Casting definitions and terminology

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My ASNT Level III VI Self Study Notes

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A As-Cast Condition: Casting without subsequent heat treatment.

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B Back Draft: Reverse taper which would prevent removal of a pattern from a mold or a core from a corebox Bar, Flask: A rib in the cope of a tight flask to help support the sand.

Backing Sand: The bulk of the sand in the flask. The sand compacted on top of the facing sand that covers the pattern.

Binder: The bonding agent used as an additive to mold or core sand to impart strength of plasticity in a dry state.

Blasting or Blast Cleaning: A process for cleaning or finishing metal objects by use of an air blast or centrifugal wheel that throws abrasive particles against the surfaces of the work pieces. Small irregular particles of metal are used as the abrasive in grit blasting; sand in sand blasting; and steel balls in shot blasting.

Bleeder: A defect wherein a casting lacks completeness due to molten metal draining or leaking out of some part of the mold cavity after pouring has stopped.

Burn-On Sand: Sand adhering to the surface of the casting that is extremely difficult to remove.

Burn-Out: Firing a mold at a high temperature to remove pattern material residue.

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C Casting Yield: The weight of casting or castings divided by the total weight of metal poured into the mold, expressed as a percent.

Centrifugal Casting: A process of filling molds by 1) pouring metal into a sand or permanent mold that is revolving about either its horizontal or its vertical axis; or 2) pouring metal into a mold that is subsequently revolved before solidification of the metal is complete. See also Centrifuge Casting.

Centrifuge Casting - A casting technique.

Cavity: The portion of a cast which forms the external shape Chaplet: A small metal insert or spacer used in molds to provide core support during the casting process.

Charge: A given weight of metal introduced into the casting furnace.

Chill: A metal insert in the sand mold used to produce local chilling and equalize rate of solidification throughout the casting.

Cleaning: Removal of runners, risers, flash, surplus metal and sand from a casting.

CO2 Process: Molds and cores made with sand containing sodium silicate are instantly hardened by permeating the sand with carbon dioxide gas.

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Coining: A press metal-working operation which establishes accurate dimensions of flat surfaces or depressions under predominantly compressive loading.

Cold Shot: Small globule of metal embedded in, but not entirely fused with the casting.

Cold Shut: A casting defect caused by imperfect fusing of molten metal coming together from opposite directions in a mold or due to folding of the surface.

Collapsible Core: A metal insert made in two or more pieces to permit withdrawal from an undercut mold surface.

Cope: The top half of a horizontally parted mold.

Core: A sand or metal insert in a mold to shape the interior of the casting or that part of the casting that cannot be shaped by the mold pattern. The portion of the cast which forms the internal shape Core Assembly: An assembly made from a number of cores.

Corebox: The wooden, metal or plastic tool used to produce cores.

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Coreprint: A projection on a pattern that leaves an impression in the mold for supporting the core.

Core Wash: A liquid suspension of a refractory material applied to cores and dried (intended to improve surface of casting).

Crush: The displacement of sand at mold joints.

Cuploa: A cylindrical, straight shaft furnace (usually lined with refractories) for melting metal in direct contact with coke by forcing air under pressure through openings near its base.

Cure: To harden.

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D Die: A metal form used as a permanent mold for die casting or for wax pattern in investment casting.

Die Casting: A casting process in which the molten metal is forced under pressure into a metal mold cavity.

Die Cavity: The impression in a die into which pattern material is forced.

Directional Solidification: The solidification of molten metal in a casting in such a manner that liquid feed metal is always available for that portion that is just solidifying.

Draft: Taper on the vertical sides of a pattern or corebox that permits the core or sand mold to be removed without distortion or tearing of the sand. Angle of draft varies and is dependant on surface length as well as process employed during cast.

Draft (Pattern) - The taper on the sides of pattern which are perpendicular to the parting plane that allows the pattern to be withdrawn from the mold without breaking the edges of the mold.

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E Ejector Pins: Movable pins in the pattern die that "push" to remove cast pattern from the dies.

External Undercut: Any recess or projection on the outside of the die block which prevents its removal from the cavity.

F Facing Sand: The sand used to surround the pattern that produces the surface in contact with the molten metal.

Feeder: Also called "riser", it is part of the gating system that forms the reservoir of molten metal necessary to compensate for losses due to shrinkage as the metal solidifies.

Flask: A rigid metal or wood frame used to hold the sand of which a mold is formed and usually consisting of two parts, cope and drag.

