How to prevent oxide streaks

Oxide streaks are non-metallic inclusions inside the ingot that flow into the surface of the extruded part parallel to the extrusion direction, forming defects. During the aluminum alloy extrusion process, it is difficult to distinguish solely based on the poor gloss of the extruded parts. After corrosion or anodizing treatment on the surface of aluminum alloy, it is easy to identify the defective parts as they do not form an oxide film. Mainly due to non-metallic inclusions in the residual metal on the surface of the ingot and inside the extrusion tube, which flow into the extruded part.

Methods for eliminating oxide streaks:

1. The temperature of the extrusion tube is lower than the temperature of the ingot.

2. Leave sufficient extrusion residue (compression residue).

3. Avoid excessive lubrication.

4. Align the center of the extrusion tube, ingot, and mold with the center of the extrusion shaft.

5. Cutting the surface of the ingot.

6. When designing aluminum profile molds, place the position of the mold hole at the center.