Abstract: An injection mold bushing which is mounted on the mold and is adapted for sprueless molding. The construction comprises an inner shank and an outer body between which is mounted a heating element for independently controlling the heat at each gate. The material passage is straight and centrally located, minimizing the likelihood of material collecting and degrading in the passage, and making it simple to clear this passage if material build-up occurs. The location of the heater and insulating construction around the bushing insures that the mold will be uniformly cool relative to the material, minimizing distortion of the molded parts.

Abstract: A machine and method for injecting structural foam or other thermoplastic materials into one or more mold cavities. The machine comprises at least one mold-mounted shut-off bushing having a material delivery chamber formed between an outer body and a shank, with a shut-off pin slidably mounted in the shank, a heater being disposed between the pin and shank so as to heat the material passage as well as the shut-off pin tip. Closing of the shut-off bushings is independent of material pressures and is carried out from the space between a mold half and its platen by a cylinder operated cam rod.