Die Casting

Die casting is the process of forcing molten metal under high pressure into mold cavities (which are machined into dies). Most die castings are made from nonferrous metals, specifically zinc, copper, aluminum, magnesium, lead, and tin based alloys, but ferrous metal die castings are possible. The die casting method is especially suited for applications where large quantities of small to medium sized parts are needed with good detail, a fine surface quality and dimensional consistency.

This level of versatility has placed die castings among the highest volume products made in the metalworking industry.

In recent years, injection-molded plastic parts have replaced some die castings because they are cheaper and lighter. Plastic parts are a practical alternative if hardness is not required and little strength is needed.

For the casting of low melting point metals (such as pot metal, lead, aluminum, or magnesium) a multi-part die is used in a process called die casting. For automotive parts such as the cases of automatic transmissions these dies may be quite complex, as they must be disassembled in specific order to ensure that the work piece is released freely from the casting die. Parts or products produced by this method are referred to as die cast. Compared to lost wax casting the marginal production can be quite cheap, once the substantial investment in tooling and materials handling equipment is made. Compared to sand casting the die casting method can reproduce fine details on complex parts and yield a smooth surface, greatly reducing machining and polishing requirements. As some small portion of metal may leak between the mating seams of the die this can result in a sharp edge of metal called flash, which must be removed by grinding and buffing. For small metal toys the term die cast is generally considered a mark of quality, especially when compared to the cheaper stamping of lithographed sheet metal, or bare stamped metal possibly later painted.