Development of electrically controlled polishing with dispersion type ER fluid under AC electric field

This paper shows that a dispersion type functional fluid and AC electric field may be used to control the distribution of abrasives in free-abrasive polishing and to improve surface roughness and finishing time. In the case of polishing conductive materials, such as cemented carbide, an AC electric field created by a mono-pole electrode has concentrated abrasives in the polishing area. To obtain a minimum surface roughness, a peak-to-valley voltage of 2 kV at a frequency of 0.8 Hz has been applied. Then the surface roughness of a cemented carbide plate was reduced from 0.65 μm Ra to 0.02 μm Ra in 5 min. But to polish non-conductive materials, such as glass and semiconductors, a multi-layered concentric electrode must be introduced. The surface roughness of borosilicate glass plates has been reduced from 13.5 nm Ra to 7.5 nm Ra in 3 min under the optimum AC electric field gradient of 2 kV/mm and 0.8 Hz frequency.