The effective factors in the warpage problem of an injection-molded part with a thin shell feature

Communication and electronic products have been developing towards the design concept of being light, thin, short, and small. To acquire the maximal internal space for parts to be packed closely into the product, one way is to reduce the wall thickness of the housing components. Therefore, the production technique of plastic injection molding of a part with a thin shell feature is becoming increasingly more important. Many factors lead to the defects of parts, such as warpage, shrinkage, sink marks, residual stress, and so on. This research used the experimental design of Taguchi method to determine the injection molding conditions, and the injection processes were simulated using the commercial software C-MOLD™. Both molding conditions and factors were discussed regarding the degree of warpage of a thin shell part. The results showed that the packing pressure had the greatest influence on the warpage, followed by mold temperature, melt temperature, and packing time. However, the warpage was only slightly influenced by the gate dimension and the filling time in thin shell injection molding. In addition, applying the experimental design of Taguchi method is a quite effective method to deduce the optimum set of effective factors in injection molding to produce plastic parts with minimum warpage.