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Anodizing Removal by Bead Blast?
Q. I am working on the EMI signature of a released product. I have been given a product straight off the manufacturing line and wish to remove the anodizing in a key location to improve the grounding and bonding between parts. Any suggestions regarding this?
I know I can strip the anodizing chemically but that is not a very exacting method. It tends to bleed or splash and otherwise gets messy. Can I soda blast the anodizing off after masking the parts? Or does it require a full bead blast?
Thanks for all help.
Mechanical Engineer - San Jose, California, USA
August 20, 2012
A. Hi,
To remove local areas of anodise it is often best to use wet/dry paper about 400 grit and elbow grease.
For spot faces make up a tool (turned bar with dia. to go into hole and shoulder right dia. for spot face) to hold a disk to get a nice result, for squares use a mask like PVC or lead tape to help prevent the wrong areas getting stripped.
My feeling on sodium carbonate is that it will be too soft, alumina will cut type 1 anodize (chromic) but will struggle with type 2 (sulfuric).
The another option requiring an amount of artistic flair is to dam the areas with a modeling clay and pipette
[pipettes on
eBay or
Amazon]
a cold strip in (take care with this chemistry). The flair comes in getting the chemistry back out (have a wash bottle handy is the secret for hitting any drips and flushing well).
Also the flair is getting the dam to hold - if it leaks have the wash bottle ready to flush the area to prevent damage.
Hope this helps.
Martin Trigg-Hogarth
surface treatment shop - Stroud, Glos, England
November 9, 2012
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