Theory of chip formation in grinding of biphasic brittle materials using the example of WC-Co carbide

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The phase fractions and the WC grain size distribution of WC-Co cemented carbides significantly influence their material properties such as, the hardness H, the Youngs modulus E and the critical fracture toughness KIc. Furthermore, during the first research period it was proven that the cemented carbide specification significantly influences the material removal behavior and consequently also the quality of the workpieces of the cemented carbides. In addition to high workpiece quality, grinding of cemented carbides has to meet economical requirements as well. A cost driver is the grinding tool wear. It must be assumed that the cemented carbide specification has a decisive influence on the grinding tool wear. Currently it is unknown how the phase fractions and the WC grain size distribution affects the grinding tool wear. Therefore, the aim of the research project is a description and an explanation model for the tool wear as a function of the WC-Co cemented carbide specification in grinding. For the investigation of the wear mechanisms, single grain cutting tests are carried out. By an analysis of the scratch tracks, the quantitative wear of the grains can be investigated. The qualitative analysis of the grains by means of scanning electron and transmission electron microscopy additionally enables the identification of the wear mechanisms. Grinding tests are then carried out in order to examine the grinding wheel wear and to check the transferability of the findings from the single grain cutting tests. Finally, a qualitative description and explanation model for grinding tool wear in grinding of WC-Co carbides is developed.