Does powder coating weaken an alloy wheel?

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Been watching some how its made videos on how high performance alloy wheels are made.

It seems that if you heat the wheel up to 500 degrees for a number of hours, that's doing one of the same procedures for strengthening the wheel.

Because the wheel is allowed to cool gradually instead of a quick immersion, won't this change the molecular structure and weaken it?

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Originally Posted by sasilverbullet
Because the wheel is allowed to cool gradually instead of a quick immersion, won't this change the molecular structure and weaken it?

Well at least not appreciably enough to impact performance. If it did then they wouldn't powder coat wheels.

Remember, there are all sorts of ways to heat treat aluminum.


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I don't think powder coating requires 500 degree Fahrenheit. More like 400 at most.
 
As a rule of thumb, anything over 350°F can overage aluminum alloy. It can lose strength and hardness.

Slow cooling doesn't do much for aluminum. The rules used for heat treating steel don't apply to aluminum.
 
I don't know about the heat, but OE wheels are powder coated, but it's not applied the wheel to hub mounting surfaces, or lug nut holes. The powder coated wheels look great, but all of the wheels I've worked on have it all over the hub centric wheel hole, the rear mounting surface, in the lug seat holes, etc. Problem is they don't balance up well because the coating on the backside varies in thickness, compared to the original machined surface. The lug nuts can easily loosen, because it is compressing the coating instead of the machined seat. The center hole won't fit over a lot of hubs after coating, which seems pretty thick compared to paint. I also have seen many powder coated wheels where they messed up the valve stem hole which they use to hang it on the rack. If you can't make it round enough to seal, then the wheel should be scrapped. If I ever have any wheels powder coated, I would insist there not be any where it's not supposed to be.
 
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Originally Posted by Traction
I don't know about the heat, but OE wheels are powder coated, but it's not applied the wheel to hub mounting surfaces, or lug nut holes. The powder coated wheels look great, but all of the wheels I've worked on have it all over the hub centric wheel hole, the rear mounting surface, in the lug seat holes, etc. Problem is they don't balance up well because the coating on the backside varies in thickness, compared to the original machined surface. The lug nuts can easily loosen, because it is compressing the coating instead of the machined seat. The center hole won't fit over a lot of hubs after coating, which seems pretty thick compared to paint. I also have seen many powder coated wheels where they messed up the valve stem hole which they use to hang it on the rack. If you can't make it round enough to seal, then the wheel should be scrapped. If I ever have any wheels powder coated, I would insist there not be any where it's not supposed to be.

Agreed. I purchased a wheel off of ebay for my parents' Altima and it had clearly been powdercoated. The center hole appears to have powdercoating and it is extremely difficult to remove the wheel from the hub for any tire service.
 
Originally Posted by Traction
I don't know about the heat, but OE wheels are powder coated...


My stock Porsche rims are painted, not powder coated.
 
I have bought four really old alloy wheels (2003) from Silverado to be used on my '14 Tahoe with winter tires. I had them sand-blasted and powder-coated, as they were in terrible shape. The shop had to do stripping and powder-coating twice, as they didn't like how they came out the first time. I stripped the coating on the mounting surfaces and under the lug nuts. They work and look just great, into third year.
Not a performance, but quite heavy vehicle at times.
 
Originally Posted by Kestas
As a rule of thumb, anything over 350°F can overage aluminum alloy. It can lose strength and hardness.


That rule of thumb is good for 2000 and 6000 series. It is most likely that a 6000 alloy will be used for forged wheels; I have no idea about cast.

On the rare chance that 7000 series is used, even 250°F is too much. Those alloys are common in aerospace and other industries needing high strength such as bicycles and guns. the M16 and AR15 and many pistols use 7075 and if powder coated, need to be carefully evaluated.

There are low temperature powders; ask the coater to use one that is definitely below 350°F for wheels, and try to determine the alloy used to allow your research.
 
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