A Comparative Study of the Performance of Uncoated, PVD, CVD and MTCVD Coated Carbide Inserts in Dry Turning of AISI4140 Steel

Abstract

An experimental study has been carried out to investigate and compare the cutting tool performances represented by insert wear, surface roughness and cutting forces of an uncoated carbide (H13A) and three coated carbides GC2015 ( TiCN / Al₂O₃ / TiN ), GC1015 (TiN) and GC4215 ( TiCN / Al₂O₃ ) during the dry turning of AISI4140 steel. Turning was carried out during 5 minutes on cylindrical specimens (80 mm diameter and 400 mm cutting length) along with a depth of 0.5 mm, a feed rate of 0.08 mm/rev, and with a cutting speed of 350 m/min. The wear results show the effectiveness of both GC2015 and GC4215 cutting inserts where the flank wear rate of the monolayer insert (GC1015) reaches approximately 2 times that of the bilayer insert (GC4215) and 4-times that of the multilayer insert (GC2015), while insert H13A demonstrated the highest wear. Moreover, SEM analysis shows that abrasion, adhesion and chipping are the dominant wear mechanisms. The surface quality obtained with the coated GC2015 insert is found to be 1.38, 1.63 and 4.63 times better than those obtained with GC4215, GC1015 and H13A inserts respectively. Finally, the coated GC2015 (CVD) cutting insert is identified as the leading material in terms of cutting force as the results found show that the ratios are ( F_t-GC4215 / F_t-GC2015 ) = 1.05, ( F_t-GC1015 / F_t-GC2015 ) = 1.13 and ( F_t-H13A / F_t-GC2015 ) = 1.77.