The key to polishing the machine is to try to get the maximum polishing rate so as to remove the damage layer from the polishing process as soon as possible. At the same time, the polished damage layer will not affect the final observed organization, that is, will not cause false organization. The former requires the use of coarse abrasive, to ensure a larger polishing rate to remove the damaged layer, but the polishing damage layer is also deep; the latter requires the use of the finest material, so that the polished damage layer is shallow, but the polishing rate is low.
The best way to resolve this paradox is to divide the polishing into two stages. The purpose of coarse throw is to remove the layer of polished damage this stage should have the maximum polishing rate, the surface damage caused by rough throw is the secondary consideration, but it should be as small as possible, followed by the fine throw (or final throw), the aim is to remove the surface damage caused by rough throw, so as to minimize the polishing damage. Polishing machine polishing, the sample grinding and throwing discs should be absolutely parallel and evenly light on the CD-ROM, attention to prevent the test specimen fly out and because the pressure is too large to produce new wear marks. At the same time, the specimen should rotate and move back and forth along the radius of the turntable in order to avoid the local wear of polished fabric too fast in the polishing process to add micro-powder suspension, so that the polishing fabric to maintain a certain humidity. Humidity is too general to weaken the polished grinding effect, the phenomenon of "trailing" in the hard phase of the specimen in the floating convex and the non-metallic inclusions in the steel and the graphite phase in the cast iron. Humidity is too small, because the friction heat will make the sample temperature, lubrication reduced, grinding lost luster, even appear dark spots, light alloy will throw the surface. In order to achieve the purpose of coarse throw, it is required that the turntable rotate speed is lower, preferably not exceeding the 600r/min; polishing time should be longer than the time taken to remove scratches, because the deformation layer is also removed. After the coarse-grained grinding smooth, but bleak, under the microscope to observe a uniform and meticulous wear marks, need to be eliminated.
The speed of the turntable can be improved properly while polishing time to throw away the damage layer of the coarse throw is advisable. After polishing, the polished flour is bright as a mirror, and no scratches can be seen under the microscope, but the grinding marks are still visible under the condition of the phase-contrast illumination. Polishing machine polishing quality seriously affect the microstructure of the specimen, has gradually aroused the attention of relevant experts.