HPC-milling of WC-Co cemented carbides with PCD

Abstract

In order to machine wear parts of small lot size made out of WC-Co cemented carbides, milling can be an economically promising alternative to grinding or electrical discharge machining (EDM) for finishing after sintering. However, milling of sintered cemented carbides implies a high risk of tool failure up to now.Based on initial feasibility studies on milling of medium Co-content carbides with PCD, the potential and limitations of this technology need to be evaluated especially with regard to suitable cutting edge geometries and cutting parameters.Major aspects of the investigations performed for varying cutting edge chamfers, radial depths of cut and cutting velocities were chip formation, cutting forces, tool wear, surface roughness and the integrity of the boundary zone. Results indicate, that machining with a tool diameter of D=10mm at axial depths of cut within the range of sintering allowances (≈0.2mm) is possible at material removal rates which can be called high productivity conditions (HPC) compared to the state of the art. Experiments show specific wear formation, hardness increase of the machined surface and change of the microstructure in the boundary zone.