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CT-250S/CT-250V Manual Cut-Off Machine
CT-250S/CT-250V is a manual cut-off machine, which designed according to the principles of safety an...
The first is the rough polishing of the metallographic polishing machine, the purpose is to remove the polished damage layer, this stage should have the maximum polishing rate, the surface damage formed by the rough polishing is a secondary consideration, but it should be as small as possible; the second is fine polishing (Or final polishing), its purpose is to remove surface damage caused by rough polishing and minimize polishing damage. The key to the polishing operation is to try to get the maximum polishing rate in order to remove the damage layer generated during polishing as soon as possible. At the same time, the polishing damage layer must not affect the final observed tissue, that is, it will not cause false tissue. These two requirements are contradictory. The former requires the use of coarser abrasives to ensure a higher polishing rate to remove the polished damage layer, but the polishing damage layer is also deeper; the latter requires the use of the finest material to make the polishing damage layer shallower, but polishing The rate is low. The best way to solve this contradiction is to divide polishing into two stages.
In addition, too much humidity will weaken the effect of polishing wear scars, causing the hard phase in the sample to appear embossed and the non-metallic inclusions in steel and the graphite phase in cast iron to produce "tailing"; when the humidity is too low, friction and heat will cause The sample heats up, the lubrication effect is reduced, the grinding surface loses its luster, and even black spots appear, and the light alloy will damage the surface. During polishing, the grinding surface of the sample and the polishing disk should be absolutely parallel and lightly pressed on the polishing disk evenly. Take care to prevent the sample from flying out and creating new wear marks due to excessive pressure. At the same time, the sample should be rotated and moved back and forth along the radius of the turntable to avoid local abrasion of the polishing fabric too fast. During the polishing process, the micro-powder suspension should be continuously added to keep the polishing fabric at a certain humidity.
What is important is that in order to achieve the purpose of rough polishing, the rotation speed of the metallographic polishing machine is required to be low, preferably not to exceed 500r/min; the polishing time should be longer than the time required to remove the scratches, because the deformed layer must be removed. After rough polishing, the polished surface is smooth, but dull and dull. There are even and fine wear scars observed under the microscope, which need to be eliminated by fine polishing.
Of course, the speed of the turntable can be appropriately increased during the fine polishing, and the polishing time is appropriate to throw away the damaged layer of the rough polishing. After fine polishing, the polished surface is bright as a mirror, and no scratches can be seen under the bright field of the microscope, but the wear marks are still visible under the phase contrast illumination. The polishing quality of metallographic samples seriously affects the structure of the samples, which has gradually attracted the attention of relevant experts. In recent years, a lot of research work has been done on the performance of polishing machines at home and abroad, and many new models and a new generation of polishing equipment have been developed. The original manual operation is developing into a variety of semi-automatic and fully automatic polishing. machine.
