Optimizing PCBN cutting tool performance in hard turning

Abstract

Surface finish, in addition to tool wear, is an important aspect of PCBN tool performance in hard turning. A set of experiments that focused on the effects of corner radius, chamfer angle/width, and edge radius in addition to severity of interruption and speed/feed at constant depth of cut were performed. The severity of interruption was critical to both tool wear and surface finish performance. The edge radius was also shown to be a key factor in determining the rate of increase in Ra with maximum flank wear length lW. Experiments in continuous hard turning were then performed to determine the evolution of Ra with lW at different V and f. Ra showed a linearly increasing trend with lW at all V and f. At constant V, Ra increased with f independent of lW, but at a constant f, Ra decreased with V as an interaction with lW. A model that relates Ra and lW, V and f was formulated and validated using more experimental data and data available in the literature. An optimization algorithm is proposed which maximizes the material removal rate holding Ra at a constant prescribed value, operating at V within a prescribed limit. The algorithm essentially takes advantage of the lower Ra at a higher V and lower lW. An internally consistent baseline is used to evaluate the significance and benefit of adopting the algorithm. Finally, guidelines for implementation in real-world situations are presented.