Powdercoating track wheels
08-21-2009, 04:51 PM
#41
Originally Posted by Neutered Sputniks,Aug 21 2009, 04:16 PM
Burden of proof is on you just as much as you're making the claim that PC'ing is bad for track wheels.
I've had people say, "Prove to me that smoking while pregnant is bad." Well, sorry... there are some kids born to smoking mothers that turn out just fine. You can't use that logic to say something is safe. It's about adjusted RISK.
Think of how long it took to "prove" second hand smoking is bad. It wasn't until the last few years that it has gained widespread acceptance of that.
It's called proof-of-concept. It starts with an observation, "PC'd wheels fail more often than OEM wheels." ALL PC'd wheels don't have to fail, but there is good reasoning to suggest it could weaken wheels.
You don't have to "prove" something always leads to catastrophic failure before reasonable action is taken. Go ahead and continue to run PC'd wheels. I know I won't.
08-21-2009, 04:57 PM
#42
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PC could not be a bad process to our wheels but be bad with how it is done. Specifically at the rate of which the temps rose during the curing process. I would imagine that the center is a lot thicker and thus takes longer for heat soak and thermal expansion while the spokes and outer rim reach temp sooner and thus expand quicker. If you were to gradually raise temp and gradually decrease temp so that there was sufficent heat soak and heat dissipation then you should not see any cracking. It also depends on who is doing the PC did you take it to a professional shop that has lots of experience with the PC process and how to avoid things like this from happening or did someone just buy a PC gun at sears or harbor freight or even eastwood and throw it in your oven, big difference.
08-21-2009, 05:12 PM
#43
That's like saying:
"Well, the s2000 has been shown to roll, so I'm just not going to drive an S on the track again."
There is more to the story than just that an S2000 rolled. We need all the facts (which is what we have when it comes to smoking and pregnancies) before we can know exactly what caused the problem - was it that the wheels were over-cured? Or that the driver had a number of off-track excursions? What tires and tire pressures?
I'm not saying PC'ing is 100% safe - I'm saying that we shouldn't jump the gun and just declare something as unsafe because 2 people have had problems. 2. Maybe those 2 went to bad PC'ers...
"Well, the s2000 has been shown to roll, so I'm just not going to drive an S on the track again."
There is more to the story than just that an S2000 rolled. We need all the facts (which is what we have when it comes to smoking and pregnancies) before we can know exactly what caused the problem - was it that the wheels were over-cured? Or that the driver had a number of off-track excursions? What tires and tire pressures?
I'm not saying PC'ing is 100% safe - I'm saying that we shouldn't jump the gun and just declare something as unsafe because 2 people have had problems. 2. Maybe those 2 went to bad PC'ers...
08-21-2009, 05:32 PM
#44
I don't think anyone is saying black and white (safe vs. unsafe).
I have no doubt that with the right type of wheel spoke, a careful PC'ing service could do it without compromising wheel strength.
I'm not arguing that at all.
I am saying that with the potential to weaken the wheels to the point where I might suffer adverse consequences, I'm not going to put my safety in the hands of a paint technician.
Who knows what happens in those shops. The tech gets distracted, sets the temp wrong, is arguing with his girlfriend, is rushing off to lunch, etc.
For cosmetic benefit at potential cost to my safety, not interested in that tradeoff.
Where this would be more likely to affect me is buying second-hand wheels. Without knowing first-hand what they did, there is now no way that I would buy used PC wheels.
I have no doubt that with the right type of wheel spoke, a careful PC'ing service could do it without compromising wheel strength.
I'm not arguing that at all.
I am saying that with the potential to weaken the wheels to the point where I might suffer adverse consequences, I'm not going to put my safety in the hands of a paint technician.
Who knows what happens in those shops. The tech gets distracted, sets the temp wrong, is arguing with his girlfriend, is rushing off to lunch, etc.
For cosmetic benefit at potential cost to my safety, not interested in that tradeoff.
Where this would be more likely to affect me is buying second-hand wheels. Without knowing first-hand what they did, there is now no way that I would buy used PC wheels.
