Machinability Characteristics of Hard SCM 440 Alloy Steel using CBN and PCBN Tools by Turning Process

Abstract

Hard turning of alloy steels are gaining momentum using super hard tools like Cubic Boron Nitride (CBN) and Polycrystalline Cubic Born Nitride (PCBN) cutting tools in many automobile and aerospace industries. The super hard cutting tools have longer tool life and replacement of tools takes long time. The production of components per cutting edge is more. Machinability of hard and difficult to cut materials by using these tools is producing good surface roughness, less tool wear, dimensional accuracy and form etc. The material used in this experiment was SCM alloy steel with hardness between 45 to 55 HRC is ideal to get low tool wear, low surface roughness. The effect of turning by parameters on the cutting force, specific cutting pressure, tool wear and surface roughness criteria were investigated during the experimentation. The surface roughness was measured by using Mitutoyo SJ 400 surface roughness tester and effect of turning parameters was examined through Scanning Electron Microscope (SEM). The research work findings will also provide useful economic turning solution by CBN and PCBN tools, which are otherwise usually machined by ceramic inserts. The present approach and tests results will be helpful for understanding the machinability of hard SCM 440 alloy steel by manufacturing engineers. The cutting velocity used in the range of 100 to 200 m/min in multiples of 25 m/min with feed rates of 0.10, 0.20 and 0.30 mm/rev and constant depth of cut of 1.00 mm