Influence of cutting edge radius on the wear resistance of PM-HSS milling inserts

The wear behaviour of PM-HSS milling inserts is investigated experimentally. Cutting inserts with different cutting edge radii tested in industrial conditions were examined. The radii have been obtained either by micro-sandblasting or by honing. The initiation and progress of the tool wear was analysed with scanning electron microscopy (SEM) of the cutting edges. The experimental results exhibit quantitatively the effect of tool radius on the performance of milling inserts. A radius on the cutting edge prevents fast and unpredictable wear. Moreover, the existence of an optimum value of the radius has been revealed experimentally. In parallel, 2D finite element cutting simulations based on Lagrangian thermo-viscoplastic formulation are used to analyse the tool-stress distributions within the tool coating and substrate. The results obtained from this study provide a fundamental understanding of the cutting mechanics for the coated tool used and can assist in the optimisation of tool edge design. Particularly, the results obtained from the simulations have confirmed that there exists an optimum cutting edge radius that minimizes tool stresses, especially within the coating layer, which seems to be a key factor in the case of milling in dry high speed conditions.