The defect analysis with MAGMASOFT® started with reproducing the original conditions and environment of the casting process and the gating system. This showed that the inclusions were caused by both reoxidation and sand erosion. As the engineers could not clearly identify which of these was the main cause for the observed problems, they decided to further investigate both objectives in the optimization process. However, the filling time could not exceed 12 seconds to continue to ensure optimal productivity.
The gating system was parametrized using 12 geometrical variables, resulting in a possible 4096 combinations. However, to keep the task efficient, the number of variables and experiments were decreased with the goal of quickly identifying the most critical tendencies. This finally resulted in a first Design of Experiments (DoE) with 16 differerent gating designs, with the aim to find a variation suitable to reduce sand inclusions and air entrapment at the same time.
The assessment showed a strong correlation between the gating geometry and reoxidation, but there was no clear tendency to solve the sand inclusion defects. The best gating system was tested to produce 50 parts, with the purpose of further reducing reoxidation combined with the best compromise for filling time, a smooth filling and sand inclusions.