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Glossary of Foundry Terms - T

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Tap

To withdraw a molten charge from the melting unit.

Tap Hole

Opening in a furnace through which molten metal is tapped into the forehearth or ladle. See Ladle.

Teapot Ladle

Ladle with external spout wherein the molten metal is poured from the bottom rather than from the top. See Ladle.

Tear, Hot

Same meaning as hot crack, but developing before the casting has solidified completely. See Hot Crack.

Tear-Ups

Defect caused by backdraft, damaged pattern or uneven drawing of pattern. See Defect.

Telltale

Any distinguishing mark, projection, groove, etc. on a pattern, core box, mold or core which acts as a guide mark for assembling matching parts. See Core, Core Box, Mold.

Temper

Reheating hardened, normalized or mechanically worked steel to a temperature below the critical range to soften it and improve impact strength. The moisture content of a sand at which any certain physical test value is obtained, i.e., temper with respect to green compressive strength, permeability, retained compressive strength, etc. To mix material with enough liquid to develop desired molding properties.

Temper Brittleness

Brittleness that results when certain steels are held within or cooled slowly through a certain range of temperature below the transformation range. The brittleness is revealed by notched-bar impact tests at room temperature or lower temperatures.

Temper Carbon

Carbon in nodular form, characteristic of malleable iron.

Temper Stressing

Quenching in water from the tempering temperature to improve fatigue strength.

Temperature

Degree of warmth or coldness in relation to an arbitrary zero measured on one or more of accepted scales, as Centigrade, Fahrenheit, etc.

Temperature, Holding

Temperature above the critical phase transformation range at which castings are held as a part of the heat treatment cycle. The temperature maintained when metal is held in a furnace, usually prior to pouring.

Temperature, Pouring

The temperature of the metal as it is poured into the mold.

Tempered Martensite

Martensite that has been heated to produce to BCC iron and a fine dispersion of iron carbide. See Martensite.

Tempering (Sand)

Addition of water to and mixing molding sand to obtain uniform distribution of moisture. See Molding Sand.

Tensile Strength (Ultimate Tensile Strength, UTS)

A measure of the amount of mechanical stress a material can withstand before it fractures. Measured in pounds per square inch (PSI), or thousands of pounds per square inch (KSI).

Ternary Alloy

An alloy that contains three principal elements.

Test Bar

Standard specimen bar designed to permit determination of mechanical properties of the metal from which it was poured.

Test Lug

A lug cast as a part of the casting and later removed for testing purposes.

Thermal Conductivity

The property of matter by which heat energy is transmitted through particles in contact. For engineering purposes, the amount of heat conducted through refractories is usually given in Btu per hour for one square foot of area, for a temperature difference of one degree Fahrenheit, and for a thickness of one inch, Btu/hr·ft·F/in.

Thermal Contraction

The decrease in a linear dimension and volume of a material accompanying a change of temperature.

Thermal Expansion

The increase in a linear dimension and volume of a material accompanying a change of temperature.

Thermal Fatigue

Failure resulting from rapid cycles of alternate heating and cooling.

Thermal Shock

Stress developed by rapid and uneven heating of a material.

Thermal Spalling

Breaking up of refractory from stresses which arise during repeated heating and cooling.

Thermal Stability

Resistance of a material to drastic changes in temperature.

Thermit Reaction

Exothermic, self-propagating processes in which finely divided aluminum powder is used to reduce metal oxides to free metals by direct oxidation of aluminum to aluminum oxide, with accompanying reduction of the less stable metal oxide. See Exothermic Reaction, Endothermic Reaction.

Thermocouple

A device for measuring temperatures by the use of two dissimilar metals in contact; the junction of these metals gives rise to a measurable electrical potential which varies with the temperature of the junction. Thermocouples are used to operate temperature indicators or heat controls.

Thermography

The technique of obtaining a photographic record of heat distribution in a solid or fluid.

Tie Bar

Rod-bar or rod-shaped part of the casting added to prevent distortion caused by uneven contraction between separated members.

Tight Flask

A type of flask which remains on mold during pouring. Lugs are normally provided for clamping cope and drag together for pouring. See Cope, Drag, Flask.

Tin

A chemical element having symbol Sn, formula weight 118.70, specific gravity 7.31, and melting point 231.85°C.

Tin Sweat

Beads or exudations of a tin-rich low-melting phase found on the surface of or on risers of bronze castings, which are usually caused from absorption of hydrogen by the molten metal.

Titanium

A white metallic element, melting point 1660°C (3020°F), having a high strength-to-weight ratio; useful in aircraft parts.

Tolerance

The permissible deviation of a dimension from the nominal or desired value. Minimum clearance between mating parts.

Tongs

Metal instrument with two legs joined by a hinger for grasping and holding things, e.g., crucible tongs.

Tool Steel

Any high-carbon or alloy steel used to make a cutting tool for machining metals and for metal-casting dies.

Tooling Points

The fixed positions on the casting surfaces used for references during layout and machining.

Top Board

A wood board on the cope half of the mold to permit squeezing the mold. See Squeeze Board.

Toughness

The ability of the metal to absorb energy and to deform plastically during fracture. Toughness values obtained in testing depend upon the test temperature, the rate of loading, the size of the test specimen, as well as the presence of a notch and its acuity.

Tower Oven

Vertical, continuous core oven with suspended shelves attached to sprocket-driven chains.

Tramp Element (Trace)

Contaminant in the components of a furnace charge, or in the molten metal or casting, whose presence is felt to be either unimportant or undesirable to the quality of the casting.

Transfer Ladle

A ladle that may 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 furnace to pouring ladles. See Ladle, Shank.

Transformation (Temperature) Range

The critical temperature at which a change in phase occurs. To distinguish between the critical points in heating and cooling those in heating are referred to as the Ac points (c for Chauffage or heating) and those in cooling, Ar (r for Refroidissement).

Trim Die

Die for shearing (or shaving) flash from a die-casting.

Trimming

Removing fins, gates, etc. from castings. See Casting, Gate, Fins.

Trowel

Tool for sleeking, patching, and finishing a mold.

Tucking

Manual pressing of sand under the flask bars, in pockets and around gaggers where ramming alone fails to give desired density to ensure firm placement. See Sand, Ramming, Flask.

Tumbling Barrel

A revolving metal, wood box, or barrel in which castings are cleaned.

Tungsten

Steel-gray, metallic element, mp 3380°C (6116°F) used for electric lamp filament, x-ray tube target, and as alloy element in high-speed steels.

Turntable

The base on which a centrifugal casting mold rests.

Tuyere

Opening in the cupola where the air blast enters. See Cupola.

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Atlas Foundry Company, Inc.
601 N. Henderson Avenue
Marion, IN 46952-3348
Telephone: (765) 662-2525 • Fax: (765) 662-2902
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