The vehicle frame is a critical structural component, and its durability is directly related to the vehicle’s overall performance and service life. A correct spray coating process is crucial for improving the durability of the vehicle frame. So, how can you properly spray the frame to enhance its durability? What are the precautions for these spray coating methods?

Ⅰ. Correct Spraying Process

First, before officially spraying the frame, thorough cleaning and pretreatment are crucial prerequisites, as they directly impact the coating’s adhesion and service life. The frame surface must be completely cleaned of oil stains (such as residual cutting oil and fingerprint grease from machining), rust (especially around welds, edges, and corners prone to oxidation), and impurities such as dust and metal debris. Cleaning methods vary depending on the application: For heavy oil stains, soak and spray with a neutral degreaser or other chemical cleaner. For stubborn rust or rough surfaces, sandblasting can remove impurities and increase surface roughness. For lighter stains, fine sandpaper can be used to polish, smooth out scratches, and remove impurities, creating a clean, smooth base for spraying.

Second, selecting the appropriate spray coating material is crucial. Each of the three types of materials performs its own specific function. Anti-rust primers should prioritize strong rust resistance and excellent adhesion, providing direct isolation from corrosive media and ensuring long-term protection for the vehicle frame. Topcoats determine the appearance and can be selected from matte to glossy finishes to match the design style. Clearcoat, as the topcoat, enhances surface texture, hardness, and wear resistance, resisting daily scratches and extending the coating’s lifespan.

Finally, controlling spray thickness and uniformity is crucial for quality assurance. Industry standards dictate a primer thickness of 50-80 microns (to balance rust resistance and drying performance), topcoat 30-50 microns (to ensure rich color), and clearcoat 20-30 microns (to ensure protection and transparency). It’s recommended to apply multiple thin coats, controlling the amount of paint delivered and the speed of the spray gun each time. Apply thin coats, allowing them to dry before applying additional coats. This prevents defects like sags and pinholes and ensures a smooth, consistent coating. The following are three commonly used materials for frame painting and their key features:

Rust-proof primer, as the basecoat that comes into direct contact with the metal surface of the frame, not only provides excellent rust-proof properties, shielding it from corrosive media such as air and moisture, preventing rust from forming on the frame, but also enhances the adhesion of the subsequent topcoat to the frame, laying a solid foundation for the overall coating and ensuring long-term protection for the frame.

Topcoat, the core material that determines the frame’s appearance, can be selected in a variety of colors and glosses to suit your needs. It also provides basic protection against minor scratches and environmental corrosion, ensuring the frame appears visually consistent with the design.

Clearcoat, as the topcoat, primarily increases the hardness and wear resistance of the frame’s surface, reducing signs of wear and tear from daily use. It also significantly improves the coating’s gloss, adding a more refined appearance and extending the overall coating’s aesthetic appeal and service life.

II. Precautions

An ideal spraying environment is crucial for ensuring coating quality. It requires dust-free conditions with appropriate temperature and humidity. A dust-free environment prevents dust and particles from adhering to the undried coating surface, preventing defects such as pitting and impurities. This is typically achieved by enclosing the spraying room and equipping it with an air filtration system. The temperature should be controlled between 15°C and 30°C to ensure proper leveling and drying of the coating. Temperatures that are too low can slow drying and reduce adhesion, while temperatures that are too high can cause the coating to cure too quickly and crack. Relative humidity should be maintained between 40% and 70%. High humidity can cause whitening and bubbles to appear on the coating surface, while low humidity can cause the coating to dry too quickly and lose gloss.

After spraying, appropriate drying and curing procedures are required. Common methods include natural drying and heat drying. Natural drying relies on ambient temperature and air flow to cure the coating, requiring no additional equipment and resulting in lower costs. However, it is significantly affected by the environment and requires a longer drying time, typically taking several hours to a day. Heat drying, which raises the ambient temperature using equipment such as ovens and infrared heaters, can significantly shorten drying time, typically taking only tens of minutes to several hours. However, precise temperature control is required, as different coatings require different heating temperatures. Excessively high temperatures can damage the coating structure, causing discoloration and cracking, while excessively low temperatures prevent optimal curing.

In addition, regular inspection and maintenance of vehicle frame coatings are key to extending their service life. Regularly inspect the coating for signs of damage, peeling, or rust, especially around vulnerable areas like corners and welds. Any issues identified require prompt action: first remove any old coating and rust from damaged areas, perform a pre-cleaning pre-treatment, and then reapply primer, topcoat, and clearcoat to prevent further damage and compromise the frame’s rust-resistant properties.

In short, the proper spray coating of a vehicle frame requires a comprehensive consideration of pre-treatment, material selection, spraying process, environmental conditions, and ongoing maintenance. Only when every link is operated strictly in accordance with standards can the durability and protection of the frame coating be effectively improved, thereby ensuring the safety performance and service life of the car.

Ⅲ.Summary

To sum up, the vehicle frame, as the core structural part of a vehicle, its durability is inseparable from the scientific and standardized spray coating process. From the thorough pre-spray cleaning and pretreatment that lays a solid foundation, to the careful selection of anti-rust primers, topcoats, and clearcoats that each take on their roles, then to the precise control of spray thickness and uniformity during the spraying process, and the strict adherence to the dust-free, temperature and humidity – suitable environment requirements, as well as the proper post-spray drying and curing methods, and the regular later inspection and maintenance. Every link is closely connected and indispensable. Only by implementing each step in accordance with the standards and paying attention to every detail in the precautions can we maximize the protective effect of the coating, effectively enhance the durability of the vehicle frame, and thus provide a solid guarantee for the long-term stable operation, overall performance and service life of the vehicle.