Numerical Simulation of Injection/Compression Molding

Injection/compression molding (ICM) is often referred to as coining, stamping, compressive-fill, or hybrid molding. It can produce parts with more homogeneous properties and less molded-in stresses, and this may not be possible with conventional injection molding. It can also produce extremely thin or large parts which may require larger machine if conventional injection molding were used. A CAE software has been developed to simulate the ICM process. Two areas will be emphasized to show the advantage of the ICM process over the conventional injection molding process. One is the opening of the mold halves during the molding process allows resin flow to proceed to the extremities of the cavity more easily and consequently reduces the injection pressure and clamping force. Process window design will be discussed. The other is the packing due to the compression motion requires less pressure gradient, i.e., more effective packing. It results in more uniform and smaller pressure throughout the entire cavity. This is essential to produce parts with low residual stress such as compact disk and lens.