have i missed something or nowhere the question about adding weight by PC is answered ?

also, what about PC on cast wheel (low pressure such Oz HLT) ?

 

Interesting topic, both sides have good points here. Forgeline & HRE both use powder coating and I believe they do this in house by the videos on there websites. Are they using a special process/method as I know that low temp powder coats are available, but many of the powder coating shops don't like to use them due to the finish has more orange peel than the higher temp/standard powder coats. I've spoken to a few powder coating shops and they state that they bake at 400, but with further questions, they like to get the part up to 400, but the oven temp might be 425, 450+. Please correct if I'm wrong, but aluminum will absorb heat quickly, specially if it's a thin wall like the rim halves on a 2 & 3 piece wheel. The powder coaters that I've spoken with don't seem to have a good understanding of this and the effects that the temp might have on a T-6061 part. I believe most aerospace T-6061 components are anodized because heat is not needed in this process, however anodizing doesn't work very well for wheels as it is not UV resistant and tends to fade, such as black, turns to purple after about a year. Clear anodizing does seem to hold up quite well for wheels I've noticed.

One last thought, who wants chrome wheels anymore....yuck!!!!!

 

Low temp powder coating looks good, seems to work well and does hold up in service.
It is all about who's doing the work.
There are new anodizing processes that are very durable and highly UV resistant as well. We recommend them for the reasons you set forth in your post.
But I will tell you, unequivocally, that baking a forged wheel at 400F is a train wreck for the part. It will over-age the alloy and begin the annealing process. Raise that to 425 or 450 and you are asking for a trip to the ER.
You are also correct about aluminum absorbing heat. It is a fast conductor and I question whether a part would stay very long at 400F if the oven was at 450F.
Bottom line, DO NOT send your valuable forged wheels to anyone that is not highly skilled at Powder Coating forged parts. Ask questions about cure temps. Ask if they have quality systems that check for hardness after coating. If not, RUN.

 

Had my HRE 3 piece wheels powder coated with no problems. Sure saves me alot of time sitting on a bucket polishing aluminum.

 

Just about everything said negatively here is not backed up by any technical data to prove their point. When heating an aluminum wheel to 400f it will in fact weaken it. Do any of the naysayers say by how much? Of couse not because they haven't done their homework and just want to be the one they want people to listen to. The manufacturer of a wheel needs to make sure the wheel has a certain strength to it for the application it is intended for. Do you think they build the wheel to the intended strength? Of course not, they usually make them around 50% stronger than needed. When heating the wheel it will weaken it by annealing it by around 2% leaving the wheel at 148% of acceptable specs. You hear the assumptions from people about "heading to the emergency room" if you coat your wheels". Really, show me one documented case where the wheel failure was directly related to powder coating the wheel. Please just one case. ANYONE? Getting the wheel to 400F will actually have the oven temps reach up to 450F. Really? My oven is not set higher than 400F and will never get to 450 if set at that temp.
Why do manufacturers of wheels void the warranty if you coat them? Because they want you to buy your differant color wheel from them so they can make more money. It's just so much easier for them to say "we don't want you to do anything to our product whether it's safe or otherwise". There are many manufacturers out there now turning to powder finish instead of paint and I doubt any are using low cure temp powders. If done correctly powder will add no more weight and sometimes actually less weight than that of paint.

 

You are simply uninformed about these risks.
Wheel makers today make their wheels as light as possible. It is utter nonsense to think there is a 50% margin for load built into these products. This is the height of engineering ignorance.
I have two sets of wheels in my possession that experienced track failures (broken spokes) after they were improperly powder coated. Thankfully, no one was hurt.
The problem is this: we simply do not know the conditions under which our wheels will be heated. We do not know how strong they will be after this backyard annealing process. So we say ABSOLUTELY NOT.
Do you test for Brinell hardness before and after every heat cycle? Do you have a quality system that insures the durability of the parts after they spend time in your 400 degree oven? Do you have a metallurgist on staff or available to verify your data? Do you have liability insurance to protect the owners of the wheels you refinish?
This ain't a forum for Kias or Yugos. These cars go 150+++ MPH and a broken wheel could spoil your whole morning.

