Causes of die casting mold failure:

① Mold thermal fatigue crack failure

During die-casting production, the mold is repeatedly stimulated by cold and heat, and the molding surface and its interior are deformed, and they are mutually involved, resulting in repeated cycles of thermal stress, resulting in damage to the structure and loss of toughness, causing the appearance of micro-cracks and continuing to grow. Once the crack expands, molten metal squeezes in, and repeated mechanical stresses accelerate the crack propagation. For this reason, on the one hand, the mold must be fully preheated at the beginning of die casting. In addition, the mold must be kept in a certain working temperature range during the die-casting production process to avoid early cracking failure. At the same time, it is necessary to ensure that there are no problems with the internal factors before the mold is put into production and during manufacturing. In actual production, most mold failures are thermal fatigue cracking failures.

② Fragmentation failure

Under the action of the injection force, the mold will initiate cracks at the weakest part, especially if the scribe marks or electrical processing marks on the molding surface of the mold are not polished, or the clear corners of the molding will first appear micro cracks , When there are brittle phases or coarse grain boundaries, it is easy to break. However, the crack propagation is very fast during brittle fracture, which is a very dangerous factor for the fracture and failure of the mold. For this reason, on the one hand, all the scratches and electrical processing marks on the mold surface must be polished, even if it is in the pouring system, it must be polished. In addition, the mold material used is required to have high strength, good plasticity, good impact toughness and fracture toughness.

③Melting failure

Commonly used die-casting alloys include zinc alloy, aluminum alloy, magnesium alloy and copper alloy, as well as pure aluminum die-casting. Zn, Al, Mg are more active metal elements, and they have good affinity with mold materials, especially Al which is easy to bite. mold. When the mold hardness is higher, the corrosion resistance is better, and if there are soft spots on the molding surface, the corrosion resistance is unfavorable. However, in actual production, dissolution is only a part of the mold. For example, the parts (core, cavity) that are directly washed by the gate are prone to corrosion, and the aluminum alloy is prone to sticking to the mold at soft hardness.