Evaluation of Ejection Force for Die Castings by FEM Thermal Stress Analysis with Elasto-Plastic-Creep Model

In the die design of high pressure die casting (HPDC), in order to prevent the casting from the warpage, it is essential to predict ejection force of each ejector pin before locating it. Recently, Shiga et al. revealed that their developed elasto-plastic-creep model is more accurate than conventional elasto-plastic models to estimate the thermal stress of casting during cooling with constraint of dies. In this study, by using the elasto-plastic-creep model, thermal stress analysis was conducted to predict the force generated on each ejector pin in the HPDC process. As a result, the force was estimated within the error of 30% in respect to the measured value. It was also predicted that increasing in the curing time increases the force.