The mould steel should meet the following working conditions:
1. Abrasion resistance
When the melt plastic material is deformed in the mold cavity, it flows and slides along the surface of the cavity, causing violent friction between the surface of the cavity and plastic, which causes the mold to fail due to wear. Therefore, the wear resistance of the material is one of the basic and important properties of the mold.
Hardness is the main factor affecting wear resistance. In general, the higher the hardness of the mold parts, the smaller the amount of wear and the better the wear resistance. In addition, wear resistance is also related to the type, quantity, shape, size and distribution of carbides in the material.
The working conditions of the molds are mostly very bad, and some of them are often subjected to larger impact loads, which leads to brittle fracture. In order to prevent sudden brittle fracture of mold parts during work, the mold must have high strength and toughness. The toughness of the mold mainly depends on the carbon content, grain size and organization state of the material.
3. Fatigue fracture performance
In the process of mold work, under the long-term action of cyclic stress, fatigue fracture is often caused. Its forms include low-energy multiple impact fatigue fracture, tensile fatigue fracture, contact fatigue fracture, and bending fatigue fracture. The fatigue fracture performance of the mold mainly depends on its strength, toughness, hardness, and the content of inclusions in the material.
4. High temperature performance
When the working temperature of the mold is higher, the hardness and strength will decrease, leading to early wear of the mold or plastic deformation and failure. Because the mold material should have high anti-tempering stability, to ensure that the mold has a high hardness and strength at the working temperature.