Performance Evaluation of Uncoated and Coated Carbide Tools During Hard Machining of AISI 4340 Steel

The present paper highlights a comparative assessment of the influence of cutting velocity on the tool performance in machining of hardened AISI 4340 steel using uncoated and coated inserts. For hard machining of the workpiece, one uncoated and two multi-layer coated inserts were utilized. A series of experiments were conducted at four different levels whereas the cutting depth and tool advancement in mm per revolution were kept constant. Two important machining characteristics are studied tool life and surface roughness by varying machining parameters. The outcomes of the investigation revealed that both the aforementioned machining characteristics were potentially influenced by the cutting speed. It was found that the high cutting speed was responsible for curtailing tool performance as well as the surface quality of the machined part. Besides, in contrast to its coated equivalent, uncoated instruments struggled to perform effectively at higher cutting velocity. Whereas, in the context of declining wear in the flank surface of the inserts at preeminent cutting speeds, the difference in the efficiencies of both the selected coated tools was not significant.