Wear performance investigation of PVD coated and uncoated carbide tools during high-speed machining of TiAl6V4 aerospace alloy

Selection of hard PVD coatings for the machining of Ti6Al4V alloy should be based on the dominant tool wear mechanism and tribological phenomena occurring at the chip-tool-workpiece interface. The present work investigates the effect of AlTiN and CrN hard coatings on the wear performance of cemented carbide cutting tools during high-speed finish turning of Ti6Al4V. The wear characteristics of the tools were evaluated by SEM and 3D wear volume measurements. The in-situ tribological performance of the coatings was characterized by chip morphology analysis, in combination with coefficient of friction measurements using a high temperature/heavy load tribometer that mimics actual machining conditions. Micro-mechanical characteristics of the coatings were also studied in detail. The results obtained show that the application of a CrN coating significantly improves tool performance due to a combination of the micro-mechanical properties of the coating and the tribological characteristics of the surface engineered layer.