forced by high pressure through suitable sprues, runners, and gates into the closed mould for final shaping and curing.
Transfer points – These are meticulously inspected and cleansed junctures where materials gracefully transition between conveyor belts, choreographed to prevent spillage and guarantee an uninterrupted transfer ballet.
Transferred arc – It is a plasma arc established between the electrode and the work-piece during plasma arc welding, cutting, and thermal spraying.
Transfer standard – It is a standard used as an intermediary to compare standards. The term transfer device is to be used when the intermediary is not a standard.
Transfer table – It is the roller table conveyor which transfer the rolling stock from the roughing mill to the finishing mill in a hot strip mill.
Transformation – It refers to a change in the physical state or structure of a metal, typically driven by changes in temperature, pressure, or composition. These transformations can be either phase changes (altering the types of crystalline structures present) or structural changes (altering the arrangement of atoms within a crystalline structure). Transformation is also the altering of fundamental attributes of a system (including value systems; regulatory, legislative, or bureaucratic regimes; financial institutions; and technological or biological systems). In statistics, a transformation is the change in the scale of a variable. Transformations are performed to simplify calculations, to meet specific statistical modelling assumptions, to linearize an otherwise non-linear relation with another variable, to impose practical limitations on a variable, and to change the characteristic shape of a probability distributions of the variable in its original scale.
Transformation hardening – Transformation hardening is a heat treatment process where a metal’s microstructure is altered, primarily through a phase transformation, to increase its hardness and strength. This is achieved by heating the metal to a specific temperature range, holding it there, and then rapidly quenching it (cooling it quickly). Normally, this process involves transforming the metal’s structure from a relatively soft phase (like austenite) to a harder phase (like martensite or bainite). Transformation hardening relies on changes in the crystal structure of the metal. The metal is heated to a temperature where a specific phase (e.g., austenite in steel) becomes stable.
Transformation-induced plasticity (TRIP) – It is a phenomenon, occurring mainly in certain highly alloyed steels which have been heat treated to produce metastable austenite or metastable austenite plus martensite, whereby, on subsequent deformation, part of the austenite undergoes strain-induced transformation to martensite. Steels capable of transforming in this manner, normally referred to as TRIP steels, are highly plastic after heat treatment, but show a very high rate of strain hardening and hence have high tensile and yield strengths after plastic deformation at temperatures between around 20 deg C and 500 deg C. Cooling to 195 deg C may or may not be needed to complete the transformation to martensite. Tempering normally is done following transformation.
Transformation induced plasticity (TRIP) steel – The microstructure of transformation induced plasticity steels is retained austenite embedded in a primary matrix of ferrite. In addition to a minimum of 5 volume percent of retained austenite, hard phases such as martensite and bainite are present in varying amounts. Transformation induced plasticity steels typically need the use of an isothermal hold at an intermediate temperature, which produces some bainite. The higher silicon and carbon content of transformation induced plasticity steels also result in significant volume fractions of retained austenite in the final microstructure. During deformation, the dispersion of hard second phases in soft ferrite creates a high work hardening rate, as observed in the dual phase steels. However, in transformation induced plasticity steels the retained austenite also progressively transforms to martensite with increasing strain, thereby increasing the work hardening rate at higher strain levels. The transformation induced plasticity steel has a lower initial work hardening rate than the dual phase steel, but the hardening rate persists at higher strains where work hardening of the dual phase begins to diminish. The work hardening rates of transformation induced plasticity steels are substantially higher than for conventional high strength steels, providing significant stretch forming. This is particularly useful when designers take advantage of the high work hardening rate (and increased bake hardening effect) to design a part utilizing the as formed mechanical properties. The high work hardening rate persists to higher strains in transformation induced plasticity steels, providing a slight advantage over dual phase in the most severe stretch forming applications.
Transformation ranges – It consists of those ranges of temperature within which austenite forms during heating and transforms during cooling. The two ranges are distinct, sometimes overlapping but never coinciding. The limiting temperatures of the ranges depend on the composition of the alloy and on the rate of change of temperature, particularly during cooling.
Transformation temperature – It is the temperature at which a change in phase occurs. This term is sometimes used to denote the limiting temperature of a transformation range. Table 1 shows transformation temperature which are used for irons and steels.
| Table 1 Symbols for transformation temperature which are used for irons and steels | |
| Accm | In hypereutectoid steel |
| Ac1 | The temperature at which austenite begins to form during heating. |
| Ac3 | The temperature at which transformation of ferrite to austenite is completed during heating |
| Ac4 | The temperature at which austenite transforms to ferrite during heating. |
| Aecm, Ae1, Ae3, Ae4 | The temperatures of phase changes at equilibrium |
| Arcm | In hypereutectoid steel |
| Ar1 | The temperature at which transformation of austenite to ferrite or to ferrite plus cementite is completed during cooling. |
| Ar3 | The temperature at which austenite begins to transform to ferrite during cooling. |
| Ar4 | The temperature at which ferrite transforms to austenite during cooling. |
| Ar’ | The temperature at which transformation of austenite to pearlite starts during cooling. |
| Mf | The temperature at which transformation of austenite to pearlite starts during cooling. |
| Ms (or Ar”) | The temperature at which transformation of austenite to martensite starts during cooling. |
| Note: All these changes, except formation of martensite, occur at lower temperatures during cooling than during heating, and depend on the rate of change of temperature. | |
Transformed beta – It is a local or continuous structure consisting of decomposition products arising by nucleation and growth processes during cooling from above the local or overall beta transus. Primary and regrowth alpha can be present. Transformed beta typically consist of α platelets which may or may not be separate by beta phase.
Transformer – It is a static arrangement of conductors and possibly magnetic materials, which transfers energy by electro-magnetic induction. It is a device which has such characteristics as (i) it transfers electric power from one circuit to another, (ii) it does so without a change of frequency, (iii) it accomplishes this by electro-magnetic induction, and (iv) where the two electric circuits are in mutual inductive influence of each other.
Transformer-board – It is a kind of insulating paperboard used for internal structures of large oil filled power transformers.
Transformer bushings – The two most common types of bushings used on transformers as main lead entrances are solid porcelain bushings on smaller transformers and oil-filled condenser bushings on larger transformers. Solid porcelain bushings consist of high-grade porcelain cylinders through which the conductors pass through. Outside surfaces have a series of skirts to increase the leakage path distance to the grounded metal case. High voltage bushings are normally oil-filled condenser type. Condenser types have a central conductor wound with alternating layers of paper insulation and tin foil and filled with insulating oil. This results in a path from the conductor to the grounded tank, consisting of a series of condensers. The layers are designed for providing around equal voltage drops between each condenser layer.
Transformer impedance – Transformer impedance is defined as the ratio of the voltage drop across the transformer under full-load conditions to the rated current. It is an important parameter which reflects the resistance of the transformer to the flow of electrical current. The impedance of a transformer can be calculated for each winding. However, a rather simple test provides a practical method of measuring the equivalent impedance of a transformer without separating the impedance of the windings.
Transformer oil – It is a hydro-carbon liquid which cools and insulates transformers and other types of electrical apparatus. In addition to dissipating heat because of the losses in a transformer, insulating oil provides a medium with high dielectric strength in which the coils and core are submerged. This allows the transformers to be more compact, which reduces costs. Insulating oil in good condition withstands far more voltage across connections inside the transformer tank than air. An arc jumps across the same spacing of internal energized components at a much lower voltage if the tank has only air. In addition, oil conducts heat away from energized components much better than air.
Transformer oil testing – It is the examination of transformer oil for its insulating strength, dissolved moisture and other properties, to ensure it is still suitable for use.
Transformer polarity – With power or distribution transformers, polarity is important only if the need arises to parallel transformers to gain additional capacity or to hook up three single-phase transformers to make a three-phase bank. The way the connections are made affects angular displacement, phase rotation, and direction of rotation of connected motors. Polarity is also important when hooking up current transformers for relay protection and metering. Transformer polarity depends on which direction coils are wound around the core (clock-wise or counter-clock-wise) and how the leads are brought out. Transformers are sometimes marked at their terminals with polarity marks. Frequently, polarity marks are shown as white paint dots (for plus) or plus-minus marks on the transformer and symbols on the name-plate. These marks show the connections where the input and output voltages (and currents) have the same instantaneous polarity.
Transformers – These are devices which transfer energy from one electrical circuit to another by means of a common magnetic field. In all the cases except auto-transformers, there is no direct electrical connection from one circuit to the other. Transformers are important equipment in power distribution system as well as in power electronic system. They can step-down high voltages in transmission at sub-stations or step-up currents to the needed level at the end-users. Additionally, several functions, for example, isolation, noise decoupling, or phase-shifting can be achieved through transformers. Transformers are highly engineered products, needing sophisticated technical and industry knowledge as well as tailored procurement, design, and testing capabilities. The main components of transformers include a laminated magnetic core, as well as primary and secondary windings. The primary winding is connected to the power source and is where the magnetic flux (a magnetic field-inducing electrical current) is produced in the core by the current and the windings and is constant in all windings.
Transformer tap switch – It is also called tap changer. It is a device which allows for adjusting the voltage output of a transformer without interrupting the load. It is used to regulate voltage by selecting different points (taps) on the transformer’s winding, effectively changing the transformation ratio.
Transforming variables – If there is evidence of marked skewness in a variable, then applying a transformation can make the resulting transformed variable more symmetrical. Transforming skew data was very important 50 years ago, since the analysis was frequently simpler for variables which were symmetrical. This was partly since a normal distribution was then frequently an appropriate model, and much of the statistical inference / modelling depended on the data being from a normal distribution. Recent advances in statistics have led to analyses being (almost as) simple for a wide range of statistical models, some of which are appropriate for modelling skew data. So now it is more important to consider the appropriate statistical model than to assume that data always need to be transformed if they lack symmetry. Transforming data is not ‘cost free’. One is to be beware of transforming when there are zeros in the data. A popular action used to be to add a small arbitrary value to the zeros and then to transform. Analyzing the zeros separately is almost always to be preferred.
Transgranular – It is through or across crystals or grains. It is also called intracrystalline or transcrystalline.
Transgranular cracking – It is cracking or fracturing which occurs through or across a crystal or grain. It is also called transcrystalline cracking.
Transgranular fracture – It is fracture through or across the crystals or grains of a material. It is also called transcrystalline fracture or intracrystalline fracture.
Transgranular stress corrosion cracking (TGSCC) – It is a type of stress corrosion cracking where the cracks propagate through the grains of a material, rather than along the grain boundaries. This means the cracks advance directly across the individual crystalline structures of the material. Transgranular stress corrosion cracking is distinct from intergranular stress corrosion cracking (IGSCC), where cracks follow the grain boundaries.
Transient – It is a momentary deviation in an electrical or mechanical system.
Transient climate experiment – If the forcing is allowed to evolve gradually according to a prescribed emission scenario, the time-dependent response of a climate model can be analyzed. Such an experiment is called a ‘transient climate experiment’.
Transient climate response (TCR) – It is a metric used to assess how much the earth’s climate system warms in response to a doubling of atmospheric carbon di-oxide (CO2) concentration. It is the globally averaged surface air temperature increase, averaged over a 20-year period, centered at the time of carbon di-oxide doubling. Specifically, it is the global mean surface temperature increase after 70 years of a 1 % per year increase in carbon di-oxide.
Transient creep – It is the first stage of creep deformation. It is also known as primary creep.
Transient fluctuations – These fluctuations refer to temporary and non-repeating variations or oscillations in a system. These fluctuations are typically brief and occur for a limited duration, often in the order of microseconds or milliseconds. They can manifest as changes in voltage, current, or other measurable parameters.
Transient heat transfer – It is also known as unsteady-state heat transfer. It is a process where the temperature of a body changes over time. Unlike steady-state heat transfer where temperatures remain constant, transient heat transfer involves variations in temperature with time. This means that the heat flux and temperature field within the system are not stable and are continuously changing.
Transient load – It is a load which changes quickly over a short period of time, rather than being a constant load. Examples include sudden impacts, rapid pressure changes, or fluctuating electrical currents.
Transient response – It is the short-time response of a system to a disturbance.
Transil – It is a brand of transient voltage suppression diode.
Transistor – It is a three terminal solid-state device which is used as an amplifier or switch.
Transition diagram – In tribology, it is a plot of two or more experimental or operating variables which indicates the boundaries between different regimes of wear or surface damage. The IRG (international research group) transition diagram is a plot of normal force (ordinate) against sliding velocity (abscissa), and is used to identify three regions with differing lubrication effectiveness. Several plots have been called transition diagrams, and the context of usage is to be established.
Transition, first order – It is a change of state associated with crystallization or melting in a polymer.
Transition flow – It is the flow of gases under conditions which is intermediate between laminar viscous flow and molecular flow. It refers to a fluid flow state which exists between fully laminar and fully turbulent regimes. It is characterized by a mixture of laminar and turbulent behaviour, where the flow pattern oscillates between the two states. This transition zone is influenced by factors like flow velocity, fluid viscosity, and pipe roughness.
Transition joint – It is a specialized method of connecting dissimilar metals, frequently used when aluminum and steel are involved. It is a bimetallic joint, meaning it involves two different metals, typically used when direct welding of the dissimilar metals is not feasible. These joints are designed to provide a strong, reliable connection while minimizing the negative effects of dissimilar metal welding, such as corrosion or brittle intermetallic compounds. It is an explosively bonded bimetal flat bar which comprises a layer each of steel and marine-grade aluminium normally with an interlayer of pure aluminium. It is used for the on-site welding of aluminium to steel, especially in shipyards and for offshore structures
Transition lattice – It is an unstable crystallographic configuration which forms as an intermediate step in a solid-state reaction such as precipitation from solid solution or eutectoid decomposition.
Transition length – It is the distance between the last fully troughed idler station and the flat driving or discharge pulley. Transition lengths is to be generous in order to minimize the edge tension and thus reducing the safety factor.
Transition metal – It is an element whose atoms naturally occur with incompletely filled ‘d’ sub-shells. These elements are grouped as the so-called d-block elements in the periodic table. Transition metal is a metal in which the available electron energy levels are occupied in such a way which the d-band contains less than its maximum number of ten electrons per atom, for example, iron, cobalt, nickel, and tungsten. The distinctive properties of the transition metals result from the incompletely filled d-levels.
Transition phase – It is a non-equilibrium state which appears in a chemical system in the course of transformation between two equilibrium states.
