Mechanism of surface formation for two-dimensional ultrasonic vibration assisted grinding of monocrystal silicon with vertical workpiece vibration

The mechanism of surface formation for two-dimensional elliptic ultrasonic vibration assisted grinding with the vertical direction to workpiece is investigated by grinding experiments and single point diamond abrasive scratching experiments on monocrystal silicon. The vibrator is produced by bonding a PZT on a metal elastic body, frequencies of both longitudinal mode and bending mode are nearly the same, and an elliptic motion occurs when two alternating current signals with phase difference are applied to the PZT. The experimental results show that the workpiece surface quality is improved obviously, and the surface roughness is decreased significantly. And moreover, the grinding grooves become much shallower and wider, and the chip is also much thicker and shorter. It is known that the percent of ductile mode removal material increases. In addition, as the relation between vibration amplitude and grinding depth of cut is changed, two kinds of material removal mechanism, continuous contact and interrupting cutting, can be realized.