Cutting Edge Radius Effects on Diamond Coated Cutting Tools: From Deposition to Machining

Diamond coatings have been increasingly extended to cutting tool applications for machining advanced materials such high-silicon aluminum alloys. Diamond coating tool behaviors are interrelatedly influenced by both the coating and subsequent machining, and yet the tool edge geometry strongly impacts the stress fields around the cutting edge during each process. To effectively use diamond coating tools, it is necessary to understand the stress modifications around the tool edge due to the deposition and during machining. In this study, finite element modeling was applied to simulate deposition stresses from coating and stress modifications due to subsequent machining affected by the edge radius. The results are summarized as follows. For deposition stresses, edge sharpness causes significant stress concentrations around the edge radius area. In machining, the thrust forces increase drastically with the increased edge radius, while the cutting forces increase only marginally. During machining, the thermal load, which causes stress reversal conditions, is more dominant to stress evolutions than the mechanical load. For all cutting conditions tested, increasing the edge radius results in increased stress reversal. The edge radius effects on stress reversal are more prominent at small uncut chip thickness and high speed, which is due to more pronounced size effects and high cutting temperatures. Though large edge radii reduce the deposition stresses, the reduction seems insufficient to compensate the added machining loads within the range of edge radii studied.