Transition point – At a stated pressure, it the temperature (or at a stated temperature, the pressure) at which two solid phases exist in equilibrium, i.e., an allotropic transformation temperature (or pressure).
Transition scarp – It is a rib mark generated when a crack changes from one mode of growth to another, as when a wet crack accelerates abruptly from region II (plateau) to region III (dry) of a crack acceleration curve.
Transition structure – In precipitation from solid solution, it is a metastable precipitate which is coherent with the matrix.
Transition temperature – It is an arbitrarily defined temperature which lies within the temperature range in which metal fracture characteristics (as normally determined by tests of notched samples) change rapidly, such as the ductile-to-brittle transition temperature (DBTT). The ductile-to-brittle transition temperature can be assessed in several ways, the most common being the temperature for 50 % ductile and 50 % brittle fracture (50 % fracture appearance transition temperature, or FATT), or the lowest temperature at which the fracture is 100 % ductile (100 % fibrous criterion). It is sometimes used to denote an arbitrarily defined temperature within a range in which the ductility changes rapidly with temperature.
Transition zone – It is the meticulously maintained zone where the conveyor belt gracefully transitions from an incline to a horizontal path, a well-tuned area preventing material spillage and ensuring the smooth harmonious operation of the conveyor.
Transit time method – It is a basic method for ultrasonic flow measurement. In this method, the measurement value is independent of the sound velocity, the pressure, the temperature and the density of the measuring medium. An essential requirement for the transit time measurement is the acoustic transparency of the measuring medium. There is required to be few solid particles or gas bubbles in the measuring medium.
Translational motion – It is the movement of an object from one point to another, without any rotation. It is like sliding an object across a surface. Rotational motion is the movement of an object around a fixed axis or point, essentially turning or spinning.
Translator – It is a solid state, three terminal device which allows amplification of signals and can be used for switching and control. The three terminals are called the emitter, base and collector.
Transmission – It is also called a gearbox. It is a mechanical device which uses a gear set (two or more gears working together) to change the speed, direction of rotation, or torque multiplication / reduction in a machine. Transmissions can have a single fixed-gear ratio, multiple distinct gear ratios, or continuously variable ratios. Variable-ratio transmissions are used in all sorts of machinery, especially vehicles. Transmission is also the process of getting a signal from one point to another.
Transmission cable – It is a specialized cable or system of conductors designed to transmit electrical signals or energy over a distance, frequently considering the wave-like nature of the signal. It is essentially a pathway for electro-magnetic waves or electrical current, acting as a link between a transmitter and a receiver.
Transmission chain – It is the observed and lubricated network of conveyor chains, ensuring wear prevention, friction reduction, and orchestrating the fluid, seamless movement of materials.
Transmission control protocol / internet protocol (TCP / IP) – It is a suite of communication protocols used to enable devices to communicate across the internet and other networks. It provides the foundational protocols for reliable data transmission, including methods for ensuring data delivery and error correction. Essentially, transmission control protocol / internet protocol is the set of rules which allows computers to talk to each other on the internet.
Transmission efficiency – It refers to the ratio of output power to input power in a system, essentially quantifying how much power is effectively transferred from one point to another. It is frequently expressed as a percentage and reflects the degree to which a system avoids energy loss during the transmission process, e.g., in an electrical transmission line, the efficiency is the power delivered at the receiving end divided by the power sent from the source. In a mechanical system, like a gear transmission, transmission efficiency is the power transferred to the output shaft divided by the power input to the system.
Transmission electron microscope – It is a microscope in which the image-forming rays pass through (are transmitted by) the sample being observed.
Transmission electron microscopy (TEM) – It is a technique which uses a beam of high-energy electrons to create a magnified image of a sample, revealing its internal structure at the atomic level. It is essentially an advanced form of microscopy which utilizes electrons instead of light to produce images. The resolution of transmission electron microscopy is considerably higher than that of light microscopes, allowing for detailed visualization of nanoscale features.
Transmission grating – It is a transparent diffraction grating through which light is transmitted.
Transmission line – Transmission lines are also known as tie lines. They connect the individual substations with each other. Electric power is transmitted at high voltage (110 kilovolts or above) to reduce the energy lost in long-distance transmission. Power is normally transmitted through overhead power lines. Underground power transmission has a considerably higher cost and greater operational limitations but is sometimes used in urban areas or sensitive locations. Transmission lines normally use high voltage three-phase alternating current. High voltage direct current (HVDC) technology is used for greater efficiency in very long distances (typically several hundreds of kilometers). A high voltage direct current electric power transmission system is also called a power superhighway or an electrical superhighway. It uses direct current for electric power transmission, in contrast with the more common alternating current transmission systems. Majority of the high voltage direct current direct current links use voltages between 100 kilovolts and 800 kilovolts.
Transmission loss – It refers to the decrease in signal intensity or power as it travels through a medium or system. This loss can be caused by factors like absorption, reflection, or conversion of energy into other forms, such as heat.
Transmission method – It is a method of X-ray or electron diffraction in which the recorded diffracted beams emerge on the same side of the specimen as the transmitted primary beam.
Transmission network – It is a system which transports electrical power from generation source to the point where it is needed, normally over long distances. It typically consists of high-voltage transmission lines and substations. In essence, it is a network designed to efficiently move electricity from power plants to substations, where it is then distributed to end-users at lower voltages.
Transmission oil – It is the oil which is used for transmission of hydraulic power. It is also the oil which is used to lubricate automobile transmission systems.
Transmission pipe – It is also known as line pipe. It is welded or seamless pipe presently produced in sizes ranging from 3 millimeters nominal to 1.2 meters actual outside diameter (OD) and is used principally for conveying gas or oil. Transmission pipe is produced with ends plain, threaded, bevelled, grooved, flanged, or expanded, as required for different types of mechanical couplers or for welded joints. When threaded ends and couplings are needed, recessed couplings are used.
Transmission substation – It is a facility within an electric power grid which connects transmission lines, frequently stepping up or down voltage to facilitate long-distance power transfer. These substations act as ‘junctions’ in the high-voltage transmission network, allowing electricity to flow between different circuits or lines.
Transmission system – It is a mechanism which transmits power or signals from one point to another. In mechanical systems (e.g., automotive), a transmission system, frequently referred to as a gearbox, is a device which transfers the engine’s power to the wheels, allowing the vehicle to move. It does this by changing the speed and torque of the engine’s rotation, enabling the vehicle to accelerate, decelerate, and handle different driving conditions. In electrical systems, a transmission system in electrical power refers to the network which carries electrical energy from generating sources to distribution systems, frequently over long distances. This system typically involves high-voltage transmission lines, either overhead or underground, to deliver large quantities of power efficiently. In tele-communications, a transmission system is a communication system which transmits signals from one place to another. These signals can be electrical, optical, or radio waves. The goal is to transmit data accurately and efficiently, using different technologies like copper cables, fibre optics, and wireless communication. In general, a transmission system involves (i) an input source, i.e., the power source or signal source, (ii) a transmission medium, i.e., the means by which the power or signal is carried, and (iii) an output destination, i.e., the point where the power or signal is received.
Transmission system operator – It is the organization which runs the transmission system between sources of power and distribution substations.
Transmission towers – Transmission towers are the most visible component of the power transmission system. They are used in high voltage alternating current and DC systems. A transmission tower is normally a tall steel structure. Its function is to keep the high-voltage conductors (power lines) separated from their surroundings and from each other. A wide variety of tower shapes, sizes, and designs exist which normally use an open lattice work or a tubular structure. Transmission towers are normally very tall with minimum height ranging from 10 metres to 50 metres and cross arms as much as 30 metres wide. The height of the tower is the sum of the minimum permissible ground clearance, maximum sag, vertical spacing between conductors, and vertical clearance between earth wire. In addition to steel, other materials can be used, including concrete and wood. There are four major categories of transmission towers. They are suspension, terminal, tension, and transposition. Some transmission towers combine these basic functions. The transmission towers are to be designed to carry three (or multiples of three) conductors. The towers are normally made of steel lattices or trusses. The insulators are either glass or porcelain discs assembled on strings or on long rods whose lengths are dependent on the line voltage and environmental conditions. Typically, one or two ground wires, also called ‘guard’ wires, are placed on top to intercept lightning and harmlessly divert it to ground. Towers for high and extra high voltage are normally designed to carry two or more electric circuits.
Transmittance – It is the ratio of the light intensity transmitted by a material to the light intensity incident upon it. In emission spectro-chemical analysis, the transmittance of a developed photographic emulsion, including its film or glass supporting base, is measured by a micro-photometer. In absorption spectroscopy, the material is the sample.
Transmitter – It is an apparatus which prepares a signal for emission into some medium, such as a radio transmitter or a sonar transmitter. It is a device translating the signal produced by a primary sensing element (PSE) into a standardized instrumentation signal such as 4-20 mA DC electric current, and field bus digital signal packet, etc. The standardized signal is then conveyed to an indicating device, a controlling device, or both.
Trans-passive region – It is the region of an anodic polarization curve, noble to and above the passive potential range, in which there is a significant increase in current density (increased metal dissolution) as the potential becomes more positive (noble).
Trans-passive state – It is the state of anodically passivated metal characterized by a considerable increase of the corrosion current, in the absence of pitting, when the potential is increased. It is also the noble region of potential where an electrode shows a higher than passive current density.
Transpiration – It is the evaporation of water vapour from the surfaces of leaves through stomata.
Transport, air pollution – It consists of the horizontal or vertical displacement of a pollutant from its emission source which can be carried through the atmosphere over some distance.
Transportation – It is the act and / or means for moving people and goods.
Transportation engineering – It is also called transport engineering. It is the application of technology and scientific principles to the planning, functional design, operation and management of facilities for any mode of transportation to provide for the safe, efficient, rapid, comfortable, convenient, economical, and environmentally compatible movement of people and goods transport.
Transport gasifiers – These are dry fed non-slagging gasifiers. The transport gasifier is based upon the hydrodynamic flow field. It has excellent gas-solids contact and very low mass transfer resistance between gas and solids. It has a highly turbulent atmosphere which allows for high coal throughput and high heat release rates at a low temperature that avoids problems with slag handling and liner erosion.
Transport integrated gasification (TRIG) technology – It is designed to process reactive low rank coals, including those with up to 50 % ash and high moisture content, and can be operated with steam and either air or oxygen as the gasification medium. Air-blown operation is preferable for power generation, while oxygen blown operation is better suited for syngas production. The system comprises a circulating gasifier, which consists of a mixing zone, riser, disengager, cyclone, standpipe, loop seal, and J-leg. This is designed to operate at high solids circulation rates and gas velocities, resulting in higher throughput, C conversion and efficiency. The raw syngas is formed in the riser portion of the unit, from which laden with unreacted solids it passes through a series of cyclones where the solids are removed. The ash material is recirculated through the riser to allow unconverted carbon to be utilized and to provide heat to the gasifier. As ash accumulates in the down comer, it is discharged from the unit. The gasifier operates at moderate temperatures and below the melting point of ash, which can increase the equipment reliability and availability. The latter is enhanced by the use of a downstream particulate filter, which eliminates water scrubbing and significantly reduces plant water consumption and effluent discharge.
Transport winds – These winds are a measure of the average rate of the horizontal movement of air within the mixing layer.
Trans-uranic elements – These are known as also trans-uranium elements. The set of chemical elements with an atomic number higher than 92, i.e., occurring after uranium in the periodic table. None of the trans-uranic elements are stable in naturally occurring conditions.
Trans-uranics – These are elements which are higher than Uranium in the Periodic table. Several waste products from nuclear fission are trans-uranics. All these elements are unstable and radioactive. The highest element currently known is Ununoctium (Uuo) and has an atomic number of 118.
Transverse bow – It is the curvature across the rolling direction of sheet or plate.
Transverse corner cracks – These are a type of defect which typically appear on the corners of steel slabs during the continuous casting process. These cracks are perpendicular to the slab’s width and can lead to significant issues in the subsequent rolling process.
Transverse cracks – These cracks normally appear due to the tensions in the longitudinal direction of the strand. The transverse cracks are normally ground within the permissible limits provided they are not deep. These cracks appear due to (i) the thermal stresses, (ii) variation in the meniscus level, (iii) presence of segregation at the bottom of oscillation mark, and (iv) friction of the strand in the mould.
Transverse direction – It is literally, ‘across’, normally signifying a direction or plane perpendicular to the direction of working. In rolled plate or sheet, the direction across the width is frequently called long transverse while the direction through the thickness is called short transverse.
Transverse electric (TE) mode – It is a mode of electro-magnetic wave propagation where the electric field vector is perpendicular (transverse) to the direction of propagation. In a waveguide, transverse electric modes are characterized by having no electric field component along the direction of propagation, but the magnetic field can have components in all three directions.
Transverse electro-magnetic (TEM) waves – These are electro-magnetic waves where the electric and magnetic fields are perpendicular to each other and also perpendicular to the direction of wave propagation. This means the oscillations of the electric and magnetic fields occur at right angles to the wave’s movement.
Transversely isotropic – It is a term describing a material showing a special case of orthotropy in which properties are identical in two orthotropic dimensions but not the third. It also means having identical properties in both transverse directions but not in the longitudinal direction.
Transverse magnetic (TM) mode – In electro-magnetism, it is a type of electro-magnetic wave propagation where the magnetic field is perpendicular to the direction of propagation, while the electric field can have components in the transverse and longitudinal directions. It is also sometimes referred to as E-mode or P-polarization.
Transverse mode of electromagnetic radiation – It is a particular electro-magnetic field pattern of the radiation in the plane perpendicular (i.e., transverse) to the radiation’s propagation direction. Transverse modes occur in radio waves and microwaves confined to a wave-guide, and also in light waves in an optical fibre and in a laser’s optical resonator. Transverse modes occur because of boundary conditions imposed on the wave by the waveguide. For example, a radio wave in a hollow metal wave-guide is required to have zero tangential electric field amplitude at the walls of the wave-guide, so the transverse pattern of the electric field of waves is restricted to those that fit between the walls. For this reason, the modes supported by a wave-guide are quantized.
Transverse reinforcement – It is an additional layer of polyamide cords for increased rip and impact resistance.
Transverse rib – It is a rib on the surface of the steel reinforcement bar other than a longitudinal rib.
Transverse rib flank inclination angle – It is the angle of the rib flank measured perpendicular to the longitudinal axis of the rib.
