Coating Thickness of Hot Dip Galvanizing

kustomizingkid · Apr 8, 2019

Having some stuff hot dip galvanized and have some internal threads and some bushing bores to deal with. I imagine that I will have to chase some threads... the bushing bores are more curious to me.

Wlodek · Apr 8, 2019

Dip galvanizing creates a relatively thick coat (and thickness depends on many factor as the temperature, the shape of the part, the time immersed, etc) and is not even in thickness. Holes especially can accumulate more martial than flats. So threads do need to be re-threaded and bores reamed back to size. Commercial hot galvanized parts, bolts, for example, have the original part thread undersized to compensate for the buildup. But those are done in closely controlled cycle.

kustomizingkid · Apr 8, 2019

Think I can clean the bores up with a hone or bottle brush? How does the edges effect the integrity of the galvanizing?

sfriedberg · Apr 8, 2019

Hot dip galvanizing is absolutely not a precision process. It can leave blobs, spikes, and thick layers well over 10 times the thickness of the minimum coating. Better to think of it like dunking your part in Plasti-Sol, although the zinc isn't quite that thick.

I doubt you will be successful restoring bores with a mild compliant abrasive. I would run a reamer through.

kustomizingkid · Apr 8, 2019

A little outside reamer territory... these are ~2" diameter bores that have a metal sleeve with a bonded rubber bushing in it.

sfriedberg · Apr 8, 2019

That's well within shell reamer territory, which are readily available up to 4" (although the big ones will hurt your wallet.) 2" shell reamer here, and corresponding arbor here.

If that's too spendy, get a 2" bar of tool steel and do a shop-made rose reamer.

true temper · Apr 8, 2019

I have seen a lot of galvanized parts cleaned up with an oxy acetylene torch and wire brush. Heat the zink till molten and brush it off.
I didn’t think it would work but it did.

Milland · Apr 8, 2019

Don't breathe the fumes...

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Coating Thickness of Hot Dip Galvanizing

kustomizingkid

Titanium

Wlodek

Aluminum

kustomizingkid

Titanium

sfriedberg

Diamond

kustomizingkid

Titanium

sfriedberg

Diamond

true temper

Stainless

Milland

Diamond

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