Abstract: Methods for enhanced purging of an injection molding shooting pot assembly are provided. Old melt is purged from a shooting pot having an injection plunger slidably received in an injection cylinder. The plunger is moved by a powered piston, which moves the injection plunger to a purging position. The plunger is then arrested in the purging position. Sufficient new melt is injected through an inlet positioned such that the new melt sweeps substantially an entire volume of the injection cylinder ahead of the injection plunger in flowing between the inlet and a single outlet remote from the inlet.

Abstract: A plasticizing unit having a plasticizing screw, an injection piston connected to the screw, a quill connected to the piston, and hydraulic cavity formed by the piston and a quill end face. Hydraulic fluid is transferred to the hydraulic cavity to move the piston and screw away from the quill. The screw and piston are subsequently moved towards the quill to displace hydraulic fluid out of the hydraulic cavity and cause back pressure. The back pressure is counteracted by acting on the back of the quill.

Abstract: A pre-plasticizing injection molding machine includes a plasticizing and flow regulating assembly connected to the tip of an injection chamber or shooting pot having an injection cylinder. A distributor valve allows the transfer of plastic resin into the shooting pot at low pressure and prevents the backward flow of resin to the plasticizing unit when the injection plunger injects the resin. A plurality of distribution channels in communication with either the distributor valve or a separate valve, and having outlets in the shooting pot angularly equispaced in proximity to the perimeter of the conical tip of the plunger uniformly distributes new resin behind resin retained in the shooting pot from the previous injection cycle, thereby obviating stagnation zones.