Letter 13031

Amount of per side surface removed by anodizing 

I would like to know if there is a standard surface removal formula for anodizing aluminum 6063 T6. Example of what I'm talking about follows. If I extrude a flat shape 2.000" wide and .125" thick, how thick will the piece be after anodize? Is there an industry standard or is it hit or miss depending upon how long it's left in the acid bath? Can the dimension be controlled?

Example: Can I remove .002 in. per side on 500 parts?

Tim A. Schau
- Portage, MI., USA

You will add rather than remove. Roughly speaking, to build an anodize thickness of .001 consumes .0005 of the aluminum substrate. Some people say .0004 some say .0006, and it might vary based on the alloy--but it's easy to remember half-and-half and you won't be off by much.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

You will build up oxide when anodizing. The ratio is about 50-50 or in other words 1 mil of oxide will increase the dimensions on the surface by .5 mil. The other .5 is desolved from the part. If your dimensions are coming in less that you started with some etching has been done or the oxide has been striped and redone.

Drew Nosti, CEF Ladson, SC

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