Foundry Returns: Metal (of unknown composition) in the form of gates, sprues, runners, risers and scraped castings returned to the furnace for remelting.

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G Gas Porosity: A condition existing in a casting caused by the trapping of gas in the molten metal or by mold gases evolved during the pouring of the casting.

Green Sand: A molding sand that has been tempered with water and is employed for casting when still in the damp condition.

Green Sand Mold: A mold composed of moist molding sand and not dried before being filled with molten metal.

H Hotbox Process: A resin-based process that uses heated metal coreboxes to produce cores.

Hot tear: Irregularly shaped fracture in a casting resulting from stresses set up by steep thermal gradients within the casting during solidification.

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I Inclusions: Particles of slag, refractory materials, sand or deoxidation products trapped in the casting during pouring solidifications.

Internal Shrinkage: A void or network of voids within a casting caused by inadequate feeding of that section during solidification.

Inverse Chill: The condition in a casting section where the interior is mottled or white, while the other sections are gray iron. Also known as Reverse Chill, Internal Chill and Inverted Chill.

Investment Casting Process: A pattern casting process in which a wax or thermoplastic pattern is used. The pattern is invested (surrounded) by a refractory slurry. After the mold is dry, the pattern is melted or burned out of the mold cavity, and molted metal poured into the resulting cavity

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L Loose Piece: 1) Core box; part of a core box which remains embedded in the core, and is removed after lifting off the core box. 2) Pattern; laterally-projecting part of a pattern so attached that it remains in the mold until the body of the pattern is drawn. Back-draft is avoided by this means. 3) Part of a permanent mold which remains on the casting, and is removed after casting is ejected from the mold.

Lost Wax Process: A casting process in which an expendable pattern made of wax or similar material is melted or burned out of the mold rather than being drawn out.

Lost Foam: A casting process in which a foam pattern is replaced by molten in a flask filled with loose sand to form a casting.

Master Pattern: The object from which a die can be made; generally a metal model of the part to be cast with process shrinkage.

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M Mold: The form, made of sand, metal or refractory material, which contains the cavity into which molten metal is poured to produce a casting of desire shape.

Mold Cavity: The impression in a mold produced by removal of the pattern. It is filled with molten metal to form the casting. Gates and risers are not considered part of the mold cavity.

Mold Shift: A casting defect which results when the parts of the mold do not match at the parting line.

Mold Wash: A slurry of refractory material, such as graphite and silica flour, used in coating the surface of the mold cavity to provide an improved casting surface.

Mold Weight: A weight that is applied to the top of a mold to keep the mold from separating.

Molding Machine: A machine for making molds

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N Nitriding: A process of shallow case hardening in which a ferrous alloy, usually of a special composition, is heated in an atmosphere of ammonia, or in contact with nitrogenous material, to produce surface hardening by formation of nitrites, without quenching.

Nobake Process: Molds/cores produced with a resin bonded air-setting sand. also known a the airset process because molds are left to harden under ambient conditions.

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P Parting Line: A mark or line produced on the cast, formed at the junction of the parting dies.

Patternmakers Shrinkage: Contraction allowance made on patterns to compensate for the decrease in dimensions as the solidified casting cools in the mold from freezing temperature of the metal to room temperature. Pattern is made larger by the amount of contraction that is characteristic of the particular metal to be used.

Porosity: Holes in the produced casting due to : Gasses trapped in the mold, the reaction of molten metal with moisture in the molten sand, or the imperfect fusion of chaplets with molten metal.

R Rod: A heavy wire or bar in a sand core used for reinforcing.

Runner: The portion of the gate assembly that connects the down gate (sprue) with the casting ingate or riser. The term also applies to that part of the pattern which forms the runner.

Runout: Unintentional escape of molten metal from a mold.

Riser: See feeder.

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S Shrink Hole: A hole or cavity in a casting resulting from shrinkage and insufficient feed metal, and formed during solidification.

Shrinkage: Decrease in volume of the metal as it solidifies.

Shrinkage Cavity: Void left in cast metals as a result of solidification shrinkage.

Shrinkage Defect: Jagged hole or spongy area of a casting lined with dendrites: generally due to insufficient feeding of molten metal during solidification. Not to be confused with Patternmakers shrinkage.

Sprues: Channels cut into a mold to allow for the entry of metal. Also the name given to the metal rods that assume this shape in the final casting.

Other Reading http://wenku.baidu.com/view/e3dbdf93daef5ef7ba0d3c2d.html

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