Injection moulding (U.S. spelling: injection molding) is a
manufacturing process for producing parts by injecting molten
material into a mould, or mold. Injection moulding can be performed
with a host of materials mainly including metals (for which the
process is called die-casting), glasses, elastomers, confections,
and most commonly thermoplastic and thermosetting polymers.
Material for the part is fed into a heated barrel, mixed (using a
helical screw), and injected into a mould cavity, where it cools
and hardens to the configuration of the cavity. After a product is
designed, usually by an industrial designer or an engineer, moulds
are made by a mould-maker (or toolmaker) from metal, usually either
steel or aluminum, and precision-machined to form the features of
the desired part. Injection moulding is widely used for
manufacturing a variety of parts, from the smallest components to
entire body panels of cars. Advances in 3D printing technology,
using photopolymers that do not melt during the injection moulding
of some lower-temperature thermoplastics, can be used for some
simple injection moulds.
