Tamara Wilhite is a technical writer, industrial engineer, mother of two, and published sci-fi and horror author.
What is Metal Casting?
Metal casting begins when liquid cast called slipped is poured into a mold. The molds set. The molds are dumped or turned over so that excess liquid can drain. In the sparing step, a tool called a spare is used to trim excess from the openings of the mold. Then a sponge is used to smooth the opens around the mold.
Stripping occurs when the molds are broken open and the casting is taken out. The castings are then sent to cast finishing. Cast finishing involves trimming the casting to remove all seams, wet sponge it, flush it with water and then band it or stamp it for identification. The material of the casting may be tested to verify its composition, or the casting may be checked for external or internal flaws.
The applicable metal casting standards depend on the type of metal used, the casting method and its stage in the manufacturing process. The steps that turn a casting into a finished product are called "metal finishing".
Iron Casting Standards
ASTM A48-03 is the standard for gray iron castings. ASTM A436-84 is the standard for austenitic iron castings. ASTM A518 is the standard for iron castings containing silicon to make it corrosion resistant.
ASTM A47 is the standard for ferritic iron castings. ASTM standard A220 is the standard for pearlitic iron. ASTM A536-84 is the standard for ductile iron castings. ASTM E30 outlines the test methods used for cast iron.
ASTM E446 gives the process for performing radiographs for steel castings that are up to two inches thick. There are further ASTM standards for iron castings based on their intended use. For example, ASTM A602-94 for iron castings used in the automotive industry, while ASTM A834-95 gives the material specifications for iron castings for general use.
Aluminum Casting Standards
ASTM B26M - 12 is the standard for aluminum alloy sand castings. ASTM B686 is the standard for high strength aluminum castings.
ASTM B179 is the standard for aluminum alloy ingots used in casting processes. ASTM B917 outlines the process for heat treating aluminum alloy castings.
ASTM E88 is the process of sampling the casted metal forms to verify their composition and makeup. ASTM B557 is the process of tension testing aluminum casted products. SAE standard ASM2771 addresses the heat treatment of castings of aluminum alloy.
Magnesium Casting Standards
ASTM B80-09 is the standard for magnesium alloy sand castings. ASTM B93 is the standard for magnesium alloy ingots used in castings. ASTM B661 outlines the process of heat treating magnesium alloys. ASTM B296 outlines the designations used for magnesium alloys, whether they are cast or wrought.
ASTM standard B557 is also includes the process for tension testing magnesium alloy, casted products. ASTM B661 outlines the recommended practices for heat treating magnesium alloys.
Zinc Casting Standards
ASTM B240-10 is the standard for zinc alloy and zinc-aluminum alloy ingots used in die castings. ASTM B86 is the standard for zinc alloy die castings. ASTM B908 outlines the color codes used on zinc casting alloy ingots. ASTM E536 gives the test methods for analyzing zinc alloys. ASTM B792 is the standard for zinc alloy ingots used in slush casting.
Master alloys used for zinc die casting alloys must meet the material specifications in ASTM B327. ASTM B949 is the general standard for zinc alloy products, whether they are ingots or slabs. ASTM E536 outlines the chemical analysis test method for zinc alloys.
ASTM E2349-12 gives the recommended safe practices during metal casting, though OSHA's safety regulations are backed by the force of law. ASTM F1002 outlines the performance requirements for the protective clothing worn by workers around molten metal. The American Foundry Society has its own standards on the foundry environment.