What does preform mould mean?

I believe you are referring to "preform mold" or "preform mould," which is a type of mold used in the manufacturing of plastic bottles.

A preform is a plastic bottle blank that is shaped like a test tube and is later blown into the final shape of the bottle. The preform mold is used to create these preforms, which are then heated and stretched using a blow molding machine to create the final bottle shape.

The preform mold is typically made from metal and has two halves that fit together to create the cavity where the plastic is injected. The mold is precision-engineered to ensure that the preforms are uniform in size and shape, which is important for creating consistent final products.