Wear Analysis of Coated Carbide Tools when Machining Nickel Base, Inconel 718 Alloy

摘要

Nickel base, Inconel 718, alloy was machined with three different grades of coated carbide tools [PVD-TiN (T1), PVD-TiN/TiCN/TiN (T2) and CVD-TiC/Al_2O_3/ TiN (T3)] at high cutting conditions in order to investigate the effect of machining parameters on tool performance and failure modes. The multi-coated PVD-TiN/TiCN/ TiN grade insert presented the best tool performance because of the improved microhardness of the coatings enhanced by PVD coating technique and abrasion wear resistance property of TiCN coating layer. Metallographic analysis of the worn tools showed the dominant failure modes of crater and flank wears to be caused singly or jointly by attrition, abrasion and diffusion wear mechanisms. Statistical analysis of the machining data revealed over 80 percent of the wear performance of the coated tools to be caused by the cutting variables of speed, feed and depth of cut. Similar analysis showed more than 98% of the tangential component force to be attributable to the influence of these cutting variables. Cutting speed showed the virtual dominance of the wear rate, with depth of cut and feed rate jointly dominating the tangential component force.