Dalian metal surface treatment: Before electroplating, the oil seal of the parts should be removed. After removing oil stains, the surface of the parts should be free of oil stains, oil stains, metal shavings, and paint marks from mechanical processing. Components connected by bolts are not allowed to be directly electroplated or chemically treated. Riveted parts, welded parts with gaps, and castings with excessive sand holes should not be electroplated or chemically treated in principle. Otherwise, corrosion may occur due to electrolyte flowing into the gaps; The surface of the workpiece after heat treatment should be cleaned, and there should be no incomplete oxide scale or residue (such as salt, alkali, molding sand, and sintered material caused by incomplete oil stains on the surface of the workpiece before heat treatment), and slight oxide scale and rust corrosion are allowed.