The injection molding machine is based on an extruder barrel and screw assembly which melts the polymer. The molten polymer is fed into a manifold where it is injected through nozzles into a hollow, heated perform mould. The perform mould forms the external shape and is clamped around a mandrel (the core rod) which forms the internal shape of perform. The perform consists of a fully formed bottle/jar neck with a thick tube of polymer attached, which will form the body.
The perform mould opens and the core rod is rotated and clamped into the hollow, chilled blow mould. The core rod opens and allows compressed air into the perform, which inflates it to the finished article shape.