In the automotive industry, there has been a trend towards large structural components manufactured by high pressure die casting (HPDC). The large-area geometries often have small to medium wall thicknesses that connect to volumetric areas. The flow paths are comparatively long and incipient solidification during mold filling cannot be ruled out. Casting defects due to cold runs, air pockets and porosity occur in close proximity and influence each other. In order to describe the casting defects and their interaction, a three phase fully coupled mold filling and solidification methodology has been developed. Liquid melt and gas are treated as compressible fluids separated by a sharp interface. Reduced melt flow due to solidification is achieved by a mushy-zone model followed by a flow-stop functionality. The formation of porosity due to volume shrinkage is combined with this method using a gas evaporation model. Only after the velocities in the melt have fallen below a critical value is the flow simulation stopped and the porosity formation until complete solidification is calculated using a purely thermal macro-shrinkage model. The model has been validated by casting trials using a specially developed test geometry for thin-walled aluminum HPDC applications.

Moderated by: Brian Thomas / Laurentiue Nastac