The Influence of Surface Treatment of PVD Coating on Its Quality and Wear Resistant

Abstract

The article deals with a determination of the influence of a cutting edge preparation on the quality and wear resistance of coated cutting tools. Cutting inserts made from a sintered carbide with a deposited layer of PVD coating were selected for measurement. Non-homogeneity caused by the creation of droplets arises in the application layer during the process of applying the coating by the PVD method. These droplets make the surface roughness of the PVD coating worse, increase the friction and thereby the thermal load of the cutting tool as well. Also, the droplets could be the cause of the creation and propagation of droplets in the coating and they can cause quick cutting tool wear during machining. Cutting edge preparations were suggested for the improvement of the surface integrity of deposited layers of PVD coating, namely the technology of drag finishing and abrasive jet machining. After their application, the areal surface roughness was measured on the surface of coated cutting inserts, the occurrence of droplets was tracked and the surface structure was explored. A tool-life test of cutting inserts was carried out for verification of the influence of surface treatment on the wear resistance of cutting inserts during the milling process. The cutting inserts with a layer of PVD coatings termed as samples A, B, and C were used for the tool-life test. The first sample, A, represented the coating before the application of cutting edge preparations and samples B and C were after the application of the cutting edge preparation. A carbon steel termed C45 was used for the milling process and cutting conditions were suggested. The visual control of surface of cutting inserts, intensity of wear and occurrence of thermal cracks in deposited PVD layers were the criterion for the evaluation of the individual tests.