Arc PVD-coated cutting tools for modern machining applications

Present research work in machining determined by ecological and economical reasons is focused on working without cooling and lubrication, high speed cutting (HSC), near net shape production and rapid prototyping. To achieve the desired aims in productivity and quality, modern high-performance machining tools as well as the adapted tooling machines and process parameters are necessary. In particular, the machining of tempered or austenitic steels requires complex mechanical, thermal and tribological properties from the applied tools. Since conventional high-speed steel or cemented carbide tools often cannot fulfil these high demands, new efficient cutting tools have to be developed. This paper presents the development of new are PVD coatings in the systems Ti-Hf-C-N. The coatings were characterized due to the desired property profile for special cutting operations. For the machining of austenitic steels, coatings with a low friction coefficient to austenite and a high adhesion to the substrate are necessary. These properties were investigated by pin-on-disc and scratch tests. The thermophysical properties and thermal stability of the coatings, which play and important role in dry machining, were determined by photothermal spectroscopy, ice-tribometer tests and high-temperature X-ray diffraction. The results of the machining tests of the new coatings deposited on cermets are presented in another paper. (C) 1997 Elsevier Science S.A.