For parts such as screw holes that cannot be repaired by mechanical methods, they must be protected before hard oxidation to avoid waste due to inability to assemble.
For the parts with uniformity and smoothness requirements, it needs to be ground afterwards, and the loss of this size should also be known in advance. When the thickness of the hard anodized film is required to be 100 μm, the actual size of one side of the part is equivalent to an increase of about 50 μm.
However, with the difference in the purity of the material itself and the difference in the process conditions, the actual thickening value to obtain reliable data size will also be different. If necessary, it needs to be tested, and then the tolerance matching allowance is determined.
How to prevent corner effect during anodizing? Because the film at the corners cannot grow three-dimensionally, the thicker the film, the more serious it is. For this reason, the corner radius of the thick anodized film should be larger. In the initial stage of pure aluminum film formation, there is no color. When the thickness of the film layer gradually increases, the color of the surface of the workpiece will gradually change from colorless to light brown to brown.