Wear of ceramic tools when machining Inconel 751 using argon and oxygen as lubri-cooling atmospheres

Abstract The aim of this work is to study the tool life and wear (types and mechanisms) experienced by ceramic tools (SiAlON, whisker and mixed ceramic) when turning the nickel-based superalloy Inconel 751 using argon and oxygen atmospheres. This material is largely used as inlet and outlet gas valves in Otto and Diesel cycle engines. Design of experiment (DOE) planning techniques were used with the following input variables: tool materials [SiAlON (Si3N4+Al2O3), Whisker (Al2O3+SiCw) and Mixed (Al2O3+TiC)], cutting speed, tool geometry and lubri-cooling atmosphere (dry cutting as a benchmark, followed by argon- and oxygen-enriched atmospheres). These atmospheres support sustainable manufacturing, in contrast to common practices in which cutting fluids are considered a polluting component. In each machining test, a new tool edge was used through the end of the tool life, with interruptions conducted for wear measurements. At the end of the tests, the tools were analysed by optical and scanning electron microscopy. The results indicated that the cutting speed, tool geometry and lubri-cooling atmosphere influence the types of wear and the tool life. Notch wear (VBN), average flank wear (VBB) and nose wear (VBC) prevailed and depended on the cutting conditions and tool material. Overall, the SiAlON tools exhibited the best tool life performance, followed by the mixed and whisker ceramics. The lowest tool life was observed for whiskers in dry conditions. Notch wear was accelerated by an oxygen-rich atmosphere, particularly at low cutting speeds. Attrition and chipping were the dominant wear mechanisms.