In the turning and milling process of cast iron and hardened steel, the appropriate corner radius is beneficial to play the performance of the CBN inserts.

The larger corner radius of the PCBN inserts could improve the surface roughness and could be with better impact resistance, but its cutting force will also increase, 

which may cause vibration. The smaller tip R with small cutting force, but the strength and the surface roughness of the workpiece are reduced. If the rigidity of the 

system is good, the cutting edge R can be appropriately large when roughing. When using a small tip R is , the feed rate is not too large to obtain a good roughness.