It is very difficult to produce thickwalled parts on conventional injection moldings without sink mark and low internal stressed. The sink mark, shrinkage and warpage in conventional injection molded part with thick walls can be eliminated when using the gas injection molding process. This occures due to the formation of gas filled cavities.
Gas injection molding process of semi-crystalline materials was studied experimentally to investigate molding conditions as gas pressure, gas filling time, mold temperature for successful processing of a thick part and a thin part with rib.
Shapes and properties of these specimens are effected by those parameters.