Experimental investigation of generated surface roughness in hard turning of Ti6Al4V using coated ceramic and CBN inserts

Abstract

Surface finish of machined parts is a significant quality mark for a range of applications such as aerospace, automotive, power transmission and generation. Therefore, optimization of surface roughness is the key factor for reliability in machining difficult-to-cut materials such as titanium-based alloys. In this study, an investigation into hard turning of Ti6Al4V alloys with varying process parameters and cutting tool materials was carried out. This study aims to compare the generated surface roughness when turning Ti6Al4V alloys using CBN and coated ceramic inserts, independently, under the same values of feed rate, cutting speed and depth of cut. The experiments were designed using Taguchi L9 and the exponential results were examined by the analysis of variance (ANOVA). The effect of process parameters and their interactions on generated surface roughness was evaluated for the two inserts. It was found improvement of surface roughness by 34% was achieved when using coated ceramic insert compared with the results obtained using CBN insert under the same range cutting conditions. CBN insert gave a better result at smallest depth of cut (0.15 mm), low feed rate (0.1 mm/rev) and high cutting speed (100 m/min) while coated ceramic tool gave a minimum surface roughness at depth of cut (0.2 mm), feed rate (0.1 mm/rev) and high cutting speed (100 m/min).