The principles for daily necessities mould selection should be as follows:
When the blank is plastically deformed in the mold cavity, it flows and slides along the surface of the cavity, causing severe friction between the surface of the cavity and the blank, 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, abrasion resistance is also related to the type, quantity, form, size and distribution of carbides in the material.
Most of the working conditions of the mold are very harsh, and some often bear large impact loads, which leads to brittle fracture. In order to prevent the mold parts from being suddenly brittle during work, the mold must have high strength and toughness.
The toughness of the mold mainly depends on the carbon content, grain size and microstructure of the material.
3.Fatigue fracture performance
During the work of the mold, under the effect of cyclic stress, it often causes fatigue fracture. Its forms are small energy multiple impact fatigue fracture, tensile fatigue fracture contact fatigue fracture and bending fatigue fracture.
The fatigue fracture performance of a 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 be reduced, leading to early wear of the mold or plastic deformation and failure. Therefore, the mold material should have high resistance to tempering to ensure that the mold has higher hardness and strength at the working temperature.
5. Cold and hot fatigue resistance
Some molds are in the state of repeated heating and cooling during the work process, which causes the surface of the cavity to be stretched and pressure to change the stress, causing surface cracking and peeling, increasing friction, hindering plastic deformation, and reducing dimensional accuracy, which leads to Mold failure. Cold and hot fatigue is one of the main forms of failure of hot work molds, and this type of mold should have high cold and hot fatigue resistance.
6, corrosion resistance
When some molds, such as plastic molds, work, due to the presence of chlorine, fluorine and other elements in the plastic, after heating, they will analyze and analyze strongly erosive gases such as HCI and HF, which will erode the surface of the cavity of the mold, increase its surface roughness, and increase wear and tear.