Transverse rib inclination angle – It is the angle between the axis of the transverse rib and the longitudinal axis of the steel reinforcement bar.
Transverse rigidity – It is the resistance to belt deformation in the belt crosswise direction.
Transverse rolling – It is used for producing preforms or finish forgings from round billets. In this type of rolling, a round billet is inserted transversely between two or three rolls, which rotate in the same direction and drive the billet. The rolls, which hold replaceable die segments with appropriate impressions, make one revolution while the work piece rotates several times in the opposite direction. Hence, the transverse rolling method can form axially symmetrical shafts with complex geometry in one operation.
Transverse rolling machine – It is the equipment for producing complex preforms or finished forgings from round billets inserted transversely between two or three rolls which rotate in the same direction and drive the billet. The rolls, carrying replaceable die segments with appropriate impressions, make several revolutions for each rotation of the work-piece. The transverse rolling machines are suitable for automatic production, using bar stock automatically fed to the rolls through an induction heating unit. There are two main types of transverse rolling machines namely (i) the two- or-three-roll machine, and (ii) a transverse rolling machine which uses two straight wedge-shaped tools.
Transverse rolling mills – These types of rolling mills are also called cross rolling or roll forging mills. These mills use circular wedge rolls. Heated bar is cropped to length and fed in transversely between rolls. Rolls are revolved in one direction.
Transverse rupture strength (TRS) – It is the stress, calculated from the bending stress formula, needed to break a powder metallurgy sample of a given dimension. The sample is supported near its ends with a load applied midway between the fixed centre-line of the supports. From the value of the break load, the transverse rupture strength (TRS) can be calculated using TRS = (3F x L)/(W x Hsquare), where ‘F’ is the load at fracture, ‘L’ is the span between supports, and ‘W’ and ‘H’ are the width and height of the test bar respectively.
Transverse strain – It is the linear strain in a plane perpendicular to the loading axis of a sample.
Transverse surface cracks – These are discontinuities which run perpendicular (roughly 90-degree) to the main direction or centre-line of a surface or object, frequently appearing on the surface. They are essentially cracks which extend across the material’s cross-section.
Transverse wave – It is a wave which oscillates perpendicularly to the direction of the wave’s advance. In contrast, a longitudinal wave travels in the direction of its oscillations. All waves move energy from place to place without transporting the matter in the transmission medium if there is one. Electro-magnetic waves are transverse without requiring a medium.
Trap – It is a receptacle for the collection of undesirable material.
Trapped air – It is the air which is enclosed in a product or between a mould surface and a product during vulcanization.
Trapped die forging – It is also called closed die forgings. These are made in cavity dies which, when closed together, trap the metal being forged causing it to flow and fill the cavity shape. Excess metal is exited from the die in the form of flash which is subsequently removed by hot trimming after forging.
Trash – It is dry solid waste material. It is also known as garbage, rubbish, or refuse, is defined as discarded materials that humans no longer find useful or want to keep. It encompasses a wide range of items, including food waste, packaging, paper, plastics, and electronic devices. The process of trash management involves collection, transportation, and disposal, often through methods like landfills, incineration, or recycling.
Trash conveyor – It is the virtuoso conveyor system which designed specifically to process and transport the silent aftermath of emptied boxes, providing a stage for their post-performance voyage.
Travelling – It is the movement of the stacker along the length of the stockpile. Bogies on which the stacker is mounted move the stacker on the rail track along the storage yard.
Traveling standard – It is a standard, sometimes of special construction, intended for transport between locations. Example is a portable battery-operated cesium frequency standard.
Travelling-wave tube – It is a type of microwave amplifier vacuum tube.
Traverse speed – It is the lineal velocity at which the torch is passed across the substrate during the thermal spraying operation.
Tray – In a distillation column, a tray is a horizontal plate placed at regular intervals inside the column, designed to improve the contact between rising vapour and descending liquid. Trays facilitate efficient separation of components by providing stages for vapour-liquid equilibrium and promoting mass transfer between the phases. They are a key component in tray columns, which are a common type of distillation equipment. Trays create multiple stages of contact between the rising vapour and descending liquid, allowing for more complete separation based on boiling points.
Trays – They are used for ore beneficiation. They are pinched sluice type gravity separators. The pinched sluice is basically an inclined slope, over which a slurry containing particles of different specific gravities are made to flow. Because of the occurrence of the gravitational and frictional forces, and a narrowing of the sluicing deck (pinching), segregation occurs with the finer heavier particles migrating to the bottom of the flowing film and the lighter coarser particles to the top. By means of a slot (concentrate off-take) near the end of sluice the fine heavy particles are removed from the light coarser particles stream, which passes over the slot and discharges at the end. Trays have several variations. They normally consist of multiple feed points per unit, with several stages (e.g., rougher / cleaner / scavenger) in each unit. The advantages of trays include (i) open for visual inspection, adjustment and cleaning, and (ii) high feed density (63 % solids) so low volume-pumping is needed. Disadvantages include (i) unwieldy because of large space requirement, (ii) low upgradation ratio (typically 3:1), (iii) controlled specific gravity of the feed is needed, (iv) low recovery of fines, (v) feed needs screening, (vi) low tolerance for slimes, (vii) there are multiple feed points and separating surfaces, and (viii) needs wash water for the density control during cleaner stages.
Tread plates – These are the elegant diamond-clad steel filler plates, gracing the gaps between rollers on roller conveyor, contributing both functionality and aesthetic finesse.
Treat – It means to apply any method, technique, or process (including neutralization and stabilization) which is designed to change the physical, chemical, or biological character or composition of a substance, including water.
Treated waste-water – It is the effluent / discharge from waste-water treatment plant which meets the quality outlined in the waste-water treatment plant approval prior to discharge to the receiving environment or the quality specified for reuse.
Treated water – It is the water which has been chemically treated to make it suitable for boiler feed.
Treatment – It normally refers to processes which modify the properties of a metal or alloy, frequently by altering its micro-structure or surface chemistry. These treatments can be broadly categorized as heat treatments, which involve heating and cooling to achieve desired properties, and surface treatments, which focus on modifying the surface of the metal.
Treatment, storage, and disposal facility (TSDF) – It is a facility which manages hazardous waste by storing, treating, and ultimately disposing of it. This facility plays a crucial role in ensuring that the hazardous waste is handled safely and responsibly, protecting both the environment and human health.
Treatment, waste-water – It refers to the process of purifying or modifying waste-water to remove contaminants, making it suitable for reuse, discharge, or disposal without harming the environment or human health. This process aims to convert waste-water into an effluent which meets specific quality standards before it is released back into the water cycle or reused for other purposes.
Trees – It is visible projections of electro-deposited metal formed at sites of high current density.
Trembler coil – It is a kind of high-voltage coil which includes an interrupting mechanism, formerly used in automobile ignition systems.
Trench – It is a long, narrow excavation dug through overburden, or blasted out of rock, to expose a vein or ore structure.
Trend – It is the pattern of gradual change in a condition, output, or process or an average or general tendency of a series of data points to move in a certain direction over time, represented by a line or curve on a graph. It is the direction, in the horizontal plane, of a linear geological feature, such as an ore zone, measured from true north. In the context of engineering and data analysis, trend refers to a discernible pattern or direction of change in a dataset over time. It is a long-term movement or inclination, frequently observed in time series data, which can be upward, downward, or flat.
Trepanning – It is a machining process for producing a circular hole or groove in solid stock, or for producing a disk, cylinder, or tube from solid stock, by the action of a tool containing one or more cutters (normally single-point) revolving around a centre.
Tresca yield criterion – It consists of prediction of yielding in ductile materials when the maximum shear stress on any plane reaches a critical value, t = tc.
TRIAC – It is abbreviation for ‘triode for alternating current’. It is a variation of the thyristor which can pass bi-directional (alternating current) current.
Triangle – It is a polygon with three corners and three sides, one of the basic shapes in geometry. The corners, also called vertices, are zero-dimensional points. It is one of the basic shapes in geometry. The corners, also called vertices, are zero-dimensional points while the sides connecting them, also called edges, are one-dimensional line segments. A triangle has three internal angles, each one bounded by a pair of adjacent edges. The sum of angles of a triangle always equals a straight angle (180-degree).
Triangle wave – It is a wave-form composed of straight-line segments which extend from minus peak to plus peak.
Triangular cross-section – It is the shape formed when a 3-D object is sliced, or intersected, by a plane, and the resulting shape is a triangle. This ‘slice’ creates a 2-D representation of the object’s internal structure, showing how it changes along the axis of the cut.
Triangular gear – A pair of triangular gears has three lobes or high points on the perimeter, rather than the two lobes in elliptical bi-lobe gears. Hence, triangular gears deliver per revolution six periods of speed increase or decrease rather than four.
Triaxiality – In a triaxial stress state, it is the ratio of the smallest to the largest principal stress, all stresses being tensile.
Triaxiality factor – It is a dimensionless parameter which characterizes the state of stress at a point within a material under load. It is defined as the ratio of the hydrostatic (mean) stress to the equivalent (von Mises) stress. In essence, it quantifies the balance between the hydrostatic compression / tension and the deviatoric (shear) stress components.
Triaxial stress – It is a state of stress in which none of the three principal stresses is zero.
Tribo- – It is a prefix indicating a relationship to interacting surfaces in relative motion.
Tribo-chemical wear – In tribo-chemical wear, the wear process is dominated by chemical reactions in the contact and the material is therefore consumed. Here, the environmental conditions in combination with mechanical contact mechanisms are of great importance. The chemical action, such as diffusion or solution, is not a wear mechanism on its own but is always in combination and interaction with other wear mechanisms. It may be more correct to talk about different mechanical wear mechanisms and consider the chemical effects as an additional influence parameter which changes the material properties of the surface in contact.
Tribo-chemistry – It is the part of chemistry dealing with interacting surfaces in relative motion. Tribo-chemistry broadly encompasses such areas as lubricant chemistry, changes in reactivity of surfaces because of the mechanical contact, oxidative wear, and other phenomena.
Tribo-electrostatic belt separator – In it the material is fed into the thin gap 9 millimeters to 15 millimeters between two parallel planar electrodes. The particles are tribo-electrically charged by inter-particle contact. For example, in the case of an iron sample comprising mainly hematite and quartz mineral particles, the positively charged (hematite) and the negatively charged (quartz) are attracted to opposite electrodes. The particles are then swept up by a continuous moving open-mesh belt and conveyed in opposite directions. The belt moves the particles adjacent to each electrode toward opposite ends of the separator. The counter current flow of the separating particles and continual tribo-electric charging by particle-particle collisions provides for a multi-stage separation and results in excellent purity and recovery in a single-pass unit. The belt allows for processing on fine and ultra-fine particles including particles smaller than 20 micrometres, by providing a method to continuously clean the surface of the electrodes and remove the fine particles, which otherwise adhere to the surface of the electrodes. The high belt speed also enables throughputs up to 40 tons per hour on a single separator by continuously conveying material out of the separator. By controlling different process parameters, the device allows for optimization of mineral grade and recovery.
Tribo-element – It is a solid body which is bounded by one or more tribo-surfaces and which resides within a tribo-system. This term is frequently associated with H. Czichos, whose systems approach to tribology identified tribo-elements, e.g., in a pin-on-disk tribo-system, the pin is one tribo-element and the disk is another.
Tribo-film formation – The high local temperatures and pressures obtained in the surface contact when two bodies are sliding against each other results in local shear deformation and fracture of the surfaces. The locally high temperatures may accelerate chemical reactions or melt the surfaces locally and wear occurs. However, these conditions do not necessarily have to be only destructive for the surfaces but can make it possible to form tribo-film with new tribological properties. Normally, tribo-films are divided into two groups namely transformation type tribo-film and deposition type tribo-film. Both are changing the surface topography, chemistry and mechanical properties. In the formation of the transformation type tribo-film, transformation of the original surface is obtained by plastic deformation, phase transformation, diffusion etc. without any material transfer. On the contrary the deposition type tribo-film is only obtained by material transfer, i.e. by molecules from the counter surface, the environment or by wear debris. Accordingly, the surface topography, chemical reactivity and adherence may influence on the formation of a tribo-film.
Tribologist – Tribologist is a specialist or expert in the field of tribology. Tribology is the study of interacting surfaces in relative motion, specifically focusing on friction, lubrication, and wear. Tribologists work in several industries to improve the efficiency and lifespan of mechanical systems by finding solutions to reduce friction, wear, and energy consumption.
Tribology – It is the study of ‘rubbing’, or ‘the study of things which rub’. Tribology is the science and technology of interacting surfaces in relative motion. It is the study of (i) friction, (ii) wear, and (iii) lubrication. It is the science and technology of interacting surfaces in relative motion and is commonly known as the study of friction, wear and lubrication. It is the science and technology of friction lubrication and wear and is of considerable importance in material and energy conservation. It is an old knowledge of great importance when it comes to everything in movement but as a scientific discipline tribology is rather new. It is also the science concerned with the design, friction, lubrication, and wear of contacting surfaces which move relative to each other (as in bearings, cams, or gears, for example).
Tribometer – It is an instrument or testing rig to measure normal and frictional forces of relatively moving surfaces. It is also a device constructed for or capable of measuring the friction, lubrication, and wear behaviour of materials or components.
Tribo-physics – It is that part of physics which deals with interacting surfaces in relative motion.
Tribo-science – It is the scientific discipline which is devoted to the systematic study of interacting surfaces in relative motion. Tribo-science includes the scientific aspects of tribo-chemistry , tribo-physics, contact mechanics, and materials and surface sciences as related to tribology.
Tribo-surface – It is a solid surface whose intermittent, repeated, or continuous contact with another surface or surfaces, in relative motion, results in friction, wear, and / or surface damage. The surface of a body subjected to a catastrophic collision is not to be normally considered a tribo-surface since significant damage to the entire body is involved.
Tribo-system – It is a system which consists of at least two contacting bodies and any environmental factor that affects their interaction. It is a physical system where interacting surfaces are in relative motion, and its behaviour is influenced by factors like friction, wear, and lubrication. It is essentially a collection of components in contact, along with their environment, which interact to perform a technical function. Tribo-systems are the fundamental objects of study in the field of tribology.
Tribo-technology – It is the aspect of tribology which involves engineering application of tribo-science and the design, development, analysis, and repair of components for tribological applications.
