What causes can affect the failure of die casting mold
Date：
2022-05-18
In the process of die casting production, the mold is repeatedly affected by cold impact heat, so that the forming surface and its internal deformation, which is associated with each other, causing repeated thermal stress, resulting in structural damage and toughness reduction, resulting in the occurrence of micro-cracks and continue to expand. When the crack grows, the molten metal squeezes into it, and repeated mechanical stresses are applied to accelerate crack growth.
1. Die casting die thermal fatigue cracking damage failure
In the process of die casting production, the die is repeatedly affected by cold shock heat, which makes the formed surface and its interior deform, thus causing mutual involvement and repeated thermal stress, leading to structural damage and toughness reduction, leading to microcracks and continued expansion. After crack propagation, molten metal will be squeezed into it, and repeated mechanical stress will be added to accelerate crack propagation. Therefore, on the one hand, the mold must be completely preheated at the beginning of die casting. In addition, the die must be kept within a certain working temperature range during die casting to avoid early cracking failure. At the same time, we must ensure that the internal factors before the mold is put into production and during the manufacturing process will not cause problems. In actual production, most die failures are thermal fatigue cracking failures
2. Reasons for fracture failure of die casting die
Under the action of the pressure injection force, the mold will initiate cracks at the weak points, especially the scribing marks or electric machining marks on the molding surface of the mold are not polished, or fine cracks will appear at the corner clearing of the molding. When there are brittle phases or coarse grains at the grain boundary, it is easy to fracture. However, the crack propagates rapidly during brittle fracture, which is a very dangerous factor for the fracture failure of the die. For this reason, on the one hand, all scratches and electric machining marks on the mold surface must be polished, even if they are in the gating system, they must also be polished. In addition, the die materials used shall have high strength, good plasticity, good impact toughness and fracture toughness
3. Reasons for corrosion failure of die casting die
The commonly used die-casting alloys are zinc alloy, aluminum alloy, magnesium alloy, copper alloy and pure aluminum die-casting. Zn, Al and Mg are more active metal elements, which have better affinity with mold materials, especially Al is easy to occlude the mold. The higher the hardness of the mold, the better the corrosion resistance. If there are soft spots on the molding surface, it is harmful to the corrosion resistance
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