Electrophoretic coating, as an advanced painting technology, has been widely used in various industries such as automotive, home appliances, and hardware due to its excellent corrosion resistance and uniform coating effect. However, in actual production, bubbles may sometimes appear in the electrophoretic coating, which not only affects the appearance quality of the product but also may reduce its corrosion resistance. This article will delve into the causes of bubbles in electrophoretic coating.

　　Firstly, improper pre-treatment is one of the common causes of bubbles in electrophoretic coating. Before electrophoretic painting, the workpiece surface needs to undergo strict degreasing, derusting, and phosphating treatment. If the pre-treatment is not thorough, residual oil, rust, or phosphating slag on the workpiece surface can form coating defects during the electrophoretic process, leading to bubbles. Therefore, ensuring the quality of pre-treatment is key to preventing bubbles in electrophoretic coating.

　　Secondly, improper control of electrophoretic bath parameters is also an important factor causing bubbles. Parameters such as solid content, pH value, and conductivity of the electrophoretic bath need to be strictly controlled within the specified process range. If the solid content is too high, it can lead to an excessively thick coating, incomplete solvent evaporation, and thus the formation of bubbles. If the pH value or conductivity is out of control, it can affect the stability of the electrophoretic process, resulting in coating defects such as pinholes and bubbles.

　　In addition, the control of voltage and temperature during the electrophoretic process also has a significant impact on the quality of the coating. Excessive voltage or temperature can accelerate the evaporation of solvents, causing bubbles to form on the coating surface. Therefore, reasonable control of voltage and temperature during the electrophoretic process is an important measure to prevent bubbles.

　　Problems in the drying process are also a cause of bubbles in electrophoretic coating. Excessive drying temperature or too rapid heating can cause the solvents on the coating surface to evaporate quickly, forming bubbles. Insufficient drying time can lead to incomplete evaporation of solvents inside the coating, leaving hidden bubbles. Therefore, formulating a reasonable drying process and strictly implementing it is crucial for ensuring the quality of the coating.

　　Finally, unreasonable workpiece structure design can also cause bubbles in electrophoretic coating. For example, dead corners or grooves in the workpiece can easily accumulate gas, forming bubbles during the electrophoretic process. Therefore, the impact of the workpiece structure on electrophoretic painting should be considered during the design phase, and design factors that may cause bubbles should be minimized.

　　In summary, the causes of bubbles in electrophoreticcoating are varied, including improper pre-treatment, improper control of electrophoretic bath parameters, unreasonable control of the electrophoretic process, problems in the drying process, and unreasonable workpiece structure design. To effectively prevent bubbles in electrophoretic coating, it is necessary to start from the source, strictly control the quality of each link, and ensure the stability of the electrophoretic painting process and the quality of the coating. With the continuous advancement of technology and the continuous improvement of processes, it is believed that the issue of bubbles in electrophoretic coating will be more effectively resolved.