In the coating industry, whether for powder coating, electrocoating, or liquid paint spraying, racks play a critical role. They not only bear the weight of workpieces and facilitate coating application but also often serve a conductive function. However, after multiple coating cycles, paint buildup on the rack surface can increase, reducing conductivity and increasing shielding effects. Continued use may lead to difficulties or even failure in achieving proper coating adhesion on workpieces. Therefore, cleaning the racks is essential to ensure their continued effective use. Below are some commonly used cleaning methods for your reference.
1. High-Temperature Pyrolysis Cleaning
High-temperature pyrolysis is currently the most common and widely used method for cleaning coating racks. This method uses high temperatures to further carbonize the resin and additives in the coating, followed by water mist treatment to pulverize the carbonized coating, ultimately achieving effective removal of the coating from the rack surface.
Common pyrolysis methods include direct sintering and pyrolysis furnace sintering. Direct sintering requires less equipment investment but is less environmentally friendly, with higher waste gas emissions and inferior cleaning results compared to pyrolysis furnace sintering. While pyrolysis furnace sintering involves higher initial equipment costs and operating expenses, it delivers superior cleaning outcomes.
2. Mechanical Sandblasting Cleaning
Sandblasting machines demonstrate significant effectiveness in removing coatings from rack surfaces, especially for racks with uneven coating thickness or complex structures. To ensure thorough coating removal without damaging the rack’s delicate structure or surface roughness, optimizing sandblasting process parameters is crucial. This involves precisely adjusting factors such as blasting pressure, media type and particle size, spray gun movement speed, and angle to achieve efficient and precise cleaning. By carefully controlling these parameters, various coatings can be effectively stripped while preserving the rack’s original form and texture, ensuring no impact on subsequent use.
For racks with thick coatings (e.g., 10 mm powder coatings), mechanical sandblasting alone may not be ideal. If feasible, softening or carbonizing the coating prior to sandblasting can significantly improve coating removal efficiency.
3. High-Pressure (Abrasive) Cleaning
Some industry practices involve high-pressure cleaning. For racks coated with soft, unbaked water-based paint films, a high-pressure water jet can effectively wash off the coating. However, for racks with unbaked but dried electrophoretic wet paint films, high-pressure water jets alone are often insufficient, requiring the use of abrasive media to remove the coating effectively.
4. Chemical Swelling Cleaning
Chemical swelling involves soaking racks in a paint stripper or applying the stripper to the surface. The stripper’s components quickly penetrate the coating, causing it to soften and swell, leading to coating detachment. Commonly available paint strippers are acidic, with main components including organic solvents, co-solvents, activators, thickeners, and anti-volatilization agents. Using paint strippers is straightforward: immerse the coated workpiece in the stripper for 0.5–5 minutes, during which the old coating swells and lifts off. Afterward, remove residual paint flakes with a high-pressure water jet and rinse thoroughly with clean water.
In addition to these methods, manual grinding can be used as needed, or specific conductive areas can be ground to meet conductivity requirements. The choice of cleaning method should be based on factors such as production line layout, environmental regulations, and equipment investment.