Sand Casting Processes

Sand casting is a mold based net shape manufacturing process in which metal parts are molded by pouring molten metal into a cavity. The mold cavity is created by withdrawing a pattern from sand that has been packed around it. Since the pattern imprint forms the cavity, the pattern creates the external shape of the cast part. If the part has undercuts or hollow internal regions, these can be formed by sand cores that are fabricated separately and then placed in the mold cavity. The cores are supported by core prints, and/or chaplets that allow the molten metal to flow between the core and the mold wall. In addition, cores may be necessary to produce a desired “zero” draft external surface, depending on the parting line selected. The parting line is formed by the interface between the cope (upper portion) and drag (lower portion) of the mold. The separate cope and drag are necessary to allow the pattern to be withdrawn from the sand and to allow the cores to be properly positioned within the mold.