Although diamond is the hardest substance found in the world, it is easy to undergo carburization reaction during the processing of iron-based metals and their alloys because it belongs to the carbon group element, resulting in excessive wear of the processing tools. Therefore, it is not suitable for processing iron-based metals and their alloys.

Cubic boron nitride (CBN) is synthesized by hexagonal boron nitride and catalyst under high temperature and high pressure. It is another new product after the advent of artificial diamond. Its hardness is second only to diamond, and its thermal stability is much higher than diamond. It has greater chemical inertness to Fe-based metals. Therefore, CBN has unique advantages in processing ferrous metal materials, providing a new means for processing such hard and tough difficult-to-process steels. Since diamond is suitable for processing hard and brittle materials, CBN can complement it. The grinding performance of cubic boron nitride abrasives is very excellent. It is not only competent for the processing of difficult-to-grind materials and improves productivity, but also effectively improves the grinding quality of workpieces. At present, the use of CBN is concentrated in two aspects: one is to manufacture abrasives, and the other is to make polycrystalline as a tool material.

The grinding performance of cubic boron nitride abrasives is very excellent. For ferrous metals, especially materials with high hardness, high toughness, high high temperature strength and low thermal conductivity, cubic boron nitride abrasives have good grinding performance. Its metal removal rate is 10 times that of diamond, which solves the processing problem of hard and tough difficult-to-grind materials. The abrasives are sharp, wear-resistant and have very small unit wear. The grinding ratio when grinding steel is 4000~10000, which is 120~150 times that of ordinary abrasive high-speed abrasives. The durability of the workpiece being ground can usually be increased by 30%-50%; CBN abrasives have good shape retention and few dressing and replacement times, thereby shortening the total processing time and facilitating processing on automatic lines. In addition, the surface quality of CBN abrasives is improved, the grinding force is small, the grinding heat is also small, the stress of the workpiece is small, the stress layer is thin, the surface accuracy and roughness meet very high requirements, the workpiece does not produce burns, cracks and annealing softening, and the fatigue strength of the workpiece can be significantly improved. Although the initial cost of cubic boron nitride abrasive tools is relatively high, the overall cost is low due to low wear, long life, and high efficiency.

Cubic boron nitride tools have high wear resistance. When processing Ni-based alloys, the life of CBN turning tools is hundreds of times longer than that of carbide tools. Due to the presence of carbide substrates in CBN polycrystalline tools, they have good impact resistance and are suitable for intermittent cutting. CBN polycrystalline turning tools have extremely low surface roughness and extremely high thermal hardness (still maintains its hardness at 1400°C). The "thermal hardness" of CBN polycrystalline tools can be used for high-speed dry cutting. The high temperature generated by high-speed cutting softens the processed material and improves the machinability of the material.

Grinding, since cubic boron nitride (CBN) tools do not have complex grooves and coatings like carbide blades, their performance mainly depends on the performance of the tool blank, and the process and precision of grinding directly determine the microscopic performance during cutting. Therefore, although the cost of tools is greatly increased by using peripheral grinders, the quality and durability of cubic boron nitride (CBN) tools will be improved.