Why cadmium plated bolts

But the most common case is that some of these properties of cadmium are important, and that's where we get into picking the ideal substitute to match the important properties for the particular situation in most cases it's a plating of a zinc alloy like tin-zinc or zinc-nickel.

High-strength fasteners should be baked for hydrogen relief, and if done properly, embrittlement issues are minimized, especially if a "porous" cadmium electroplating process has been used that allows hydrogen de-embrittlement procedures to work well check into LHE cadmium plating, and TiCad.

Hot dip galvanized coatings are, as mentioned, much thicker than electroplating, so it is necessary to use special threading allowances so the nuts and bolts don't jam. One such approach involves not galvanizing the threads of nuts usually by cutting the thread after galvanizing rather than before.

Good luck. The advantages are: better uniformity of the layer important to get a good thread , no hydrogen in the process no hydrogen embrittlement , very environment friendly process, very good corrosion resistance. Gentle readers: While proprietary processes may include improvements, please see letter where a discussion of generic Sherardizing is pursued.

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Also, while I don't like to be argumentative, claims that new processes gives better corrosion resistance than hot dip galvanizing must always be taken with a grain of salt because hot dip galvanized parts have survived years and we obviously have no real-world experience even approaching that with new processes.

And accelerated corrosion testing is notoriously non-representative of actual service life for zinc coated parts because in the "real world" a glassy protective zinc carbonate surface grows over the years from a reaction with the small amount of carbon dioxide in the atmosphere, and offers outstanding corrosion resistance, but accelerated tests must pretend this doesn't happen and just see how fast they can dissolve zinc. I need information; I need hex bolts hot-dip galvanized.

Hi, Agustini. The hot-dipping process usually involves cleaning, fluxing, immersion in molten zinc, and a chromate final rinse. Processing of bolts will probably involve a spinning step to help keep the threads clear of zinc bridging.

Lubricity This coating can effectively improve the lubricity and this is why it is recommended that people looking for eye bolt anchor can go for the one with this type of coating. This can be the ideal choice for moving parts of machines, which in turn work towards prevention of galling and it will also bring down friction, which will be of high importance in the functioning of machinery, where metal surfaces commonly touch each other.

Dacromet Dacromet Geomet Geomet Geomet SermaGard SermaGard Log in or Sign up. Pilots of America. Why cadmium plated bolts rather than stainless steel? I wonder why there is the widespread use of cadmium plated steel fasteners, rather than stainless? Cad plated stuff doesn't last for ever, but stainless does unless it's crap stainless. And the pricing seems comparable.

Cadmium has been outlawed in most applications outside aviation and military, so all the parts are pricey. I know stainless on stainless can over many years weld together so it is claimed though this seems to have been solved with current alloys, and stainless nuts and bolts are in widespread use outside aviation.

Henning , Apr 16, Can Duralac be used between a bolt and a nutplate?? Tom-D , Apr 16, Last edited: Apr 16, Dan Thomas , Apr 16, Geoffrey Thorpe , Apr 16, Generally, the more "stainless" the alloy, the crappier it is for durability, tensile strength, fatigue resistance, and machinability.

The only good thing about stainless is that it doesn't rust. With such high pressure to optimize strength and weight in aircraft, it's no wonder that Cad-plated steel is a popular choice. Tom-D , Apr 17, I am still looking for a reason why SS is not used in the myriad places on an airplane where the tensile or shear strength is very obviously not an issue by several orders of magnitude and where cadmium plated screws corrode quite happily after a few years. Henning , Apr 17, Last edited: Apr 17, Dan Thomas , Apr 17, Geoffrey Thorpe , Apr 17,