When a high-speed rotating grinding wheel breaks during grinding operations, abrasive fragments are scattered at high speed. Generally, the windows of work zone enclosures are made of a transparent polycarbonate plate to allow observation of grinding conditions. However, the collision mechanism of abrasive products against polymer materials, such as polycarbonate, have not been clarified. Here, we performed collision experiments and the finite element method (FEM) of an abrasive projectile (WA46O8V) against the polycarbonate plate and investigated the collision mechanism. The results indicated that the impact resistance of the polycarbonate plate is proportional to the square of the plate thickness, similar to rolled steel plate. On the other hand, the deformation of the polycarbonate plate by the collision of a projectile is dominated by viscoelasticity, which is different from rolled steel plate in which it is dominated by plasticity.

Cutting processes in micro milling of inclined workpieces with miniaturized ball end mills are discussed. The effects of cutting speed on the cutting force and machining error were investigated with changes in the cutting area on the cutting edge, which was controlled by the inclination angle of the workpiece. The resultant cutting force F_xz in x and z directions decreases when the cutting speed increases under a constant depth of cut and feed rate. Then, the tool displacement δ_t', which induces machining error, increases with the cutting force F_xz. As the tool displacement is linearly associated with the static load applied to the tool, the tool displacement can be predicted by the maximum cutting force and the machining error can be compensated by controlling the depth of cut. In cutting tests, the machining errors become less than 1 μm in milling with 0.4-mm diameter ball end mills.

One means of achieving highly efficient high-quality grinding is to use grinding technology applying chemical reactions. The adherence of chemically reactive substances to abrasive grains is expected to improve the efficiency of the chemical reaction in the vicinity of the abrasive grains. We have developed a new abrasive grain composite technology applying twin-nozzle PELID, which makes it possible to combine different types of easily crushed fine particles or different types of microabrasive particles.