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ABRASION RESISTANCE. Degree of resistance of a material to abrasion or wear. White iron is extremely abrasion resistant because of its large amount of combined carbon in the form of iron carbide, Fe3C.
ABRASIVES. Hard granular materials for grinding, polishing, blasting either bonded together in the form of wheels or bricks or bonded to paper or cloth belts or discs by glue or resins; or used loose and propelled by centrifugal force from a wheel or an entrained in an air stream. Metallic shot, sand, or grit are used in the latter application. Natural abrasives include emery, garnet, and silica; synthetic abrasives are corundum and silicon carbide.
ACCELERATOR. A material which increases the reaction rate of organic binders. It usually acts as a catalyst in the reaction.
ACID. A term applied to refractories and minerals or slags which have a high silica content. Most frequently used with reference to the characteristic reactions between a slag and the refractory lining of a cupola or furnace used for ferrous alloys.
ADDITION AGENT. Any material added to a charge of molten metal in the bath or ladle to bring the alloy to the required specification.
ADDITIVE. Any material added to a molding sand to promote casting “peel’’, to improve flowability or, to reduce expansion, e.g., sea coal, pitch, cereal graphite, plumbage.
AERATION. The fluffing of a molding sand just before dropping it into the flask.
A.F.S. (AMERICAN FOUNDRYMEN’S SOCIETY). This abbreviation will be found in connection with various tests, numbers, etc., among the foundry definitions.
AIR BELT. Chamber surrounding the cupola at the tuyeres, to equalize volume and pressure of blast and deliver it to the tuyeres. Commonly called a windbox.
AIR DRIED. Surface drying of cores in open air before baking in an oven; also applied to molds which air-dry when left open, which may cause crumbling or crushing when the mold is closed; a core or mold dried in air, without application of heat.
AIR-DRIED STRENGTH. Tenacity (compressive, shear, tensile, or transverse) of a sand mixture after being air dried at room temperature.
AIR FURNACE. A reverbatory type of furnace which is fired by fuel burning at one end of the hearth; the metal is melted by the hot gases which pass over the charge and move toward the stack at the other end. Heat is reflected from the parabolic roof and side walls.
AIR QUENCHING (NORMALIZING). Cooling of alloys in air from above the transformation range.
ALLOY. A metallic mixture composed of two or more chemical elements of which at least one must be a metal. Usually an alloy has properties which are different from its components.
ANNEALING. A heat treating process in which castings are heated in a furnace above the transformation temperature and then are allowed to cool to room temperature before removing from the furnace. A full annealed casting has few residual stresses and is in its softest condition.
APRON FEEDER. A continuous pan conveyor, carried by two strands of chain, used for carrying castings or feeding sand at a controlled rate from a storage hopper.
AS CAST. Referring to a casting which has received no heat treatment other than normal gate and riser removal and sand blasting.
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