Tool Wear Analysis on Multi-Layered Coated Carbide Tools in Face Milling of AISI 1045 Steel

Face milling tests on AISI 1045 steel were performed to study the flank wear of multilayered coated carbide tools. The cutting tools were dual (TiN/TiAlN) and triple (TiN/Al₂O₃/TiCN) layered, coated carbide inserts processed by PVD and CVD respectively. As expected, the depth of cut (DOC) did not play an important role on the development of flank wear while the cutting speed had a significant role in the development of flank wear. Using confocal laser scanning microscopy (CLSM) and wavelet transform, the flank wear evolution was analyzed and abrasive wear was found to be a dominant tool wear mechanism. Adhesion of the work material was also observed after the carbide substrate was exposed. Edge chipping and micro-fracture were additional tool failure modes. After comparing the performance of the two inserts, we concluded that the dual layer coating was superior to the triple layer coating under various cutting conditions mainly due to the benefit coming from the coating processes themselves. It was claimed that the superior performance of the multilayer coating came from preventing the gross crack-induced removal of coating materials by propagating the fracture along the coating interfaces. However, no such observations were found in our milling experiment. Therefore, the hardness of the coating materials is the most important criteria for the development of flank wear.