Analytical Methodology for Prediction of Warpage of Two Shot Injection Compression Molded Polycarbonate Glazing 2011-01-0003

Automotive OEM's are looking for innovative material solutions that will help them to reduce weight, thereby reduce carbon footprint. One such emerging area to meet this objective is glazing, where traditionally glass is used as the material. Polycarbonate which is an engineering thermoplastic has the potential to replace glass, providing 30 to 40% of weight saving. Two shot injection compression process is primarily adopted for manufacture of these large complex polycarbonate-glazing panels, in order to reduce residual stresses and clamp force. This involves combination of two processes, first the injection compression of clear panel and second overmolding of black out portion with integral features. Prediction of deformation of these molded large panels is a critical parameter for successful replacement of glass. A novel prediction methodology to address this critical parameter is discussed along with comparison of results with experimentation. This paper focuses on development of one such methodology to predict the deformation. It involves prediction of residual stresses of each shot using flow analysis and then exporting it to a structural solver by coupling them together with appropriate method. Different approaches of doing this are explained along with comparison of results with experimentation.