Causes and Solutions for Aluminum Profiles That Cannot Be Colored During Processing

Process Control

Due to the most significant characteristic of 6082 aluminum alloy being its content of refractory metal Mn, the appropriate presence of Mn can easily lead to intra-granular segregation and reduced solid-liquid region plasticity, resulting in insufficient crack resistance. Therefore, the casting process mainly needs to focus on three points: First, during melting, attention should be paid to controlling the temperature between 740~760℃ and stirring evenly to ensure complete melting of the metal, accurate temperature, and uniform composition. Second, during casting, consideration should be given to the fact that Mn increases the alloy’s viscosity, reducing its fluidity and affecting the alloy’s casting performance. The casting speed should be appropriately reduced and controlled within the range of 80~100 mm/min. Third, increase the cooling intensity and accelerate the cooling speed for the aluminum profile to help eliminate intra-granular segregation. Control the primary cooling intensity and increase the secondary cooling intensity to reduce stress concentration during casting and avoid casting billet crack defects. The cooling water pressure should be controlled within the range of 0.1~0.3 MPa.

Causes and solutions for aluminum profiles not being able to be dyed:

1. The thickness of the anodized film is insufficient. The solution is to check whether the anodizing process is standard, and see if factors such as temperature, voltage, and conductivity are stable. If there are abnormalities, make the necessary adjustments to standardize them. If there are no abnormalities, the oxidation time can be appropriately extended to ensure the film reaches the required thickness.

2. The pH value of the dye solution is too high. In this case, use acetic acid ice to adjust the pH to the standard value.

3. The workpiece is left in the water tank for too long after oxidation. It is recommended to dye promptly. If this situation has already occurred, the workpiece can be briefly activated in the anodizing tank or nitric acid neutralization tank before dyeing, which will yield good results.

4. Improper selection of dye. The appropriate dye should be chosen.

5. The dye has decomposed or become moldy. In this case, the dye needs to be replaced.

6. The oxidation temperature is too low, resulting in a dense film. The oxidation temperature can be appropriately raised.

7. Poor conductivity. This may be due to poor contact of the anodizing copper rod or the cathode lead plate, resulting in poor conductivity. Pay attention to cleaning the anodizing copper rod and the cathode lead plate to ensure good conductivity.

Because the molds for radiator profiles consist of many thin teeth and must withstand very high extrusion pressure, each tooth needs to have high strength and toughness. If there is a significant difference in performance between them, the teeth with lower strength or toughness are prone to breakage. Therefore, the quality of the mold steel must be reliable. It is best to use H13 steel produced by a reputable manufacturer or high-quality imported steel. The heat treatment of the mold is extremely important; vacuum heating and quenching should be used, and high-pressure pure nitrogen quenching is preferable to ensure that all parts of the mold have uniform properties after quenching. After quenching, three tempering processes should be carried out to ensure that the mold hardness is maintained at HRC48–52 while providing sufficient toughness. This is an important condition to prevent mold teeth from breaking.