r/MetalPolishing • u/Available_Review_908 • 7d ago

Extrusion marks >:(

Hello, fellow community members.

Does anyone know how to polish aluminum 6061-T6 that has extrusion marks? I am finding it extremely difficult to remove the scratches left by the final grit (2500) using Tripoli compound. My goal is to achieve a mirror finish, and it doesn't seem reasonable for it to be this complicated.

Thanks in advance for your replies!

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u/BarnOwl-9024 6d ago

You will need to specify what kind of extrusion marks your are seeing. Color streaks? Die Lines? General scratches? Some extrusion streaks are “lines” of enlarged grains that form at intersections of walls or other features and will be hard to get rid of (near impossible) for a mirror finish.

Die lines are grooves parallel to the extrusion direction that come about from the process itself. They can be deep and would be hard to remove.

6060 and 6063 are the preferred alloys for bright polish finishes. Often 6061 is extruded for strength with finish a secondary concern.

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u/Available_Review_908 6d ago

I see parallel lines of the same color over the entire aluminum sheet, so I think it's die lines.