A NUMERICAL STUDY OF EXTERNALLY SOLIDIFIED PRODUCTS IN THE COLD CHAMBER DIE CASTING PROCESS

The fraction of melt which solidifies in the shot sleeve before the metal is injected into the die cavity is referred to as externally solidified products (ESP). ESP may affect the melt fluidity, cavity fill, microstructure and mechanical properties of final castings. The objectives of this research are to conduct simulations to investigate the amount of ESP formed during shot sleeve pouring and shot delay time period, and its distribution in the shot sleeve; to examine what amount of ESP will travel into the die cavity, and the final location of the ESP in the casting; to understand the gains and the limitations of computer modeling for the ESP study; to obtain insights on how to minimize or eliminate cold flakes in castings. The modeling activities in this research are categorized into two related studies. First, a FLOW3D athermal shot sleeve model was developed, which can estimate the ESP formation during the shot sleeve pouring and shot delay time period. The athermal shot sleeve model was developed and verified via an experiment conducted at OSU. Subsequently, the athermal model was applied to Briggs & Strattons tensile bar casting to examine the ESP formation for this specific die casting process. Second, an isothermal cavity fill modeling using the marker/particle feature was developed to investigate ESP final distribution in the tensile bar cavities. ii