Interpretation of PVD Coated Inserts Wear Phenomena in Turning

Abstract

PVD coatings attribute excellent cutting performance to cemented carbide inserts. Based on the continuous chip formation, coatings experience distinct failure mechanisms in turning. To clarify the influencing parameters on coating wear resistance release, turning experiments with a TiAIN derived coating, deposited on cemented carbide inserts, have been carried out. The experimental results are explained through analytical ones obtained by means of FEM calculations, indicating a coating static decohesion at low cutting speeds, owing to its overstressing. At higher cutting speeds, a coating adhesion improvement was found out, whereas a further cutting speed increasing reveals the dominant influence of tribomechanical abrasive phenomena and adhesion release on the coating wear behavior. As the overall cutting length increases, a progressive local coating decomposition occurs. Herewith chip formation alterations are induced, such as a gradual increase of the chip compression ratio and a consequent reduction of the tool contact stresses.