Hard turning in continuous and interrupted cut with PCBN and whisker-reinforced cutting tools

PCBN (polycrystalline cubic boron nitride) is the most widely used material for tools employed in hardened steel turning applications due to its high hardness, wear resistance and thermal stability. However, its high costs severely limit its use. Alumina-based ceramics reinforced with whiskers, an alternative and less expensive material for these tools, has been used successfully in turning interrupted surfaces. The objective of this work is to investigate the conditions under which PCBN and ceramic tools can promote optimal results in the turning of hardened steel with continuous and interrupted surfaces. These tools were used in the radial turning of hardened steel with three types of surfaces: continuous surfaces and surfaces with 4 and 8 interruptions. The results indicated that, in continuous turning, the longest tool life was achieved using PCBN, but similar tool longevity was attained in interrupted turning using both PCBN and ceramic. In terms of roughness, the PCBN tools showed better results for continuous and interrupted surfaces.