Tri-calcium aluminate – Its chemical formula is 3CaO·Al2O3 (C3A). It is the most basic of the calcium aluminates. Its melting point is 1,542 deg C and density is 3.064 grams per cubic centimeters.
Tri-chloro-ethylene (TCE) – It is a stable, low boiling-point liquid which is toxic if inhaled. It is a non-flammable, colourless liquid chemical compound with the chemical formula C2HCl3. It is used as a solvent or metal degreasing agent and in several industrial applications.
Trickling filter– It is a waste-water treatment system where micro-organisms attached to a media (like rocks or plastic) are used to remove organic matter from waste-water. The waste-water is distributed over the media, and as it trickles through, microorganisms growing as a bio-film degrade the organic pollutants.
Triclinic – It means having three axes of any length, none of the included angles being equal to one another or equal to 90-degree.
Triethanolamine (TEA) – It is a chemical compound belonging to the family of ethanol-amines. It is a viscous, colourless to pale yellow liquid with a mild ammonia-like odour. It is a tertiary amine, meaning it has three alcohol groups (–OH) attached to a nitrogen atom. Triethanolamine is derived from the reaction of ethylene oxide and ammonia.
Trigger – It a small device which releases a spring or catch and so sets off a mechanism.
Trigger circuit – It is the circuit used to gate a thyristor which causes it to conduct current.
Triggered capacitor discharge – It is a high-voltage electrical discharge used in emission spectroscopy for vapourization and excitation of a sample material. The energy for the discharge is obtained from capacitors which are charged from an alternating current or direct current electrical supply. Each discharge can be either oscillatory, critically damped, or overdamped. It is initiated by separate means and is extinguished when the voltage across the analytical gap falls to a value which no longer is sufficient to maintain it.
Trigger transformer – It is a transformer which generates a pulse to initiate some other device, such as a thyristor or a flash tube.
Trigonal crystal system – It is a classification for crystalline solids characterized by a three-fold rotational symmetry axis. It is also known as the rhombohedral system and is sometimes considered a sub-division of the hexagonal system. This system is defined by three equal axes inclined at 120-degree to each other, and one perpendicular axis.
Trim – It is the internal components of a valve which modulate the flow of the controlled fluid. In a globe valve body, trim typically includes closure member, seat ring, cage, stem, and stem pin. Trim is also the ancillary boiler components, like water level controls, pressure controls, and temperature controls.
Trimean (TM) – It is also called Tukey’s trimean. It is a measure of a probability distribution’s location defined as a weighted average of the distribution’s median and its two quartiles, TM = (Q1+2Q2+Q3)/4. This is equivalent to the arithmetic mean of the median and the midhinge, TM = TM=12(Q2+Q1+Q32)1/2[Q2+(Q1+Q3)/2]. The name Trimean has given its name to a set of techniques called exploratory data analysis.
Tri-metal bearing – It is a bearing consisting of three layers. Tri-metal bearings are normally made of bronze with a white metal facing and a steel backing.
Trim inclusion – It means edge trimming accidentally wound into a roll of foil.
Trimmer– In light-frame construction, a trimmer is a timber or metal beam (joist) used to create an opening around a stairwell, skylight, chimney, and the like. Trimmers are installed parallel to the primary floor or ceiling joists and support headers, which run perpendicular to the primary joists. It can also refer to a jack stud which supports a header above a window or door opening. Trimmer is also a miniature adjustable electrical component. It is meant to be set correctly when installed in some device, and never seen or adjusted by the device’s user. Trimmers can be variable resistors (potentiometers), variable capacitors, or trimmable inductors. They are common in precision circuitry components, and need to be adjusted when the equipment is serviced.
Trimmer blade – It is the portion of the trimmers through which a forging is pushed to shear off the flash.
Trimmer die – It is the punch press die which is used for trimming flash from a forging.
Trimmer punch – It is the upper portion of the trimmer which contacts the forging and pushes it through the trimmer blades. The lower end of the trimmer punch is normally shaped to fit the surface of the forging against which it pushes.
Trimmers – It is the combination of trimmer punch, trimmer blades, and perhaps trimming shoe which is used to remove the flash from the forging.
Trimming – In forging, it is also removing any parting-line flash or excess material from the part with a trimmer in a trim press. It can be done hot or cold. In drawing, it is shearing the irregular edge of the drawn part. In casting, it is the removal of gates, risers, and fins. Trimming in a lathe (using a cutting tool), roll trimming in a lathe, rotary shearing, die trimming (regular and pinch), and trimming on special machines are the techniques normally used for trimming drawn work-pieces.
Trimming press – It is a power press suitable for trimming flash from forgings.
Trimming shoe – It is the holder used to support trimmers. Sometimes it is called trimming chair.
Trim, soft-seated – It is the valve trim with an elastomeric, plastic, or other readily deformable material used either in the closure component or seat ring to provide tight shutoff with minimal actuator forces.
Tri-nitro-toluene (TNT) – It is a pale yellow, solid organic nitrogen compound used mainly as an explosive, prepared by stepwise nitration of toluene. Since tri-nitro-toluene melts at 82deg C and does not explode below 240 deg C, it can be melted in steam-heated vessels and poured into casings.
Triode – It is an electron device, nearly always a vacuum tube, which has three active electrodes.
TRIP aided bainitic ferrite (TBF) steel – This steel is also a low alloy grade which can be produced by existing heat treatment facilities. Its key component is stable retained austenite. TRIP aided bainitic ferrite steels of strength ranging from 980 newtons per square millimeter 1,470 newtons per square millimeter have been developed. Cold forming techniques to overcome spring-back and excessive necking as well as spot weld nuggets have been developed for TBF steel having strength 1180 N/sq mm. TRIP aided bainitic ferrite steel of strength 1,180 newtons per square millimeter is being used in A-pillars and B-pillars as well as on rocker reinforcements in some car models. In some models, TRIP aided bainitic ferrite steels constitute presently 4 % of the body in white. Some car manufacturers are planning to increase the use of cold formed, ultra-high strength steels up to 25 % in near future.
Triple-action press – It is a mechanical or hydraulic press having three slides with three motions properly synchronized for triple-action drawing, redrawing, and forming. Normally, two slides i.e., the blank-holder slide and the plunger, are located above and a lower slide is located within the bed of the press.
Triple bond – It is a bond which involves the covalent sharing of three pairs of electrons (e.g., the diatomic nitrogen molecule, N2, is composed of two nitrogen atoms linked by a triple bond).
Triple bottom line (TBL) – It is an approach which expands the traditional focus on financial profit to include social and environmental impacts. It is a sustainability framework which considers ‘people, planet, and profit’, essentially evaluating the organizational performance in three dimensions namely social, environmental, and financial. Triple bottom line approach focuses on fiscal responsibility, environmental responsibility, and social responsibility.
Triple curve – In a pressure- temperature (P-T) diagram, it is a line representing the sequence of pressure and temperature values along which two conjugate phases occur in univariant equilibrium.
Triple pin-on-disk test – It is a specific type of pin-on-disk tribometer test where three pins are used instead of a single pin, allowing for more complex wear and friction studies.
Triple point – It is a point on a phase diagram where three phases of a substance coexist in equilibrium. It is the intersection of the boundaries of three adjoining grains, as observed in a metallographic section.
Tripod – It is a portable three-legged frame or stand, used as a platform for supporting the weight and maintaining the stability of some other object. The three-legged (triangular stance) design provides good stability against gravitational loads as well as horizontal shear forces, and better leverage for resisting tipping over because of the lateral forces can be achieved by spreading the legs away from the vertical centre. Tripod is also a type of foundation for offshore wind turbines. The tripod is normally more expensive than other types of foundation. However, for large turbines and higher water depth, the cost disadvantage can be compensated when durability is also taken into account.
Tripod support – It is the nimble three-legged stand, a supporting artist for small roller and skate-wheel conveyors, effortlessly moved and aligned to maintain the conveyor’s graceful elevation.
Tripoli compound – It is a buffing compound containing around 75 % free or crystalline silica.
Tripper – It is a device for discharging material from a belt at some intermediate position.
Tripper car – It is a specialized piece of equipment, frequently used in mining operations and material handling systems, designed to distribute bulk materials like ore or coal from a conveyor belt onto another location, such as a storage silo or a different conveyor. Tripper cars are an important part of a stacker, allowing the incoming conveyor to deliver material to an elevated position along a belt conveyor.
TRIP steel – TRIP steels are high strength steels. TRIP stands for ‘transformation induced plasticity’. They are new generation of low alloy steels. These steels offer outstanding combination of strength and ductility as a result of their micro structure. TRIP steels rely on the transformation of austenite grains into the harder phase of martensite during deformation for achieving their mechanical properties. The locations of these grains in the microstructure are of major importance because they influence the impact of the TRIP effect, the microstructural localization and therefore the macroscopical deformability of the material.
Tritium – It is an isotope of hydrogen with mass number 3, i.e., it contains two neutrons as well as one proton. It is radioactive with beta decay to Helium-3. Tritium is also a waste product from the irradiation of water under certain specific conditions. It is also used in certain luminous tubes.
Triton – It is the nucleus of tritium (3H), the triton is the only known radioactive nuclide belonging to hydrogen and beta-decays to Helium-3 with a half-life of 12.4 years.
Trolley – It is a device which travels along a bridge girder (in an overhead crane) or a monorail track, jib boom, or bridge girder. It is the unit which carries the hoisting mechanism. It travels on the bridge rails in a direction at right angles to the crane runway. It is a crucial component for positioning a hoist above a load to be lifted. Trolley frame is the basic structure of the trolley on which are mounted the hoisting and traversing mechanisms.
Trolley conveyor – These conveyors consist of a series of trolleys supported from an overhead endless track and propelled by an endless chain or cable, with the loads normally suspended from the trolleys. This is one of the most versatile types of chain conveyors which can work in horizontal and inclined paths, vertical curves and horizontal turns to follow complicated routes. Different structural members are used as track for overhead trolley-conveyor which includes I-beam, double angles, T-rails, steel bars, pipes and fabricated sections. However, I-beam is the most common track. These tracks are laid at a higher level, suspended from roof, building structures or hung from floor-mounted columns, and routed around obstacles. Overhead operation allows free floor space and no interference with equipment or traffic at the floor level. For this reason, trolley conveyors are frequently being called overhead conveyors.
Trolley pole – It is a support for a current collector on a vehicle.
Trolley-bus – Strictly, it is a passenger vehicle which collects motive electric power from a pair of over-head conductors.
Troostite – It is an obsolete term. It is a previously unresolvable, rapidly etching, fine aggregate of carbide and ferrite produced either by tempering martensite at low temperature or by quenching a steel at a rate slower than the critical cooling rate. The preferred terminology for the first product is tempered martensite, for the latter, fine it is pearlite.
Tropical climates – These climates are defined by a monthly average temperature of 18 deg C or higher in the coolest month, featuring hot temperatures and high humidity all year-round. Annual precipitation is frequently abundant in tropical climates, and shows a seasonal rhythm but can have seasonal dryness to varying degrees. There are normally only two seasons in tropical climates, a wet (rainy / monsoon) season and a dry season. The annual temperature range in tropical climates is normally very small. Sunlight is intense in these climates. There are three basic types of tropical climates within the tropical climate group namely (i) tropical rainforest climate (‘Af’), (ii) tropical monsoon climate (‘Am’) and (iii) tropical savanna or tropical wet and dry climate (‘Aw’ for dry winters, and ‘As’ for dry summers), which are classified and distinguished by the precipitation levels of the driest month in those regions.
Tropical cyclone – It is the general term for a strong, cyclonic-scale disturbance which originates over tropical oceans. Distinguished from weaker systems (frequently named tropical disturbances or depressions) by exceeding a threshold wind speed. A tropical storm is a tropical cyclone with one-minute average surface winds between 18 meters per second and 32 meters per second. Beyond 32 meters per second, a tropical cyclone is called a hurricane, typhoon, or cyclone, depending on the geographic location.
Tropopause – It is the atmospheric boundary which demarcates the lowest two layers of the atmosphere of earth namely troposphere and stratosphere, which occurs around 17 kilometers above the equatorial regions, and around 9 kilometers above the polar regions.
Troposphere – It is the lowest part of the atmosphere from the surface to around 10 kilometers in altitude in mid-latitudes (ranging from 9 kilometers in high latitudes to 16 kilometers in the tropics on average) where clouds and ‘weather’ phenomena occur. In the troposphere, temperatures normally decrease with height.
Tropospheric zone – It is the ozone created in both naturally and by photochemical reactions involving gases resulting from human activities (photochemical ‘smog’) is known as troposhperic ozone. In high concentrations, tropospheric ozone can be harmful to a wide-range of living organisms. Tropospheric ozone acts as a greenhouse gas.
Trouble-shooting – It is a form of problem solving, frequently applied to repair failed products or processes on a machine or a system. It is a logical, systematic search for the source of a problem in order to solve it, and make the product or process operational again. Trouble-shooting is needed to identify the symptoms. It is determining the most likely cause is a process of elimination and eliminating potential causes of a problem. Finally, trouble-shooting needs confirmation that the solution restores the product or process to its working state.
Troughability – It is the property of a belt which permits it to conform to the contour of troughing idlers.
Troughed bed – It is the melodiously shaped belt conveyor, featuring a deep divot, dedicated to processing recyclable materials with finesse, from glass to metal, debris wood, and beyond.
Troughed belt conveyor – It is a type of conveyor belt system where the belt is designed to create a trough on the carrying side, allowing it to carry larger quantities of material, especially bulk solids, with less spillage. This is achieved by using idlers (rollers) that are angled to form the trough shape. In this conveyor, comparatively wide flat belt is supported on troughed carrying rollers or shaped supporting surface so that the two edges of the active side of the belt are elevated from the middle part to form a trough. This provides a higher carrying capacity than a flat belt of equal width for conveying bulk materials or those materials which can slide off flat belts. These conveyors are used in handling bulk materials of different classes. The return side of the belt is normally kept flat supported on cylindrical rollers. The troughed conveyors which are used within a plant for moving bulk materials from one point to another point are normally termed as ‘normal’ or ‘transfer’ conveyors. These are comparatively of shorter lengths, and path of movements are in straight line in a horizontal or an inclined plane. The stresses in the belts are within limits of cotton fabric belts. However, troughed belt conveyors are frequently used for transportation of bulk materials over long distances, by means of a series of conveyors, over paths which are combination of inclines, declines and horizontal sections, following the natural contours of the ground. These are generally termed ‘long-centre’ conveyors. There is no clear demarcation between a normal or long-centre conveyor. Long centre conveyors are those where belt tension is high warranting use of high-tension quality belts with less belt stretch, and low acceleration through gradual starting controls for the drive
Troughed belt training idlers – These idlers automatically train belts and protect belt edges from damage caused by misalignment. Positive action type are normally used for belts operating in one direction, and actuating shoe type are normally used for two- directional operation (reversing).
