Abstract
The drilling of microholes with a diameter smaller than 0.1 mm by grinding, which has not been reported previously, was attempted. Cemented tungsten carbide micropins were fabricated by electrical discharge machining and used as grinding tools. These micropins can be employed for grinding because discharge craters formed on their surfaces act as abrasive grains of grinding wheels. Workpieces were ultrasonically oscillated to decrease grinding force, because ultrasmall-diameter tools were easily broken. Helical tool feeding was also employed, where tools were moved in planetary motion. Microholes 30 μm in diameter were successfully drilled in crown glass. Ultrasonic oscillation decreased grinding force, although no effect of helical tool feeding was observed.
