Common faults and causes of die casting molds
During the casting process of the mold, some failures and damages often occur, and the use of a very serious defect such as the mold is lower than the standard part. It is understood that the most common failure form of the die-casting mold in the production process: fracture failure, failure and dissolve.
Three kinds of thermal fatigue crack damage and failure, three reasons for failure, also have a specific introduction.
1. Fracture failure
Under the action of injection pressure, the most vulnerable place where the mold will crack, especially the surface of the traces of the molding line or the electrical machining marks are not completed, or the place where the clear angle is formed will be the first small crack, in the The existence of brittle phase or coarse grains at grain boundary means easy fracture. Rapid crack propagation, brittle fracture, and die fracture are risk factors for failure. So, on the one hand, scratches on the surface of the mold, electrical machining marks must be ground, and even if it is in the gating system, it must also be illuminated. It also requires high strength, good plasticity using advanced materials, and good impact toughness and fracture toughness.
2.Second, corrosion failure
Commonly used molds and zinc alloys, casting alloys, aluminum alloys, magnesium alloys and copper alloys, there are also pure aluminum alloy die-casting, zinc metal elements, aluminum, magnesium is a lively, they have good affinity, mold materials, Especially aluminum sheets. When the hardness of the mold is high, it has good corrosion resistance, and if there are soft spots on the molding surface, it is anti-corrosion.
3. Thermal fatigue crack damage failure
In the production of die-casting molds, the surface chilling effect of hot forming and its internal deformation, repeated cycles of thermal stress with each other, lead to structural damage and loss of elasticity, resulting in the appearance of micro-cracks, and continue to expand, when the crack expands, the fluid Diapirs and molten metal, and repeated mechanical stress accelerate crack growth. Therefore, on the one hand, the die-casting mold must be fully preheated to start. In addition, it is necessary to maintain a certain working temperature range in the process of die casting to avoid early cracking failure. At the same time, ensure that the pre-production and internal production of the mold is not a problem. Due to the actual production, die failure is the most thermal fatigue crack failure.
