Die casting

Die casting is the process of forcing molten metal under high pressure into the cavities of steel moulds. The moulds are called dies. Dies range in complexity to produce any non-ferrous metal parts (that need not be as strong, hard or heat-resistant as steel) from sink faucets to engine blocks (including hardware, component parts of machinery, toy cars, etc). In fact, the process lends itself to making any metal part that:

must be precise (dimensions plus or minus as little as 50 µm--over short distances),
must have a very smooth surface that can be bright plated without prior polishing and buffing,
has very thin sections (like sheet metal--as little as 1.2 mm),
must be produced much more economically than parts primarily machined (multicavity die casting moulds operating at high speed are much more productive than machine tools or even stamping presses),
must be very flexible in design; a single die casting may have all the features of a complex assembly.
If several machining operations would be required or assembly of several parts would be required (to make a finished part), die casting is probably far more economical. This level of versatility has placed die castings among the highest volume products made in the metalworking industry.

Common metals used in die casting include zinc and aluminum. These are usually not pure metals; rather are alloys which have better physical characteristics.

In recent years, injection-molded plastic parts have replaced some die castings because they are usually cheaper (and lighter--important especially for automotive parts since the fuel-economy standards). Plastic parts are practical (particularly now that plating of plastics has become possible) if hardness is not required and if parts can be redesigned to have the necessary strength.