Ducati Monster Forum

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)

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

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.

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.

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.

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.

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.

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.


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.

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.

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).

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/ (http://thepowdercoater.com/)

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.

So far I've chrome plated, anodized, hard anodized, powdercoated, polished (bare finish) and painted aluminum wheels without problems.

Only cavaet is that within the SSS wheel nut pinch area, I usually tape it off if when powdercoated and paint later.  I've seen powdercoat under compression slowly erode away.  Never a problem with chrome or anodizing or paint though.

did you have to do any special preperations for SSS?

ive hit it with a sander and as RB said, its pretty bare.

Media blast is best because it gets all the nooks and crannies but sanding is fine too. Prep is similar to paint prep with the exception that you can paint over paint (mostly) whereas I would only powdercoat a bare surface.

in that case, would i want to etch up the surface for a better adhesion? id think not right?

Why are you prepping it yourself? Are you doing your own powder?

I just had my MTS frame, rims, triples, and a few other pieces powdercoated. The bill for media blasting all of it was only $80. No much to not have to hassle with it.  :-\ Total price (prep & powder) was $310 for all of it, including tax.

I also had a GT mountain bike frame powdercoated quite a few years ago (very thin wall aluminum tubing  ;))...the powdercoater media blasted that as well. Prep & Powder was $100.

Powder is cheap.

I never tried etching because I have the convenience of my own cabinet. Blasting leaves the surface feeling kind of like 1200 grit paper. Nice surface for the finish to bite into.

Suppose it would work though as long as it's neutralized after and doesn't leave a black oxide finish. I'm sure you could test a piece first. Make sure it feels a little rough after.

good to know.  [thumbsup] regarding your other post....


Still waiting on Marchensini's response. From what I've read, you can shape the wheel, spray it and temper it. The tempering process is done at around 375-450degrees for 8 hours. Ive heard you could redo the process, but it isnt as good as the first time around (that last part doesnt make much sense to me because these metals are always recycled and go through thousands of heat treatments and end up fine). All of that information is completely unverified because there are so many variations of that story. But hey, it might be true but its on such a small scale it doesnt matter. which is what my guess is. and If it was a huge deal, people wouldnt be PCing wheels at all right?

That was my "common sense" take on all this.    ;)

 [bang] you still dont get the question. im just gonna about face.

I'm sorry. It was 5am and I wasn't quite cognitive yet. Just woke up to let the dog out, no  [coffee] yet.

You were saying that tempering the wheel can't be a big deal.

The temp range you described is powdercoat baking/curing temp although for much longer than 20min. As long as the finish didn't "overcook" I guess you could leave the wheel in the oven for 8hrs (and whatever controlled cooling is required) after coating to re-temper. The longest I ever left a part in was 25min so I don't know how the finish (we use corvel brand) reacts to an extended heat cycle.

i have done this, and it will trash the powder coating, but you should test this before you take my word for it.

First off, heat treatment of aluminum is a different process than that used for steels.

Here's a primer on heat treating aluminum:
http://www.keytometals.com/Article7.htm (http://www.keytometals.com/Article7.htm)

Here's an eng-tips forum thread that's directly on point:
http://www.eng-tips.com/viewthread.cfm?qid=151053&page=10 (http://www.eng-tips.com/viewthread.cfm?qid=151053&page=10)

Regarding this:


You need to check load vs. deflection up to where the sample *fails*.
Failure, in this case, would be a permanent bend in the sample.
Unless you're pushing hard enough on the sample to get a permanent bend in it, or break it, you're just checking the Modulus of Elasticity.
Modulus of Elasticity is the 'spring rate' of the material.
Heat treatment generally does not change the Modulus of Elasticity of a metal.

powdercoating should have a negligible effect. Im a metallurgist.

Whether you are powder coating or painting don't handle the bare aluminum with bare hands or it will need to be etched to remove skin oil. If not you will have a corrosion/adhesion/fish eye issue in that area.

Had a conversation today with the ceramic thermal coater.  Great for exhausts, steel frames, etc.  But keep it away from your aluminum rims.  Ceramic coating heats 525-550 degrees for a few hours to bake the surface.  He did a set of rims and they went "soft" -- ie: the heat process changed the aluminum characteristics.  He only made it a few miles before starting to bend the outer flange edges.

