The hardness of cubic boron nitride (CBN) is second only to PCD and single crystal diamond. It can still maintain the hardness of cemented carbide at 25 degrees Celsius at a high temperature of 1000 degrees Celsius. Specificationï¼? Introduction of CBN inserts The hardness of cubic boron nitride (CBN) is second only to PCD and single crystal diamond. It can still maintain the hardness of cemented carbide at 25 degrees Celsius at a high temperature of 1000 degrees Celsius. The high strength of CBN comes from its intercrystalline bonds. Equipped with a hardness alloy matrix with very good hardness and toughness, the tools made with it can withstand great cutting forces when deep cutting materials with high hardness and high toughness. The intergranular bond also provides acceptable impact strength. This is very necessary when cutting continuous and discontinuous sections.