Anodizing dimensional changes?

[desert_roamer]

If anodizing grows a thickness of say 0.001 does that mean 0.001 is added to the dimension of the part or is some of that anodizing layer grown under the original machined dimension?

Thanks.

[mcaswell]

Re: Anodizing dimensional changes?

It's added on top of the aluminum.

[PRD#5]

Re: Anodizing dimensional changes?

Actually, it's 1/2 build-up, 1/2 penetration.
Example: .001 plating thickness adds .0005 to the surface. It would add .0005 to each side of a hole making it .001 smaller. On threads it's 4:1 due to the thread angle. So, .001 thickness would yeild .0005 per surface x 4 = .002 on diameter.

Hope this helps,
Don

[desert_roamer]

Re: Re: Anodizing dimensional changes?

PRD#5 wrote:
Actually, it's 1/2 build-up, 1/2 penetration.
Example: .001 plating thickness adds .0005 to the surface. It would add .0005 to each side of a hole making it .001 smaller. On threads it's 4:1 due to the thread angle. So, .001 thickness would yeild .0005 per surface x 4 = .002 on diameter.

Hope this helps,
Don

Thanks, it does. I was trying to figure out if I need to ream close fit holes over size prior to anodizing. I decided to go 0.001 O/S and will try to get a 0.001 anodize thickness.