Steve Ham has specialized in injection molded structural plastics processes since 1973. External gas molding is an advanced injection process producing highly cosmetic and functional moldings. Development of large piece low pressure injection molding started with the structural foam process decades ago and evolved. Counter pressure and co-injection were early adaptations to improve surface finish. Gas assisted injection molding emerged as a method to produce large thin walled pieces with thicker structural ribs.
Many specialized technologies have been developed in recent years including External Gas Molding. With a properly designed mold, a cushion of gas is injected between the mold cavity and the plastic surface. Volumetric resin shrinkage is contained to the core side of the molding while holding appearance surface packed against the mold cavity. The process works quite well with counter-pressure and thermal cycling filling techniques.
Steve Ham is available as a consultant to industry to help with design and manufacture of products utilizing advanced injection molding products.