Compared with PCD cutting tools, you may not be very familiar with PCBN cutting tools. PCBN is mainly used for processing high-hardness black metals, such as quenched steel, cast steel, and powder metallurgy. It can withstand high temperatures, and its hardness remains at 8000HV. It is a better tool material for improving production efficiency and processing difficult materials. However, this material is not suitable for processing steel below 45HRC, as it is prone to adhesion wear and cracking. So, what are the cutting performance of PCBN cutting tools?
Because CBN crystals and diamond crystals are both sphalerite-type and have similar lattice constants and chemical bond types, CBN has a hardness and compressive strength close to diamond, and because it is composed of N and B atoms, it has a higher thermal stability and chemical inertness than diamond. The main properties of PCBN cutting tool material are as follows:
The microhardness of CBN single crystal is HV8000-9000, which is the second highest hardness substance currently known, and the hardness of PCBN composite sheet is generally HV3000-5000. Therefore, it has higher wear resistance than cemented carbide and ceramics when used for processing high-hardness materials, reducing the dimensional deviation or dispersion in the processing of large parts, especially suitable for highly automated equipment. It can reduce the time for tool change and adjustment, and fully play its efficiency.
The heat resistance of CBN can reach 1400-1500℃. Its hardness at 800℃ is the same as the room temperature hardness of Al2O3/TiC ceramics. Therefore, when the cutting temperature is high, the workpiece material softens, and the hardness difference between the tool and the workpiece increases, which is beneficial for the cutting process and has little effect on the tool life.
CBN has high oxidation resistance and does not undergo oxidation even at 1000℃. It does not react chemically with ferrous materials at 1200-1300℃, but it will undergo hydrolysis with water at around 1000℃, causing a large amount of CBN to be worn. Therefore, when using PCBN cutting tools for wet cutting, attention should be paid to the selection of cutting fluid. Generally, wet cutting does not significantly improve the life of PCBN cutting tools, so dry cutting is often used when using PCBN cutting tools.
The thermal conductivity of CBN material is lower than that of diamond but much higher than that of cemented carbide. As the cutting temperature increases, the thermal conductivity of PCBN cutting tools increases, so that heat can be quickly transferred from the tip of the tool, which is beneficial to improve the machining accuracy of the workpiece.
The above is a complete introduction to the cutting performance of PCBN cutting tools. In general, due to its high hardness and wear resistance, chemical inertness with iron family metals at high temperatures, PCBN is mainly used for cutting difficult-to-machine materials and high-hardness materials.
English
日本語
한국어
français
Deutsch
Español
italiano
русский
português
العربية
tiếng việt
