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Aluminum alloy common dyeing problems and solutions

A&L Aluminum Co., Ltd. is a professional aluminium extrusion manufacturers.


Can’t dyeing

1. Anodized film thickness is insufficient. The solution is to check whether the anodizing process is normal and whether the temperature, voltage, conductivity, etc. are stable. If there is any abnormality, please adjust the specifications accordingly. If there is no abnormality, the oxidation time can be appropriately extended to ensure that the film thickness reaches the standard.
2. The pH of the dyeing solution is too high. At this time, the glacial acetic acid can be used to adjust the pH value to the specified value.
3. After oxidation, the workpiece is left in the sink for too long. Advocate timely dyeing. If this happens, the workpiece can be placed in an anodic oxidation tank or in a nitric acid neutralization tank for appropriate activation and then dyed. The result will be very good.
4. Improper dye selection. Need to use the right dye.
5. The dye has been decomposed or mildewed and dyes need to be changed.
6. The low oxidation temperature leads to a dense film. The oxidation temperature can be appropriately increased.
7. Poor conductivity. Poor contact of the anode copper rod or cathode lead sheet may indicate poor batch conductivity. Pay attention to cleaning anode copper rod and cathode lead plate to ensure good contact.


White point


1. Washing is not clean, should be enhanced washing.
2. The water used for washing is too dirty and easy to contaminate the membrane. At this time, the water should be changed to ensure the quality of washing.
3. The oxide film is contaminated by soot, acid and alkaline mist in the air. Strengthen washing, timely dyeing, timely transfer can greatly reduce this symptom.
4. The oxide film is contaminated by oil and sweat. The protection must be strengthened and the appearance of the workpiece must not be touched by hand
5. The dye solution contains insoluble impurities, which is contaminated by oil and destroys normal dyeing. At this time, the dye solution should be filtered or replaced.
6. Workpiece crevices, residual acid outflow in deep holes, water wash for this type of work piece.
7. The dye solution is contaminated with Cl-, resulting in spot corrosion of the dyed workpiece. At this time, the dye must be replaced, and care should be taken to avoid introduction of impurity ions during the operation.



 Light color, color difference

1. Uneven film thickness. The probable reason is that the temperature and concentration of the anodizing bath are not uniform, and it is necessary to stir the compressed air in the bath to solve these problems.
2. Dye fluid temperature or concentration is not uniform. Introducing stirring process.
3. Dyeing speed is too fast. The bottom of the workpiece first enters into the dye solution and finally leaves the dye solution, so the bottom is most easily dyed dark. The solution is to dilute the dye and extend the dyeing time appropriately.
4. Poor conductivity. May cause loose racking. Pay attention to tightness to avoid such problems.
5. Dye is too thin, dye can be added to increase the concentration.
6. Dye temperature is too low. Can be heated to below 60°C.
7. Improper dissolving of the dye, or floating of insoluble dyes, is easy to produce color difference. The solution is to improve the dye dissolution.


Dyed escape

1. The dye solution has a low pH, which can be transferred to the standard value with dilute ammonia.
2. Cleaning is not clean. Should strengthen the washing.
3. Incomplete dissolution of dye, enhanced dissolution to complete dissolution.
4. Dyeing fluid temperature is too high, reduce the temperature.
5. Oxide film has small pores because the oxidation temperature is too low and the film is inhibited from being dissolved by sulfuric acid. The oxidation temperature can be appropriately adjusted to avoid this problem.
6. Dyeing is too fast, and the dyeing time is too short. Dilute solution can be adjusted to reduce the dyeing temperature and extend the dyeing time.
7. Sealing hole temperature is too low, heating solution.
8. Sealing solution pH is too low, use dilute ammonia to increase the specification value.
9. The stained surface is easy to wipe off. The main reason is that the film is rough, usually caused by too high oxidation temperature. Care should be taken to control the oxidation temperature within the specification.