An effective way to improve the cutting performance of coated tools through annealing

The evolution of the physical vapor deposition (PVD) method as an effective thin film production technique has contributed to the wide application of thin hard coatings for cutting tools. In former investigations it was discovered that by increasing the cutting speed, temperature dependent phenomena are activated in the coating material, which can improve their mechanical properties and, furthermore, their cutting performance. In order to investigate and exploit these phenomena, coated tools were annealed at various temperatures. The occurring coating material properties and especially their stress–strain curves, after the heat treatments were carried out, were determined by means of a novel evaluation procedure of nanohardness measurement results. Furthermore, the coating fatigue strength was depicted through impact test experiments. Thus it was deduced that by appropriate annealing, the coatings obtain enhanced mechanical properties and, as milling investigations with appropriately annealed coated cutting inserts indicate, their cutting performance is improved.