Metal products generally need to be sprayed with a paint layer on the surface to play an aesthetic and protective role. However, before painting, the metal products often need to be surface treated. This article describes two methods of surface treatment.
1. Manual processing method
| Tool category | operation method | Quality requirements | Remark |
| emery cloth | For slight rust, use No. 80-100 emery cloth to grind 5-6 back and forth along the object surface to remove the rust . For the moderate rust layer, first use No. 60 emery cloth to repeatedly polish the rust layer until it is basically clean, and then use No. 80-100 emery cloth to repeatedly polish until the surface of the object is completely exposed to metallic luster. For severe forehead rust layer, the rust layer should be cleaned with a wire brush first, and then polished with emery cloth. | After the rust is effectively removed, the floating rust should be wiped off with cotton gauze or towel dipped in gasoline or detergent. After the quality of the workpiece derusting on the same day is checked and passed, the primer should be applied immediately for protection to prevent rust from returning to moisture. | The abrasive cloth is mainly used for general rust removal, and it is not suitable for abrasive cloth rust removal for workpieces with complex shapes. |
| wire brush | Only suitable for rust removal on narrow shaped workpiece surfaces. If it is moderately rusted, brush 8 to 10 back and forth vigorously along the direction of the structure at each point to clean the rust, and apply forceful brushing repeatedly until the rust is clean. | The surface of the workpiece can basically reveal the true color of the metal . Obvious rust is not allowed in dead corners and other places. | After the rust is removed, wipe off the floating rust with gasoline, and immediately apply primer for protection. |
| Steel shovel (it can be made by welding the alloy cutter head used by the lathe on the steel surface with a diameter of 10mm to form a steel plate with good steel quality) | It is mainly suitable for workpieces with severe corrosion, such as angle steel frames, chemical equipment and other unconditional mechanical derusting workpieces. During operation, the rust is removed in sequence along the surface of the object until the true color of the metal is basically completely exposed, and then polished with a coarse emery cloth. | There is no rust or floating rust on the large surface and obvious parts. There shall be no obvious rust and dust accumulation in the narrow and dead angle parts. | Primer protection immediately after gasoline wipe. |
2. Mechanical treatment
| Machinery category | operation method | Quality requirements | Remark |
| electric grinding wheel | First fix the grinding wheel on the shaft head of the machine head . Plug in the power to start the trial run of the Grinder, and start working after confirming that it is running normally. When working, first smooth the iron burrs, etc., and then remove the rust and oxide layer. | No rust on the surface, fully revealing the true color of the metal. The oxide layer needs to be removed. Use abrasive cloth with wire brush or steel shovel to remove rust on the parts that cannot be ground by the Grinder. There must be no leakage | During operation, insulated shoes, insulated gloves and dust mask should be worn to prevent electric shock or inhalation of rust and dust to damage the health of the human body. |
| Electric disc steel brush | Fix the disc steel brush on the setting position of the machine, and conduct a test run by starting it . General rust should be removed until the metallic luster is completely exposed, and severe rust needs to be removed repeatedly until it is effectively cleaned. | There is no rust and oxide layer on the large surface, and the rusty parts need to fully expose the true color of the metal. After each workpiece is qualified, immediately use gasoline to clean the floating rust. | Apply primer protection immediately after the day's work is qualified. |
| Polisher (electric) | Flatly clamp the emery cloth on the bottom plate of the Grinder, and the disc Grinder can be clamped tightly on the grinding disc with the matching circular hole-shaped emery cloth to power on or raise the air for trial operation. Remove rust, oxide layer and old paint layer in sequence. The parts that cannot be ground by the Grinder can be removed with a needle beam descaler. After the rust and oxide layer on each side of the workpiece are effectively cleaned, it needs to be fully polished again. Make the surface of the object show the natural color of the metal and have uniform wear marks, which can enhance the adhesion between the primer and the metal surface. | There is no rust, oxide layer and other sundries on the surface. The surface of the workpiece after cleaning should be smooth and clean, with even and fine grinding marks. There is no rust and dust accumulation on the edges, dead corners and other parts. |
Note: The several mechanical rust removal methods introduced in the above table mainly refer to the surface treatment of small batches of workpieces with rust and no oil on the surface of the steel plate. For oily and rusty workpieces, use gasoline or detergent to remove oil, and then use mechanical tools to remove rust or directly use chemical treatment for surface treatment. For qualified T parts or equipment, mechanical sandblasting, shot peening and other methods can be used for treatment.
