Pre-treatment process: Oil decontamination of aluminum profile
→ water washing → alkali washing (degreasing)→ water washing → pickling → water washing → chrome → water washing → pure water washing
Spraying process: Spray primer → top paint → gloss paint → baking (180-250℃)→ quality inspection
The multi-layer spraying process is three times spraying, spraying bottom paint, top paint and gloss paint and secondary spraying (primer, top paint).
1. Purpose of pre-processing
Before spraying aluminum profiles and plates, the surface of the workpiece should be deoiled and decontaminated and chemically treated to produce chromified film, which increases the bonding force and anti-oxidation ability of the coating and metal surface and is conducive to extending the service life of the film.
2. Primer coating
As the primer coating of the closed substrate, its function is to improve the permeability resistance of the coating, enhance the protection of the substrate, stabilize the metal surface layer, strengthen the adhesion between the finish coat and the metal surface, and ensure the color uniformity of the finish coat. The thickness of the finish coat is generally 5-10 microns.
3. Top coat coating
Topcoat coating is a key layer of spraying layer, which is to provide the decorative color needed for aluminum profiles, so that the appearance of aluminum profiles can meet the design requirements, and protect the metal surface from the erosion of the external environment, acid rain, pollution, prevent ultraviolet penetration, and greatly enhance the anti-aging ability. Topcoat coating is the thickest layer of paint coating in spraying, and the thickness of the paint layer is generally 23-30 microns.
4. Cover varnish coating
Gloss paint coating is also known as varnish coating, the main purpose is to more effectively enhance the resistance to external erosion of the paint layer, protect the top paint coating, increase the metallic luster of the top paint color, the appearance is more bright color, dazzling, the thickness of the coating is generally 5-10 microns, the total thickness of three spraying layers is generally 40-60 microns, special needs can be thickened.
5. Curing treatment
The curing temperature is familiarly between 180°C-250°C, and the curing period is 15-25 minutes. Different aluminum profile manufacturers will provide the best temperature and time according to their own coatings, and some aluminum profile manufacturers will change the two curing times of three spraying to one curing according to their own experience.