Put workpiece in grain suspension liquid and then, put both of them in ultrasonic wave field. Relying on the shock effect of ultrasonic wave filed, the grains are ground and polished on the surface. Ultrasonic wave polishing make a small macroscopical strength and does not make the workpiece out of shape. However, it is difficult to make and install the workpiece.

Ultrasonic wave polishing can be combined with chemical and electro-chemical method. After the etch of solution and electrolysis, use ultrasonic wave to shake the solution making the out come break away from the surface of the workpiece. Then the left of the surface get etched or encounter balance the electrolyte. The cavavition of ultrasonic wave can restrain the process of etch, which is benefit for the surface luminosity.

By using this technique, it can reach surface roughness about Ra 0.008um which is the highest among all the polishing methods.

Optics glasses mold usually use this method.