Troughing – It is the routine inspection and maintenance of the troughing idlers and rollers, ensuring a balletic handling of materials and preventing any spillage faux pas.
Troughing carrying idlers – Because of the increased cross sectional fill depth, troughed belts can carry far higher tonnages than flat belts of the same width and speed. Troughing carrying idlers are sometimes referred to as troughers or carriers, and are the most common type of belt conveyor idler used. Rolls are normally fabricated from steel tube with end disc (bearing housings) welded to the tube ends. Rolls made from high molecular weight polyethylene are used where abrasion, material build-up, or corrosion create short shell life with steel roll idlers. Troughing carrying idler sets are made with troughing angle (the angle made by the inclined roller with horizontal) of 15-degree, 20-degree, 25-degree, 30-degree, 35-degree, 40-degree, 45-degree, and 50-degree. Troughing angle of 15-degree is applicable only to two roll troughed idlers. Historically, 20-degree troughing idlers have longer application histories than either 35-degree or 45-degree troughing idlers. As conveyor belt design technology has advanced, allowing greater transverse flexibility, 35-degree troughing idlers have become the most widely used type of troughing idler.
Troughing idler – It is a type of conveyor idler designed to support a conveyor belt in a trough shape, rather than flat. This shape helps to prevent spillage of materials being conveyed and increases the belt’s carrying capacity. Troughing idlers are made as either in-line or off-set centre roll design. Three roll, in-line, equal length roll troughing idlers are normally used and offer the best all-around shape to carry a maximum load cross section. The offs-set centre roll idler, utilizing the wing or side rolls located in an adjacent parallel plane to the centre roll, is used in either the grain industry where thin belts are used or underground mining where height clearance is minimal. A picking and feeder (or picker) idler design uses a long (extended) centre roll and short side rolls inclined at 20-degrees to allow maximum product dispersal for inspection or sortation. Unequal length roll troughing idlers are also available where the side rolls are inclined at 35-degrees or 45-degrees.
Trough-to-flat transition zone – It is the transition length between the deepest trough station and the pulley. This length is to be sufficiently high to prevent major additional tensions in the conveyor belt edges.
Trouton’s rule – It states that the (molar) entropy of vapourization has almost the same value, around 85 to 88 Joules/(K·mol), for several kinds of liquids at their boiling points. The entropy of vapourization is defined as the ratio between the enthalpy of vapourization and the boiling temperature.
Troy ounce (oz) – It is a unit of weight for precious metals that is equal to 31.1034768 grams (1.0971699 ounces avoirdupois).
TR test – It is also called temperature retraction test. It is a method used to evaluate the visco-elastic properties of rubber and rubber-like materials at low temperatures. It helps determine a material’s suitability for low-temperature applications by assessing its ability to regain elasticity after being cooled and stretched. The test is frequently used to determine the brittleness point or compression set of elastomers. TR test is a method for evaluating the low temperature characteristics of a vulcanized part by measuring the temperature at which retraction over the range of 10 % to 70 % of original elongation occurs. The test is normally used to determine the susceptibility of a rubber crystallize. The sample is stretched at room temperature, cooled to very low temperature, released and warmed at a uniform rate.
Truck – It is a vehicle which is designed to transport freight, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction, with a cabin which is independent of the payload portion of the vehicle. Smaller varieties can be mechanically similar to some automobiles. Commercial trucks can be very large and powerful and can be configured to be mounted with specialized equipment, such as in the case of refuse trucks, fire trucks, concrete mixers, and suction excavators. A truck is also a commercial vehicle without a trailer or other articulation is formally a ‘straight truck’ while one designed specifically to pull a trailer is not a truck but a ‘tractor’.
Truck frame – It is the most important component of forklift which forms the base of the machine. All of the key components of the forklift including wheels, counterweight and mast are attached to the truck frame.
Truck, railway – It is also called bogie. It comprises two or more wheelsets (two wheels on an axle), in a frame, attached under a vehicle by a pivot.
True current density – The preferred term is local current density.
True density – It is the ratio of the mass of the solid material of a porous refractory to its true volume.
True fracture stress – It is the load at fracture divided by the actual cross-sectional area of the material at the point of fracture. Unlike engineering stress, which uses the initial cross-sectional area, true fracture stress considers the reduced area due to deformation, especially necking in ductile materials. This provides a more accurate representation of the stress at the moment of fracture.
True porosity – It is the ratio of the total volume of the open pores and the closed pores in a porous refractory to its bulk volume.
True strain – It is the ratio of the change in dimension, resulting from a given load increment, to the magnitude of the dimension immediately prior to applying the load increment. In a body subjected to axial force, true strain is the natural logarithm of the ratio of the gauge length at the moment of observation to the original gauge length. It is also known as natural strain.
True stress – It is the value obtained by dividing the load applied to a member at a given instant by the cross-sectional area over which it acts.
True value – It is error free value of the measurement variable. It is given as difference between the instrument reading and the static error. Mathematically, true value = obtained instrument reading – static error. % error = [(standard reference value – obtained reading) / standard reference value] x 100.
True volume – It is the volume of the solid material in a porous refractory.
Truing – It is the removal of the outside layer of abrasive grains on a grinding wheel for the purpose of restoring its face.
Truncated cone – It is also known as a frustum of a cone. It is a cone which has been cut off at the top with a plane parallel to the base. This results in a cone-shaped object with two circular ends, one larger than the other.
Truncated distribution – A truncated statistical distribution occurs when a response above or below a certain threshold value is discarded. For example, assume that certain instrumentation which can only read measurements within a certain range—data obtained from this instrument which can result in a truncated distribution, as measurements outside the range are discarded. If measurements are recorded at the extreme range of the measurement device, then the distribution is to be censored.
Truncated mean – It is also called trimmed mean. It is a statistical measure of central tendency, much like the mean and median. It involves the calculation of the mean after discarding given parts of a probability distribution or sample at the high and low end, and typically discarding an equal amount of both. This number of points to be discarded is normally given as a percentage of the total number of points, but can also be given as a fixed number of points.
Truncated section – It refers to a part of something that has been shortened, cut off, or removed from the original form, normally by removing the end or apex. This concept applies to several contexts, including data, text, numbers, and even geometric shapes.
Trunk – It is the thick base of a burr. In telecommunications, a trunk is a communication link which carries multiple signals simultaneously, frequently connecting switching centres. In software engineering, a trunk refers to a main branch or codebase which holds the core functionality, where release branches are derived from.
Trunnion – It is the part of a ball valve which holds the ball on a fixed vertical axis and about which the ball turns. The torque requirements of a trunnion mounted ball valve are considerably less than for a floating ball design.
Trunnion ball valve – It has a mechanical means of anchoring the ball at the top and the bottom, this design is normally applied on larger and higher-pressure valves (say, above 100 millimeters and 4 megapascal pressure).
Trunnion bearing – It is a bearing which is used as a pivot to swivel or turn an assembly.
Trunnion discharge – For cylindrical mills which are continuously fed, the discharge of the ground product is through the far end of the mill (trunnion discharge).
Trunnion mounting – It is a style of mounting the disk or ball on the valve shaft or stub shaft with two diametrically opposed bearings.
Trunnion wheels – In rotary kiln, these wheels act as the cradle for the rotating drum shell. They ensure smooth and concentric rotation during operation. They also act as a wear piece, because they are easier and less costly to replace than the riding ring itself. The wheels are mounted to steel support bases with sealed roller bearings. Support rollers bear the weight of the drum. Two smooth trunnion rolls per riding ring, shrunk onto journals, generally turn in plain bearings with immersion or pressure-flow lubrication. Antifriction bearings are also sometimes used. One or more thrust rolls arranged parallel to the kiln axis, bear the downslope forces exerted by the kiln. These have hydraulic position adjustments so that the kiln can be moved in the longitudinal direction.
Truss – It is an assembly of two-force structural members such as beams, connected at nodes, where the members are organized such that the assemblage as a whole behaves as a single, rigid object.
Truss connector plate – It is also called gang plate. It is a kind of tie. Truss plates are light gauge metal plates which are used to connect prefabricated light frame wood trusses. They are produced by punching light gauge galvanized steel to create teeth on one side. The teeth are embedded in and hold the wooden frame components to the plate and each other.
TR-XLPE – It stands for ‘tree retardant cross-linked poly-ethylene’. It is a thermoset plastic compound used for insulating cables. It is designed to improve the longevity and reliability of cables, particularly in medium and high-voltage applications, by mitigating the effects of ‘water treeing’, a process where water and electrical stress can degrade the insulation.
Tryout – It is preparatory run to check or test equipment, lubricant, stock, tools, or methods prior to a production run. Production tryout is run with tools previously approved. New die tryout is run with new tools not previously approved.
T-score – It is a standard score derived from a z-score by multiplying the z-score by 10 and adding 50. It is useful in comparing different test scores to each other as it is a standard metric which reflects the cumulative frequency distribution of the raw scores.
TSP technology – This technology is suitable for low carbon to high carbon grades of steels, stainless steels, high strength low alloy (HSLA) steels, silicon steel, API (American Petroleum Institute) steel grades, and drawing quality steel. One of the strengths of the mill is its versatility. It can produce coil or discrete plates enabling a wide range of width and gauges to be produced. The casting of intermediate thickness slabs has some advantages. The slab is thin enough to eliminate the need for a separate roughing mill and thick enough to maintain good quality. The intermediate thickness allows for greater slab width, reduced reheating time and hence reduced scale formation compared to 50 millimeters thin slabs. After casting, slabs are sent to directly to reheating furnace to equalize the slab to the correct rolling temperature. The typical holding time to heat a slab to 1,250 deg C is 12 minutes to 13 minutes. Once the strip has been reduced to 20 millimeters to 25 millimeters thickness, it is coiled to in the coiling furnace to retain strip temperature. The strip is then reversed back and forth through the rolling mill. A total of three flat roughing passes and six coiling finishing passes are generally required to finish gauges to 1.5 millimeters thickness.
t-statistic – When a sample is used to calculate ‘sigma’ square, an estimate of the population variance sigma square, and the parent population is normally distributed, the sampling distribution of the test statistic ‘t’ is approximately t-distributed.
TT drive – It is a belt-to-belt booster drive to reduce belt tension. It is originally from the German term ‘Treib-Traggurt’. It increases belt wear, maintenance and reduces system availability.
t-test for correlated means – It is a parametric test of statistical significance used to determine whether there is a statistically significant difference between the means of two matched, or non-independent, samples. It is also used for pre–post comparisons.
t-test for correlated proportions – It is a parametric test of statistical significance used to determine whether there is a statistically significant difference between two proportions based on the same sample or otherwise non-independent groups.
t-test for independent means – It is a parametric test of significance used to determine whether there is a statistically significant difference between the means of two independent samples.
t-test for independent proportions – It is a parametric test of statistical significance used to determine whether there is a statistically significant difference between two independent proportions.
Tube – It is a long hollow cylinder which is used for moving fluids or to protect cables and wires. Tube is very frequently defined by the outside diameter (OD) and a wall thickness. Hence a 200 millimeters tube has an outside diameter of 200 millimeters. The term tube covers three sub-groups namely (i) pressure tubes, (ii) structural tubing, and (iii) mechanical tubing. Tubes are frequently made to custom sizes and can frequently have a large number of specific sizes and tolerances than pipes. The term ‘tube’ is also normally applied to non-cylindrical sections (square or rectangular).
Tube, alclad – It is the composite tube composed of an aluminum alloy core having on either the inside or outside surface a metallurgically bonded aluminum or aluminum alloy coating which is anodic to the core, hence electrolytically protecting the core against corrosion.
Tube, arc-welded – It is the tube made from sheet or plate butt welded by either gas tungsten or gas metal arc welding method, with or without the use of filler metal.
Tube-axial fan – It is a propeller fan placed inside a cylinder but with higher pressures and better operating efficiencies than propeller fans. These fans are suited for medium-pressure and have high airflow rate applications, e.g., ducted heating, ventilation, and air conditioning (HVAC) installations They are relatively expensive and have moderate air flow noise. These fans can quickly accelerate to rated speed because of their low rotating mass. They generate flow in reverse direction, which is useful in several ventilation applications. They create sufficient pressure to overcome duct losses and are relatively space efficient, which is useful for exhaust applications air flow noise. These fans have relatively low energy efficiency (65 %).
Tube bloom – This term is not recommended. The term tube stock is preferred.
Tube, brazed – It is a tube produced by forming and seam brazing sheet.
Tube, butt-welded – It is a welded tube, the seam of which is formed by positioning one edge of the sheet against the other for welding.
Tube conveyor – When small piece goods in standardized containers, called carriers, are transported pneumatically over short distance through pipe, it is called tube conveyor. This type of transportation of piece goods is used for sending samples to the laboratories and in telegraph offices, banks, stores, and newspaper offices. The pipes of these installations can be round (up to 100 millimeters diameter) or elliptical. The carriers are moved at speeds range of 6 meters per second to 12 meters per second.
Tube drawing – It is a process to size a tube by shrinking a large diameter tube into a smaller one, by drawing the tube through a die. This process produces high-quality tubing with precise dimensions, good surface finish, and the added strength of cold working. For this reason, this process is established for several materials, mainly metalworking but also glass. Since it is so versatile, tube drawing is suitable for both large- and small-scale production. The large-scale production of glass typically uses a one step process where glass is directly drawn into a tube from a melting tank. There are five types of tube drawing namely tube sinking, mandrel drawing, stationary mandrel, moving mandrel, and floating mandrel. A mandrel is used in several of the types to prevent buckling or wrinkling in the work-piece.
Tube, drawn -It is a tube brought to final dimensions by cold drawing through a die. This product can be produced from either seamless or non-seamless extruded stock or from welded stock.
Tube, embossed – It is a tube, the outside surface of which has been roll embossed with a design in relief regularly repeated in a longitudinal direction.
Tube, extruded – It is a tube formed by hot extruding. This product can be either seamless or non-seamless.
