The key to the operation of the polisher is to try to get the maximum polishing rate in order to remove the damage layer from the polishing as quickly as possible. At the same time, the polishing damage layer will not affect the final observed tissue, ie, it will not cause false tissue. The former requires the use of coarser abrasives to ensure a larger polishing rate to remove the polished damage layer, but the polished damage layer is also deeper; the latter requires the use of the finest material to make the polished damage layer shallower, but polished The rate is low.
The best way to resolve this contradiction is to divide the polishing into two phases. The purpose of rough polishing is to remove the polished damage layer. This stage should have the maximum polishing rate. The surface damage caused by rough polishing is a secondary consideration, but it should be as small as possible. Secondly, fine polishing (or final polishing). The purpose is to remove surface damage from rough polishing and minimize polishing damage. When the polishing machine is polished, the sample grinding surface and the polishing disc should be absolutely parallel and evenly pressed on the polishing disc, taking care to prevent the sample from flying out and creating new wear marks due to too much pressure. At the same time, the sample should be rotated and moved back and forth along the radius of the turntable to avoid local wear of the polished fabric too fast. During the polishing process, the fine powder suspension should be continuously added to keep the polishing fabric at a certain humidity. Too much humidity will weaken the wear scar, so that the hard phase in the sample will appear embossed and the non-metallic inclusions in the steel and the graphite phase in the cast iron will produce a "tailing" phenomenon; if the humidity is too small, the sample will be generated due to frictional heat generation. The temperature rises, the lubrication is reduced, the surface is tarnished, and even dark spots appear, and the light alloy will throw the surface. In order to achieve the purpose of rough throwing, the rotating speed of the turntable is required to be low, preferably not exceeding 600r/min; the polishing time should be longer than the time required to remove the scratches, because the deformed layer is also removed. After rough polishing, the surface is smooth, but it is dull and dull. Under the microscope, there is a uniform and fine wear scar, which needs to be removed by fine polishing.
The speed of the turntable can be appropriately increased during fine polishing, and the polishing time is preferably to throw away the damage layer of the rough throw. After fine polishing, the polished surface is as bright as a mirror. No scratches can be seen under the bright field conditions of the microscope, but the wear marks are still visible under phase contrast lighting conditions. The polishing quality of the polishing machine seriously affects the structure of the sample, which has gradually attracted the attention of relevant experts. At home and abroad, a lot of research work has been done on the performance of the polishing machine. Many new models and a new generation of polishing equipment have been developed, which have been developed into various semi-automatic and fully automatic polishing machines from the original manual operation.