PCBN Inserts are not suitable for low-speed machining hardened steel. CBN tools are based on the cutting heat generated during cutting, and soften the workpiece 

material in a small range of the cutting area to cut.

According to the shape of the hardened parts and the processing technology requirements, it is necessary to perform machining, such as turning, milling, boring, drilling and 

reaming. The hardened steel machining has the following characteristics:

1) High hardness, high strength, almost no shaping. Hardened steel is just the most difficult material to cut.

2) Large cutting force and high cutting temperature.

3) It is not easy to produce built-up edge. Hardened steel has high hardness and brittleness. It is not easy to produce built-up edge when cutting, and the surface to be processed

 can obtain better surface finish.

4) The edge is easy to break and wear. Due to the high brittleness of the hardened steel, the contact time between the chip and the edge during cutting is short, and the cutting 

force and the cutting heat are concentrated near the cutting edge of the tool, which easily causes the edge to crack and wear.

5) Low thermal conductivity. Due to the low thermal conductivity of hardened steel, the cutting heat is difficult to carry away by the chips, and the cutting temperature is high, which accelerates the tool wear.