Experimental study and theoretical analysis on die soldering in aluminum die casting

The die surface states and chemical element distribution of the soldering region in a failed die from a die casting plant have been studied. The results show that there exist numerous microholes, microcavities and cracks on the die surface of the soldering region. The diameter of the smaller microholes is about 0.6 μm and that of the bigger microholes is more than 15 μm. According to the aluminum distribution on the cross-section of die soldering region, the mechanisms causing die soldering are being discussed and the soldering is classified as physico-chemical, mechanical and mixed soldering. Based on the theoretical models proposed in this paper, the effects of process parameters, including temperature and the chemistry of the die and the aluminum casting alloy, the injection pressure and the die surface state, on soldering phenomena have been studied. In addition, the formation and spread of soldering to a given die in the die casting process have also been discussed.