Tube extrusion process – It is a manufacturing process where material, typically a metal or plastic, is forced through a die to create a hollow, cylindrical product, frequently with a specific cross-section. This process involves heating and pressurizing the material, then pushing it through a die to form the desired shape.
Tube, finned – It is the tube which has integral fins or projections protruding from its outside surface.
Tube, fluted – It is a tube of nominally uniform wall thickness having regular, longitudinal, concave corrugations with sharp cusps between corrugations.
Tube furnace – It is an electric heating device which is used to heat materials inside a cylindrical tube. It typically features a cylindrical heating chamber, frequently made of quartz or ceramic, with heating elements surrounding the outer surface. Samples are placed within the tube and subjected to controlled heating, making it ideal for several applications like annealing, sintering, and materials research.
Tube, heat-exchanger – It is a tube for use in apparatus in which fluid inside the tube is to be heated or cooled by fluid outside the tube. The term is normally not applied to coiled tube or to tubes for use in refrigerators or radiators.
Tube, helical-welded – It is a welded tube produced by winding the sheet to form a closed helix and joining the edges of the seam by welding.
Tube hole – It is a hole in a drum, heater, or tube sheet to accommodate a tube.
Tube, lap-welded – It is a welded tube, the seam of which is formed by longitudinally lapping the edges of the sheet for welding.
Tube, lock-seam – It is a tube produced by forming and mechanically lock seaming sheet.
Tube mill – It is an apparatus consisting of a revolving cylinder about half-filled with steel rods or balls and into which crushed ore is fed for fine grinding.
Tube, open-seam – It is a shape normally produced from sheet of nominally uniform wall thickness and approximately tubular form but having a longitudinal unjointed seam or gap of width not higher than 25 % of the outside diameter or highest overall dimension. It is also referred to as butt-seam tube.
Tube piercing – It is also known as rotary piercing. It is a hot forming process used to manufacture seamless tubular metal products. It involves piercing a solid tube blank or ingot into a hollow tube using rotating rolls. This process is also referred to as the Mannesmann process. Pipe rolling, in the context of tube piercing, refers to the process of shaping the pierced tube into a desired final form, frequently involving further rolling operations to refine its dimensions and properties.
Tuberculation – It is the formation of localized corrosion products scattered over the surface in the form of knoblike mounds called tubercles. The formation of tubercles is normally associated with biological corrosion.
Tube, redraw – This term is not recommended. The term tube stock is preferred.
Tube reducing – It means reducing both the diameter and wall thickness of tubing with a mandrel and a pair of rolls.
Tube rolling – It is the most widely used method of producing composite tubular parts which need high strength-to-weight properties as well as high production capabilities. The tube rolling process utilizes prepreg materials having accurate resin content, which are produced on very precise prepreg and filming machines. The combination of accurate resin content and good fiber areal weight in prepreg materials offers designers a method to produce structurally sound tubular parts at a very rapid rate using relatively unskilled factory labour. Tube rolling has several advantages over other methods of producing composite tubes.
Tube, seamless – It is a tube which does not contain any fine junctures (metallurgical welds) resulting from the method of manufacture. This product can be produced by die and mandrel or by hot piercer processes.
Tube sinking – It is drawing of tubing through a die or passing it through rolls without the use of an interior tool (such as a mandrel or plug) to control inside diameter. Sinking normally produces a tube of increased wall thickness and length.
Tube, sized – It is a tube which, after extrusion, has been cold drawn a slight quantity to minimize quality.
Tube, stepped drawn – It is a drawn tube whose cross section changes abruptly in area at intervals along its length.
Tube stock – It is a semi-finished tube suitable for subsequent reduction and finishing.
Tube spinning – It is a rotary-point method of extruding metal much like cone spinning, except that the sine law does not apply. Since the half angle of a cylinder is zero, tube spinning follows a purely volumetric rule, depending on the practical limits of deformation which the metal can stand without intermediate annealing. Tube spinning is also limited by the smallest percentage reduction in thickness which ensures complete flow of the metal. This minimum reduction is normally 15 % to 25 %, depending on the metal and on the thickness of the original tube.
Tube, structural – It is the tube normally used for structural purposes.
Tube, welded – It is a tube produced by forming and seam welding sheet longitudinally.
Tubing – It consists of hollow rods of glass used especially in the production of laboratory equipment and fluorescent lighting. This term is not recommended. The term tube is preferred.
Tubing, electrical metallic – It is a tube having certain standardized length and combinations of outside diameter and wall thickness thinner than that of rigid conduit, commonly designated by nominal electrical trade sizes, for use with compression-type fittings as a protection for electrical wiring.
Tubular conductor – It is a tubular product suitable for use as an electric conductor.
Tubular products – These are cylindrical, hollow items like pipes or tubes, frequently made of steel. They are used in several applications, including oil and gas, construction, manufacturing, and transportation.
Tuff – It is a rock which is composed of fine volcanic ash.
Tukey’s test of significance – It is a single-step multiple comparison procedure and statistical test normally used in conjunction with an ANOVA to find which means are significantly different from one another. Named after John Tukey, it compares all possible pairs of means and is based on a studentized range distribution ‘q’ (this distribution is similar to the distribution of ‘t’ from the t-test).
Tumble grinding – It consists of several surfacing operations ranging from deburring and polishing to honing and micro-finishing metallic parts before and after plating.
Tumbler test– In this test a 10 kilograms representative sample of the -75 millimeters to +50 millimeters ‘square hole screen’ coke is placed in a specified tumbler drum and rotated for 1,400 revolutions. The test is based on American standard ASTM D3402. The coke stability is reported as the percentage of coke + 25 mm after 1,400 revolutions and the hardness as the percentage of coke + 6.3 millimeters after 1,400 revolutions. Higher values of these indices indicate the strength of the coke.
Tumbling – It means rotating of work-pieces, normally castings or forgings, in a barrel partly filled with metal slugs or abrasives, to remove sand, scale, or fins. It can be done dry, or with an aqueous solution added to the contents of the barrel. Tumbling is also a finishing process for removing flash from a moulded rubber part by placing in a rotating barrel with or without the added finishing material such as shells, or dry ice etc.
Tumbling autogenous mills – These mills are drum mills which consist of horizontally rotating slightly inclined cylinders of large diameter and small length and fitted with lifting bars. Coarse feed is entering the mill from one end and outlet is at the other end. In the mill, the feedstock is lifted and then allowed to drop through a significant height. Three significant mechanisms cause the breakdown of the mineral. These are (i) impact due to the fall of the mineral onto the charge below causes a reduction in the size of the feedstock, (ii) attrition of smaller particles between larger grinding bodies. and (iii) abrasion or rubbing off of particles from the larger bodies. Steel or ceramic balls are often added to aid with the reduction process. In this case the mill is then referred to as a semi autogenous (SAG) mill. The process can be carried out wet or dry. Feed is grinded during its way through the mill. The mill is normally used for grinding of ores. Lining of the cylinder plays very important role. It protects the mill from abrasions and at the same time it helps in lifting of the material from the bottom of cylinder. The types of lining are (i) smooth liner, (ii) wave liner, (iii) ship lap liner, (iv) step liner, and (v) Osborn liner.
Tundish – Tundish is a refractory-lined vessel with a variety of possible geometries. It is a rectangular big end up refractory lined open container which can have a refractory lined cover on the top. There are several types and shapes of tundish. Tundishes are normally of elongated and geometrically simple shape. The main function of the tundish is to be a steel reservoir between the steel teeming ladle and the mould, and in the case of multi-strand continuous casting machines to distribute the liquid steel into the different moulds. Tundish ensures the feed of the liquid steel to the continuous casting machine during the change of steel ladles, thus acting as a buffer of liquid steel. Since the tundish act as a reservoir of liquid steel during the period of ladle change periods and since it continues to supply liquid steel to the moulds when the incoming liquid steel has stopped due to ladle change, it makes the sequence casting by a number of ladles feasible. The contributions of the tundish in the process of continuous casting are (i) to reach stability of the liquid steel streams entering the casting mould, and in turn, to achieve a constant casting speed, (ii) to cast a sequence of heats, (iii) to change over the empty steel teeming ladle for a full steel teeming ladle without interrupting the flow of liquid steel in the moulds, (iv) to make a mixed grade with steel from two different grades of two different heats, if needed, (v) to provide possibility to prevent inclusions and slag from entering tundish and thus slipping into mould, (vi) to enhance oxide inclusion separation, (vii) to maintain a steady liquid steel height above the nozzles to the moulds, thereby keeping steel flow constant and hence casting speed constant as well, and (viii) to provide more stable stream patterns to the moulds.
Tundish board lining – This lining consist of board systems comprising low density, highly insulating, disposable, pre-formed, and pre-cured refractory boards. Easy deskulling, no equipment investment and the low cost of silica variety also contributes to its run-away popularity among many steel makers. Initially, silica-based boards have been used which allowed only ‘cold start’ practice. Later, magnesite-based boards have been introduced to fulfill the requirement of pre-heatability, i.e., a ‘hot start’ practice for low hydrogen considerations in the manufacture of high alloy quality steels. However, the labour intensiveness, presence of joints and sand backing, and breakages etc. remains as inherent handicaps of board lining system. However, board lining system is popular in places where labour costs are low and application technologies are not readily available.
Tundish car – It is used for the transfer of a tundish. It is a self-propelled carriage which transports a tundish. Each tundish is heated to a high temperature by a heating apparatus at a standby position and is transported to the casting station by the tundish car immediately before casting begins. In addition to the travelling function, the tundish car comprises a lifting function for inserting a submerge nozzle arranged at the bottom of each tundish into a mould, a centering function for adjusting the position of the submerged nozzle, and an automatic liquid steel level control function for keeping the liquid steel at a constant level to separate impurities by flotation. The size of the tundish car is normally increased as the number of strands increases, and the interference with adjacent apparatuses becomes tighter. Hence, it is required to have a mechanism which is lean in terms of structure dynamics. Tundish car is normally of half suspended design and is mounted at the main operating platform. It is normally hydraulic powered and is used to support and convey the tundish for casting or heating.
Tundish cover – It is a lid-like refractory lined structure placed on top of a tundish. It serves to protect the molten steel inside from oxidation, isolate the steel surface, and prevent freezing, among other functions.
Tundish design – Historically, tundish design concepts have been geared toward steady-state operation rather than transitional, or non-steady-state issues. Today, the functions of the tundish include more than the basic purpose of acting as a buffer reservoir between the ladle and the mould(s). Tundishes also carry the requirements for effective inclusion removal, thermal equilibration, chemical homogenization, and provision of a non-reactive container environment which supports the kinetics and thermodynamics of these functions. A proper basic design is critical in order for the tundish to be used as an inclusion, temperature, and chemistry refining vessel, or at least have this vessel be a non-contaminator in these phenomena. When selecting the overall tundish design for a particular steelmaking operation, the needs and concerns of the steelmaker which are to be addressed are (i) consideration of the steel product(s) to be cast, (ii) matching the number of strands to the pacing of the steel melting shop, (iii) cleanliness improvements, (iv) lining thickness and configuration, (v) necessity for costly tundish flow modifying devices, (v) tundish fly capability to support extended continuous casting, and (vi) yield losses.
Tundish flow modifying devices – While linings are an important part of the tundish refractory system, the major work for removing inclusions is being carried out by the refractory shapes in the tundish known as flow modifying devices. If the turbulent energy from the ladle shroud can be harnessed, the steelmaker can then focus on metallurgical measures to improve inclusion flotation in the tundish. Principal among these flow modifying devices are dams, weirs, and baffles etc., which serve to assist in directing inclusions upward to a captive tundish slag layer.
Tundish flow pattern – It is to be designed to increase the liquid steel residence time, prevent ‘short circuiting’ and promote inclusion removal. Tundish flow is controlled by its geometry, level, inlet (shroud) design, and flow control devices such as impact pads, weirs, dams, baffles, and filters.
Tundish flux – It is a material placed atop molten steel in a tundish to prevent heat loss and oxidation, and to help refine the steel by removing non-metallic inclusions. Itis essentially a type of slag which acts as a protective cover for the molten metal.
Tundish impact pad – It is also called tundish impact or refractory. It is a specialized lining at the bottom of a tundish. It is designed to withstand the impact and turbulence of molten metal entering the tundish, protecting the structure and ensuring controlled flow.
Tundish lining – It is crucial for protecting the tundish from the harsh conditions of molten steel and slag. Common materials used for tundish wear lining include magnesia (MgO)-based materials, silica boards, and several castable refractories. These materials are chosen for their ability to withstand high temperatures, resist chemical reactions with molten metal, and minimize thermal losses. Tundish permanent lining also called safety lining is the last defense to prevent a breakout of liquid steel through the tundish steel shell, hence, the aim is to minimize any wear and keep it in operation for as long as possible.
Tundish metallurgy – Tundish is the last metallurgical vessel before continuous casting. It plays an essential role in delivering steel with the correct composition, quality, and temperature to the moulds. This function has become increasingly important over the last couple of decades with increasingly stringent requirements for the quality of steel products. Tundish serves as an important metallurgical reaction vessel, where quality can be improved, maintained, or lost. The fundamental aspects of the solutions to the tundish metallurgy challenges are based on several basic principles namely (i) use of a tundish size appropriate for the steel melting shop’s spacing and transition requirements, (ii) sending of heats on time, in temperature, and with properly cleaned liquid steel, (iii) maximization of ladle free open performance, (iv) opening of the heats submerged and fully shrouded, (v) utilization of automatic ladle slag detection and shut-off, (vi) avoiding of easily reducible oxides in slags, linings, and refractories, (vii) designing of slags to meet the application requirements, (viii) ensure that the transfer systems are not subject to leaking or air aspiration, (vii) designing of the tundish flow modifying devices, including impact pads for maximizing flotation and minimizing transitions, (viii) running of the tundish at its maximum volume during steady-state operations, (ix) utilizing technologies such as inert gas purging for minimizing transient effects, (x) monitoring of the temperature continuously, if possible, (xi) avoiding large temperature swings for maintaining a stable tundish flow, (xii) understanding and solving of the root causes to the clogging problems, (xiii) maximizing of the yield and productivity, and (xiv) not jeopardizing the people (safety is always to be the first objective) or the mould.
Tundish nozzle – It is also known as a tundish slide gate nozzle. It is a refractory component used in tundish to control the flow of molten steel from the tundish to the continuous casting mould. It is a critical part of the tundish slide gate system, which regulates the steel flow and enables precise control of the casting process.
