Material streaks in anodizing? Here comes the remedy!

Aluminum alloy products appear after anodizing material lines, which is a headache for many businesses. When doing oxidation, the material of the product is separate from the oxidation manufacturer, which means that there will inevitably be a dilemma between the material supplier and the oxidation manufacturer.

First of all, what is the material grain? How is it produced?

After the general aluminum alloy products are anodized by sulfuric acid, a uniform AL2O3 oxide film can be generated on the outer surface, but for some large aluminum alloy parts, especially alloys with higher Cu content, black spots or stripes will appear after anodizing.

metallographic structure

Because an extruded profile or stretched aluminum alloy product, the suture line or some specific parts of the product in the process, due to high temperature extrusion, make it locally produced peroxide, that is, the metallographic structure has changed, followed by the formation of a relatively thick oxide film in some suture parts, when the whole product is anodized again, It is necessary to remove the naturally generated oxide film, but due to the formation of a thicker oxide film or changes in the metallographic structure, the removal work cannot be completely removed at this time.

The results of comprehensive analysis of aluminum alloy phases show that elements Si, Mg, Fe, Cu and Ni are always one of the components of intermetallic compounds, and the influence of these elements on the shape and color of the formation of intermetallic compounds can usually be determined. For example:

The presence of magnesium causes the compound to be branched in shape and pale in color (AL8Mg5 phase, S equal).

Iron makes the compound elongate into a needle shape, and the color becomes bright gray (AL3Fe phase, T2 phase, N is equal);

Copper makes the compound dense and pale in color (AL2Cu phase, S equal),

The effects of manganese are unique. The manganese-containing compounds are thick and dense, sometimes with a typically intricate shape, and have their characteristic light brown color (AL8MnFe phase, ALFeSiMn equal).

Because the material composition of the product is not the same in the suture part, when it is oxidized again, the oxide film generated in this part is different from the other parts, and after the complete oxidation process, a gray grain will appear in the suture part. Such lines cannot be removed by polishing or grinding.

How to remedy material marks?

1.The simplest and most effective way: find the material supplier to replace the mold, so as to make up for some of the damage on the mold.At present, most of the domestic 6063 grade industrial aluminum profiles adopt the way of forward extrusion, and aluminum products are easy to make the mold sticky aluminum when they pass through the mold under high temperature and pressure. Resulting in the aluminum profile sticking tear tear.

2.When the number of products is too small, you can reduce the brightness of the product and make the sand surface rough to cover the material as much as possible.General aluminum or shallow or deep grain, for good aluminum, sandblasting can generally cover the grain, the thicker the sand, the greater the sandblasting pressure, the better the hiding effect. However, the process followed by sandblasting is oxidation, and in the process of oxidation testing, the grain will become obvious with the extension of the test time.