Material removal, tool wear and temperature effects in slicing, scratching and grinding of brittle materials

This work is an experimental study of the basic laws of material removal in sawing and grinding, mechanical wear and electrolytic sharpening of metal bonded diamond tools, especially in the ELID (Electrolytic In-process Dressing) grinding of brittle materials. The transient temperature distribution and thermal layer thickness in scratching and grinding processes are analyzed theoretically and numerically. The heat partition in scratching and grinding of glass using a brass-bonded diamond tool with water cooling and air cooling was studied numerically.; The French-Preston law was found valid in sawing plastic and glass plates in different environments. This suggests that sawing of glass takes place by a process of microscopic fracture. On the other hand, the mechanism for sawing PC (Polycarbonate) appears to be plastic deformation or ductile tearing.; For a given normal load, the cutting efficiency increases initially with current and then reaches a plateau. In the plateau region, the tool sharpness is not sensitive to the current. If ELID grinding is operated in this window, a stable machining quality should be achieved.; The tool wear rate in ELID can be separated into two parts: the mechanical wear and the anodic dissolution. The mechanical wear can be calculated from G ratio and the anodic dissolution can be calculated from Faraday's law and the current efficiency. The current efficiency is around 0.5 in most cases when the current density reaches a critical value [76]. For our experiments, the current efficiency was between 0.41–0.57.; The normalized maximum temperature and temperature half-decay thickness beneath the diamond abrasive are not sensitive to the convection condition in scratching and grinding glasses. This can be found conveniently from our proposed plots. FEA simulation showed that cooling did not change the shape of the temperature profile, but changed the heat partition, which was 2.24% in water cooling and 3.42% in air cooling. Jaeger's estimate [54] would predict 3.2% heat entering the glass substrate. So, his estimate is good in the air cooling case but not valid in water cooling cases, where the maximum temperature might be over estimated by 43%.