How to reduce the defects of zinc alloy die casting

How to reduce the defects of zinc alloy die casting

Control the generation of pores: The key is to reduce the amount of gas mixed into the casting. The ideal metal flow should be continuously accelerated into the cavity from the nozzle through the shunt cone and the flow channel to form a smooth and consistent metal flow. The design of the runner, that is, the pouring flow should be gradually reduced from the nozzle to the inner door at an accelerated rate, so that this purpose can be achieved. In the filling system, the mixture of gases is due to turbulence mixing with the metal liquid phase to form pores. Through the study of the simulated die casting process of metal liquid from the casting system into the cavity, it is obvious that the rapid transition and incremental pouring flow path will lead to the turbulent flow of molten metal and entrainment of gas. Stable molten metal facilitates the flow of gas from the flow path and cavity into the overflow tank and exhaust tank, and then out of the mold. ​​

For shrinkage holes: In the die-casting curing process, the various parts of the die-casting curing process should be dissipated evenly and solidified at the same time as possible. Through reasonable nozzle design, gate thickness and position, mold design, mold temperature control and cooling, shrinkage holes can be avoided. For intergranular corrosion phenomenon: mainly control the content of harmful impurities in alloy raw materials, especially lead < 0.003%, pay attention to the impurity elements brought by waste. ​​

For water marks and cold separation lines: increase the temperature of the mold, increase the speed of the inner door, or increase the overflow trough of the cold separation zone to reduce the appearance of cold separation lines. ​​

For hot cracks: the thickness of die casting parts should not change sharply to reduce stress; Relevant die casting process parameters should be adjusted; Mold temperature should be reduced.