Does galvanizing provide good insulation?

[zappedagain]

I know it typically blocks a decent chassis ground connection for a screw terminal. You have to mask the terminal off before the part is galvanized, scrape through the coating afterward, or use a star washer to 'bite' through it.

Is it a reliable insulator though? Has anybody seen any specs on it?

What about in an explosive environment, where items are classified as metallic (conductors) or non-metallic (insulators). Isn't the zinc-oxide from the galvanization process a non-conducting metal?

Thanks,

John D

 

[mcgyvr]

Galvanizing is conductive (not as conductive as other materials but far from an insulator)...

On any steel chassis parts we make we start with galvannealed steel sheets (because it cuts out one plating step prior to powdercoating) and simply mask the ground area then powdercoat..leaving the exposed galvannealed steel. This is fully acceptable by UL,etc...

 

[zappedagain]

Do you use star washers to bite through the galvannealed coating? Or is your connection 'good enough'? Is the galvanizing process different for aluminum and steel? I might need to go ask the chemical forums...

Thanks,

John D

 

[mcgyvr]

No star washers are used with our galvannealed steel surfaces. Prior to us masking we used to include "paint piercing" washers to bite through the powdercoat to raw metal..

Maybe you mean anodizing for aluminum and not galvanizing? Galvanizing is for steel.

 

[jraef]

Galvanizing of steel means coating it with Zinc, a conductive metal. The way I was made to understand the issue of requirements for scraping through it or using star washers is because if you don't, the conductivity across dissimilar metals over time may change with electrolysis and/or corrosion, so "biting through" the zinc coating to give you a steel-on-steel connection forestalls that issue for a while longer.

Galvanizing does not apply to aluminum or any other metal, it's something that applied to steel or iron.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[IRstuff]

Aluminum has a variety of surface treatments: anodization, chromate conversion, Iridite, etc. Anodization results in a nearly non-conductive surface.

Some conversions, including Iridite, will conduct somewhat, but electrical bonding per mil spec requires bare metal.

TTFN

FAQ731-376

 

[itsmoked]

Galvanizing is just coating steel with zinc. Zinc is a metal. Metals are considered conductors.

Anodizing is an oxide. Most oxides are NOT conductive. If you anodize some aluminum you must do something 'else' if you want to electrically connect to the aluminum thru the anodizing.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[zappedagain]

Doh! I meant anodization, not galvanization.

Please continue any discussions in thread248-260313.