Aluminum 5083 Anodization

[T105]

Hi,

As far as I know, hard anodizing cannot be perceived as coating. Taking this statement into consideration. I would like to know, from your experiences etc., whether it is expected that the dimensions of an aluminum part change after the anodizing or not.

Although we put the drawing note stating the dimensions apply after treatment. I still want to know if the dimensions and tolerances of the part change after anodizing.

The material is Aluminum 5083 and anodizing is per MIL-A-8625 Type III, Class 1. 0.0015-0.0025 inches thickness.

Best regards

 

[swall]

Yes, dimensions will change. A .001" thick coating will result in part growth of approximately .0005" in each area of the part that is anodized.

 

[israelkk]

Putting the drawing note stating that the dimensions apply after treatment is trying to move the responsibility to the machining house which usually has no control and knowledge on the hard anodizing process. The 0.0015-0.0025 thickness range is quite large. The anodizing process can be controlled with a tolerance of 0.00015" (~0.004 mm). The 0.001" tolerance on the hard anodizing thickness may "eat" the machining tolerance of the part prior to hard anodizing.

What is the pre-anodizing dimension tolerance?

 

[drawoh]

T105,

Dimensions definitely change. In addition to the thickness of the anodic coating, the parts usually are etched. An anodize process can result in a net removable of material.

If your fabricator organizes anodizing, you need to specify tolerances after anodizing. Otherwise, you cannot inspect the parts. Your fabricator can talk with the anodizer about their process.

JHG