powdercoating question

[Magnus]

i found out that aluminum melts at 1200 degrees, steel at around 2800 degrees...  not sure about magnesium.  i would imagine that you don't actually need to reach these temperatures to weaken the metal, though...  what those numbers are would be interesting to know.

[ducpainter]

Mag + enough heat = kiss your good bye

When I worked at the fab shop we had a contract with Allied to fix missile fins.

We had a guy welding mag.

It was really bright....

[Jarvicious]

As far as weakening the strength of the wheels under even a 500F degree temp, you shouldn't have a problem.  For the metal to start to be structurally modified (meaning the crystalline structure of the metal is realigned such that the metal is comparably soft)  you have to heat it up to (I believe, don't quote me) around 8/900 degrees F, and this is usually obtained by a much more direct heat such as a oxy and natural gas or acetylene torch.  Essentially, the metal has to be heated to "red hot" where you can physically see the metal glow, but even then aluminum has to be quenched or cooled very quickly after that amount of heating for it to keep its annealed, or softened state.  Then, EVEN IF your wheel was softened by such a process, both the physical act of riding or driving on the wheel and the wheel's (hopefully minimal) exposure to varying temperatures and moisture conditions will further harden it over time.  Magnesium I think has around the same properties as aluminum and is a pretty frequent alloy material.  The mix of aluminum you have will make a bit of difference as well, i.e. the ratio of aluminum to copper to mag to silicon..... bla bla bla.  If the heating process does for any reason cause a stress at a joint or something of that nature, it's going to be a SUPREMELY poor weld and a wheel that you probably didn't want in the first place, baked or not.  Here's a tasty little article that deals mostly with small stock and wire, but the rules should still generally apply.

http://www.evergreengardenworks.com/copperwi2.htm

Ok, I just finished the article myself and the end states that aluminum annealing is usually at around 570+ and immediately quenched after the fact.  It's a bit closer than I thought, but you're still not at risk for metal fatigue. 

[Magnus]

excellent info, thanks

[bullethead]

Any suggestions on color and brand of powder coating material to match Ducati champagne?

[Popeye the Sailor]

i found out that aluminum melts at 1200 degrees, steel at around 2800 degrees...  not sure about magnesium.  i would imagine that you don't actually need to reach these temperatures to weaken the metal, though...  what those numbers are would be interesting to know.

The temps which cause metal to weaken significantly are fairly low, actually.



This is why the steel in the WTC failed despite the low temperatures, btw.

[He Man]

resurecting this thread...

After reading a bunch of stuff on aluminum, im still undecided on weather to powder coat them or not. Though aluminum wont melt till 1100, it is defintely possible for it to weak at a much lower temp.

Ive heard of a difference in reaction to the baking temperature of powders of  cast vs forged aluminum wheels. The annealing of aluminum begins around 350-400 degrees from what most people say. However further research pointed that the anealing process of forged 6000 series aluminum is along the line of eight hours (could not find data for cast aluminum) because of this, i think a 30 minutes of outgassing and 20 minutes of 400 will not cause any significant damage to the wheel. at the same time, im not the one that wants to find out. My main concern is the fact taht i ride in the pot hole wonder land of america and do not want my wheels to break mid way...thats a easy trip to the morgue after a taxi decides to drag my body 30 miles across the city.

The census is still split down the middle. I have really do not have enough information to make an informed decision...

Also, it seems that this is true about swing arms too. Plenty of people PC wheels and swing arms....i havent been able to find any cases where a wheel broke in normal usage due to a cracked wheel/ swing arm either.

Anyone care to shed more light on this topic? I emailed the Myth Busters this question too!

[Mother]

lots of good information here. At some point there should be a realization that you are WAY overthinking this issue. wheels of all alloys and flavors have been PC'ed for years, you are spinning yourself up.

[He Man]

I disagree, i dont think theres lots of good information here just lots of people who have done them without issue... I called a few auto shops and asked if they would PC wheels. I got mixed answers. Its not safe to, what type of wheels, to sure no problem.

I have plenty of scrap 6061 T6 aluminum, and ill try to run some controlled tests, from what I read. Its very possible for 400 degrees to soften the metal. As  Mr incredible pointed out, the point at which a metal weakens is far beyond that of melting. especially when there are moments involved. Specially in wheels, I think many of the reasons (if PC does indeed weaken the wheels) why they rarely fail, is due to the design of the wheel. Its much stronger then it needs to be. Which would make sense since i've found people with broken wheels after PC (of course they hit a curb or something). But the damage is quite significant, all of the spokes snapped and the central hub was left on the vehicle.

Take a look at steel, it melts at 2500F, but the failure point can be anywhere as low as 1300F and high as 2000F depending on its alloy...

[Mother]

you are going to do controlled tests to determine if a process that is already done...nevermind, enjoy.

[He Man]

I'm sorry did someone already test a wheel to see if the metal gets softer after baking it?

Link please.

and for each link you give, i can give just as many to refute it.

Who is right? who is wrong? Just because people powder coat their wheels doesn't make the idea any less plausible.

[ducpainter]

engineers....

[lauramonster]

that's why you haven't found an answer.  It's not right or wrong.  It's a crap shoot.  Hope it works in your favor.

[Mother]

OOh OOh

this is a perfect time for my much retold favorite engineer story

I was working at UMCD as a millwright

Myself and a grizzly old journeyman of undetermined age (guesses had him at 78) were dispatched to rebuild a 4 story lift.

when we got there, 3 engineers were standing there with fancy laser measuring devices, a handfull of plans, and literally scratching their heads

their determination was that the lift or surrounding bulkheads were misaligned and the lift needed to be completely torndown

the bulkheads remeasured

and possibly the floor torn out and replaced as well

this old millwright told 'em to piss off

had me hang a plumb bob from 4 stories up

loosened the 2 inch bolts in the floor with this giant metric adjustable he always had with him

hit the lift's main rails with a sledge hammer

and re tightened the bolts

all in the space of time it took me to return to the 1st floor

and the lift lined up within spec

The engineers left in a huff

[Triple J]

I prefer empirical evidence when available.

Lots of people have powdercoated their wheels without any problems. Therefore it is OK.  (I just picked up my Multi wheels yesterday from the powdercoater)

...and I'm an engineer.