Although China's carbide started late, but the development is rapid. At present, cemented carbide moulds have basically been serialised and standardised. From the development of recent years, the theory of research and design of cemented carbide mould materials in China has been more in-depth and scientific, and the application is also more extensive. The characteristics of cemented carbide are high hardness, good wear resistance and high compressive strength, thus suitable for making powder metallurgy moulds (such as cemented carbide pressing moulds) and other moulds.
1. High hardness and good wear resistance
The hardness of cemented carbide is second only to that of gold steel and cubic boron nitride, with a hardness range of HRA86 to 94, the ZUI low hardness of cemented carbide (HRA84 to 86) is greater than the ZUI high hardness of tool steel (HRC64 to 69). The wear resistance of high cobalt type carbide moulds is better than that of HRC63 a 65 tool steel, and the mould life is longer.
2. High modulus of elasticity
The high modulus of elasticity means that the mould has a high resistance to deformation. The modulus of elasticity of carbide is 3-4 times that of tool steel, so the deformation of a hard alloy mould is smaller than that of a steel mould under the working stress of pressing, i.e. the size of the product and the size of the mould are very close, so the processing accuracy of the product is high. Also due to the higher modulus of elasticity, the elastic after-effects are smaller and have a considerable advantage for controlling cracks in pressed blanks etc. The flexural deformation is also much less when subjected to forces. This is of particular value when making long moulded parts with thin, sharp edges.
3. Low coefficient of friction
When drawing metal materials, the power consumption can be reduced considerably. In addition, it has a small adhesion (affinity) to the metal being worked, which makes the surface of the mould less susceptible to strain and pulling. As a result, Zhuzhou Cemented Carbide Mould not only has a high life span, but also has a good surface quality of the processed products, which can even reach the mirror surface processing, thus eliminating the subsequent polishing and grinding processes of the products.
4. Superior thermal performance
The coefficient of thermal expansion of cemented carbide is only 1/2 that of steel, so even if the temperature rises at work, the resulting mould size error is 1 times smaller than that of steel moulds.
