Polishing Machine Supplier: What Is the Working Principle of a Polishing Machine?

The key to operating a polishing machine is to achieve a high polishing rate so as to remove the damage layer generated during grinding as quickly as possible. At the same time, it is essential that this polishing-induced damage layer does not interfere with the microstructure observed in the final examination—that is, it should not produce artificial features. To meet the former requirement, coarser abrasives must be used to ensure a high polishing rate for removing the grinding-induced damage layer; however, this also results in a deeper polishing damage layer. Conversely, to minimize the polishing damage layer, finer abrasives are required, which yield a shallower damage layer but at a lower polishing rate. A good solution to this trade-off is to divide the polishing process into two stages: rough polishing, whose purpose is to remove the grinding-induced damage layer; in this stage, a high polishing rate is desirable, and although the surface damage produced by rough polishing is of secondary importance, it should still be kept as small as possible; and fine polishing (also known as final polishing), whose goal is to eliminate the surface damage introduced during rough polishing, thereby minimizing the overall polishing damage.

During polishing with a polishing machine, the specimen’s polished surface must be kept perfectly parallel to and lightly and evenly pressed against the polishing cloth; care should be taken to prevent the specimen from flying off and to avoid introducing new scratches due to excessive pressure. At the same time, the specimen should rotate about its own axis while simultaneously moving back and forth along the radius of the polishing disc, so as to prevent localized over-wearing of the polishing cloth. Throughout the polishing process, a fine-powder suspension should be continuously added to maintain a consistent level of moisture on the polishing cloth. If the moisture is too high, the abrasive action of polishing will be weakened, causing hard phases in the specimen to appear raised and protruding, and resulting in “trail” effects for non-metallic inclusions in steel and graphite phases in cast iron; if the moisture is too low, frictional heat will raise the specimen’s temperature, reducing the lubricating effect, causing the polished surface to lose its luster and even develop black spots, while light alloys may suffer surface burn. To achieve coarse polishing, the rotational speed of the polishing disc should be kept relatively low, not exceeding 600 r/min; the polishing time should be longer than that required to remove scratches, since it is also necessary to eliminate the deformation layer. After coarse polishing, the polished surface will be smooth but dull and lack luster, with uniform, fine polishing marks visible under the microscope—these still need to be eliminated through fine polishing. During fine polishing, the disc speed may be appropriately increased, and the polishing time should be adjusted so as to remove the damage layer left by coarse polishing. Following fine polishing, the polished surface will be as bright as a mirror, with no visible scratches under bright-field microscopy; however, under phase-contrast illumination, polishing marks may still be discernible.

The quality of polishing performed by a polishing machine has a significant impact on the microstructure of test specimens and has thus gradually attracted the attention of experts in the field. Both domestically and internationally, extensive research has been conducted on the performance of polishing machines, leading to the development of numerous new models and next-generation polishing equipment. These machines are evolving from purely manual operation toward a wide range of semi-automatic and fully automatic systems. The following section introduces the performance and characteristics of several commonly used mechanical polishing machines. Polishing machines are specifically designed for surface treatment of metal products such as steel, aluminum, and copper, as well as tubular components, offering a variety of effects. With dozens of original manufacturer-supplied accessories to meet diverse needs, they can effortlessly produce patterns with varying degrees of precision, including snowflake finishes, brushed textures, wave patterns, matte surfaces, and mirror-like finishes. They also enable rapid repair of deep scratches and minor scuffs, as well as quick grinding and polishing of weld seams, sprue marks, oxide films, stains, and paint residues. These machines are suitable for deburring, creating rounded corners, and decorative metal finishing, while ensuring that no shadows, transition zones, or unevenness in the finished surface occur during processing. As such, they are essential equipment in metal product manufacturing lines.

Polishing machines are suitable for the following industries: woodworking and furniture manufacturing, including sanding and brushing of flat wood panels, metal furniture handles, and other workpieces; hardware (metal) materials and products, such as aluminum profiles and related products, stainless steel products and utensils, copper profiles and products, plumbing and bathroom fixtures, locks, lighting fixtures, nameplates and signage, metal craft ornaments, knives and scissors, door hinges, automotive and bicycle parts, tableware, button and fastener products, buttons, belt buckles, mobile phone casings, and watch components—covering sanding and brushing of these workpieces; electronic components and equipment, including electronic parts and flat-surface sanding and brushing.