Sequential injection molding process

Claim 1

A process for molding plastic parts utilizing an injection molding machine having primary and secondary injection means operating at primary and secondary injection pressures, respectively, and primary and secondary clamping means including clamping control means for clamping at least one first mold located at a first molding station and at least one second mold located at a second molding station, said molds comprising cooperating mold halves supported by fixed and movable platens, said platens being arranged in tandem and one movable platen supporting said secondary injection means, comprising the steps of: providing a molten plastic distributor means on said one movable platen operable to communicate, selectively, with one of said cooperating mold halves at each molding station, closing and clamping said molds, wherein said molds are clamped at each station by the primary clamping means and the secondary clamping means in combination, injecting a molten plastic from said primary injection means at said primary injection pressure through said distributor means into said first clamped mold at a first molding station to fill said first clamped mold, cooling the molten plastic in said first clamped mold, and injecting sufficient molten plastic to fill said second mold at said second molding station from said primary injection means at said primary injection pressure and cooling the molten plastic in said second clamped mold, maintaining secondary injection pressures by said secondary injection means at said first and second molds for a sufficient interval after filling and during cooling to compensate for shrinkage, unclamping and opening said first mold, and removing the molded part.