The injection blow moulding machine is a self contained unit that carries out the preparation of the melt, the injection moulding of a pre-form and the blowing of the final product.
Instead of extruding a parison between an open mould as in Extrusion Blow Moulding the first stage of Injection Blow Moulding is very similar to conventional injection moulding. The objective of this stage is to injection mould a pre-form. For a simple bottle this would consist of the neck being produced as required, complete with the external thread and a closed tube of much smaller diameter than the eventual bottle. The tube has the same (or smaller) internal diameter as the finished bottle, which is formed by the steel core pin. It is about the same length as the finished bottle and the wall thickness is such that the pre-form contains sufficient material to make the body of the bottle. The wall thickness is the difference between the core pin and the injection mould cavity The perform is fed from the injection moulding unit on what will become the base of the bottle.