Evaluation of wear mechanisms of coated carbide tools when face milling titanium alloy

In this paper, the performance and the wear mechanisms of coated carbide tools have been investigated when face milling titanium alloy, Ti–6Al–4V. The two tools used were PVD–TiN and CVD–TiCN + Al2O3 coated. Tool life, tool failure modes and wear mechanisms were examined for various cutting conditions. Both tools experienced long tool life at the low cutting speed of 55 m/min and feed of 0.1 mm per tooth. When considering the volume of material removed and tool lives, the CVD coated tools gave a better performance than the PVD coated tools. Excessive chipping at the cutting edge and chipping and/or flaking on the rake face were the dominant failure modes under most cutting conditions. Analysis carried out with the SEM suggests that coating delamination, adhesion of work material, attrition, diffusion, plastic deformation and thermal cracks were the operating wear mechanisms of the coated tools.