Abstract: The present invention provides a process for fluid assisted injection molding comprising the step of providing an injection molding apparatus having a mold body that defines a mold cavity. The process further comprises the steps of supplying a quantity of fluent plastic to the mold cavity, followed by injecting a fluid into the mold cavity. The fluid forms an expanding fluid pocket in the mold cavity, driving plastic to the furthest recesses of the mold and ensuring a smooth surface finish of the final molded product. A reservoir is selectively connectable to a plastic injection runner, and can be opened to the runner to receive molten plastic ejected by the introduction of the fluid to the mold cavity. When the reservoir is thusly connected, the pressure of the fluid forces the plastic through a supply passage, in a direction substantially opposite to its initial injection direction.

Abstract: A method for the compression molding of a plastic article is provided. The method includes the steps of loading plastic material, that is preferably unheated, into a two piece molding chamber having at least one heating element, closing the molding chamber, and heating the plastic element. The method further includes the step of injecting fluid, for example air, into the plastic material to create at least one cavity within the plastic material. The air may be injected directly into the plastic material, or it may be injected along an upper surface of the chamber. Upon injection of air into the at least one cavity, a portion of the plastic material is forced to exit the chamber.

Abstract: A method of providing gas assistance to a plastic injection molding process including an initial burst of gas at the supply pressure.

Abstract: A nozzle having an internally threaded bore communicating through a mold body with a source of a pressurized gas, and an externally threaded pin received within and engaging the threaded bore. The pin has a machined longitudinal surface creating an air passage through the bore when the pin is in place. At the outlet end of the nozzle the pin carries one or more washers having air passages machined therein.