Performance evaluation of wiper coated ceramic tool when hard turning tool steel

Abstract

Hard turning is a technique that can be used as a substitute to grinding in the finishing operation for hardened steel (45 HRC and above). However, the use of this technique is limited due to the high cost of the cutting inserts. The developments of new cutting tools such as ceramic and CBN has made hard turning feasible. This project was undertaken to evaluate the performance of wiper coated ceramic tool (KY 4400) when turning hardened ASSAB DF-3 grade hardened steel with hardness 55 HRC. Various cutting speeds: 100, 155 and 210 m/min and various feed rates: 0.05, 0.125 and 0.2 mm/rev were used. The process was performed under dry cutting condition with a constant depth of cut of 0.2 mm. The machinablity responses that have been studied were tool life and surface roughness. This study shows that the effects of cutting speed and feed rate on the tool life are statistically significant. Specifically, at low cutting speed and low feed rate, wiper inserts are able to produce higher tool life compared to higher cutting speed and higher feed rate. Also this study shows that the effects of cutting speed and feed rate on the surface roughness are also statistically significant, specifically, at high cutting speed and low feed rate, wiper inserts are able to produce better surface finish. Tool life and surface roughness models were developed using the 3- level full factorial design. Analysis done showed that both mathematical models for tool life and surface roughness can be used to predict the machining response within the limits of cutting speed and feed rate that have been investigated.