Cutting performance optimization of PVD coated inserts in milling, considering the cutting conditions, the tool geometry and the coating material properties K.–D. Bouzakis 1 , N. Michailidis 1 , K. Efstathiou 1 , G. Erkens 2 1. Laboratory for Machine Tools and Manufacturing Engineering, Mechanical Engineering Department, Aristoteles University of Thessaloniki, 54006, Greece Tel. 0030 31 996079, 0030 31 996021, Fax. 0030 31 996059, bouzakis@eng.auth.gr 2. CemeCon GmbH, Adenauerstr. 20B1, D-52146 Würselen, Germany ABSTRACT. The evolution of the Physical Vapour Deposition (PVD) method as a thin film production technique enabled the broad diffusion of thin hard coatings also in manufacturing technology. Coated tools may reach a cutting accomplishment of ten - up to one hundred times greater than the corresponding of the same uncoated ones under the same cutting conditions. However, despite this performance of modern coated systems, thin films experience a variety of failure mechanisms during their operation, which is strongly dependent on the manufacturing case and the cutting conditions. This wide application of thin hard PVD coatings under severe dynamic stress states on cutting tools, leads to the need of the precise knowledge of coating mechanical properties such as the coating fatigue and static stress limits. In the present paper the coating impact test is applied to determine the fatigue behavior of coating-substrate compounds in a form of generally applicable diagrams. The failure mechanisms of coatings are also examined and interpreted in milling, offering an overview of the operational limits of coated tools. In order to utilize the superior characteristics of coatings towards improving the cutting performance, it is highly recommended to optimize the cutting insert wedge radius, as well as the feedrate and the cutting speed. Herewith a premature coating failure and a consequent rapid wear development can be prevented. KEYWORDS: Milling, PVD coatings fatigue, Coating stress-strain curve, Cutting wedge radius, Feedrate