In the old language, metal injection was known as die casting. It is the process of applying pressure with special machines to inject metals heated to their melting temperature into pre-prepared moulds. The most commonly used metals and alloys in metal injection are aluminium, zamak (a zinc and aluminium alloy), brass, magnesium, and lead. Metal injection machines are the machines that do this printing. This process is carried out by machines of various types (hydraulic, pneumatic, servo, hybrid, and vacuum), primarily cold chamber and hot chamber metal injection machines. Cold chamber machines are used to cast aluminium and brass, whereas hot chamber machines are used to cast zamak. Hot chamber machines are significantly faster than cold chamber machines. They can, however, only print metals and alloys with low melting points, such as zamak alloys, magnesium, and lead.