Numerical simulation of flows, heat transfer and solidification in pressure die casting

A recent study shows that, when liquid metal is injected as a jet into a die cavity, the liquid-air interface roughens and, in most instances, the interface breaks up. A mixing zone with liquid droplets and air is created. This is especially true in high pressure die casting where cavity fill is carried out at high flow velocities. It suggests that casting porosity can result from the liquid surface irregularities and the droplets produced during cavity filling. A computer model has been developed to simulate such flows. It is used here to examine simultaneously the flow, heat transfer and solidification in a process of casting a rectangular plaque with a thickness to length ratio of 0.1. Heat transfer and solidification are coupled throughout the process, ie. during the periods of both filling and residual flow. Complete results for the distributions of velocities, pressures, volume fractions of liquid, temperatures, thickness and porosity of solidified metal are obtained.