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plating, anodizing, & finishing Q&As since 1989




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What type of sealant will maintain maximum hardness of hard anodize?

June 14, 2010

I have a spindle shaft that requires hard anodize coat, MIL 8625, type III, I am asking for .002" thickness, buildup & penetration, and I need to have a smooth enough surface to allow me to align my other parts within .000050" or better. I would like to have the surfaces sealed, but I still wish to have the maximum hardness possible after sealing. Is there a sealing method available that will preserve the hardness more than the normal sealing methods?

Douglas Page
product designer - Morgan Hill, California

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First of two simultaneous responses -- June 15, 2010

Wow! Most people cannot repeatedly measure a half of a tenth, let alone maintain that as a tolerance of two mating parts. You must have some of the top thousandths of one percent of certified assembly personnel.
You will have to hone the parts to get that level of measurement. There is no plating or anodizing that will come close without post treatment machining.

James Watts
- Navarre, Florida

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Second of two simultaneous responses -- June 15, 2010

Douglas

For what purpose do you wish to seal the anodize?

Willie Alexander
- Colorado Springs, Colorado

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June 16, 2010

Hydrated Aluminum Oxide IS softer than plain aluminum oxide. Do note seal. Maybe use a light oil.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina