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Home > Glossary of Foundry Terms > A

Glossary of Foundry Terms - A

To help site visitors understand more about metal casting and foundry operation terms and terms associated with the iron foundry and other metal foundry industries, Atlas Foundry Company has included this one-of-a-kind glossary. The glossary is organized as an alpha listing to enable visitors to quickly find the term being looked for. We have added a substantial number of cross-links to help our site visitors view similar or related foundry terms.

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The displacement and/or detachment of metallic particles from a surface as a consequence of being exposed to flowing solids, fluids or gases.

Abrasion Resistance

Degree of resistance of a material to abrasion or wear.


Any substance used for abrading, such as grinding, polishing, blasting etc. Abrasive materials come in all shapes and forms, powders, bonded to wheels, boards, papers; they can be sand, files, emery, and so on.

Abrasive Wear

The displacement and / or detachment of metallic particles from a surface as a consequence of being exposed to flowing fluids or gases. See Abrasion.


Materials for grinding, polishing, blasting, either in loose form or bonded to form wheels, bricks, or files, or applied to paper and cloth by glue or resin. Natural abrasives include emery, corundum, garnet, sand, flint, etc. Metallic shot and grit are also used as abrasives in cleaning castings.


The temperature at which austenite begins to form on heating. See Austenite.


In hypoeutectoid steel, the temperature at which transformation of ferrite into austenite is completed upon heating. See Hypoeutectoid Steel, Ferrite, Austenite.


A substance that hastens a reaction usually acting as a catalyst; as used in sand additive resins.

Acceptable Quality Level (AQL)

A quality level established on a prearranged system of inspection using samples selected at random.


In hypereutectoid steel, the temperature at which cementite goes into complete solution with austenite. See Hypoeutectoid Steel.


A solution or liquid with a pH less than 7. A term applied to slags, refractors, and minerals containing a high percentage of silica. A chemical term to define a material, which gives an acid reaction. See pH, Slag.

Acid Brittleness (Picking brittleness)

Lack of ductility, induced in steel when it is pickled in dilute acid to remove scale - commonly attributed to the absorption of hydrogen. See Ductility.

Acid Embrittlement

Embrittlement during pickling due to absorption of hydrogen.

Acid Melting

Melting in a furnace with refractory material that has an acid reaction. Material may be silica, sand, siliceous rock, or silica brick.

Acid Process

A steel making method using an acid refractory-lined (usually silica) furnace. Neither sulfur nor phosphorus is removed.

Acid Steel

Steel melted in a furnace which has an acid bottom and lining, under a predominantly siliceous slag.


Adapti Investment Casting Process

A lost wax process employing one of three methods; centrifugal, vacuum or gravity-pouring casting. See Investment Casting.

Addition Agent

Any material added to a charge of molten metal in bath or ladle to bring alloy to specifications. A reagent added to the plating bath. See Alloy, Ladle.


Any material added to molding sand for reasons other than bonding or improvement of bond is considered an additive. Bonds can be of varying types: carbonaceous (sea coal, pitch, fuel oil, graphite, gilsonite); cellulose (wood flour, cereal hulls); fines (silica flour, iron oxide, fly ash); cereals (corn flour, dextrine, sugar); and chemical (boric acid, sulfur, ammonium compounds, diethylene glycol). See Sea Coal.

Adeline Steelmaking Process

Method of producing a precision casting of steel or steel alloys using aluminolthermic process and lost wax, followed by centrifugal action. See Lost Wax Process.

ADI - Austempered Ductile Iron

A very high strength, high ductility, iron grade created through heat treating. See Ductility.

Aecm, Ae1, and Ae3

Equilibrium transformation temperatures in steel.


Making contact between air and a liquid by spraying liquid into the air or by agitating the liquid to promote absorption of air. Also act of fluffing molding sand.


A device for fluffing (or decreasing the density of) and cooling sand by the admixture of air. See Molding Sand.

AFS Fineness Number

Approximately the number of meshes per inch of a sieve that just would pass the sand sample if its grains were uniform in size. In other words, it is the average of the grains in the sand sample. See American Foundrymen's Society.

AFS Tests

A number of standard tests determined by American Foundrymen's Society to evaluate molding and core sands. See Core Sand, Molding Sand.

Age Hardening

Hardening by aging, usually after rapid cooling or cold working. See Precipitation Hardening.


A change in properties of metals and alloys which occurs slowly at room temperature and will proceed rapidly at higher temperatures. A change in the metal or alloy by which its structure recovers from an unstable condition produced by quenching, quench aging, or by cold working, strain aging. The change in structure consists. The change in properties is often, but not always, due to a phase change, precipitation, but never involves a change in chemical composition of the metal or alloy. See Age Hardening, Precipitation Hardening.

Air Belt

Chamber, surrounding the cupola at the tuyeres, to equalize the volume and pressure of the blast and deliver it to the tuyeres. See Cupola, Tuyere.

Air Channel

A groove or hole which carries the vent from a core to the outside of a mold. See Core, Mold.

Air Control Equipment

Any device used to regulate the volume, pressure, or weight of air.

Air-Dried (Dry)

A core or mold dried in air, without application of heat. See Core, Mold.

Air Furnace

A form of reverberatory furnace for melting ferrous and nonferrous metals and alloys. Flame from fuel burning at one end of the hearth passes over the bath to the stack at the opposite end of the furnace. Heat also is reflected from the roof and side walls.

Air Hammer

Chipping hammer operated by compressed air.

Air Hardening

Full hardening of a metal or alloy during cooling in air or other gaseous medium from a temperature above its transformation range.

Air Hoist

Lifting device operated by compressed air.

Air Hole

Hole in a casting caused by air or gas trapped in the metal during solidification. See Casting.

Air Injection Machine

An early type of die casting machine in which air pressure acting directly on the surface of molten metal in a closed gooseneck forces the metal into the die.

Air Quenching

Accelerated cooling of alloy in an air stream from temperatures above the Ac3 temperature. See Ac3.

Air Scale

Scale left on ferrous metal in processing, usually from heating in presence of air.

Air Setting

The property of some materials to take a permanent set at normal air temperature. Examples are gypsum slurry, investment molding materials, core and mold washes, etc. See Core, Mold.



A cleaning operation, as cleaning sand from molds.

Air-Hardening Steel

A steel containing sufficient alloy to fully harden during cooling in air. Typically this term is restricted to steels being able to harden in sections of about 2 inches (51 mm) or more.

Airless Blast Cleaning

A process whereby the abrasive material is applied to the object being cleaned by centrifugal force generated by a rotating-vane-type wheel.

Alkaline Derusting

An electrical process for derusting steel, cast iron and other ferrous alloys without using heat.

Allowance (Tolerance)

In a foundry, the clearance specified; difference in limiting sizes, as minimum clearance or maximum interference between mating parts, as computed arithmetically.


A substance having metallic properties and composed of two or more chemical elements of which at least one is metal. A metallic material formed by mixing two or more chemical elements. Usually possess properties different from those of the components. As examples, Brass is an alloy of copper and zinc and Cast Iron contains iron, carbon and silicon. See Cast Iron.

Alloy Steel

Steel containing significant quantities of alloying elements other than carbon and the commonly accepted amounts of manganese, silicon, sulfur, and phosphorus.


Procedure of adding elements other than those usually comprising a metal or alloy to change its characteristics and properties.

Alloying Elements

Elements added to nonferrous and ferrous metals and alloys to changer their characteristics and properties.


Body-centered cubic type of pure iron stable below 1,670°F (910°C).

Alpha Martensite

A form or stage of martensite of somewhat arbitrary distinction, probably representing the least developed and most distorted stage in the transformation of austenite to martensite at ordinary temperatures. See Martensite.

Alpha Process

A shell molding and core-making method in which a thin resin-bonded shell is baked with a less expensive, highly permeable material. See Shell Molding.

Alternating Stress

Stress produced in a material by forces acting alternating in opposite directions.


Ambient Air

The surrounding air.

Ambient Temperature

Temperature of the surrounding air.

American Foundry Society

Association that provides and promotes knowledge and services that strengthen the metal casting industry for the ultimate benefit of its customers and society.

Ames Portable Hardness Tester

The Rockwell penetration method of testing hardness of metals can be made with this tester by applying pressure to the penetrator by screw action. See Rockwell Hardness.

Analysis Line

In spectrographic analysis, the particular spectral line used in determining the concentration of an element.


Appliance used to hold cores in molds.

