Powder Coating Questions

[He Man]

Been doing lots of reseaerch about powder coating forged aluminum wheels. theres a lot of mixed data out there and was wondering what some of you guys may know.

How many of you guys have PCed their wheels?
What type of wheels do you have?
Does PC'ing wheels cause the integrity of the metal to weaken?

Some people say it will, some people say it wont, and i can't seem to find any real events of wheels that were PCed that broke without some sort of outside stress (hitting a curb....etc)

[hcomp]

I have not done any motorcycle wheels. However, I have PC'd several forged aluminum car wheels with success.   

[He Man]

Well since no one really knows, ive decided to run some tests.

I got strips of 6061 table vice and a force guage + an oven.

[Duck-Stew]

Well since no one really knows, ive decided to run some tests.

I got strips of 6061 table vice and a force guage + an oven.

I've powdercoated forged AL Marchesini's and they were fine.

[He Man]

I am hypothesizing that it is the structure of the wheel itself that prevents you from seeing the effects of baking the alloy at 400degrees and the fact that wheels are built to withstand a lot of force that pretty much negates the fact that PCing the wheel will cause the wheel to fail.

I still think there is some truth in the weakening of Aluminum alloys at powder coat temps. I will find out soon. The piece has been cooling down in the oven for about 40 minutes and i just lowered it to 100 degrees and im gonna let it cool in the oven for another 20 minutes then take it out to air cool.


test results : inconclusive, both samples took 75lbs to begin deflecting. I will try to seriously anneal a piece later this weekend...400degrees for a a few hours then slowly cool it over the course of a few hours and retest.

[Chchadder]

But are those aluminum strips heat treated the way that wheels are out of the factory?  It's the reheating process after heat treatment that is supposed to weaken aluminum.  If the aluminum you are heating has not been prepared the way that wheels generally are, you have a crucial confound in your experiment.

[He Man]

But are those aluminum strips heat treated the way that wheels are out of the factory?  It's the reheating process after heat treatment that is supposed to weaken aluminum.  If the aluminum you are heating has not been prepared the way that wheels generally are, you have a crucial confound in your experiment.

The forged Al wheels are T6 grade (from the best of my knowledge from researching) and the strips i have are also T6 so they are both made from the same standard. The difference between the two is, the wheel is shaped before its tempered, these are tempered as sheets.

[TAftonomos]

There sure are a whole bunch of powdercoated wheels out there running around.  I don't think I've ever heard of a wheel failing because of being powdercoated.

[RB]

if you are doing the swing arm, you will just need to prep the surface as it is already bare. I have a powder coater that is willing to PC my wheels, but he won't burn the PC off due to the extreme temperatures. If it helps, he also rides, and has done many wheels, or so he tells me.

[He Man]

There sure are a whole bunch of powdercoated wheels out there running around.  I don't think I've ever heard of a wheel failing because of being powdercoated.

Thats the best arguement ive heard and most reasonable one. There really has been no case of this. As I posted in another thread (quite possibly this one, im not even sure what day it is anymore!) many of the photographs ive seen from people who claimed powder coating weakened their wheels, were pretty daunting, but they were all damaged by some outside force, or was a wheel known to have some issues.

Some of the photographs of cars that wiped out and hit a curb(wish i saved them) showed the entire internal hub still connected to the wheel and all spokes  snapped right off. Ive googled pictures of non PC forged and cast wheels where the same type of event only caused the lip to fold onto itself and a stress fracture that snapped the wheel.

Do note you cannot really compare both events since speed is unknown, strength of the wheel is unknown, etc. So as far as I can tell, you are very right. No one who has ever actually had a powder coated wheel outright fail for no reason.

if you are doing the swing arm, you will just need to prep the surface as it is already bare. I have a powder coater that is willing to PC my wheels, but he won't burn the PC off due to the extreme temperatures. If it helps, he also rides, and has done many wheels, or so he tells me.

Im very glad he decided to not do that. I got bored and hit another piece of 6061 with a propane flame and let it cooled down inside the oven. the piece will snap when you try to fold it. It is only a few mms thick, but compared to a T6 treated one that will fold onto it self, its very easy to destroy the strength of aluminum with a high flame.

edit: forgot it was the yellow can, aka MAPP gas.

[hcomp]

Some of the photographs of cars that wiped out and hit a curb(wish i saved them) showed the entire internal hub still connected to the wheel and all spokes  snapped right off. Ive googled pictures of non PC forged and cast wheels where the same type of event only caused the lip to fold onto itself and a stress fracture that snapped the wheel.

I had the entire center hub of a wheel separate from hitting an apex curb, and they were not powder coated, painted, or covered in anyway.  It was a Panasport wheel to boot.

[Howie]

If you heat aluminum without quenching it wouldn't you be annealing it, not hardening it?  Wheel cracking is from being to hard, wheel bending is from being too soft.  If soft enough, it could collapse (not likely).

[He Man]

I really dont know, this subject gets talked about so much online that im not sure what source to believe or not.

I thought that annealing aluminum requires you to bake it for approximately 8 hours and to slowly cool down at a rate of 50F per hour until 200 then air cooled. (of course this is general for al). and i might be mixing this up with the term "aging". which is similar, but done for a much shorter amount of time.

If you quench it, it should make it brittle and thats defintely something we do not want to do while PCing.

[Jtree007]

I really dont know, this subject gets talked about so much online that im not sure what source to believe or not.

I thought that annealing aluminum requires you to bake it for approximately 8 hours and to slowly cool down at a rate of 50F per hour until 200 then air cooled. (of course this is general for al). and i might be mixing this up with the term "aging". which is similar, but done for a much shorter amount of time.

If you quench it, it should make it brittle and thats defintely something we do not want to do while PCing.

Powder Coating the wheel should not be that big of a deal.  I have a close friend of mine that specializes on powder coating automotive parts.  I have seen the work done and I have seen the aftermath of accidents where the wheel could be damaged.  I have never seen any issues and really don't see any reason for there to be any. 400ºF is pretty hot, but if you relate that to the heat that is in braking systems and various other applications where al is used.  I don't think there would be any real change in strength or brittleness.  If you are looking to get some powder coating done, then I would go for it and not worry about it. 

BTW my friend and his services can be found at http://thepowdercoater.com/

[He Man]

thank you for that data. Ive decided that once i make sure my oven works as intended (heats up as evenly as possible) im gonna go and powder coat it.
On most forums ive read were full of ignorant assholes claiming to be metallurgist that became powder coaters that used to be engineers.