Metal powder coating, Powder coating for aluminium profiles
Metal powder coating (Spray painting) surface finish is an anti-oxidation and anti-corrosion method that inhibits the ingress of corrosive agents by forming a protective coating on the metal substrate. It functions by blocking the penetration of water, oxygen, and ions, thereby delaying the electrochemical corrosion process; the continuity and adhesion of the coating directly determine the effectiveness of the protection.
Metal powder coating and spray painting process
- 1: The cleanliness of a metal surface significantly affects the adhesion of the paint coating; failure to completely remove residual or adsorbed water, oil, and other foreign matter often leads to defects such as pinholes, nodules, peeling, or poor adhesion.
- 2 Painting must be carried out promptly—within 24 hours—following processes such as the phosphating of metal parts, the chemical oxidation or anodizing of aluminium profiles (aluminum alloy parts), or the chemical oxidation of magnesium alloy parts. Similarly, steel parts that have undergone sandblasting or shot peening must be painted within six hours. This procedural requirement is a proven method for enhancing the adhesion between the coating film and the substrate, as well as improving corrosion resistance.
- 3: Inadequate oil-water separation in the compressed air used for spraying—resulting in excessive water and oil content—inevitably compromises the quality of the paint coating and leads to various defects. Therefore, regularly cleaning or replacing the filter elements in oil-water separation units to ensure clean compressed air is beneficial for improving the performance of the paint coating.
- 4: Temperature and humidity at the painting site have a significant impact on the quality of the paint coating. The temperature should be maintained between 10°C and 30°C, and relative humidity should not exceed 80%; the work area must be kept clean, hygienic, tidy, and organized.
- 5: Excessively high temperatures and high relative humidity can cause the paint coating to blush (turn white) or develop an “orange peel” texture, while excessively low temperatures can cause the paint to run or sag, adversely affecting the quality of the coating on the metal surface.
- 6: Air spraying is the standard method for applying paint to metal surfaces. To effectively ensure coating quality, the distance between the spray gun and the surface should be maintained between 200 mm and 300 mm, and the compressed air pressure should be controlled within the range of 2 to 4 kg/cm².
Automatic Powder Coating & Painting Line
A automatic powder coating and painting line is a specialized assembly line system used in industrial manufacturing for the surface painting and powder coating of workpieces. It comprises pre-treatment equipment, a powder coating system, painting equipment, a curing oven, a heat source system, an electrical control system, and a suspended conveyor chain. Learn More >>