Angle Testing

A method of ultrasonic testing using shear waves introduced from the surface of the material at approximately 45°F or °C.


The characteristic of exhibiting different property values in different directions with respect to a fixed reference system in the material.


The process of heating a metal and slowly cooling it, reducing the brittleness and increasing the strength of the metal. See Bright Annealing, Double Annealing.


Forming a conversion coating on a metal surface by electrolytic oxidation with the work forming the anode. This process is most frequently applied to aluminum.

Anticarburizing Compounds

Compounds applied to metallic surfaces to prevent surface carbonization.


One of the elements; its chemical symbol is Sb. Its formula weight is 121.76, specific gravity 6.62, and melting point 630.5°C.

Antioch Process

Plaster molding process using a mixture of about 50% sand, 40% gypsum, and 8% fibrous talc mixed with water in the proportion of 100 parts by weight material with 50 parts water.

Antipiping (Material)

Usually refers to an insulating material placed on top of a sprue or riser that keeps the metal in liquid or semiliquid form for a long period of time and minimizes the formation of the usual conical pipe or shrink in the top of a sprue or riser. See Riser, Sprue.

Apparent Contraction

The net contraction of a casting dimension due to true metal contraction, mold wall movement and restraint during solidification and cooling. See Solidification.



A metal barrel, frame, or plate to support or carry part of a mold or core. A device to reinforce or lift a mass of sand. See Core, Mold.

Arc Cutting

Using an electric arc to cut metal.

Arcair Torch

An electric arc torch with air ducts running parallel to the electrode, used to remove metal and surface defects from ferrous castings. See Casting.

ARD Process

A refinement of the precision casting process, using plastic patterns produced in automatic injection machines. See Casting, Pattern.

Argon Oxygen Decarburization (AOD)

A secondary refining process in which argon, oxygen and nitrogen are injected into a molten bath of steel. The AOD process improves metal cleanliness and thus gives superior mechanical properties.

Arnold's Fatigue Test

(Named after John Arnold), a test for fractures using 850 cyclic stress reverses per minute, recording the number of cycles required to produce fracture.

Arrestor, Dust

Equipment for removing dust from air.

Artificial Aging

An aging treatment above room temperature. See Aging, Age Hardening.

As Cast (As-Cast, u.m.)

Referring to metal which has not received finishing (beyond gate removal or sandblasting) or treatment of any kind including heat treatment after casting. Similarly as drawn as forged and as rolled. See Heat Treatment.

As-Cast Condition

Casting without subsequent heat treatment. See Casting, Heat Treatment.

Assembling (Assembly) Line

Conveyor system where molds or cores are assembled. See Core, Mold.

Atomic Probe Field Ion Microscopy (APFIM )

An analytical technique in which atoms are ionized by an electric field near a sharp specimen tip. The field then forces the ions to a fluorescent screen which shows an enlarged image of the tip and individual atoms are made visible.

Atmosphere, Furnace

Gases with which metal is in contact during melting or heat treating. See Heat Treating.

Atmosphere, Neutral

Furnace atmosphere which is neither oxidizing nor reducing can be made up of an inert gas e.g. argon, or the products of combustion.

Atmosphere, Oxidizing

Furnace atmosphere which gives off oxygen under certain conditions or where there is an excess of oxygen in the product of combustion, or the products of combustion are oxidizing to the metal being heated.

Atmosphere, Reducing

Furnace atmosphere which absorbs oxygen under suitable conditions or in which there is insufficient air to completely burn the fuel, or the product of combustion is reducing to the metal being heated.

Atmospheric Riser (Williams)

Blind riser that employs atmospheric pressure to aid feeding. Insertion of a small sand core into the riser provides a means for ingress of air into the interior of the riser, and forces the metal into the casting cavity. See Riser, Cavity, Mold or Die.


The smallest particle of an element.


The face-centered-cubic phase of iron and steel, also referred to as gamma iron. In steel, a solid solution in which gamma iron is the solvent. See Gamma Iron.

Austenite Steel

Any steel containing sufficient alloy to produce a stable austenitic (gamma iron) crystalline structure at ambient temperatures. See Gamma Iron.


Usual reference is to an alloy steel or iron with structure at room temperature that is normally composed essentially of austenite.


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Marion, IN 46952-3348
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