Analysis Of Common Problems In Anodizing Aluminum Profiles

When anodizing aluminum profiles, the surface pretreatment process must be carried out first, that is, the method of water washing to remove the dust and oil stains on the surface; Or a mirrored or matte surface can be obtained by mechanical means. If the surface pretreatment is not thorough, the original oxide film on the substrate surface can not be removed clean, it is difficult to generate an artificial oxide film, and it is impossible to obtain a uniform color.

After some aluminum products are anodized, the surface will appear with black spots, stripes, or holes, and some even have no oxide film, causing these phenomena for the following reasons:

① The alloy composition of the aluminum profile is related: aluminum magnesium alloy or pure aluminum is easy to generate a good quality oxide film, aluminum silicon alloy or aluminum copper alloy, the difficulty of oxide film generation is slightly greater, and the oxide film color is black and dark, affecting the appearance.

(2) The uniformity of the organization and phase is related: if the metal phase produced on the surface is not uniform or the organization is not uniform, it will lead to an uneven oxide film, if the uneven silicon content in the aluminum alloy causes a local non-oxidation phenomenon, and even pores.

③ Metal ions in the electrolyte: if the content of impurity ions such as iron and copper in the electrolyte is too high, there will be black spots.

④ The suspended impurities in the electrolyte: if the dust and debris in the electrolyte are suspended too much, it will cause the oxide film to appear in streaks, reduce the corrosion resistance of aluminum profiles, and affect the use effect.

Because the resistance of the anodic gas oxide film is relatively large, in the process of anodic oxidation will produce a lot of heat, the higher the voltage in the tank the greater the heat generated, must use stirring or cooling device to keep the temperature of the electrolyte at 13-26 ° C, if more than 30 ° C, the oxide film will appear loose powder easy to fall off the phenomenon, and even the phenomenon of burning. Seriously affect the quality of the oxide film, especially in the summer when the temperature is higher, it is necessary to take measures after more than 2 slots, otherwise the produced aluminum profile will not have the function of anti-corrosion.

Because the aluminum oxide film is insulated, to ensure its conductivity, it is necessary to use a conductive rod of copper or copper alloy to hang the aluminum profile on the fixture, control the contact area between the fixture and the profile, the contact area is too large, the contact impression between the fixture and the profile is larger, which is easy to cause residual oxide film accumulation to form an uneven oxide film; The contact area is too small, the density of the current increases, and it is easy to burn the oxygen fixture and the oxide film, forming a bad oxide film, which affects the effect of anodizing aluminum profiles.