The main causes of die casting die failure are as follows:

1、 Fragmentation failure: under the action of the injection force, the mold will crack at the weakest part, especially when the scribe mark or electric machining mark on the mold forming surface is not polished, or the fine crack will appear at the clear corner of the molding first. When there is brittle phase at the grain boundary or the grain is coarse, it is easy to fracture. However, the crack propagates rapidly during brittle fracture, which is a very dangerous factor for the fragmentation failure of the die. Therefore, on the one hand, all scratches and machining marks on the mold surface must be polished, even if it is in the pouring system. In addition, the die materials used are required to have high strength, good plasticity, good impact toughness and fracture toughness.

2、 Thermal fatigue cracking damage and failure: during die casting production, the mold is repeatedly subjected to the action of cooling and heating, and the forming surface and its interior are deformed and involved with each other, resulting in repeated cyclic thermal stress, resulting in secondary damage and loss of toughness of the organizational structure, leading to the emergence and continuous expansion of microcracks. Zhongshan Huashi Fushun Special Steel said that once the crack expands, molten metal will squeeze in, Coupled with repeated mechanical stress, the crack propagation is accelerated. Therefore, on the one hand, the die must be fully preheated at the beginning of die casting. In addition, in the process of die-casting production, the die must be kept in a certain working temperature range to avoid early cracking failure. At the same time, it is necessary to ensure that there are no problems due to internal factors before the mold is put into production and during manufacturing. Because in actual production, most die failure is thermal fatigue cracking failure.

3、 Corrosion failure: common die-casting molds include zinc alloy, aluminum alloy, magnesium alloy and copper alloy, as well as pure aluminum die-casting. Zn, Al and Mg are more active metal elements, which have good affinity with die materials, especially al easy to bite die. When the die hardness is high, the corrosion resistance is good, while if there are soft spots on the forming surface, the corrosion resistance is unfavorable.

In case of early failure of the die, it is necessary to find out the internal or external causes for future improvement.

① During die casting production, the mold is repeatedly subjected to the action of cooling and heating, and the forming surface and its interior are deformed and involved with each other, resulting in repeated cyclic thermal stress, resulting in secondary damage and loss of toughness of the organizational structure, leading to the emergence and continuous expansion of micro cracks. Once the cracks expand, molten metal will squeeze in, Coupled with repeated mechanical stress, the crack propagation is accelerated. Therefore, on the one hand, the die must be fully preheated at the beginning of die casting. In addition, in the process of die-casting production, the die must be kept in a certain working temperature range to avoid early cracking failure. At the same time, it is necessary to ensure that there are no problems due to internal factors before the mold is put into production and during manufacturing. Because in actual production, most die failure is thermal fatigue cracking failure.

② Fragmentation failure under the action of injection force, the mold will crack at the weakest part, especially when the scribed trace or electric machining trace on the mold forming surface is not polished, or the fine crack will appear first at the corner clearing of the molding. When there is brittle phase at the grain boundary or the grain is coarse, it is easy to fracture. However, the crack propagates rapidly during brittle fracture, which is a very dangerous factor for the fragmentation failure of the die. Therefore, on the one hand, all scratches and machining marks on the mold surface must be polished, even if it is in the pouring system. In addition, the die materials used are required to have high strength, good plasticity, good impact toughness and fracture toughness.

③ Melting failure has been mentioned before. The commonly used die-casting alloys include zinc alloy, aluminum alloy, magnesium alloy and copper alloy, as well as pure aluminum die-casting. Zn, Al and Mg are more active metal elements. They have good affinity with mold materials, especially Al, which is easy to bite. When the die hardness is high, the corrosion resistance is good, while if there are soft spots on the forming surface, the corrosion resistance is unfavorable. However, in actual production, corrosion is only a local part of the mold. For example, the parts directly washed by the gate (core and cavity) are prone to corrosion, and the die sticking of aluminum alloy is easy to occur at the parts with soft hardness.