The importance of mold material selection

Mould material selection is a very important link in the whole mould making process. Mold material selection needs to meet the three principles, mold to meet the wear resistance, strength and toughness and other work requirements, mold to meet the process requirements, at the same time the mold should meet the economic applicability.

requirements

1. When the abrasive blank is plastically deformed in the mold cavity, it flows and slides along the surface of the mold cavity, causing severe friction between the surface of the mold cavity and the blank, thus leading to the failure of the mold due to wear. So the material wear resistance is one of the super basic and important properties of mold. Hardness is the main factor affecting wear resistance. Generally, the higher the hardness of the mold parts, the smaller the wear, the better the wear resistance. In addition, wear resistance is also related to the type, quantity, morphology, size and distribution of carbides in the materials.

2. Most of the working conditions of the strong and ductile molds are very harsh, and some of them often bear a large impact load, leading to brittle fracture. In order to prevent the mold parts from breaking suddenly, the mold should have higher strength and toughness. The toughness of the die mainly depends on the carbon content, grain size and microstructure of the material.

3. Fatigue fracture is often caused by the long-term effect of cyclic stress in the working process of fatigue fracture mold. Its forms include multiple impact fatigue fracture with small energy, tensile fatigue fracture, contact fatigue fracture and bending fatigue fracture. The fatigue fracture performance of the die 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 decline, leading to early wear or plastic deformation of the mold and failure. Therefore, the mold material should have higher anti-tempering stability, to ensure that the mold in the working temperature, has a higher hardness and strength.

Some molds are in the state of repeated heating and cooling in the process of work, so that the surface of the cavity is subjected to the effect of tension, pressure and variable stress, causing surface cracking and peeling, increasing friction, hindering plastic deformation, reducing the dimensional accuracy, resulting in mold failure. Cold and heat fatigue is one of the main failure modes of hot working dies.

6. Corrosion resistance some molds, such as plastic molds, when working, due to the presence of chlorine, fluorine and other elements in the plastic, after heat decomposition precipitation HCI, HF and other strong corrosive gas, erosion of mold cavity surface, increase its surface roughness, aggravate wear failure.