Improvement in warpage prediction results through integrative simulation with Moldflow & Ultrasim®
For plastic parts that are manufactured by injection molding process, it is mandatory nowadays to predict accurate warpage at a preliminary stage. However, the existing process simulation method with Moldlfow has some limitations and is based on several simplified assumptions, e.g. it ignores temperature dependent mechanical properties. To compensate for these limitations, BASF has introduced a new module for its Ultrasim® tool which is based on an integrative simulation technology, using first Moldflow results for the filling and packing phase but then map those onto a FEM model using a more complex material model to simulate the cooling and shrinkage phase. This thermo-mechanical material model has been carefully developed by considering temperature dependent, non-linear mechanical properties and stress relaxation behavior. The model also considers time dependent description of the warpage starting from packing phase of the molding process, followed by actual cooling and ejection. In this study, Polybutylene terephthalate (PBT) polymer (unfilled – Ultradur® B4520 and 30% glass filled – Ultradur® B4300G6) and Polyamide (Ultramid® A3WG10 which is 50 % glass filled) materials have been considered for warpage correlation study. The accuracy of the prediction has been compared between the classical simulation approach with Moldflow, the new Ultrasim® approach and the actual experimental inspection results.