Also the higher temps of ceramic coating cause metal to relieve stress and move about some due to the heating/cooling cycle.  Thus sometimes dimensions might change a bit ala an exhaust system in radius bends. (good thing to know)

I know powdercoaters go to 400 degrees.  Wheels I've had done in the past were "low temp" powdercoating with lower temps specified.  I called them today and asked them the specifics they had done wheels for myself and customers in the past. 

So I definitely wouldn't go above 400+ for extended periods of time. 

some really good stuff here, Speeddog good point! That was a big flaw on my part. I will retest till failure. though id need to find thinner pieces cause i dont have more than 75lbs of weights!

Motocreations, that is defintely some useful information. I have been looking for low temp powders with very little luck. I have however, found short duration powders via powders by the pound. the cure time is only 10 mins @ 400 after outflow. I am ebay sniping a IR thermometer. I plan on doing some test to see how evenly my oven heats up by hanging pieces of aluminum at various location and logging the temp. one of the things that ive read is to make sure the aluminum heats up slowly.  can anyone recommend otherwise?

If any one knows where i can find low temp powder please post up!

ducpainter, thanks for the tip, i thought it wasn't a big deal as long as i wore gloves, but further research says that your much better off donning gloves and washing your hands with the gloves on to ensure that there is no oil as you handle the bare aluminum.

No need to re-test, there are volumes of info out there on this. Do a search. ASTM, ASME and others will have more info then you will need to know, and it will be repeatable, done in laboratory settings, not in someones kitchen.

There is no problem with the heat on aluminum. There are some colors of powder that will  cure at lower temps. I did a search on this years ago when I was getting a set of magnesium wheels done. White was the lowest temp at the time.

took weeks to get back to me, but for those who are interested marchesini doesnt PC any of their wheels.

"We don’t have a big experience on Powder coat. We suggest to use the liquid paint. This is what we use actually."-Marchesini.

 :o   No shit!      Veeeeery  interestink.


That r sum thick, tough liquid paint they're using there.

I can't believe I managed to dig this thread up, but I though I remembered a pretty lengthy PC thread from sometime last year.

http://ducatimonsterforum.org/index.php?topic=6485.0 (http://ducatimonsterforum.org/index.php?topic=6485.0)

I don't think you have to worry about how fast/slow you heat the metal up unless the wheel is extremely cold at the time you put her in the oven.  It's basically the same situation as when you run a really hot pan/dish under really cold water, so as long as the rims are around about room temp, you should be fine. 

+1 on keeping your greasy little mitts of the metal once you've had them blasted.  I've only done a few things in my time where I really wanted to yield a good finish, but each thing I painted ended up having problems with the final finish due to a lack of prep.  Prep prep prep!  If you're wiping the piece down just before you coat and you still have some residual grunge on the rag, redo it.  Like DP said, even a little finger grease can put a wrench in the works. 

Edit:  Just saw that you brought that thread back last month anyway.  I'm out of the loop  :)

no sheet is da right wurd two say all right.

I finger banged a 1098R, dem wheels were warm to the touch, almost swore it was PC since it was thick as walrus.

Sorry I got into this thread so late.
I work for a very well known custom wheel manf. and we sell powdercoated wheels all day long (and have been for years). All of our wheels are manf. out of T-6061 Alum, polished, and then powdercoated.
We have never had a failure period, let alone one caused by the powdercoating process.

As the thread says, I think results from powdercoating (good or bad) is all based on what material is being coated, who is doing it, the prep work involved before coating, etc..

I had no hesitations about getting my wheels powdercoated.  I have Marchesini wheels, taken from a Monster S4 Senna.  The wheels were red when I bought them, and I had them powdercoated in a low-gloss black.  Since the powdercoated wheels were installed, I have ridden about 7000 miles on them.

I have no empirical evidence that suggests powdercoating has weakened these Marchesini wheels.  As long as the process heat isn't excessive (as noted previously in this thread), you should have no problems running powdercoated wheels. 

(http://www.rpmri.com/gallery2/d/1263-1/Toasty_rsz58.jpg?g2_GALLERYSID=a2536b9647bb1b7ca0f9493beeb01f62)