Polyurethane @silica core-shell particles have low density and a smooth spherical shape. For precision machining of metal surfaces used in optical mirrors, we applied core-shell particles as abrasives with rotary tool machining and abrasive slurry jet machining. In this study, Ni surfaces were machined to a depth of approximately 60 nm to evaluate the relations between slurry conditions and workpiece roughness. The results showed that while the effect of abrasive size on roughness varied depending on the machining method, surface roughness decreased with increasing slurry concentration in both methods. After adjusting the slurry conditions, the surface roughness was sub-nanometer level for both methods in the range of approximately 0.25 μm² to 26000 μm²

Internal threading was carried out using a TiSiN-based-coated thread mill with helical interpolation motion by simultaneous control of three axes on a machining center, and the machining phenomena were measured and discussed. The workpiece material was S50C. The subjects were the internal threads cut by the thread mill on pilot holes (diameter = 8.5mm), or the pilot holes and internal threads were machined simultaneously by the thread mill. The experiments were conducted under cutting conditions in which the feed rate of one blade was kept constant and the cutting speed was varied. The tool vibration was measured with a wireless tool holder system, the cutting force was measured with a piezoelectric dynamometer, and the machining characteristics in the high-speed cutting range were examined.