Powder Coating Hubs and Cylinders

Travis

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Is it safe to powder coat hubs? I know plenty of people do it but you need to heat the parts to about 400+ degrees during the process. I've read that it's hot enough to do something to aluminum hubs and will slightly weaken them.

Also, I've read you shouldn't powder coat cylinders because it will make them not cool as effectively? Any insight on that?
 
not sure about the alum hubs,
but i have heard that about the fins not transfering the heat as efficiently.

ive also heard that when painting the head with high heat paint, you should
do it in very thin coats, for that same reason i believe.
 
I thought the thin coats was recommended to get coverage between fins. I would think that thickness of the of paint or powder in the end is what would affect heat transfer if it really even matters at all.
 
I've read that ruff pourous castings dissapate heat much better than shiny surfaces. Also that flat black paint on a ruff surface cools even more efficiantly that unpainted. I've run air cooled VW engines for years and seem to run cooler oil temps with the flat black painted surfaces of the engine block and heads. I also keep my engine tins black. Shiney crome looks good, but will run hotter than painted. For what it's worth.:)
 
Yeah that's where I've heard it could happen but I've never seen any pictures or heard of anyone who has seen it. I guess I stick with polish or paint for the hubs.
 
I don't think powder cating the hubs is a problem.If they crack it's probably due to age more than anything.All the flat track racers around here get their complete wheels done and they claim it prevents the spokes from coming loose from all the pounding on the track.
If there was a safety issue i'll bet they would'nt be doing it as some ofthese guys are hitting 100 mph on the big tracks.
 
big al, just when I'm set on never powder coating a wheel hub, you throw that into the mix and make me want to do it. Someone has got to know a thing or two about hardening metals and how sticking aluminum in a 400 degree oven would affect the properties of the metal. :shrug:
 
Just found this on: http://my.execpc.com/~davewrit/Powder.html

Found your article most enlightening. A metallurgist friend told me a few years ago that things like aluminum wheel spindles should not be powder coated. He explained that aluminum billet material (6061-T6 ?) changed crystal structure at a critical temperature around 410 degrees F (as I recall). The thrust was that the heating step would adversely affect the strength of the material. Non-structural components would be OK, but not something that "holds the spokes on".

The metallurgist is correct. Products like wheel billets, scuba tanks, etc. can be powder coated, but only with powders which cure below peak metal temperature of 300 degrees F. The crystalline realignment at 400 degrees F causes the previous ductile aluminum to become brittle. Imagine the catastrophe when an 80 cu. ft. scuba tank explodes under 3000 psi pressure after an unauthorized powder coat (this actually happened). To my knowledge, all Aluminum wheels and other strength-critical aluminum components are powder coated with these cooler curing powders.

So I guess it can be done safely with low temp curing powders...
 
I would'nt lie to you guys.I was just at the powder coat place yesterday and he had at least 4 or 5 alum rims and hubs there and he does them regularly.
 
I powdered coated my rims and hubs many times and I never had a problem. I recently powdered coated my XS project. When I brought them to Buchanan's for stainless spokes, I noticed that Buchanan's offers powder coating options. Thanks TC
 
I would'nt lie to you guys.I was just at the powder coat place yesterday and he had at least 4 or 5 alum rims and hubs there and he does them regularly.

I certainly never thought you would! :thumbsup:

Do you know what temp your local coater runs at? Perhaps you could find out for us if you dont. Buchanans also?????

Be interesting to know if either of them have a point of view on it......Or maybe they just reckon it's bulltish!
 
Yes but at what temperature? Maybe most of the powder coating places know to powder structural aluminum pieces at a lower temp? :shrug: Or maybe all that stuff about "changed crystal structure at a critical temperature" is bull shit. I have not idea what it even means so I'm not one to say if it's accurate or not.
 
I just last night watched 'FactoryMade' on the science or discovery channel, about the making of aluminum wheels. They heated the shit out of the billets to make the wheel blanks and the forming process. Then they were heated again to stabilize. All the temps were over 700 degs F as I recall. I will see if I can find the episode on-line and watch it again. I also had the Porsche wheels on my VW shorty picup powder coated, and they are aluminum. There is way more side loads on car wheels then bikes. I'd say go for it. Most of us are building choppers and bobbers that won't be testing the strength limits anyway.:twocents:
 
I would guess that car wheels etc would be forged????????

Another guess would be the actual material - 6061 T6 is mentioned with a question mark!
Finding what a stock hub is made of, probably forged.......(maybe no good to re heat forged pieces?)
While a custom billet piece would be machined.....
There's a PHD for the bloke who comes up with all the right answers to this one!

Old XS hubs compared to new slicker hubs made of different metals.......
 
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