With increasing demand for various hard-brittle materials, the polishing performance of lapping must be improved. The number of abrasives used to cut the material surface and the relative velocity between abrasives and the material are considered to affect the material removal rate in the lapping process. Here, we describe a novel lapping method using mixed particle slurry taking into consideration stagnation of abrasives on the lap plate. Here, various oxide particles were added to the slurry containing aluminum oxide (WA). The lapping experiment of glass using the mixed particle slurry showed that the material removal rate was dependent on the oxide particles added to the slurry. The slurry with addition of silica showed a 45% increase in the material removal rate compared with the conventional slurry. Analysis of zeta potential demonstrated that the relationship of zeta potential between abrasives and particles greatly affected the material removal rate. The concentration and diameter of particles added to the slurry were optimized. The surface roughness of the cast iron lapping plate affected the polishing performance with the conventional slurry containing only WA abrasives, while the mixed particles slurry showed an almost constant material removal late regardless of the surface morphology of the plate.

Monitoring technology has attracted attention in the field of factory automation that relies on the Internet of Things (IoT). However, it is difficult to monitor process information from a round machining tool during rotating operations. Therefore, we developed a novel tool holder equipped with a wireless communication function to monitor tool vibration. As a new application, we attempted to measure tool holder vibration and machine tool servo information during free-form surface finishing by a ball end mill. Based on the obtained data, the characteristics of the spindle and feed axes of the machine tool were considered. The results showed that monitoring is effective in improving machining of free-form surface finishes.