Semi-orthogonal turning of hardmetal with CVD diamond and PCD inserts at different cutting angles

Thick CVD diamond brazed inserts and PCD cutting tools were compared in dry turning of WC-18 wt% Co bars. Machining of hardmetal by chip removal is a recent alternative technology to wheel grinding, aiming the reduction of the operation time, the elimination of cooling lubricants and single step shaping of complex geometries. Two cutting angle configurations were used: i) neutral (0°) rake angle and 11° clearance angle; ii) negative (−6°) rake angle and 6° clearance angle, named here as TP and TN, respectively. Roughing and finishing operations were performed with adequate cutting parameters. In roughing conditions, the TP-CVD inserts presented the best performance regarding the cutting forces, tool wear and workpiece surface quality, while no significant differences were found between the TP-CVD and TN-CVD tools in the hardmetal finishing. Contrarily to CVD diamond, the currently available commercial option, the PCD tool, was not able to machine such an abrasive material, not only due to its lower hardness but also because adhesion wear is promoted by the presence of the common cobalt binder of the hardmetal and the PCD composite.