Abstract: A method and apparatus for the injection molding of plastics wherein the sprue bushing is provided with a plurality of grooves in its bore as contrasted with the conventional sprue bushings having smooth bores. The sprue formed is complementarily ribbed and these irregular surfaces speed cooling of the sprue and facilitate manual handling thereof.

Abstract: An injection molding machine for plastic material comprising an injection cylinder; a displaceable element axially disposed in the cylinder, one of the cylinder and displaceable element being movable with respect to the other; an injection nozzle on one end of the injection cylinder; a feed device including a feed hopper and a plunger reciprocally mounted in said hopper in communication with the other end of the cylinder; a pressure block between the feed device and the other end of the cylinders and a substantially continuously curving passage in the pressure block.

Abstract: An injection molding machine comprising an injection cylinder; a displacement element axially disposed in the injection cylinder; one of the cylinder and displacement element being movable with respect to the other; an injection nozzle on one end of the injection cylinder and a feed device including a feed hopper and a plunger reciprocally mounted in the hopper on the other end of the cylinder; a pressure source for driving the plunger; and switches for varying the working position of the plunger, the plunger stroke, the stroke frequency of the plunger and the pressure of the pressure medium.