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Better Finish for Fasteners

August 31, 2008

We use electro-zinc plated nut, bolts & washers of size M8x35 & M6x25 in our products which are exposed to the open including rain. Hence these get rusted within a couple of months.
I would like to know if there are any alternative finishes available, which would help increase life of these bolts & nuts to at least 5 years.

We have enquired about hot dip galvanised finish but these fasteners are too small to be hot dip galvanised & it is costly too. We have heard of cobalt zinc finish also. It would be nice if you could enlighten me more on this finish too.

Your valuable advice will be highly appreciated.

Aditya V
buyer - Mumbai, Maharashtra, India

Hi, Aditya. Zinc plating is the least expensive finish. So if you are looking for improvement at no additional cost, it's not going to happen. But for a small premium, alloy plating like zinc-cobalt, zinc-nickel, and tin-zinc can improve the corrosion resistance. For a somewhat larger premium a number of finishes are possible including dip-spin coatings, mechanical plating, and thermal diffusion.

But get some samples and a quote for the alloy plating. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
September 2, 2008

adv.

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