Why CBN and not diamond?:

Low wear on the CBN wheel! - Cubic crystalline boron nitride – CBN, a boron-nitrogen compound, is the hardest material after diamond. CBN has a higher thermal stability than diamond - hardly suffers any loss of hardness even at temperatures above 1000 °C. Since CBN, unlike diamond, does not contain any carbon, it is ideal for grinding hardened carbon-containing steels.

Better tool life! - The heat generated during grinding is better dissipated thanks to the very high thermal conductivity of CBN, which means that the workpiece heats up less and, as a result, the structure of the cutting edge zone is significantly less affected.