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"Black oxide over cad plated NAS6604 fasteners?"March 12, 2021
Q. Hello, we have an assembly specifying NAS6604 cad plated bolts, which must be painted black before assembly and handled with kid gloves. I'd prefer to have them black oxided if possible - does anyone know if this could possibly void the NAS6604 spec?
- Orefield Pennsylvania
A. Hi Jim. hopefully someone who knows more about NAS bolts will chime in, but my understanding is that NAS6604 refers to a certain style of bolt in a 1/4" diameter size, and that this will be followed by a dash and another number indicating the bolt length. When no other letters are appended, cadmium plating is implied.
So I don't think the black paint is part of the NAS spec, but a requirement added by the buyer for the particular situation. Therefore I think the buyer would have to tell you whether a black oxide process on the cadmium plating would meet their needs or not. EPI (Electrochemical Products Inc.) [a finishing.com supporting advertiser] offers black oxide processes specifically for cadmium.
Luck & Regards,
Ted Mooney, P.E. RET
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