Test MethodMeasurement of residual stresses in film insert molded parts with complex geometry

Residual stress distribution of injection molded and film insert injection molded products were measured by using the hole drilling method after ejection and annealing, respectively. Non-isothermal three dimensional flow analysis was carried out for filling, packing and cooling stages. The flow analysis results were transported to a finite element stress analysis program and three dimensional stress analysis was performed for prediction of residual stresses in the parts. For comparison, residual stress distribution was measured by the layer removal method and calculated by the three dimensional numerical simulation in order to evaluate accuracy of the hole drilling method. Residual stress distributions obtained by both experiments and numerical methods accorded well with each other. Therefore, the hole drilling method is a reliable and useful method for measurement of residual stresses in injection molded parts, especially, products with complex geometry.