The key to the operation of the polisher is to achieve a high polishing rate in order to remove the damage layer caused by the polishing as soon as possible. It is also necessary that the polishing damage layer does not affect the observed tissue. The former requires the use of coarse abrasive, has a larger polishing rate to remove the polished damage layer, but the polish damage layer is also deeper; The latter requires the use of fine materials, so that the polishing damage layer is shallow, but the polishing rate is low.

The solution to this contradiction is to divide the polishing process into two stages. The purpose of roughing is to remove the surface damage layer. This stage should have a large polishing rate. The surface damage caused by roughing should be a secondary consideration, but should be as small as possible. The second is fine throwing (or final throwing), its purpose is to remove the surface damage caused by rough throwing, polishing damage reduced to a small. Polishing machine polishing, the sample surface and polishing disc should be parallel and evenly light pressure on the polishing disc, pay attention to prevent the sample flying out and because the pressure is too big and produce new wear marks. At the same time, the sample should rotate and move back and forth along the radius direction of the turntable to avoid local wear of the polished fabric too fast. In the process of polishing, the micro powder suspension should be added constantly to keep a certain humidity of the polished fabric. When the humidity is too high, the abrasive effect of polishing will be weakened, and the hard phase in the sample will appear protruding, and the non-metallic inclusions in steel and graphite phase in cast iron will have the phenomenon of "tailing". When the humidity is too small, the sample will heat up due to friction heat, the lubrication effect will be reduced, the grinding surface will lose luster, and even appear black spots, and the light alloy will be thrown on the surface. In order to achieve the purpose of coarse casting, the rotary speed is required to be low, not over 600r/min; The polishing time should be longer than the time required to remove the scratches, as the deformable layer should also be removed. After rough polishing, the grinding surface is smooth, but dull, and there are even and fine grinding marks observed under the microscope, which need to be eliminated by fine polishing.