Subject: Re: Dimensional changes from anodizing

From: [email-masked] (Gaffer2)
Date: 14 Dec 1994 20:20:05 -0500

In article <[email-masked]>, [email-masked] (David Kucharczyk)
writes:

I have found an increase of .00003-.00005 on O.D. surfaces. Not really
much to worry about there. As far as threads go, it will increase a little
more in the root of the thread but less than .0001"

[email-masked]

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From: [email-masked] (Steve Walcher)
Date: Sat, 17 Dec 1994 20:36:08 GMT

In article <[email-masked]>, David Kucharczyk <[email-masked]> wrote:
>
>Does anodizing aluminum increase the size of the part being anodized ?
>If so by how much ?  Do I need to cover any precision areas such as 
>threads and holes that take press fit bushings ?

Generally 1/2 of the anodize will penetrate the aluminum and 1/2 will build
up.  Coating thicknesses can vary significantly, anywhere from
.00007"-.002"  (.000035-.001 buildup per surface).  Be sure to specify a
thickness and be sure your finisher knows their process.  In some situations
you can specify "no dimensional change" and the finisher will etch away
enough of the aluminum prior to anodizing.
If you have some really tight dimensions you may want to have them masked or
plan to hone or gring them to finished size after anodize.