Tundish powder – It is a free flowing non-toxic and non-hazardous mixture. It seals the surface of the liquid steel in the tundish. It is also known by several other names such as tundish covering compound, tundish covering flux, tundish flux, tundish covering slag, or tundish flux slag. Tundish powder has got very good insulating properties. It plays an important role in the continuous casting of liquid steel and is one of the influential and critical factors in the stable operation of the continuous casting machine. The use of a suitable tundish powder is an essential feature of the present-day tundish metallurgical practice. However, the selection of powder is specific to the grade of steel and product quality requirements. Tundish powders are basically of two types. The first type is acidic in nature and is normally based on rice husk ash or fly ash. The second type is basic in nature and normally is based on MgO (magnesium oxide). Today, several types of tundish powders with different compositions and shapes (granular, powder form, and extruded powders) are produced to suit the casting of diverse steel grades. The factors which influence the properties of tundish powders are (i) chemical composition, (ii) mineralogical composition, (iii) grain size composition, (iv) manufacturing process, (v) drying or roasting method, and (v) free carbon content. Each shape and type of the tundish powder has its own advantages and disadvantages, such as price, health issues, flow-ability, thermal insulation, and melting rate.
Tundish refractories – These are the refractories which are used to line the tundish, These refractory materials are essential for containing the molten steel without excessive heat loss and for protecting the tundish structure from the harsh conditions of the casting process. Refractory materials used in tundish linings include (i) bricks (fireclay bricks or high-alumina bricks are normally used), (ii) coatings (gunnable coatings, sprayable slurry coatings, and insulating refractory boards are normally used, (iii) Fibre materials (ceramic fibre materials are used for tundish boards or covers, and (iv) magnesia-chrome (this material is favoured for its high-temperature resistance, stability, and chemical resistance. Importance functions of tundish refractories are (i) heat retention, (ii) structural protection, (iii) flow control, and impact protection.
Tundish size – It is defined by its wall angles and the length, height, and width dimensions, while geometry is frequently dictated not only by the number of strands to be cast, but also by available shop floor layout constraints.
Tundish slag – It refers to the molten non-metallic material (slag) which floats on top of the molten steel in the tundish. Tundish slag plays a crucial role in protecting the steel from oxidation and helping to remove impurities. As a contrast to the ‘inert tundish practice’ a concept of ‘active tundish slag’ is here introduced. Overall, the tundish is the last reactor where important metallurgical operations can still be done. If the liquid steel interaction with the tundish slag can be optimized the liquid steel quality can be maintained and improved in the tundish. An appropriate tundish slag is able to absorb deoxidation and reoxidation products. It can also bind occasional macro-inclusions entering from ladle. Especially in transient casting conditions, start-up and ladle changes in sequential casting, the tundish conditions are most critical and the active slag can show its merits. The most essential functions of tundish slag are summarized in Tab 1 in which also thermodynamic and kinetic constraints and means to influence interaction phenomena are given. The first item concerns a typical non-equilibrium condition between liquid steel and slag in the tundish. When the slag contains some unstable oxides, they can be reduced by some components dissolved in liquid steel. A common example is a slag containing some FeO which is then reduced by elements like aluminum, titanium, or silicon dissolved in the liquid steel. Also, other components like MnO, and even SiO2 in slag can be reduced by dissolved aluminum in aluminum-deoxidized liquid steel. These events are characterized as reoxidation reactions since they cause selective oxidation of components in liquid steel and result in formation of oxide inclusions in steel which can deteriorate cleanliness.
Tundish well nozzle – It is a critical refractory component which is used to control the flow of molten steel from the tundish to the mould. Specifically, it is located within the tundish, in a well-like area, and acts as a nozzle, regulating the steel flow.
Tuned circuit – It is a circuit which displays a peak response at some frequency.
Tungsten (W) – It is also called wolfram. It is a chemical element having atomic number 74. It is a metal found naturally on earth almost exclusively in compounds with other elements. Its important ores include scheelite and wolframite, the latter lending the element its alternative name.
Tungsten carbide rolls – Tungsten carbide (WC or W2C), is a chemical compound containing tungsten and carbon. Its extreme hardness makes it useful in the manufacture of mill rolls for extended life in applications where long rolling campaigns are required. Tungsten carbide rolls are used in the modern high speed wire rod mills which uses ‘no twist finishing blocks, and in some shape-rolling mills. In tungsten carbide rolls, tungsten carbide is the major alloying constituent which gives the roll high wear resistance and hardness. The other constituent is the binding material cobalt although nickel has been increasingly being used. The normal use of a single carbide grade throughout the entire finishing block is not always the optimum solution. At least two or more grades are occasionally to be considered. These rolls need high quality cooling water in a narrow pH range and having limited hardness. Using roll cooling water outside the recommended pH range leeches the binder from the roll causing premature roll surface failure. Several grades of carbide rolls are available based on grain size and binder content and binder composition. The range of application in recent years has extended the use of carbide rolls back into the intermediate mills by using a carbide sleeve mounted on a steel shaft. The mounting is carried out by a mechanical method or by creating a composite roll by pressing and sintering a carbide ring on the shaft.
Tungsten inclusions – These are particles of metallic tungsten embedded in the weld metal which originate from the tungsten electrode used in tungsten arc welding. Causes are excessive welding current allowing the melting and deposition of tungsten in the weld and incorrect polarity of electrode using a direct current source. Tungsten inclusions can also be caused from dipping the electrode into the molten weld metal or by touching the filler rod to the electrode during welding. Tungsten inclusions normally occur at the start of welds when the electrode is usually cold. Small globular and widely scattered tungsten inclusions are sometimes permissible, but sharp-edged inclusions are dangerous.
Tungsten inert gas (TIG) – It is also known as gas tungsten arc welding (GTAW) – It is a manual welding process which uses a non-consumable tungsten electrode, an inert or semi-inert gas mixture, and a separate filler material. Especially useful for welding thin materials, this method is characterized by a stable arc and high-quality welds, but it needs high operator skill and can only be accomplished at relatively low speeds. In this process, a non-consumable tungsten electrode is used and an arc is struck between this electrode and the work-piece surface. Tungsten inert gas welding can be used on nearly all weldable metals, though it is more frequently applied to stainless steel and light metals. It is frequently used when quality welds are extremely important.
Tuning of the foundation – Foundation, for which its vertical natural frequency is above the operating speed of the equipment, is termed as over-tuned foundation or high-tuned foundation and the foundation, for which its vertical natural frequency is below the operating speed of the equipment, is termed as under-tuned foundation or low-tuned foundation.
Tunnel – It is a horizontal underground opening, open to the atmosphere at both ends.
Tunnel-boring-machine – It is a machine used to excavate a tunnel through soil or rock by mechanical means as opposed to drilling and blasting.
Tunnel furnace – It is also known as a tunnel kiln. It is a type of continuous kiln used in several industrial processes, particularly for heating or firing materials. It involves passing materials through a long, enclosed tunnel, where they are subjected to controlled heat and atmosphere.
Turbidimetry – It is a method used to measure the turbidity (cloudiness) of a solution by quantifying the amount of light that is attenuated (reduced) as it passes through the sample. It is typically used for solutions with relatively high concentrations of large, scattering particles. Turbidimetry is a non-destructive technique, meaning it does not alter the sample during measurement.
Turbidity – It is the cloudiness of water. It is determined by the presence of suspended matter such as clay, silt, organic matter, and living organisms. High turbidity can reduce light transmission, and hence reduce photo-synthesis of aquatic plants. The degree of turbidity is measured with a turbidometer.
Turbidometer – It is an instrument used to measure turbidity, which is the cloudiness or haziness of a liquid because of the suspended particles. It does this by measuring how much light is transmitted through the liquid after it has been scattered by those particles.
Turbine – It is a rotary mechanical device which extracts energy from a fluid flow and converts it into useful work. The work produced can be used for generating electrical power when combined with a generator. A turbine is a turbo-machine with at least one moving part called a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades so that they move and impart rotational energy to the rotor. Gas, steam, and water turbines have a casing around the blades which contains and controls the working fluid. Modern steam turbines frequently use both reaction and impulse in the same unit, typically varying the degree of reaction and impulse from the blade root to its periphery.
Turbine blades – These are aero foils mounted in the rim of a turbine disc, used to convert the kinetic energy of a fluid (like steam, water, or air) into rotational motion. They are found in different turbines,
Turbine disc – It is a rotating wheel-like component in a turbine, typically made of metal, which secures blades and transmits rotational forces. These discs are crucial in gas turbine, steam turbines, and other fluid-powered systems. Turbine discs are designed to withstand extreme centrifugal forces, temperatures, and vibrations. including steam turbines and gas turbines.
Turbine flow meters – These are also known as turbine wheel totalizers. These are similar in their design to Woltman totalizers, with one essential difference i.e., the measurement of the rotation is made electrically with almost no feedback on the rotor. The turbine rotors are light in weight producing minimal friction in the bearings. As a result, the span can be expanded since the system responds with higher sensitivity. Smaller nominal diameters are possible. The turbine flow meter measures gases and liquids with increased viscosities.
Turbine oil – It is an oil which is used to lubricate bearings in a steam or gas turbine.
Turbine rotor – It is the rotating part which transfers energy. It is essentially a shaft or drum with blades attached, and it spins as a fluid (like wind or steam) flows through the turbine and interacts with those blades.
Turbine totalizers – Turbine totalizers are indirect volume totalizers in which the flow causes a vaned rotor to revolve. The number of rotor revolutions is proportional to the total flow and the frequency of the revolutions to the flow rate. The different designs are differentiated by the direction of the inflow and by the method utilized for measured value acquisition.
Turbo blower – It is also known as a turbine blower or turbo-charger. It is a dynamic air or gas compressor. It uses a rotating impeller (like a turbine) to draw in air or gas, compress it, and then release it with increased pressure and flow. This high-pressure air is then used for various applications like combustion, ventilation, or pneumatic conveying.
Turbo generator – It is an electric generator directly coupled to a turbine, whether steam, gas, or water, to generate electricity. It converts mechanical energy from the turbine into electrical energy. These generators are a primary source of electricity generation in power plants worldwide.
Turbo-machinery – It describes machines which transfer energy between a rotor and a fluid, including both turbines and compressors. While a turbine transfers energy from a fluid to a rotor, a compressor transfers energy from a rotor to a fluid. It is an important application of fluid mechanics. These two types of machines are governed by the same basic relationships including Newton’s second law of motion and Euler’s pump and turbine equation for compressible fluids. Centrifugal pumps are also turbomachines which transfer energy from a rotor to a fluid, normally a liquid, while turbines and compressors normally work with a gas.
Turbulence – It is also called turbulent flow. It is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to laminar flow, which occurs when a fluid flows in parallel layers with no disruption between those layers. Turbulence is normally observed in everyday phenomena such as surf, fast flowing rivers, billowing storm clouds, or smoke from a chimney, and majority of fluid flows occurring in nature or created in engineering applications are turbulent. Turbulence is caused by excessive kinetic energy in parts of a fluid flow, which overcomes the damping effect of the fluid’s viscosity. For this reason, turbulence is normally realized in low viscosity fluids. In general terms, in turbulent flow, unsteady vortices appear of several sizes which interact with each other, consequently drag because of the friction effects increases.
Turbulent burner – it is a burner in which fuel and air are mixed and discharged into the furnace in such a manner as to produce turbulent flow from the burner.
Turbulent flow – It occurs when the flow velocity is high and the particles no longer flow smoothly in layers and turbulence or a rolling effect occurs. The flattening of the velocity profile takes place.
Turk’s head – It is a machine which is used for squaring. A Turk’s head consists of a frame in which are mounted four rolls with their axes at 90-degree and adjusted so that the roll surfaces form an opening of the same shape as the section to be formed. The Turk’s head is mounted on a draw bench, and the round tubes / rods are passed through the rolls in the same manner as they are passed through dies.
Turk’s-head rolls – These are four undriven working rolls, arranged in a square or rectangular pattern, through which metal strip, wire, or tubing is drawn to form square or rectangular sections.
Turn – It is a complete encirclement of the slots into which the coil is placed.
Turn-buckle – It is a mechanical virtuoso with screw-threaded ends, the turnbuckle orchestrates tension and structural harmony within the conveyor system.
Turn-down ratio – It refers to the width of the operational range of a device, and is defined as the ratio of the maximum capacity to minimum capacity, e.g., a device with a maximum output of 10 units and a minimum output of 2 units has a turn-down ratio of 5. The term is normally used with measurement devices and combustion plant like boilers and gasifiers. Turn-down ratio is also the ratio of maximum to minimum fuel or steam input or boiler output.
Turning – It is removing material by forcing a single-point cutting tool against the surface of a rotating work-piece. The tool may or may not be moved toward or along the axis of rotation while it cuts away material.
Turning radius – It refers to the minimum radius within which a vehicle can complete a 180-degree turn, or a semi-circular turn, without skidding. It is essentially the smallest circle a vehicle can fit into while turning. This term is also sometimes used inter-changeably with ‘turning circle’ or ‘turning diameter’.
Turnings – It refers to the small, curled shavings or chips produced during machining processes like turning, drilling, or milling. These are a common type of ferrous scrap and are generated from cutting metal on a lathe, for example. They are also known as borings, swarf, or chips.
Turning wheel – It is the wheel-mounted maestro on an adjustable bracket, ensuring the proper orientation of packages in a seamless conveyor performance.
Turn-over – It refers to the total value of sales (revenue) generated by the organization, or the rate at which assets are used or replaced within a period. It is a key indicator of how efficiently the organization is converting resources into revenue and can be measured across different aspects like inventory turn-over, asset turn-over, or accounts receivable turn-over.
Turn-table – It is he rotating bed, the centre-piece for transferring packages from one conveyor system to another, orchestrating a fluid dance of materials.
Turquoise hydrogen – It combines the use of natural gas as feedstock with no carbon di-oxide production. Through the process of pyrolysis, the carbon in the methane becomes solid carbon black. A market for carbon black already exists, which provides an additional revenue stream. Carbon black can be more easily stored than gaseous carbon di-oxide. At the moment, turquoise hydrogen is still at the pilot stage.
Turret – It is a rotating toolholder that allows for quick and easy switching between different cutting tools. It is a common component of lathes and CNC (computerized numerical control) turning centres, enabling continuous machining operations without stopping for tool changes.
