Attention must be paid when opening die of zinc die casting
1. Fragmentation failure
Under the effect of injection pressure, the mold will crack at the weak place, especially the scratches or electrical machining marks on the molding surface of the mold are not polished, or the fine corners of the mold will show fine cracks prematurely. When there is a brittle phase or coarse grains at the grain boundaries, it simply cracks. However, the crack propagation is rapid during brittle cracking, which is a very risky factor for the fracture of the mold.
Solution: It is necessary to polish the scratches and electrical machining marks on the zinc die-casting parts, even if it is in the pouring system, it is necessary to polish. In addition, the mold materials used are required to have high strength, good plasticity, good impact resistance and crack resistance.
Pay attention to these problems, not only to make zinc die castings smoother when opening the mold, to replace the quality of the mold, but also to have a longer life. The quality of the zinc alloy die castings is undoubted.
2. Thermal fatigue cracking damage failure
When the zinc die-casting is produced, the mold is repeatedly subjected to the effect of cold shock heat, the molding surface and its interior are deformed, and they are involved to each other to exhibit repeated thermal stress, which leads to damage to the structure 2 and loss of tolerance, causing the appearance of micro-cracks. And continue to expand. Once the crack grows, there is molten metal squeezed in, plus repeated mechanical stresses to accelerate the crack growth.
Solution: At the beginning of die casting, the mold must be fully preheated. In addition, when the die-casting of zinc die-casting parts is opened, it is necessary to keep the mold in a certain working temperature range to avoid the early cracking failure.