Die casting molds in the production process, the most common form of failure: fracture failure, failure and dissolution.
Three kinds of thermal fatigue crack damage damage, three reasons for failure, there are also specific introductions.
First, the failure of the fracture
Under the action of injection pressure, the mold will not crack the most vulnerable part of the crack initiation, especially the surface of the molding line or the surface of the electromachining trace, or the place where the clear angle is formed will be the first small crack. The brittle phase of the grain boundary or the presence of coarse grains is easily broken. A risk factor for rapid crack propagation, brittle fracture, and mold fracture failure. Therefore, on the one hand, scratches on the surface of the mold, the traces of electrical machining must be ground, even if it is in the casting system, it must be illuminated. It also requires high strength, good plasticity using advanced materials, and good impact toughness and fracture toughness.
Second, corrosion failure
Commonly used molds and zinc alloys, cast alloys, aluminum alloys, magnesium alloys and copper alloys, also have pure aluminum alloy die-casting, zinc metal elements, aluminum, magnesium are a lively, they have good affinity, mold materials, Especially aluminum sheets. When the mold has high hardness and good corrosion resistance, if the molding surface has soft spots, it is anti-corrosion.
Third, thermal fatigue crack damage failure
The production of die-casting molds, the surface chilling effect of the hot forming surface and the internal deformation again and again, the thermal stress of repeated cycles appearing, causing structural damage and loss of elasticity, leading to the appearance of microcracks, and continuing to expand, when the cracks expand, the fluid The diapir and molten metal, and repeated mechanical stresses accelerate the crack propagation. Therefore, on the one hand, the die-casting mold must be sufficiently warm-started. In addition, it must be kept at a certain operating temperature range during the die-casting process to avoid early cracking failure. At the same time, it is not a problem to ensure that the mold is put into production before and during production. Due to actual production, mold failure is the hottest fatigue crack failure.