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First, thermal fatigue crack damage failure

Die casting production, die again and again by the chilling effect of thermal forming surface and its internal deformation, with each other and appear repeatedly cyclic thermal stress, lead to structure damage and loss of resilience, cause the emergence of micro cracks, and continue to expand, once the crack expand, fluid diapir and molten metal, and repeated mechanical stress to accelerate the extension of crack. Therefore, on the one hand, the die must be fully preheated at the beginning of die-casting. In addition, the mold must be kept within a certain working temperature range in the process of die casting to avoid early cracking failure. At the same time, to ensure that the mold before production and manufacturing internal causes of no problems. Because of the actual production, most of the die failure is thermal fatigue cracking failure.

Ii. Fragmentation failure

Under the action of the injection force, the mold will be at the weakest crack initiation, especially on the molding surface of the marking marks or electric machining marks were not polished, or the shape of the clear Angle will be the first to appear fine cracks, when there is brittle phase or grain boundary coarse, that is easy to fracture. Brittle fracture is a very dangerous factor for fracture failure of die. To this end, on the one hand, where the surface of the mold scratches, electrical processing traces must be polished, even if it is in the casting system parts, must also be polished. In addition, high strength, good plasticity, impact toughness and fracture toughness are required.

Three, corrosion failure

The commonly used die casting alloys include zinc alloy, aluminum alloy, magnesium alloy and copper alloy, as well as pure aluminum die casting. When the hardness of the mold is higher, the corrosion resistance is better, and if there are soft spots on the molding surface, the corrosion resistance is adverse.