The effect of aCN/TiAlN coating on tool wear, cutting force, surface finish and chip morphology in face milling of Ti6Al4V superalloy

As a widely used material in aerospace and medical industry, Ti6Al4V titanium alloy is regarded as difficult-to-machine. In this study, aCN/TiAlN coating was deposited on carbide cutting tools as an attempt to increase the machinability of this alloy. Wear behavior and cutting performance of the aCN/TiAlN coated carbide tools in face milling of Ti6Al4V were investigated under dry conditions. The effect of coating on cutting forces, chip formation and surface integrity of the workpiece with regard to surface finish was investigated. Mechanical and tribological properties of coated samples were characterized by nanoindentation, scratch test, 3D-profilometer, confocal microscope and pin-on-disc test. SEM was employed in combination with EDS for structural and compositional characterization of worn samples. According to the results, abrasive wear and adhesive wear are dominant tool failures on the coated tools. Higher wear resistance and ~ 15% longer lifetime were obtained with aCN/TiAlN coated carbide tools in milling of Ti6Al4V. The coating proved to be effective on chip formation and workpiece surface finish. Due to its superior properties in terms of adhesion, wear resistance, surface finish and chip formation, aCN/TiAlN coating is a good candidate for use in face milling of Ti6Al4V alloy.