2020-12-22
| Anodized aluminum dyed black 1. Design of fixtures and characteristics of making fixtures 1. The fixture used for anodizing is completely different from the hanger used for electroplating. It is not suitable to use a hanger similar to the hook used for electroplating as the anodizing fixture, because the fixture and workpiece surface will quickly become oxidized during anodizing. In this process, a slight looseness of the clamp and the workpiece will change the contact position and block the flow of current. For this reason, a flexible clamp must be used to clamp the workpiece. Only in this way can the anodizing process proceed normally. 2. The fixture structure is suitable for individual type. If the assembled type is used, the riveted or welded part will loosen due to corrosion after several times of use, which will hinder the normal flow of current during the anodizing process. At the same time, the fixture must have a certain cross-sectional area. A fixture with a certain cross-section has sufficient elasticity and clamping force to keep the workpiece in good contact with the fixture, and to ensure the normal flow of current required when the clamped workpiece is anodized. Avoid burning the workpiece due to heat generated by poor contact. 3. It is better to choose hard aluminum for making fixtures. Hard aluminum has good elasticity and is fastened and durable. 2. Workpiece clamping 1. The fixture will also produce an oxide film during the anodizing process. For this reason, the oxide film must be removed before using the used fixture again. The film removal can be carried out in the degreasing solution of aluminum. The oxide film on the contact part of the fixture and the workpiece can also be filed with a file. This method can also extend the service life of the fixture for some fixtures. 2. The position of the workpiece should be selected properly, generally it should be installed on the secondary surface of the workpiece (that is, the non-decorative part). Otherwise, the contact part of the workpiece and the fixture will not be able to form an oxide film because it is covered by the fixture, and of course it will not be dyed. There will be obvious white spots, which will affect the appearance quality. In addition, after the workpiece is clamped, whether the recessed part suspended in the solution will generate air pockets should also be considered. 3. The clamp is not the same as the hanger, and the clamp has a certain degree of flexibility. Particular attention should be paid when clamping deformed workpieces, and excessive force should be avoided to cause deformation of the workpiece. 4. When the workpiece is clamped too loosely, the current between the fixture and the workpiece will be on and off from time to time. In this case, it is likely to burn the workpiece. 5. Some units use screen cloth to wrap some small pieces or use other methods to perform anodizing treatment. Although this method can save man-hours and improve efficiency in certain occasions, it can only be used for some natural anodizing with low quality requirements. Even if a small number of workpieces cannot form oxide films at the mutual covering parts, it is not easy to be identified. But for the workpiece that needs to be dyed black, it is obviously not advisable to use this clamping method. It must be clamped one by one to ensure the quality of anodizing. |
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