 

I am not a metallurgist but spent many hours with metallurgists educating myself on just this subject. I am also a 20 year veteran Nascar race car driver and know that any wheel put under the stresses we subject them to are liable to break which is why almost no wheel on the market is warranteed under race conditions. Show me your technical data that proves the wheels you mentioned failed due to powder coating or, as I asked previously, show me one documented case where the wheel failure was directly attributed to the coating process with data to back the claim. While I agree there are hack garage coaters out there who dont know what they are doing the powder coating industry as a whole should not be criticized. There are literally hundreds of thousands of wheels out there that have been correctly powder coated without issue. I see charts showing the aging process of alumnum and it is usually done at much higher temps than the coating process and the metal is maintained at those temps for 5-7 hours before cooling. The 10 minutes at 400F is not enough to degrade the material to such that it will fail. If you think I am wrong then post the data to show the strength of the wheel to begin with, the strength after 10 minutes at 400f and the acceptable limits from the manufacturer.

 

The failed wheels in question were annealed due to the temperature during the powder coat curing process. We confirmed this when the Brinell hardness was below spec. Like you, I don't think 400 degrees for 10 minutes is a big deal. HOWEVER:
We don't know how hot the cure temp was. We don't know how long the wheels were exposed to a high temperature. We only know they were a LOT softer than when they left our factory.
And that is ENTIRELY my point. We don't know. And neither does the car/wheel owner.
Part of the magic of forged wheels is the strength of the metal due to careful heat treating. For example, 6061/0 (no heat treat) has a nominal tensile strength of about 18,000 psi. After careful heat treating, this alloy has a tensile strength approaching 50,000 psi. WAY STRONGER!!!!
That's why we say NO Powdercoating and NO Chrome plating.
And, among forged wheel manufacturers, we are not alone in taking this position.
Don't do it.

 

So because one garage hack didn't know what he was doing you want to condemn the whole industry? I had a guy do a ****ty paint job on my truck once, therefore you should never have anyone paint your stuff.
The wheel in question did not meet spec. What spec was that? The spec the manufacturer wanted them in? The spec that was safe for its intended purpose? Who decides what the safe specs are for a wheel under race conditions. You may know your business but it seems to me that you don't know jack about powder coating. The only problem I have with you is you take what little info you have on something and then make a blanket negative statement which makes you sound ignorant from my point of view.
The bottom line is you should ask as many questions as you feel necessary when choosing a powder coater. I am probably the most expensive coater in my area and theres a dang good reason for that. I don't cut corners so I don't cut pricing. I have done my research and know the ins and outs of my industry and stand behind my work.

 

I am not attacking you or your industry. We don't recommend powder coating because of the variables involved.
I have no earthly idea who you are or how good you are or aren't. We don't condemn anyone. We just don't recommend the process for our product.
We are joined by many other Forged Wheel companies in the industry.
I feel I have said enough on this subject.

 

If you are in the wheel manufacturing business I challenge you to educate me more. Take a wheel and run it up to 450F PMT (part metal temp) for 10 minutes and then run your brindle test on it and see how much it actually weaked it. What is the recommended safe strength of a wheel for racing purposes? After doing the cure test will that wheel fall below those specs? After speaking to metallurgists they told me the cure parameter we use would weaken the wheel by approx. 2%. This would bring your 50,000psi stength down to 49000psi, well within your specs I am sure. What is the tensile strength of other masnufacturers racing wheels that don't fail even though they may be way less tensile strength than your?
While I agree you may not want to powder coat wheels subjected to 10/10ths racing environment to just tell people to run from powder coating is not doing yourself any justice. I use 450 for your test as an extreme. Most powders cure at 400F for 10 minutes and my times and temps are carefully monitored. Take the challenge and prove me wrong.

 

It is called a Brinell hardness test. It is a key factor in determining the strength of the alloy. Your ignorance of this standard confirms my worst suspicions.
You may be willing to accept some decline in alloy performance. We are not. Our tolerance is zero.
We do not recommend powder coating our products. You will find almost no Forged Wheel companies who will.
I have made our reasons clear. Others may speak up if they wish.

We will not retreat from our position. The risks are too great.

 

Your unwillingness to back your claims confirms my suspicions. Someone who makes claims and won't back them with technical data that proves what they say is infact an issue that should be of concern. Because you have a standard and won't budge from it does not mean that what we will do will have an effect that is detrimental to the parameters of the application. If you can't provides numbers to back your claims then your opinion is usless to the subject.

 

I have expressed my concerns as carefully as possible regarding the risks of powder coating. We are not experts at this process. But we know excessive temperatures will damage our wheels.
HRE, Champion and many others share our concerns.

Unlike you, I have no personal or business agenda regarding powder coating.
I have only the safety of my customers to protect.

I will leave it to our highly informed members to make the decision.

 

My agenda is not business motivated but more to have your members more highly informed which you have failed to do by providing data to back your claims.