Six essential properties of precision stamping die in working process
1. Wear resistance
During the plastic deformation of the blank in the cavity of the precision stamping die, both flow and slide along the surface of the cavity, resulting in severe friction between the surface of the cavity and the blank, resulting in the failure of the die due to wear. Therefore, the wear resistance of the material is one of the most basic and important properties of the mold.
Hardness is the main factor affecting wear resistance. Generally speaking, the higher the hardness of die parts is, the smaller the wear loss is, and the better the wear resistance is. In addition, the wear resistance is also related to the type, quantity, morphology, size and distribution of carbides in the material.
2. Strength and toughness
Most of the working conditions of precision stamping dies are very bad, some of them often bear large impact load, which leads to brittle fracture. In order to prevent sudden brittle fracture of die parts, the die should have high strength and toughness.
The toughness of die stamping mainly depends on the carbon content, grain size and microstructure.
3. Fatigue fracture properties
In the working process of precision die, fatigue fracture often occurs under the long-term effect of cyclic stress. Its forms include low energy multiple impact fatigue fracture, tensile fatigue fracture, contact fatigue fracture and bending fatigue fracture.
The fatigue fracture performance of 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 precision die is higher, the hardness and strength will decrease, which will lead to the early wear or plastic deformation of the die. Because the die material should have high tempering stability, in order to ensure that the mold has high hardness and strength at the working temperature.
5. Cold and hot fatigue resistance
Some precision molds are in the state of repeated heating and cooling in the working process, which makes the surface of the cavity subject to tension and pressure variation stress, causing surface cracking and spalling, increasing the friction force, hindering plastic deformation, reducing the dimensional accuracy, thus leading to the failure of the die. Hot and cold fatigue is one of the main failure modes of hot working dies. This kind of dies should have high resistance to cold and hot fatigue.
6. Corrosion resistance
When some precision moulds, such as plastic moulds, exist chlorine, fluorine and other elements in the plastics, they decompose and precipitate strong corrosive gases such as HCI and HF after being heated, which erode the surface of the mould cavity, increase the surface roughness and aggravate the wear failure.