Powder coating is a surface treatment method for products. It is environmentally friendly, non-toxic to humans, offers excellent coating appearance, requires low skill levels from workers, and is more cost-effective than traditional painting.
The process is divided into four main stages: pre-treatment, electrostatic powder spraying, high-temperature curing, and decorative finishing. Below is a brief description of each stage:
1. Pre-Treatment
Purpose:
To remove oil, dust and rust from the surface of the workpiece, and to form a "phosphate layer" that enhances corrosion resistance and improves the adhesion of the coating.
Process Steps:
Degreasing, derusting, phosphating and passivation. After pre-treatment, the workpiece surface is free of oil, rust, and dust. A uniform, rough, gray phosphate film forms on the originally shiny silver surface, which helps prevent rust and increases the adhesion of the powder coating.
2. Electrostatic Powder Spraying
Purpose:
To evenly apply powder coating to the surface of the workpiece. Special workpieces (including areas prone to electrostatic shielding) should be coated using high-performance electrostatic spray equipment.
Process Steps:
Using the principle of electrostatic adsorption, a layer of powder coating is evenly applied to the surface. Oversprayed powder is collected through a recovery system, screened, and reused.
3. High-Temperature Curing
Purpose:
To heat the powder-coated workpiece to a specified temperature and hold it for a set time, allowing the powder to melt, flow, and cure, achieving the desired surface finish.
Process Steps:
The coated workpiece is placed in a curing oven and heated to a preset temperature (typically 185°C), then held for a specific duration (usually 15 minutes). After curing, the workpiece is removed and cooled to obtain the final product.
Note: The curing oven consists of a heating and control system (electric, fuel, gas, or coal heating) and an insulated chamber.
4. Decorative Finishing
Purpose:
To achieve special visual effects on the powder-coated workpiece, such as wood grain, patterns, or gloss enhancement.
Advantages of Powder Coating:
1. Environmentally friendly
2. High efficiency
3. High material utilization
4. Excellent coating performance
5. Single-coat application
Author: Wang Bo
Date: September 3, 2025