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MIL-C5541-Class 3 Question

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Q. Hello ,
our customer stated the surface treatment as followed on the drawing:

MIL-C-5541 [affil. link or DLA], Class 3 - passivation with surtec 650
black anodized

The parts are almost completely black anodized and only some areas are masked for electrical contact.

FAIR = First article inspection report

As we have to do a FAIR 9102 (AS 9102 [affil. link]) my question is if the above mentioned MIL is sufficient to specify the treatments.

For my understanding the parts will be chromated and than masked and black anodized to get the final result.

For black anodizing MIL-A-8625 [affil. link or DLA], Type II, Class 2, black is normally used do we have to add this to the drawing or is 5541 sufficient?

Thanks for your help.

Xzibi Hatle
- Hamburg Germany
December 19, 2022

A. Hi Xzibi,
Chromate conversion coating and anodizing are totally separate processes; so, while specifying MIL-C-5541 gives a standard to follow for the chromate conversion coating, it says nothing about the anodizing. I think you most definitely must add "per Mil-A-8625 Type II, Class 2" after "Black anodized".

I have no experience with FAIR but am under the impression that it requires quite a bit of detail in the sequence of operations.
Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Q. Hi Ted,
thanks for your feedback, much appreciated . From my research I found that also the MIL-C-5541 is now MIL-DTL-5541 as the customer wants Surtec 650 I guess we should also refer to the newest norm?

Xzibi Hatle
- Hamburg Germany
December 20, 2022

A. Hi again. I have no experience with FAIR and can't advise exactly what should go on the forms, but you don't want to change them unnecessarily. So, you probably should start with MIL-DTL-5541 [affil. link or DLA] rather than an outdated spec.

Surtec 650 is a proprietary rather than a generic process, but a customer can certainly specify a proprietary if they wish.
Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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