The problem of extending life of die casting die has been concerned by the application enterprises. The material of reasonable selection of die forming parts has been paid much attention by the manufacturers of die-casting mould and ordering party. Because the choice of die casting die is the basic condition of die life.
Extend die casting die life, besides want to choose high quality steel, also should pay attention to the following problem.
1. The design of casting and die casting shall be reasonable.
Due to the unreasonable design of the casting structure, the thin section of the die is formed, which is the source of the fracture. If the skew value is not reasonable, it will cause the core, the mold or the removal of the scratch; The chamfered Angle at the junction of the cavity wall is slightly leaky, which causes the stress concentration crack; In the design of pouring system, if the flow direction, sectional area, and injection speed are not controlled properly, the erosion of the type wall or core will be caused. When the metal liquid enters the cavity, the vortex is formed. As the velocity of the vortex core is infinite, it has a strong etching effect on the mold surface, resulting in local pull and insufficient rigidity of the mold. Due to the one-sided emphasis on saving the steel, the early deformation or fracture occurs sometimes. The accuracy grade of each component is chosen improperly, or because of the existence of the surplus gap, the thermal conductivity decreases, and the thermal fatigue is produced prematurely. Or because the assembly size is too tight, forming prestress, the die burst in the die casting process. The rapid ejection mechanism has been considered in the modern mold structure, on the one hand, to improve the production efficiency. On the other hand, it is also to reduce the casting time and remove the heat load of the mould material. In die - casting die design, reduce the Mosaic as much as possible to enhance the rigidity of the cavity.
When designing the mould, we should fully consider the heat balance of the mold, so that the mold can maintain a stable and reasonable working temperature.
2. Ensure the tooling quality.
During the grinding process, the friction heat caused by the grinding wheel is not sharp enough to cause surface grinding cracks. In addition, due to the existence of grinding stress, the thermal fatigue capability of the mould can be reduced.
The surface of the cavity, especially the surface roughness of the sprue, has a few scratches and marks on the surface, which are the source of the crack. The mating precision between the die insert and the plate is improperly selected, or it may be caused by too loose influence on the heat conduction efficiency, or due to the prestress caused by the over-tightening. The installation precision between the die and the machine, including the parallelism and perpendicularity, may affect the premature wear of the guide. In the process of the application of electric spark machining die, in the process of processing, due to the local high temperature forming the surface of the back fire zone. The structure and chemical composition of the area are different from the substrate, the hardness is high, and the residual stress is present on the surface, and the post-processing surface is easy to form fine cracks and must be polished.
3. Adopt the best mold heat treatment specification.
The material of die casting mould should have high thermal strength and tempering stability, so that high thermal fatigue resistance and wear resistance can be obtained.
4. High energy density surface treatment of mold.
High energy density surface reinforcement is the application of extremely high energy to the material surface, so that the physical and chemical changes occur to achieve the purpose of reinforcement.
5. Specification for operation of die casting die.
1)The stress in the mould preheating and maintaining the thermal equilibrium mold is proportional to the temperature gradient in the mold, so it is understandable to increase the preheating temperature properly.
2)The film coating of mold coating has an important role in protecting the mould material.
3)It is very important to inspect and inspect molds regularly during service.
4)Die casting die installation and operation procedures.