The Current Situation of Carbide Cutting Tools Material
Material, structure and geometry are three key factors that decide carbide cutting tools performance. But material is most important among this three factors. Carbide cutting tool material has developed from high speed steel and hard alloy to high performance ceramics and super hard materials at the begining of the 20th century. Heat resistant temperature and cutting speed also has a big improvement. So material improvement make its cutting speed have a big changes every 10 years in the study report of CIRP.
Now let me introduce 4 common materials and its basic performance.
1. High speed steel
HSS has a good toughness and forming ability, but it also has some defects such as poor wear resistance and heat resistance, which can hardly meet the higher and higher requirements of modern cutting on tool materials. In addition, some of the major elements in HSS (such as tungsten) are being depleted worldwide, and it is estimated that the reserves will only last 40 to 60 years. Therefore, HSS is facing a serious development crisis.
2. Ceramic material
Compared with hard alloy, ceramic material has higher hardness, red hardness and wear resistance. Therefore, when processing steel, the durability of ceramic tools is 10 — 20 times than carbide tools. Its red hardness is 2-6 times than hard alloy, and chemical stability, oxidation resistance are better than cemented carbide. The disadvantages of ceramic materials are large brittleness, low transverse fracture strength and poor impact loading capacity.
3. Metal ceramic
The cutting efficiency and working life of cermet tools are higher than those of cemented carbide and coated cemented carbide tools. Because the bond between cermet and steel is relatively low, when using cermet tool to replace coated carbide tool to process steel workpiece, chip formation is relatively stable, it is not easy to occur in the automatic processing of long chip winding phenomenon, the edge of parts basically no burr. The disadvantage of cermet is the poor thermal shock resistance, easy to crack, so the range of use is limited.
4. Cemented carbide
Cemented carbides are prepared by powder metallurgy of WC, TiC, TaC, NbC, VC and other refractory metal carbides as well as iron group metals as binder. Compared with high speed steel, it has higher hardness, abrasion resistance and red hardness. Compared with superhard materials, it has higher toughness. Due to the good comprehensive performance of cemented carbide, it has been widely used in the cutting tool industry, at present more than 90% of foreign turning tools, more than 55% of milling cutter are made of cemented carbide materials.
In order to improve carbide cutting tools toughness and hardness, we still keep in study. In following 10 years, we hope it has a new break through.