A small amount of polishing fluid is dripped into the drum and mixed with water. During the finishing process, it adheres to the surfaces of the parts and abrasives, serving the following functions: ① Softening effect: It chemically reacts with the oxide film on the metal surface, softening it and making it easier to remove through polishing, thereby improving polishing efficiency. ② Lubricating effect: Similar to polishing lubricants, it provides lubrication between the polishing blocks and metal parts, resulting in a smooth surface finish. ③ Cleaning effect: Like a detergent, it removes oil and dirt from the surface of metal parts. ④ Anti-rust effect: After polishing and before cleaning, the parts exhibit a certain level of rust resistance for a short period. ⑤ Cushioning effect: When agitated with water during the finishing process, it reduces the impact between parts.