Metallographic polishing balances removal rate with the depth of surface damage. Coarser abrasives remove the grinding-damaged layer more quickly but can leave deeper polishing damage. Finer abrasives create less damage but remove material more slowly. The goal is to reveal the actual microstructure without preparation artifacts.
The source divides polishing into rough and final stages. Rough polishing removes the grinding-damaged layer at a high removal rate while limiting new damage; final polishing removes the damage left by rough polishing. The specimen face is kept parallel to the polishing disk under light, even pressure to prevent ejection or new scratches. Specimen rotation and radial movement distribute cloth wear. Abrasive suspension maintains suitable moisture: excess moisture can produce relief and trailing artifacts, while insufficient moisture can cause heating, poor lubrication, dark spots and surface damage. For rough polishing, the archived article recommends disk speeds no greater than 600 r/min and sufficient time to remove both scratches and the deformed layer. These historical instructions require confirmation against the specific machine and preparation procedure.
For final polishing, the source suggests a somewhat higher disk speed and enough time to remove the rough-polishing damage. A mirror-like surface may appear scratch-free in bright-field microscopy while retaining visible marks under phase-contrast illumination. Preparation quality affects interpretation of the microstructure. Polishing equipment has developed from manual operation to semi-automatic and fully automatic systems.
The article also discusses mechanical polishing of steel, aluminum, copper and metal tubes, with different attachments for textured, brushed, wavy, matte and mirror finishes. It describes scratch repair, grinding and polishing of welds, gate marks, oxide films, stains and paint, together with deburring, edge rounding and decorative finishing. Listed applications include wooden boards, metal furniture handles, aluminum and stainless-steel products, copper profiles, plumbing and sanitary fittings, locks, lighting, signs, decorative hardware, knives, scissors, hinges, vehicle parts, cutlery, buckles, buttons, phone housings, watch components and electronic parts. These are general historical examples rather than a confirmed scope for every Ruiming machine.