During the processing, transportation, and storage of workpieces, the surface often contains oxide skin, rust mold residue, molding sand, welding slag, dust, oil, and other dirt. To ensure that deep layers can firmly adhere to the surface of the workpiece, it is necessary to clean the surface of the workpiece before painting. Otherwise, it not only affects the adhesion and corrosion resistance between the coating and the substrate metal, but also allows the substrate metal to continue to corrode even with coating protection, causing the coating to peel off, affecting the mechanical properties and service life of the workpiece. Therefore, surface treatment before painting the workpiece is an important guarantee and measure to obtain a high-quality protective layer and extend the service life of the product.

To provide a good surface of the workpiece, the treatment of the workpiece surface before painting includes the following points:

1. No oil or moisture
2. No rust or oxides
3. No adhesive impurities
4. No residues such as acid or alkali
5. The surface of the workpiece has a certain roughness

Common surface treatment methods include:

Manual processing: such as scrapers, wire brushes, or grinding wheels. Rust and oxide scale on the surface of workpieces can be removed by hand, but manual processing is labor-intensive, has low production efficiency, poor quality, and incomplete cleaning.

Chemical treatment: mainly using acidic or alkaline solutions to react with the oxides and oil stains on the surface of the workpiece, dissolving them in acidic or alkaline solutions, in order to achieve the purpose of removing rust, oxide skin, and oil stains on the surface of the workpiece. Chemical treatment is suitable for cleaning thin plate parts, but the disadvantage is that if the time is not properly controlled, even with the addition of corrosion inhibitors, it can cause excessive corrosion of the steel. For more complex structural components and parts with holes, the residual acid immersed in the gaps or holes after being washed with acidic solution is difficult to completely remove. If not handled properly, it will become a hidden danger of corrosion in the future of the workpiece, and chemicals are easily volatile and costly. The chemical discharge after treatment is difficult, and if not handled properly, it will cause serious pollution to the environment. With the increasing awareness of environmental protection, this treatment method is being replaced by mechanical treatment.

Mechanical processing method: mainly includes shot blasting method and shot blasting method. Shot blasting cleaning is a method of using centrifugal force to accelerate the projectile and shoot it onto the workpiece for rust removal and cleaning. However, the flexibility of shot blasting is poor, and due to site limitations, there is some blindness in cleaning the workpiece, which can easily create blind spots on the inner surface of the workpiece that cannot be cleaned.

The equipment structure is complex, with many vulnerable parts, especially blades and other parts that wear out quickly, require a lot of maintenance time, incur high costs, and require a large one-time investment.