Turret, ladle – In the continuous casting machines (CCMs), a ladle turret is a rotating mechanism used to support and transfer molten steel ladles between the furnace and the casting machine, specifically the tundish. It ensures a smooth, uninterrupted flow of steel from the ladle to the casting process.
Turret lathe – It is a type of metal-working lathe which uses a turret head to hold multiple cutting tools, allowing for rapid switching between operations for efficient production of duplicate parts. This machine, also known as a capstan lathe, is distinguished by its ability to perform several cutting operations on the same work-piece with minimal setup time.
Tuyere – It is an opening in a cupola, blast furnace, or converter for the introduction of air or inert gas. In blast furnaces, tuyeres are special shaped nozzles through which hot air blast is injected into the blast furnace. They are made of copper and are normally water cooled since they are directly exposed to the furnace temperature.
Tuyere coolers – Tuyere coolers are the water-cooled copper devices in which the tuyeres become fixed in the furnace housing. They help to make the heat exchange of the tuyere, taking away heat and preventing their passage into the surroundings of the blast furnace. They play a significant role in the tuyeres’ resilience, helping to achieve the functional stability of the blast furnace.
Tuyere platform – It is the maintenance platform at the tuyere level to facilitate changing of tuyeres and blow pipes.
Tuyere stock – It is assembly of gooseneck, expansion bellow, connecting pipe, elbow, peep hole, blow pipe, fixing arrangement and tensioning device. Tuyere stocks connect bustle pipe to the tuyeres. The purpose of tuyere stocks is to supply hot blast air into the blast furnace.
Twaron – It is a brand name of Teijin Aramid. It is a para-aramid, high-performance yarn. It is a heat-resistant fibre, helps in ballistic protection and cut protection.
Twin – It consists of two portions of a crystal with a definite orientation relationship, one can be regarded as the parent, the other as the twin. The orientation of the twin is a mirror image of the orientation of the parent across a twinning plane or an orientation which can be derived by rotating the twin portion about a twinning axis (simple shear twinning). In other cases (hexagonal close-packed lattices, for example), simple shear does not place all twinned atoms in mirror positions, so that a second set of additional ‘shuffle’ movements are required. See also annealing or growth twin and mechanical twin (deformation twin).
Twin bands – These are bands across a crystal grain, observed on a polished and etched section, where crystallographic orientations have a mirror-image relationship to the orientation of the matrix grain across a composition plane that is usually parallel to the sides of the band.
Twin plane re-entrant edge (TPRE) mechanism – It is a growth mechanism in crystal formation where re-entrant edges, formed by the intersection of twin planes, act as preferential nucleation sites for new atomic layers. This leads to the formation of characteristic 141-degree re-entrant corners and 219-degree ridges, and the growth is typically two-dimensional.
Twin-bed demineralization system – It consists of two columns or beds, one containing a cation exchange resin, and the other containing an anion exchange resin. Process water is cycled through the beds sequentially, first through the cation resin, where mineral contaminants are replaced by hydrogen ions, and next through an anion resin, where mineral contaminants are replaced by hydroxyl ions, which combine with the hydrogen ions to form pure water.
Twin boom stacker – It has two booms, one on each side of the stacker with a luffing arrangement. Two booms make it possible to form stockpiles on both sides of the stacker without the slewing mechanism.
Twin bridges – These are a set of two bridges running parallel to each other. A pair of twin bridges is frequently referred to collectively as a twin-span or dual-span bridge. Twin bridges are independent structures and each bridge has its own superstructure, substructure, and foundation. Bridges of this type are frequently created by building a new bridge parallel to an existing one in order to increase the traffic capacity of the crossing. While majority of the twin-span bridges consist of two identical bridges, this is not always the case.
Twin carbon arc brazing – It is a non-standard term for carbon arc brazing.
Twinning induced plasticity (TWIP) steels – These steels have high manganese content (17 % to 24 %) which causes the steel to be fully austenitic at room temperatures. This causes the principal deformation mode to be twinning inside the grains. The twinning causes a high value of the instantaneous hardening rate (n value) as the micro-structure becomes finer and finer. The resultant twin boundaries act like grain boundaries and strengthen the steel. Twinning induced plasticity steels combine extremely high strength with extremely high formability. The ‘n’ value increases to a value of 0.4 at an approximate engineering strain of 30 % and then remains constant until a total elongation around 50 %. The tensile strength is higher than 1,000 mega-pascals (MPa).
TWIP steel – TWIP stands for’ twinning induced plasticity’. TWIP steels are a class of austenitic steels which can deform by both glide of individual dislocations and mechanical twinning. The steels are fully austenitic and non-magnetic, with no phase transformation. These steels represent one of the types of new families of high strength steels which have been developed in recent years to meet the increased demands of weight reduction in automobiles. The formation of deformation twins causes a large degree of deformation. This deformation mode is the reason behind the naming of this group of steels.
Twist – It is the spiral turns about its axis per unit of length in a yarn or other textile strand. Twist can be expressed as turns per unit length, and so forth. ‘S’ and ‘Z’ refer to direction of twist, in reference to whether the twist direction conforms to the middle-section slope of the particular letter.
Twist, balanced – It is an arrangement of twists in a combination of two or more strands which does not cause kinking or twisting on themselves when the yarn produced is held in the form of an open loop.
Twist boundary – It is a sub-grain boundary consisting of an array of screw dislocations.
Twisted pair – It consists of two wires twisted around each other, possibly covered with an overall sheath. This configuration rejects some kinds of interference.
Twist exit guide – The twist exit guide is normally designed to provide maximum stability where greater inter-stand distances are involved. The guide accommodates plane or profile rolls and features symmetrical roll gap adjustment and an easily accessible single point twist angle mechanism. The twist exit guide is either in outboard twisted style or of cartridge style. Both guide types are of fabricated steel construction with incorporated round body style stripper guides. Direct water cooling and lubrication are usually also included to optimize roll and bearing life. Separate mounting feet normally ensure that the guides can be modified to suit all types of stand and rest bar mountings.
Twist hackle (ceramics, glassy materials) – It is a hackle which separates portions of a crack surface, each of which has rotated from the original crack plane in response to a twist in the axis of principal tension. In a single crystal, a twist hackle separates portions of the crack surface, each of which follows the same cleavage plane, the normal to the cleavage plane being inclined to the principal tension. In a bi-crystal or poly-crystalline material, a hackle is initiated at a twist grain boundary.
Two-axle wagon – It is a type of railway vehicle which is used for transporting goods. It is distinguished by having two sets of wheels and axles. These wagons, also known as freight cars.
Two-bell charging system – It refers to a top charging mechanism in a blast furnace which utilizes two bells (one small and one large) to control the entry of raw materials (like ore, coke, and limestone) into the furnace. This system minimizes the escape of hot gases from the furnace during the charging process. Two-bell system needs less height than other systems and it is a comparatively simple device. The drawback is that the large bell seal and the large bell hopper gas seal are difficult to maintain at higher top pressure. A good seal cannot be held at the periphery of the large bell or the small bell as these areas are in the raw material flow. Because of the large size and heavy weight of the components, fabrication and maintenance is difficult, slow, and expensive and needs considerable furnace downtime to replace.
Two bell-top with seal valves and revolving chute – This system consists of a large bell, a small bell, and a seal chamber with a revolving chute added above the small bell. Materials are introduced onto the small bell through two openings, each equipped with a seal valve. These seal valves are smaller than the small bell and the sealing surfaces are out of material flow, leading to effective sealing. The revolving chute consists of one or two openings, which direct the material flow evenly onto the small bell. The small bell hopper is fixed and the small bell has only vertical movement. The large bell and hopper are the same as in the two-bell type. The advantage of this system is that it overcomes the deficiencies of the conventional two bell system. By placing gas seal valves above the upper bell, this arrangement ensures that the large bell always is at the same pressure. The large bell functions as only a burden distribution device and has no gas sealing requirement. The pressure-containing components are the seal valves and the small bell. Both of these are considerably smaller and easier to maintain during shorter duration the BF scheduled outages.
Two-dimensional (2D) object – It is a flat object which has length and width but no depth, such as a shadow or a map. Basic shapes such as circles, squares, and triangles have just two dimensions. If a two-dimensional shape is graphed on a coordinate plane, only the x-axis and y-axis are needed.
Two-dimensional (2D) shape – It consists of a length and a width but does not have any depth or height. Some common two-dimensional (2D) shapes are squares, rectangles, triangles, circles, and hexagons
Two-high mills – These mills have the most commonly used rolling mill configuration. In this configuration, there are two horizontally mounted rolls. The rolling mill-motor drives either both rolls (top and bottom) or only one roll (normally the bottom roll) with the top roll rotating due to the friction between the roll and the work piece. As per the rolls rotation direction, the mill can be either non-reversing (unidirectional) mill or reversing mill. It is a type of rolling mill in which only two rolls, the working rolls, are contained in a single housing.
Two-high mill roll configuration – This is the most commonly used rolling mill configuration. In this configuration, there are two horizontally mounted rolls. The rolling mill-motor drives either both rolls (top and bottom) or only one roll (normally the bottom roll) with the top roll rotating due to the friction between the roll and the work piece. As per the rolls rotation direction, the mill can be either non-reversing (unidirectional) mill or reversing mill.
Two-phase electric power – It is an electric power system using two sets of alternating currents, displaced in time by a quarter period.
Two-port network – It is a network which has two places to exchange energy with its surroundings.
Two-pulley hitch – It is a special transition section, choreographed like a serenade, gracefully moving products from horizontal positioning to incline in a harmonious conveyor performance.
Two-random-variable model – It refers to a statistical model that involves two random variables, frequently denoted as ‘X’ and ‘Y’. These models are used to analyze the relationship between the two variables, such as their joint probability distribution, correlation, or dependence. The key aspect is that both ‘X’ and ‘Y’ are random, meaning their values are uncertain and determined by the outcome of a random process.
Two rollers die process – In this process, a workpiece is deformed between two hardened steel dies to form threads. The dies, which have the desired thread profile, are rotated synchronously and can have a feed movement to perform the forming process. This process, unlike cutting, does not remove material but instead reshapes and strengthens it.
Two-sided Laplace transform – It is also called bilateral Laplace transform. It is a variant of the Laplace transform which simplifies certain operations. It is an integral transform equivalent to probability’s moment-generating function. Two-sided Laplace transforms are closely related to the Fourier transform, the Mellin transform, the Z-transform and the ordinary or one-sided Laplace transform.
Two-stage burner – It is a component of a furnace or heating system which can operate at two different levels of output, allowing for a more efficient and consistent heating experience. It can run at a lower level to maintain a comfortable temperature and switch to a higher level when more heat is needed, especially during colder periods.
Two-stage combustion – It is also known as staged combustion or air staging. It is a technique where the combustion process is divided into two distinct phases or zones. This is typically done to control emissions, particularly nitrogen oxides (NOx), by strategically managing the air-fuel ratio and temperature in different stages.
Two-tailed test – It is a test of hypothesis for which the study hypothesis is not directional, i.e., the study hypothesis allows for the possibility that the true parameter value can fall on either side of the null-hypothesized value. It is a test of significance in which both directions are, a priori, equally likely.
Two-tone – It is a sharp colour demarcation in the appearance of the metal because of a difference in the work roll coating.
T-X diagram – It is a two-dimensional graph of the isobaric phase relationship in a binary system. The coordinates of the graph are temperature and concentration.
Tying and strapping machines – Tying and strapping machines are used for coils, bundles, and piles. These machines are designed for continuous operation. Tying machines use commercial size wires for tying and the machine head is hydraulically operated. The strapping machines are pneumatically operated and use commercial steel straps of different available width. Strapping can be carried out either by clamping or welding.
Tying machines – Tying machines are used for coils, bundles, and piles. These machines are designed for continuous operation. Tying machines use commercial size wires for tying and the machine head is hydraulically operated.
Tyndall effect – It is the effect of light scattering by colloidal or suspended particles.
Type I error – It is the probability of rejecting a true null hypothesis in a statistical test. If, as the result of a test statistic computed on sample data, a statistical hypothesis is rejected when it is to be accepted, i.e., when it is true, then a type I error has been made. Alpha, or level of significance, is pre-selected by the analyst to determine the type I error rate. The level of confidence of a particular test is given by 1- alpha.
Type II error – It is the probability of failing to reject a false null hypothesis in a statistical test. If, as the result of a test statistic computed on sample data, a statistical hypothesis is accepted when it is false, i.e., when it should have been rejected, then a type II error has been made. Beta is pre-selected by the analyst to determine the type II error rate. The Power of a particular test is given by 1-beta.
Type metal – It consists of any of a series of alloys containing lead (58.5 % to 95 %), antimony (2.5 % to 25 %), and tin (2.5 % to 20 %) used to make printing type. Small quantities of copper (1.5 % to 2 %) are added to increase hardness in some applications.
Typical basis – It is the typical property value which is an average value. No statistical assurance is associated with this basis.
Tyre – It is also spelled as tire. It is a ring-shaped component which surrounds a wheel’s rim to transfer a vehicle’s load from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels. Majority of the tyres are pneumatically inflated structures, providing a flexible cushion which absorbs shock as the tyre rolls over rough features on the surface. Tyres provide a foot-print, called a contact patch, designed to match the vehicle’s weight and the bearing on the surface that it rolls over by exerting a pressure which avoids deforming the surface. The materials of modern pneumatic tyres are synthetic rubber, natural rubber, fabric, and wire, along with carbon black and other chemical compounds. They consist of a tread and a body. The tread provides traction while the body provides containment for a quantity of compressed air. In a rotary kiln, the tyre is a large, circular steel ring which is mounted on the kiln shell and supports the kiln’s weight, allowing it to rotate. It effectively transfers the weight of the rotating kiln to the support rollers, ensuring smooth rotation and bearing the stresses of heat and contact. Tyres determine in what type of terrain the truck can operate over. Pneumatic tyres are used for outdoor service (rough terrain). Cushion tyres are used both for indoor and outdoor service (smooth terrain) while solid tyres are used for indoor service.
TZM alloy – It is a high-temperature molybdenum alloy which is mainly composed of molybdenum with additions of titanium, zirconium, and carbon. It is a popular material in aerospace, defense, and industrial applications because of its excellent strength, high-temperature stability, and resistance to creep. The alloy typically contains about 0.5 % titanium, 0.08 % zirconium, and 0.02 % carbon, with the remainder being molybdenum.
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