Hard Turning of AISI D2 Steel Using CBN Tools under MQL: Assessment of MRR, Tool Life and Surface Integrity of the Workpiece

Abstract

Hard turning (HT) is a machining method which is widely adopted nowadays to produce an improved surface finish without the application of a grinding process. The available literature conveys to us that studies have been done to improve surface finish by using small feeds and high speed. This study is an effort to enhance the tool life, material removal rate (MRR) and surface roughness of the workpiece by using different combinations of cutting factors and a lubricating technique called minimum quantity lubrication (MQL). The workpiece used for this experiment is AISI D2 steel and the used tool inserts are cubic boron nitride (CBN) tools. The HT of the workpiece is done under 3 different cutting velocities, feeds and depths of cuts. The flow rate for the MQL process is kept at 240 ml/hr. We observed that at the highest speed and lowest feed, the achieved surface roughness was the best. Furthermore, the MQL showed some great results in the context of tool life as it was improved by approximately 48% as compared to that of dry machining. Also, there was an improvement of up to 12% in the context of surface finish. However, there was not any effect of MQL on MRR as it purely relies on cutting velocity, depth of cut and feed. Also, it did not have any effect on the
workpiece and tool insert material used.