High speed turning for hard material with PCBN inserts: tool wear analysis

Abstract

Because of tool wear, High Speed Machining (HSM) is rarely used for hard turning process and the cutting speeds are generally selected around 100 or 200 m/min. In this work, HSM is performed for hard turning of a 50 HRC hardened steel (AISI 4140/42CrMo4) with a PCBN tool by using high cutting speeds (300 and 400 m/min). The results show that HSM for hard turning can be acceptable for industrial application by providing very good surface roughness and keeping significant tool life. A qualitative correlation is also presented between the crater wear and the temperature distribution at the tool-chip interface, predicted by a thermomechanical model. Flank wear, crater wear and surface roughness are examined in order to choose an appropriate wear criterion. Investigations by SEM/EDS and white light interferometry highlight the importance of crater wear and help us to better understand the role of chemical/diffusion phenomena in wear mechanisms.