PCBN, is a material with excellent hot hardness that can be used at very high cutting speeds. It also exhibits good toughness and thermal shock resistance.. Modern CBN grades are ceramic composites with a CBN content of 40-65%. The ceramic binder adds wear resistance to the CBN, which is otherwise prone to chemical wear. Another group of grades are the high content CBN grades, with 85% to almost 100% CBN. These grades may have a metallic binder to improve their toughness. CBN inserts are available in both solid and tipped geometries. For tipped CBN inserts the CBN is wire cut from a CBN disk. The CBN is then brazed onto a cemented carbide insert body to form a tipped CBN insert. CBN grades are largely used for finish turning of hardened steels, with a hardness over 45 HRc. Above 55 HRc, CBN is the only cutting tool which can replace traditionally used grinding methods. Softer steels, below 45 HRc, contain a higher amount of ferrite, which has a negative effect on the wear resistance of CBN. CBN is also be used for high speed roughing and finishing of grey cast irons in both turning and milling operations. CBN has been used to machine the following parts: transmission system parts from input shafts to gears, printing press rolls, paper pulp rolls, welded overlay rolls, plasma sprayed rolls. steel mill rolls, brake rotors, brake drums, pulleys, cast iron cylinder liners, engine blocks, CV joints, steering pump parts and air conditioning compressor machining. Hard turning is defined as the process of single point cutting of part pieces that have hardness values over 45 Rc. Typically, however, hard turned part pieces will be found to lie within the range of 58-68 Rc