Optimization of the cutting edge radius of PVD coated inserts in milling considering film fatigue failure mechanisms

The fatigue and wear behavior of PVD coatings on cemented carbide substrate s in milling are investigated experimentally and analytically through Finit e Elements Method (FEM) simulation of the cutting process. Cutting inserts with different cutting edge radii and at various feedrates were examined. T he initiation and progress of the tool failure is depicted through Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray microspectral invest igations of the used cutting edges. The FEM simulation of the contact betwe en the tool and the workpiece enables a quantitative description of the inf luence of mechanical stress components on the coating fatigue failure. Here by critical coating fatigue stresses determined by means of the impact test were considered. The experimental and computational results exhibit quanti tatively the effect of tool radius and feed rate on the coating fatigue fai lure as well as on the overall cutting performance for various substrates a nd film structures. In order to utilize the superior characteristics of coa tings towards improving the cutting performance, it is highly recommended t o optimize the cutting insert wedge radius, as well as the cutting conditio ns. Herewith a premature coating failure and a consequent rapid wear develo pment can be prevented. (C) 2000 Elsevier Science B.V. All rights reserved.