Note on the outer round polishing machine
When the polishing machine is used, the sample grinding surface and the polishing disc should be absolutely parallel and evenly light on the polishing disc, and the circular pipe polishing machine can prevent the specimen from flying out and generate new wear marks due to the pressure. At the same time, we should make the sample rotation and move back and forth along the radial direction, so as to avoid the polishing fabric local wear too quickly in the polishing process, we should continuously add micro powder suspension, so that the polishing fabric to maintain a certain humidity. Humidity is too general to weaken polishing grinding marks and the specimen in hard phase showed embossed and steel in non metallic inclusions in steel and cast iron graphite phase "trailing" phenomenon; humidity is too small, due to friction heat will make the sample temperature, reduced lubrication, grinding to lose luster, and even spots, light alloy will hurt the surface polishing. In order to achieve the purpose of rough polishing, the rotary speed is low, it is best not to exceed 500r/min; polishing time should be longer than the time required to remove the scratches, because the deformation layer is also removed. After rough polish smooth, but under the microscope with intense darkness without light, wear uniform, fine polishing to be eliminated. Fine polishing appropriately increasing the speed dial polishing time to remove the damaged layer of rough polishing is appropriate. After the fine grinding polishing and it is bright as a mirror, under bright field microscope conditions can not see scratches, but in contrast lighting conditions, can still see the wear scar. The quality of polishing machine has seriously affected the organization structure of the sample, which has been gradually paid attention to by the experts.