PET preform mold for plastics materials (PET) have been made in some manner for centuries. Some of these PET preform moulds were fine works of art, as, for example, the moulds used by craftsmen in glass. The coming of the modern plastics moulding materials brought about great advancement in this old art, and transformed it into a science. Mass production PET preform moulding machinery has been developed, and new PET preform mould steels and alloys have been introduced to withstand severe service. Accuracy is a requirement in modern manufacturing, and PET preform moulded plastics are produced by steadily mounting standards of precision, which have necessitated new machine tool applications and methods.