Filling and postfilling analysis of injection/compression molding

Injection compression molding is a process that modifies the original injection molding process to have a compression stage after the injection. This process is suitable for precision injection molding parts. The success of an injection compression molding process relies on proper design of the mom and selection of process conditions. The main scope of this study is to develop a process simulation tool for the injection compression molding process. The simulation tool is used to predict the state variations of the material during the molding, including molding flow, distributions of temperature and pressure, and the material shrinkage. The effect of the compression action on the molding part was investigated by this study. The compression action can provide more uniform packing on the mold cavity. But, with the non-uniform cooling, material can have different fluidity in the cavity, which induces pressure gradients during the compression action. From the simulation results, it is demonstrated that a two-stage compression action in the injection compression molding process can reduce the pressure gradient in the cavity and still have low shrinkage. By using this method, products with higher precision and lower warpage can be molded.