The coating process for automotive parts is a complex procedure, and its key process elements mainly include the following aspects:

Coatings: They are the core materials in the coating process, including primers, intermediate coatings, and topcoats. Primers should have good adhesion and anti-rust properties to provide a solid foundation for subsequent coatings. Intermediate coatings are mainly used to fill and smooth the surface, increasing the thickness and fullness of the coatings. Topcoats need to have excellent decorative properties, weather resistance, and corrosion resistance, such as acrylic resin coatings, polyurethane coatings, etc.
Solvents: They are used to dissolve the film-forming substances in coatings and adjust the viscosity and drying speed of coatings. Appropriate solvents can enable better application of coatings and ensure the quality of the coatings.
Additives: Such as leveling agents, defoamers, and driers. Leveling agents can make the coatings form a smooth and flat surface after coating. Defoamers can eliminate bubbles in coatings to prevent pores from appearing in the coatings. Driers can accelerate the drying speed of coatings.

Spray Booths: They provide a clean and well-ventilated coating environment, which can effectively control the temperature, humidity, and wind speed to ensure the uniform spraying of coatings and reduce the impact of impurities such as dust on the coatings.
Spray Guns: They are tools for atomizing coatings and spraying them onto the surfaces of automotive parts. Different types of spray guns, such as air spray guns, airless spray guns, and electrostatic spray guns, have different spraying effects and application ranges.
Drying Equipment: They are used to accelerate the drying and curing process of coatings. Commonly used ones include hot air circulation drying ovens, infrared drying equipment, etc., which can provide appropriate drying temperatures and times according to the characteristics and process requirements of coatings.

Spraying Pressure: It affects the atomization effect and spraying efficiency of coatings. If the pressure is too high, it may lead to excessive atomization of coatings, making the coatings thinner and uneven. If the pressure is too low, the coatings will be poorly atomized, and phenomena such as sagging and orange peel may occur.
Spraying Distance: Generally, it is advisable to be between 200 and 300 mm. If the distance is too close, the deposition amount of coatings on the surface of parts will be too large, and sagging is likely to occur. If the distance is too far, the coatings will be scattered and lost a lot, resulting in uneven coating thickness and possibly affecting the adhesion.
Spraying Speed: It is usually between 30 and 60 cm/s. If the speed is too fast, the coatings will be too thin and the hiding power will be insufficient. If the speed is too slow, local accumulation of coatings may occur, resulting in sagging or excessive coating thickness.
Drying Temperature and Time: Different coatings have different requirements for drying temperature and time. For example, acrylic coatings are generally dried at 60 - 80 °C for 30 - 60 minutes. If the temperature is too high or the time is too long, the coatings may change color or become brittle. If the temperature is too low or the time is too short, the coatings will not be fully cured and their performance will not meet the requirements.

Degreasing Treatment: It is to remove oil, grease, and other impurities on the surfaces of automotive parts to improve the adhesion of coatings. Commonly used methods include solvent cleaning, alkaline cleaning, ultrasonic cleaning, etc.
Rust Removal Treatment: For parts with rust, rust removal treatment is required. Methods such as pickling, sandblasting, and shot blasting can be used to completely remove the rust layer and prevent the rust spots from continuing to expand under the coatings, which would affect the protective performance of the coatings.
Phosphating Treatment: It forms a phosphate chemical conversion film on the metal surface, which can increase the bonding force between the coatings and the metal substrate and improve the corrosion resistance.

Temperature: Generally, the environmental temperature for coating operations should be controlled between 15 and 35 °C. If the temperature is too high, the drying speed of coatings will be too fast, which may lead to poor leveling and the appearance of orange peel. If the temperature is too low, the coatings will dry slowly and may even affect the curing effect of the coatings.
Humidity: The environmental humidity should be maintained at 40% - 70%. If the humidity is too high, the moisture in coatings will not be easily evaporated, which will prolong the drying time of coatings and may also lead to problems such as whitening and blistering of coatings. If the humidity is too low, the solvents in coatings will evaporate too quickly, which may affect the leveling and adhesion of coatings.
Ventilation: Good ventilation can timely discharge the solvent vapor and waste gas generated during the coating process, keep the air fresh, be beneficial to the drying and curing of coatings, and also ensure the health and safety of operators.