The influence of thin hard coatings on frictional behaviour in the orthogonal cutting process

New knowledge about the tribological response deriving from the interaction of the substrate/coating-chip system, with special attention to the orthogonal cutting process when chatter-free end turning using natural contact tools, is developed. In order to evaluate the frictional behaviour of this process under modified contact conditions, experimental investigations including the contact temperature, the contact loads, friction and the frictional heat flux per unit area were carried out. In contrast to the most obvious approach, the coefficient of sliding friction versus the cutting speed, the contact temperature, the normal pressure and the interface control factor is considered. A number of different coating structures, starting from single up to three and four layer films, in combination with medium carbon and austenitic stainless steels, were tested. It is pointed out that the results obtained provide a modified approach to the frictional behaviour of the cutting process and its controllability. Among various responses, specific for such tribo-contact pairs, of particular interest is the self-adaptation resulting in controlled generation of friction energy and conduction of the frictional heat flux.