How to prevent dents in extruded aluminum alloy

Pits are defects on the surface of extruded aluminum profiles that result in point or strip like peeling. White dots or stripes can be clearly observed through corrosion, and at the microscopic level, defects may also be filled by deposition. The segregation of oxides, Al Fe or Al Fe Si compounds in aluminum alloy ingots is caused by uneven surface coating and unstable flow on the surface of the sizing strip during extrusion. Methods for eliminating dents:

1. Replace the filter for molten metal with fine mesh.

2. Reduce the iron content of the cast billet.

3. Cutting the surface of the ingot.

4. Perform sufficient homogenization treatment.

5. When squeezing, the surface of the sizing belt should be slightly angled to make it easier for the worn coating of the sizing belt to be carried out.

6. Polish the surface of the sizing belt.

7. Increase the compression surplus.

8. Reduce the extrusion speed.

9. To prevent oxidation of the surface layer of the sizing belt, nitrogen gas is sprayed.

10. Cooling aluminum alloy molds.