Identification of active number of grits and its effects on mechanics and dynamics of abrasive processes

The investigation of grit-workpiece interaction in micro scale is an important issue in abrasive processes as it sheds light on the chip formation process. As a practical condition, grinding is accompanied by vibration because of the wheel run out and wheel-workpiece interaction. The initial condition of the wheel also changes because of wear mechanisms. Considering these situations, the number of engaged grits called active grits has been determined in this study by developing the kinematic equations of the process. Grit properties especially grit height distribution, grinding conditions and wheel vibration are influential parameters determining the active number of grits. Its effect on the undeformed chip thickness frequency, surface roughness and grinding force has been discussed in detail and experimentally investigated by conducting grinding tests at various conditions using different CBN electroplated wheels including fresh, trued and worn wheels. In addition, a normality analysis has been performed for different wheels used in this study indicating a non-normal height distribution for the trued and worn wheel and a normal distribution for the fresh wheels. The active number of grits has been validated by comparing the surface roughness obtained from the model and the experiments in parallel and perpendicular to the cutting direction and a good agreement has been found between the results and the model