The black-grey spots of the extrusion aluminum profile

After the anode oxidation of extrusion aluminum profile, there will be near-circular black-grey silk spots, which are distributed at equal distances on the surface of the profile vertically attached bed, with different sizes.

The main reasons:

Because the air cooling at the outlet of the extruder is not enough, resulting in aluminum profiles in the higher temperature contact with the swing bed, the cooling speed of the contact site is different from other locations, there is a large Mg2Si phase, after anode oxidation treatment, the part becomes black and gray.

Solutions

1. Strengthen the air-cooled strength, avoid the space of the bed profile is too small, to ensure the air-cooled temperature gradient.

2. Conditional factories should adopt the method of combining atomized water-cooled and air-cooled to completely eliminate dark spots.