Reduction of Blister Occurrence after Plating in Zinc Alloy Die Casting by Optimization of Gating System

Abstract

In die casting, laminations are a serious problem because they cause blisters, stripping defects and zinc deposition on the mold surface. Blisters and stripping defects reduce the quality of the product, and zinc deposits on the mold surface reduce productivity. Therefore, the analytical prediction of the risk of lamination formation and the optimization of the gating system for reducing the occurrence of defects due to laminations are very important before designing a mold. To optimize the gating system, we used an evaluation criterion formulated using the shear rate of the molten metal flow in a die casting simulation. In this study, we proposed a coupling analysis method consisting of mold temperature and mold filling analyses, and applied it to the optimization of a gating system based on the evaluation criterion. Using this method, we eliminated the occurrence of blisters due to laminations after plating.

(a) Prediction of lamination formation by simulation. (b) Blisters generated by actual die casting. (c) Microscopy images of blisters observed in areas A and B.