Performance evaluation of coated ceramic cutting tools with T-land edge preparation when turning hardened tool steel

Abstract

Hard turning is a technology that can be used in the finishing operations for hardened steel (45 HRC and above).The development ceramic and CBN cutting tool has made hard turning possible. This project was undertaken to investigate the performance of KY 4400 ceramic cutting tool with T-land edge preparation when turning XW 42 grade hardened steel (54-55 HRC) under various cutting speeds: 115, 145 and 183 m/min, and various feed rates: 0.098, 0.125 and 0.16mm/rev. Information on tool life, material removal rate and surface roughness were obtained, evaluated and compared with wiper and conventional inserts. The tool life and material removal rate of T-land is higher compared to wiper and conventional inserts. However, in terms of surface roughness, wiper inserts are able to generate better surface finish compared to T-land and conventional inserts. The tool failure mode and wear mechanism were also investigated. The wear mechanisms responsible for the wear formation were abrasion and diffusion. Flank wear and crater wear were the main wear observed during the turning of XW 42 grade hardened steel 54-55 HRC using KY 4400 ceramic cutting tool. At the cutting speed of 183 m/min and feed rate of 0.16 mm/rev catastrophic failure occurred. At other cutting conditions investigated, the failure mode was due to flank wear. The tool life and surface roughness models were developed using 3 level factorial design. Analysis done showed that both mathematical models for tool life and surface roughness can be used to predict the machining response with the limits of cutting conditions investigated.