Shrinkage and Warpage Analysis of Plastic Injection Molded Parts

New developments allow for the prediction of the size, warped shape and mechanical properties of a plastic part dependent on the specific conditions under which it was injection molded. These developments include computer programs designed to capture the discrete information under which the plastic material was formed, through all phases of the molding cycle. This is then combined with results of laboratory testing where the material's shrinkage and mechanical properties have been expressed in terms of its fundamental characteristics relative to how they were molded. Following this phase, external loads can be applied to the computer model of the part and stress analysis performed allowing an accurate accounting of the residual stress and anisotropic properties resulting from molding. This paper will concentrate on the aspects of predicting shrinkage and warpage.