The influence of the diamond wheel grinding process on the selected properties of boron nitride dispersion in cemented carbide (BNDCC) composites

The paper presents the results of research into the influence of the process of grinding boron nitride dispersed cemented carbide (BNDCC) composite using diamond wheel with vitrified bond on the selected properties of this composite. Cutting tools of BNDCC composite were manufactured using several machining operations. At first stage, they were EDM (electrical discharge machining) wire cut from tablets and later on ground with diamond wheels (which removed the "white layer" produced by EDM cutting). Rake and flank faces of prepared cutting tools were examined by microscopic, topographic, and surface analytical techniques before and after grinding. The paper presents comparative results of BNDCC tools and tools made of H10S cemented carbide. Values of the grinding efficiency parameters, Q (w) , average material removal rate of grinding, Q' (w) , average material removal rate per unit active grinding wheel for the two materials, were similar, indicating an insignificant effect of introduction of the harder BN phase into WCCo on these parameters. R (a) , surface roughness of flank face, was 0.040 mu m for BNDCC composite and 0.51 mu m for H10S after grinding, compared to 1.14 and 1.30 mu m, respectively, before grinding. WC residual stress measurements in the flank faces of BNDCC tools were inconclusive; in the flank faces, the stresses were compressive, decreasing, e.g., from - 230 to - 1670 MPa after grinding. For the H10S tools, there was no comparable effect. The results also indicate that the vitrified bonded diamond abrasive wheel used is effective in grinding WCCo and BNDCC cutting tools.