Hard anodizing process requirements

In order to obtain a good quality hard anodized film and ensure the required standards of the parts, it must be processed according to the following requirements.

The machined parts are not allowed to have sharp angles, burrs and other sharp edges and corners, due to hard oxidation, the general anodic oxidation time is very long, and the oxidation process (A1 O2 → A12O3 Q) itself is an exothermic reaction. In addition, because the edges and corners of general parts are often the parts where the current meets, these parts are most likely to cause part of the parts to overheat and cause the parts to be burned. Therefore, all edges and corners of aluminum and aluminum alloy should be chamfered, and the radius of the chamfer y circle should not be less than 0.5 mm.

After hard anodizing, the brightness of the surface of the part is changed, for the rougher surface, after this treatment can appear flatter than the original, and for the parts with higher original brightness, often after this treatment, the brightness of the flashing surface has decreased, and the fluctuation of the decline is about 1~2 levels.

Due to the high thickness of the hard oxide film, if the aluminum parts that need to be further processed or the parts that need to be installed in the future, a certain machining allowance should be left in advance and the clamping part should be specified.

Because the standard of the parts should be changed during hard anodizing, it is necessary to guess the possible thickness and standard tolerance of the oxide film in advance during machining, and then determine the practical standard of the parts before anodizing, so that after processing, it can meet the specified tolerance planning.
Generally speaking, the standard for adding parts is roughly about half the thickness of the oxide film generated.

In the process of oxidation, the parts due to hard anodizing must withstand high voltage and high current, and the fixture and parts must adhere to the excellent contact, otherwise the defect of breakdown or burn the contact part of the parts will be formed due to poor contact. Therefore, it is required to plan and manufacture special fixtures for different shapes of parts, as well as the specific requirements of parts after oxidation.

For example, on the same part, there are both general anodizing and hard anodizing parts, because the specific process is arranged according to the brightness and precision of the part. Generally, the first thing to do is to carry out general anodizing, in the hard anodizing, the surface that does not need to be insulated by hard anodizing, the insulation method is with a spray gun or brush, and the nitro glue or perhydroethylene glue will be coated on the surface that does not need to be treated, and the insulation layer should be coated thin and uniform, and each layer should be monotonous at low temperature for 30~60 minutes, and a total of 2~4 layers can be coated.