08-21-2009, 05:49 PM
#47
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Originally Posted by Voodoo_S2K,Aug 21 2009, 05:34 PM
Just pointing out the hyprocrisy of your "cavalier" comment.
If I make a mistake on the track, it endangers others and I should regret that, but it falls into the category of "stuff happens" or "racer's luck" -- there's nothing I could do while sitting in front of my keyboard right now to prevent it.
On the other hand, you're choosing to disregard multiple comments on a forum dedicated to metallurgy explicitly stating that some powder coating processes subject wheels to temperatures known to reduce the strength of aluminum. Disregarding the world's body of materials science knowledge solely because you haven't personally witnessed a wheel fail constitutes a conscious, avoidable endangerment of others, and is thus hardly comparable.
08-21-2009, 06:07 PM
#48
Registered User
The guy on this thread sounds credible, but who's to say whether he knows what he's talking about: http://forums.nasioc.com/forums/show....php?t=1793970
Wheels, cast, or forged are typically made of aluminum alloys that are solution heat treated then artificially aged. Typically to a T6 condition.
The solution temperature is in the 900-1000 deg F range for about 8 hours. At this point the aluminum (Al) is fully annealed, dead soft and easy to bend (straighten). With time the Al age and become harder. After about 4 hours forget about straightening.
For a T6 condition the Al parts are put in an oven at about 300 degrees F for 4 hours. Now the parts are strong, hard, and ductile. That's not a contradiction.
Powder coating requires a 300-400 degree F bake. When you do this to a T6 part you run the risk of over aging the Al and if you do you wind up with a stronger, harder part with little, or no ductility. i.e. brittle.
The part/Wheel manufacture can allow for and combine the paint cure with his aging and not suffer any detrimental effects and lower his overall cost as there is only one bake.
Since most wheel makers don't share their alloy and manufacturing details there are a lot of can's, may's, and could's. "Do you feel Lucky?"
The solution temperature is in the 900-1000 deg F range for about 8 hours. At this point the aluminum (Al) is fully annealed, dead soft and easy to bend (straighten). With time the Al age and become harder. After about 4 hours forget about straightening.
For a T6 condition the Al parts are put in an oven at about 300 degrees F for 4 hours. Now the parts are strong, hard, and ductile. That's not a contradiction.
Powder coating requires a 300-400 degree F bake. When you do this to a T6 part you run the risk of over aging the Al and if you do you wind up with a stronger, harder part with little, or no ductility. i.e. brittle.
The part/Wheel manufacture can allow for and combine the paint cure with his aging and not suffer any detrimental effects and lower his overall cost as there is only one bake.
Since most wheel makers don't share their alloy and manufacturing details there are a lot of can's, may's, and could's. "Do you feel Lucky?"
08-21-2009, 06:17 PM
#49
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Ok, here's a brief article on a website for the coatings industry that explicitly states that powder coating can damage aluminum: http://www.pcimag.com/Articles/Feature_Art...000f932a8c0____
[QUOTE]Question: We are a job shop that was asked to powder coat billet aluminum parts for a customer. The customer asked if the cure cycle will affect the physical properties of the billet aluminum?
Answer: Yes, the cure cycle can adversely affect the strength of the material. Peak substrate temperatures should be below 300
[QUOTE]Question: We are a job shop that was asked to powder coat billet aluminum parts for a customer. The customer asked if the cure cycle will affect the physical properties of the billet aluminum?
Answer: Yes, the cure cycle can adversely affect the strength of the material. Peak substrate temperatures should be below 300
08-21-2009, 06:33 PM
#50
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Originally Posted by PedalFaster,Aug 21 2009, 07:17 PM
Ok, here's a brief article on a website for the coatings industry that explicitly states that powder coating can damage aluminum: http://www.pcimag.com/Articles/Feature_Art...000f932a8c0____
My point about the hyprocrisy comment is that calculated risks are taken; be it making a bad decision on the track, perhaps weaked wheels, or failed BSK's/A-Arms.