Effect of tool wear on surface finish for a case of continuous and interrupted hard turning

Steel components are often hardened for reasons of wear resistance and production technology. Due to component quality requirements (surface finish, accuracy of shape and size), the parts must be finished in a highly heat-treated or hardened state. The machining of hardened steel components with PCBN inserts having a geometrically defined cutting edge has gained substantially in importance due to improvements in the performance of such modern cutting tool materials. However, there are still insufficiently explored areas related to tool wear and surface quality that make implementation of this technology slow. This paper presents aspects related to surface quality for a case of interrupted and continuous hard turning. New findings concerning the evolution of common surface roughness parameters as well as the evolution of surface topography with the increase of tool wear are presented. The study employs two workpiece materials that were less considered for hard turning investigations to the authors best knowledge. A good correlation between flank wear aspect and machined surface was observed. A different surface finish evolution was remarked for the continuous and interrupted cutting situations.