cavity (gate) and leads from the mold cavity through verti- cal channels (risers or feeders). Sand inclusions Cavities or surface imperfections on a casting caused by sand washing into the mold.
Scrap a) Any scrap metal melted (usually with suitable additions of pig iron or ingots) to produce castings. b) Reject castings. Segregation A casting defect in which alloying elements are concentrated in specific regions, usually as a result of the primary crystallization of one phase with the subsequent con- centration of other elements in the remaining liquid. Semi-permanent mold A permanent mold in which sand, plastic or graphite cores are used. Shakeout The process of separating the solidified casting from the mold material (Fig. 7).
Short run a) Insufficient metal in a ladle to fill the mold. b) When metal freezes at the gates before filling the mold. Shrinkage Contraction of metal in the mold during solidifica- tion. The term also is used to describe the casting defect, such as shrinkage cavity, which results from poor design, insufficient metal feed or inadequate feeding.
Slag A fused nonmetallic material that protects molten metal from the air and extracts certain impurities from the melt. Slag inclusions Casting surface imperfections similar to sand inclusions but containing impurities from the charge materi- als, silica and clay eroded from the refractory lining, and ash from the fuel during the melting process. May also originate from metal-refractory reactions occurring in the ladle during the pouring of the casting.
Slurry A flowable mixture of refractory particles suspended in a liquid (Fig. 8).
Sodium silicate/CO2 process Molding sand is mixed with sodium silicate and the mold is gassed with CO2 to produce
a hard mold or core.
Sprue (downsprue-downgate) The channel, usually vertical, through which molten metal enters the mold.
Industry Trade Associations
American Foundry Society Inc. 1695 N. Penny Lane Schaumburg, IL 60173 Tel: 800/537-4237; 847/824-0181 Fax: 847/824-7848 Website:
www.afsinc.org
Cast Metals Institute Inc. 1695 N. Penny Lane Schaumburg, IL 60173 Tel: 800/537-4237; 847/824-0181 Fax: 847/824-7848 Website:
www.castmetals.com
Ductile Iron Society
15400 Pearl Road, Suite 234 Strongsville, OH 44136 Tel: 440/665-3686 Fax: 440/878-0070 Website:
www.ductile.org
Investment Casting Institute 136 Summit Avenue Montvale, NJ 07645-1720 Tel: 201/573-9770; Fax: 201/573-9771 Website:
www.investmentcasting.org
2011 CASTING SOURCE DIRECTORY
Iron Casting Research Institute 2802 Fisher Road Columbus, OH 43204 Tel: 614/275-4201 Fax: 614/275-4203 Website:
www.ironcasting.org
Non-Ferrous Founders’ Society 1480 Renaissance Drive, Suite 310 Park Ridge, IL 60068 Tel: 847/299-0950; Fax: 847/299-3598 Website:
www.nffs.org
North American Die Casting Assn. 241 Holbrook Drive Wheeling, IL 60090 Tel: 847/279-0001; Fax: 847/279-0002 Website:
www.diecasting.org
Steel Founders’ Society of America 780 McArdle Drive Unit G Crystal Lake, IL 60014 Tel: 815/455-8240; Fax: 815/455-8241 Website:
www.sfsa.org
METAL CASTING DESIGN & PURCHASING 49
Stress relieving A process of reducing residual stresses in a casting by heating it to a suitable temperature and holding it for a sufficient time. Superalloy An alloy developed for very high temperatures where relatively high stresses are encountered and where oxidation resistance is needed.
Surface treating Any method of treating the surface of a metal to make it more resistant to weather or chemical attack.
Test bar A standard specimen bar designed to permit deter- mination 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 expansion The increase in a linear dimension and volume of a material accompanying a change of temperature. Tilt-pouring In permanent molding, when the mold is moved from a low angle to a vertical position during pouring.
Vent An opening or passage in a mold or core to facilitate escape of gases when the mold is poured.
Warpage a) A deformation other than contraction that devel- ops in a casting between solidification and room temperature. b) A distortion occurring during annealing, stress relieving and high-temperature service.
Wax pattern A precise duplicate, allowing for shrinkage, of the casting and required gates, usually formed by pouring or injecting molten wax into a die or mold.
Yield or casting yield The percentage of quality degated castings produced in relation to the amount of molten metal poured.
METAL
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