Powder Coated Rims thread

[amp583]

Can someone post their rims that were originally bought a stock color but powder coated later. Please post your before color, after color (images) and additional details if possible. I'm looking to PC my newly aquired Spec B rims but would like to start an extensive image based thread about PC' rims.

[dmanaenk]

You gonna powdercoat 06-07 spec.b rims?

I say ban.

[BrooklynBoy]

^^why ban? They powder coated them at the factory. (I'm assuming they will be re-done to factory specs / original color). (Any other color would be pure heresy).

[dmanaenk]

Anywho, powdercoating cast rims isn't the best idea.

[BAC5.2]

Anywho, powdercoating cast rims isn't the best idea.

 

I'm pretty sure that this isn't true.

[BrooklynBoy]

There might be something to that........powdercoating process gets the metal to over 400 degrees F. Someone who knows a lot more than me should chime in right about now to tell us whether or not that would affect the temper/strength of the metal.

[BAC5.2]

There might be something to that........powdercoating process gets the metal to over 400 degrees F. Someone who knows a lot more than me should chime in right about now to tell us whether or not that would affect the temper/strength of the metal.

 

It wont.

[dmanaenk]

I'm pretty sure that this isn't true.

Could be, but I'm fairly certain that there are responses from BBS posted on nasioc, advising against powdercoating their cast wheels.

[BAC5.2]

I don't see why.

 

The microstructure of Aluminum isn't going to change with the relatively low time and temperatures associated with powdercoating, around 390*F for anywhere from 4 to 12 minutes, or lower temps for longer times. It's all dependent on the coating media.

 

The microstructure of Aluminum doesn't begin to be effected until around 560 or 570*F, and even then it requires "moderate" exposure times (varies depending on temper).

 

Of course, if you are a NOOB at powdercoating, you CAN jack up your wheels. But I'm just assuming that anyone with any brains will take their wheels to a shop who knows what they are doing.

[dmanaenk]

^ If you muddle through countless threads about the topic - the only definite thing one can come out with is that without actual knowledge of the actual alloy and the actual manufacturing process of the specific rim it is impossible to make any kind of definite judgement.

[BAC5.2]

Or, if you have an understanding of materials science, you can make generalizations about the tempering process and material response of aluminum.

 

On the whole, aluminum and its alloys don't lose temper below that 560-570*F limit.

 

Bake the powdercoat correctly, and there will be no microstructure change in the alloy, and no mechanical property changes.

 

In the grand scheme of things, 390F is almost nothing. They make Aluminum baking sheets, pots, pans, and flashing around chimneys and such. If you can boil vegetable oil in an aluminum pan, you are exceeding the temperature required for powdercoating.

[dmanaenk]

So the whole big debate about powdercoating forged alloy wheels is non-sense as well?

[BrooklynBoy]

Or, if you have an understanding of materials science, you can make generalizations about the tempering process and material response of aluminum.

 

On the whole, aluminum and its alloys don't lose temper below that 560-570*F limit.

 

Bake the powdercoat correctly, and there will be no microstructure change in the alloy, and no mechanical property changes.

 

In the grand scheme of things, 390F is almost nothing. They make Aluminum baking sheets, pots, pans, and flashing around chimneys and such. If you can boil vegetable oil in an aluminum pan, you are exceeding the temperature required for powdercoating.

You seem to know a lot about materials science so you get this question directly.......isn't there an inherent difference between cast aluminum ,forged ,and sheet/plate aluminum ?

[BAC5.2]

I'd say so, yes. I'd be SHOCKED if you found a single "powdercoating caused rim failure" case.

 

If you look at the heat ranges of pads, you get localized heating of wheels that will exceed 400F. I remember a Sport Compact Car article where the hat of a stock STi and EVO rotor was reaching upwards of 500F.

[BAC5.2]

You seem to know a lot about materials science so you get this question directly.......isn't there an inherent difference between cast aluminum ,forged ,and sheet/plate aluminum ?

 

Sort of.

 

From a material standpoint, 7075 is 7075 is 7075, whether you cast it, forge it, or look at it funny, the material itself isn't changing. From a mechanical properties standpoint, you have mechanically introduced differences, and it all has to do with grain-flow.

