Cadmium plating

[Mike Cordeiro]

I need to have some bolts and nuts re-plated but the last time I had it done the bolts wouldn`t turn into the nuts and landed up having to buy the whole lot new. I thing the coating somehow was to thick.

Does anyone know of a RELIABLE Cadmium plating bussiness in the JHB area?

Regards
Mike

[MADDOG]

Be very careful when plating HT bolts. I would recommend you buy ready plated bolts and insist that they have been through a de-embrittalment process. Plating HT bolt leads to hydrogen embrittalment and unless treated will lead to failure.

Rather pay a bit more for the right part now than be sorry later.

[ZULU1]

I had already sent Mike a PM "urgently" advising him of same, however whilst on the subject of stressed components, it may be an idea to advise "readers" of the dangers of using stainless steel as well as the types of HT bolts and fasteners available. Always replace with the manufacturers spec bolt and never, ever, ever, re- plate anything. In fact plating in the first place is also bad news !! With the exception of Mild steel which is not unlike cheese ! it matters not cos it normally holds up garden fences !!

A fastener marked 8,8 is 80% yield 80 tonne material for example, 10,9 12.9 and so on for other grades. 12,9 is actually a socket screw type grade and may not be suitable for trike wings. So please tread very, very carefully in this subject.

A bolt marked A2 and A4 are stainless 304 and 316... use them on yachts and vintage cars...trust me they crack and are totally useless for any stressed environment. They look pretty and thats about it ! I am scared of them.

This area of aircraft maintenence actually really concerns me because of the lack of "innocent ignorance" with possible usage resulting in airframe failure.

My advice is to actually pay the price and purchase from the OEM. This is a subject that should be covered on the annual inspection. How many Aps know the fundamentals of metallurgy ?

Some of us as "doff enjinears" studied this subject for years and trust me it gets much worse when you play with Aluminium !!


Hope this helps a bit and well done Maddog.

eish Zulu1