Use of magnetic fields in aluminum investment casting

The mould filling process of aluminum investment casting consists basically of the flow in a U-bend showing a high pouring velocity at the beginning and decreasing velocity values during the course of the process. The high velocities during the starting phase are supposed to cause distinct problems like bubble or inclusion entrapment. We present results on the design and application of a DC magnetic field in order to control this pouring process. Based on numerical simulations and modeling cold metal pre-experiments, DC fields were designed and installed in various casting processes under industrial conditions. The statistics of the casting products show a significant improvement of the casting parts quality. In addition, modeling studies have been performed for an AC magnetic field which may serve for a melt braking at the beginning of the casting process, but a pumping of the melt in a later stage, too.