Letter 28044

Coating process for corrosion-free fasteners  

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Dear sir,

We are manufacturing Ground Power Equipments for all kinds of Aircrafts. We are facing a lot of problems particularly with all kinds of fasteners we use. Currently we are using green passivation for hex head fasteners. I request you to suggest me to choose what kind of coating should be used to get 100% corrosion free with relevent growth thickness.

S.Manickaraj
electronic manufacturer - Coimbatore, Tamilnadu, India

No coating process will deliver 100 percent corrosion-free fasteners, but I suspect you already actually know that. The zinc plating with olive drab passivation that I assume you are using is already a pretty good finish. It can be improved by switching to an alloy zinc plating like zinc-nickel or zinc-cobalt, but what wasn't clear to me was whether the fasteners corrode before they are installed or after. If after, the first question is what are you joining together--because you may be encountering galvanic corrosion.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

Dear Sir,

The most cost effective solution for you will be to zinc iron or zinc cobalt plate your fasteners as Mr TM has suggested above. We can do this for you; we have probably the largest alloy plating facility nerby you for this kind of work.

Regards

Khozema Vahanwala Saify Ind   Bangalore, Karnataka, India

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