Common problems and solutions for aluminum oxidation dyeing
一. Cannot be dyed
1. The thickness of the anodized film is insufficient. The solution is to check whether the anodizing process is standardized and whether the temperature, voltage, conductivity and other factors are stable. If there are any abnormalities, please adjust the specifications accordingly. If there are no abnormalities, the oxidation time can be appropriately extended to ensure that the film thickness reaches the standard.
2. The pH value of the dye solution is too high. At this time, glacial acetic acid can be used to adjust the pH value to the standard value.
3. After oxidation, the workpiece is left in the water tank for too long. Timely dyeing is advocated. If this situation has occurred, the workpiece can be placed in an anodizing tank or a nitric acid neutralization tank for appropriate activation treatment before dyeing. The effect will be very good.
4. Improper selection of dyes. Appropriate dyes need to be selected.
5. The dye has decomposed or become mildewed. At this time, the dye needs to be replaced.
6. The oxidation temperature is too low, resulting in a dense film. The oxidation temperature can be appropriately increased.
7. Poor conductivity. Possibly poor electrical conductivity in the batch indicated by poor contact between the anode copper rod or the cathode lead plate. Pay attention to cleaning the anode copper rod and cathode lead plate to ensure good contact.
二. White spots, dew whiteness
1. Water washing is not clean, so washing should be strengthened.
2. The water used for washing is too dirty and can easily pollute the film. At this time, the water should be replaced to ensure the quality of washing.
3. The oxide film is polluted by smoke, acid and alkali mist in the air. Strengthening washing, timely dyeing and timely transfer can greatly reduce this symptom.
4. The oxide film is contaminated by oil and sweat stains. Protection must be strengthened and the outer surface of the workpiece cannot be touched with hands.
5. There are insoluble impurities in the dye liquor, which are contaminated by oil and destroy normal dyeing. At this time, the dye liquor should be filtered or replaced.
6. Residual acid flows out of gaps and deep holes in the workpiece, and water washing of such workpieces must be strengthened.
7. The dye liquor is contaminated by Cl-, causing pitting corrosion of the dyed workpiece. At this time, the dye must be replaced, and care should be taken to avoid introducing impurity ions during the operation.
三. Light color and color difference
1. Uneven film thickness. The possible reason is that the temperature and concentration of the anodizing bath liquid are uneven. The bath liquid should be stirred with compressed air to greatly solve such problems.
2. Uneven temperature or concentration of dye liquor. Introduce mixing process.
3. The dyeing speed is too fast. The bottom of the workpiece enters the dye solution first and leaves the dye solution last, so the bottom is the most susceptible to deep dyeing. The solution is to dilute the dye and extend the dyeing time appropriately.
4. Poor conductivity. It may be caused by loose hanging tools. Pay attention to hanging tightly to avoid such problems.
5. If the dye is too thin, you can add dye to increase the concentration.
6. The temperature of the dye solution is too low. The dye liquor can be heated to below 60°C.
7. Improper dye dissolution or floating insoluble dye can easily cause color difference. The solution is to improve dye dissolution.
四. Hair dyeing and color escaping
1. The pH value of the dye liquor is on the low side and can be adjusted to the standard value with dilute ammonia water.
2. Not clean. Washing should be strengthened.
3. The dye is not completely dissolved, strengthen the dissolution to achieve complete dissolution.
4. The temperature of the dye liquor is too high, lower the temperature.
5. The pores of the oxide film are small because the oxidation temperature is too low, which inhibits the film from being dissolved by sulfuric acid. The oxidation temperature can be appropriately raised to avoid this problem.
6. The dyeing is too fast and the dyeing time is too short. You can adjust the dilute dye solution, lower the dyeing temperature, and extend the dyeing time appropriately.
7. The sealing temperature is too low, please heat it up to solve the problem.
8. The pH value of the sealing solution is too low. Use dilute ammonia to increase it to the standard value.
9. The dyed surface is easy to wipe off. The main reason is that the film is rough, usually caused by the oxidation temperature being too high. Care should be taken to control the oxidation temperature within the specification range.
