Abstract
Hard turning has been applied in machining since the early 1980s. There is an effort to substitute finish grinding by hard machining, because of machining by cutting tool with defined geometry. For machining of hardened steels (up to 45 HRC) are used two different cutting materials. PCBN are used the most for discontinuous machining of hardened steel (up to 63 HRC) and mixed ceramic tools, which are used in the experiment. This paper reports a development of surface roughness parameters when using wiper tool geometry of mixed ceramic tool and conventional geometry of mixed ceramic tool in hard turning. Roughness parameters (Ra, Rz, Rsk, Rku, RSm, Rdq) are measured when changing the feed, depth of cut and cutting speed are constant.