Guidelines for avoiding pits when anodizing aluminum profiles

Anodizing of aluminum alloy is a common surface treatment process, which forms a dense alumina film on the surface of aluminum alloy by electrolytic oxidation to improve its corrosion resistance, wear resistance and aesthetics. However, in the process of anodizing, if the operation is improper, it is easy to have some problems, resulting in unstable product quality. Here are some common problems and how to avoid them:

1) White spots, exposed white ‌ : this may be due to washing is not clean, washing water is too dirty, oxide film is polluted, there are insoluble impurities in the dye solution and other reasons. Solutions include strengthening water washing, replacing water washing, strengthening protection to avoid touching the workpiece, filtering or changing the dye solution ‌.

2) potholes and bubbles: This is one of the most common problems in the anodizing of aluminum alloys. The appearance of holes and bubbles is mainly due to the oil, water or other impurities on the surface of the aluminum alloy is not thoroughly cleaned. The key to solving this problem lies in pre-processing. To ensure that the surface of the aluminum alloy is thoroughly clean, you can use degreasing, alkali washing, pickling and other cleaning processes to completely remove the grease and impurities on the surface.

3) insufficient film thickness ‌ : this may be due to the anodizing process is not standardized, such as temperature, voltage, conduction and other factors are unstable, resulting in insufficient film thickness. The solution includes checking and adjusting the anodic oxidation process parameters to ensure the stability of temperature, voltage, conductivity and other factors. If necessary, the oxidation time can be extended appropriately to ensure the film thickness meets the standard ‌.

4) Uneven film layer: The anodized film layer is uneven, possibly because the current distribution is uneven or the distance between the anode and cathode is not appropriate. In order to avoid this problem, it is necessary to ensure that the current distribution in the electrolyzer is uniform, adjust the distance between the anode and the cathode, ensure that the contact of the aluminum parts is good, and avoid the uneven current distribution caused by poor local contact.

5) The film is easy to fall off: if the film layer after anodizing aluminum alloy is easy to fall off, it may be because the surface of aluminum contains more impurity elements, or the process parameters of anodizing (such as the composition of the electrolyte, temperature, voltage, etc.) are not suitable. The methods to improve the adhesion of the film include optimizing the composition of the aluminum alloy, adjusting the process parameters of anodizing, and proper surface pretreatment of the aluminum alloy before anodizing.

6) Color inconsistency: When performing color anodizing, color inconsistency is a common problem. This may be caused by uneven aluminum alloy material, unstable control of anodizing process parameters (such as temperature, voltage, time), or improper control of dye concentration, temperature and time in the dyeing process. In order to avoid this problem, it is necessary to control the quality of aluminum from the source, while strictly controlling the process parameters of anodizing and dyeing.

7) dyeing flowers, escape color ‌ : may be due to the low pH value of the dye, cleaning is not clean, the dye is not completely dissolved and other reasons caused. Solutions include adjusting the pH value of the dye solution, strengthening washing, and ensuring that the dye is completely dissolved ‌.

8) Electrolyte pollution: electrolyte pollution will also affect the quality of the anodic oxide film. With the increase of use time, various impurities will accumulate in the electrolyte, including metal ions, organic matter, etc., which will affect the growth of the film layer. Therefore, it is necessary to replace or filter the electrolyte regularly to keep it clean.

All in all, there are various quality problems in the aluminum oxidation process. To solve these problems, we need to start with material selection, surface pretreatment, process parameter control, electrolyte management and other aspects, and carefully control each link to ensure the quality of the final product ‌.