By “Preform Cap”, I’m going to assume that you are aski […]
By “Preform Cap”, I’m going to assume that you are asking about the injection molded PET Polyester Preform that will later be blown to the full bottle size. These machines begin as more or less general purpose IMMs, but are modified specifically to make PET preforms. Dryers tailored for use the driest air of any plastics dryers, with dew points as low as -40, while at the same time heating the PET to a temperature generally not seen on any other materials. This additional heating step also prepares the PET for proper crystallization as the material passes through the screw and barrel of the IMM, which is not much different from a “standard” IMM - although the screw is usually specifically designed for PET molding. The molds tend to be very different and very specialized, often costing more than the machine itself. Frequently, the mold opens with the preform only partially solid (at this point, it would be too soft and hot to be ejected. That plate moves out of the way while another plate containing empty cores immediately take their place. A few seconds later, the first set of cores with PET preforms on them ejects the preforms - just before it is needed to inject the next set onto them.Wholesale Cap mould Manufacturers
If you happened to actually be asking about the Caps for preforms, that’s another specialized process, much of the time - although the material for most caps is Polypropylene, the fastest process compression molds caps one at a time, but at very fast speeds, like a machine gun.