Investigation of wear resistance of coated PcBN turning tools for hard machining

The machining of steels with a hardness of 50 HRC and above was in the past primarily only possible with grinding processes. Since the application of cutting inserts made of polycrystalline cubic boron nitride (PcBN), hard turning as a production process with higher material removal rates has established as an economic alternative or supplement to grinding. The increasing number of materials with difficult machining characteristics requires a further development of cutting tools. Physical Vapor Deposition (PVD) coatings lead to an increase of wear resistance, but have thus for not been studied on PcBN substrates. In this contribution, different hard coatings were deposited on PcBN cutting inserts. To identify wear resistance of the coating systems tribological investigations and cutting tests were performed. Furthermore, simulations for evaluation of the coatings as a thermal barrier have been carried out. For the verification of the simulation results, temperature measurements in the cutting process were performed. Based on these investigations the wear behavior of the different coating systems has been analyzed.