1) To meet the requirements of working conditions
1. Wear resistance
When the blank is plastically deformed in the cavity of the auto parts mould, it both flows and slides along the surface of the cavity, causing severe friction between the cavity surface and the blank, resulting in the failure of the auto parts mould due to wear. Therefore, the wear resistance of the material is one of the important basic properties of the mould.
Hardness is the main factor affecting wear resistance. In general, the higher the hardness of auto parts mould 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.
2. Strong toughness
Most of the working conditions of auto parts moulds are very bad, and some often bear large impact loads, resulting in brittle fracture. In order to prevent sudden brittle fracture of mould parts during operation, the mould must have high strength and toughness.
The toughness of the mould mainly depends on the carbon content, grain size and organizational state of the material.
3. Fatigue fracture performance
During the working process of the mould, fatigue fracture is often caused under the action of cyclic stress. Its forms include small-energy multiple impact fatigue fracture, tensile fatigue fracture, contact fatigue fracture and bending fatigue fracture.
The fatigue fracture performance of auto parts moulds 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 auto parts mould is high, the hardness and strength will decrease, resulting in early wear of the mould or plastic deformation and failure. Therefore, the mould material should have high anti-tempering stability to ensure that the mould has high hardness and strength at working temperature.
5. Heat and cold fatigue resistance
Some moulds are in a state of repeated heating and cooling during the working process, which causes the surface of the cavity to be subjected to tension, pressure and stress, causing surface cracking and peeling, increasing friction, hindering plastic deformation, and reducing dimensional accuracy, resulting in Mould failure. Hot and cold fatigue is one of the main forms of hot work die failure, and the helper die should have high resistance to cold and heat fatigue.
6. Corrosion resistance
When the auto parts mould is working, due to the presence of chlorine, fluorine and other elements in the plastic, strong corrosive gases such as HCI and HF are decomposed after heating, which erodes the surface of the mould cavity, increases its surface roughness, and aggravates wear failure.
Post time: May-25-2022