Thermomechanical Coating Load in Dependence of Fundamental Coating Properties

The conventional development of a coating system for cutting tools includes a variety of test series with elaborate experimental parameter studies. In particular, experimental investigations of the cutting behavior cause a significant consumption of cost, time and resources. In order to adapt the coating properties to the specific requirements of the cutting process, it is desirable to reduce the experimental effort of coating development by simulation of the machining process. Therefore, the main factors of the thermo-mechanical coating load in machining AISI 4140 were identified by means of 2D FEM chip formation simulations. In order to provide the required thermal and mechanical coating properties for the simulations, CrAlN-based coatings were deposited onto cutting inserts and extensively characterized. Within the simulations, the coating properties were varied between the physical and technological boundaries of CrAlN-based coatings. It was shown that the Young's modulus, the coating thickness and the friction coefficient significantly influence the thermomechanical load and the stress distribution within the coating. Finally, the cutting performance of the coated inserts was experimentally investigated and compared with the results of the simulations. Here, it was shown that delamination of the coating is particularly influenced by coating thickness.