 

If you look at the grain layout of a gravity-cast situation, you'll see a LOT of grain boundaries, not a lot of grain density. Luckily, I don't know of any wheels that are gravity cast.

 

In low/high pressure castings, you have much greater grain density, which means less grain motion, and a stronger wheel for less material.

 

Forging has the greatest grain density, and the best grain orientation. Long grains mean fewer grain boundaries for crack propagation and higher grain density means further grain motion restriction. Voids decrease as you increase forming pressure, so you have a more uniform material.

 

Ultimately, this is almost independent of temperature sensitivity. The anneal temp of aluminum ranges from 570F to 770F, depending on the alloy. Changing manufacturing process isn't going to change this.

 

I can't see any problem with subjecting a wheel to under 400 degrees for 10 minutes. A hot lap around a track or down a mountain will have rotor hat temperatures knocking on that 400 degree range PDQ.

 

Like I said, I'd be shocked if you found a single wheel failure due to proper powdercoating.

[dmanaenk]

Define failure. Wheels falling off? Probably not. Wheels loosing strength and bending where they shouldn't? It happens. Don't want to start any kind of debate, so I'm just gonna provide a link to one of the decent threads on this on nasioc.

[BAC5.2]

I got to post 3 in that thread.

 

The heat of powdercoating won't anneal the rim. Period. Powdercoating takes place below 400F, annealing of aluminum takes place no lower than 570F.

 

Powdercoat away!

 

Edit: LyveWRX seems to know what he is talking about, except he is confusing two things. First, that some alloys of aluminum have an anneal temp for 300F. And second that powdercoating takes place anywhere from 300F to 500F for 1 hour.

 

The first, I think he has units messed up. I haven't found a single alloy of aluminum that has an anneal temp below 300C, or 570F.

 

Second, powdercoating is around 400F for something in the neighborhood of 10 minutes.

 

I'm no expert on Aluminum, I'm just drawing from my materials science experience. He may know more than I do about anneal temps of specific alloys, and I may be wrong. I think the likelihood of damage due to correct powdercoating is slim-to-none.

 

The guys who bend post-powdercoated forged wheels never mention how they were coated. Stuffing a rim in your home oven and setting it to 500F for 90 minutes is the wrong way to coat a wheel. A home oven doesn't have NEARLY the temperature control of a proper powdercoating oven.

 

Remember, powdercoating is a surface treatment. All you need to do is completely melt the beads. Annealing requires total material temperature saturation. Forged wheels have less material than cast wheels, so they'll heat and cool more quickly, but they still won't magically exceed the temperature of the oven.

 

Edit 2: I glazed over the whole thread. I didn't check LyveWRX's references, because frankly I don't care that much, but I still doubt that proper powdercoating will weaken a wheel. If a particular alloy has an anneal temp below 450F (not C), then I'd be weary. Somehow, I don't think they'd use anything less than a 6 or 7 series, T6 tempered alloy.

 

6061-T651, for example has an age temp of 350F (not C), but that has no impact on anything. Age temp is the temp at which the temper is achieved. You stick base 6061 in a 350F oven for 8 hours, and you get the T6 temper. 6061 has an anneal temp of 775F (not C)... for 2 to 3 hours. The forge-temp is 900+F (not C). 7075 is very similar to these numbers (though with a slightly lower age-temp).

 

I can see no apparent reason that 400F for even 20 minutes (which is a LONG time for powdercoating) would cause any damage to a wheel.

 

I'll cover my butt and say that you should take my posts for just words.

[BrooklynBoy]

http://www.eng-tips.com/viewthread.cfm?qid=151053&page=10.

I think these metal guys have another point to consider......"Over-ageing" which can reduce the fatigue life of the rim.

[dmanaenk]

I got to post 3 in that thread.

 

The heat of powdercoating won't anneal the rim. Period. Powdercoating takes place below 400F, annealing of aluminum takes place no lower than 570F.

 

Powdercoat away!

Read the whole thing.

[BAC5.2]

I edited my above post... twice... after reading the whole thing.

 

Over-aging won't occur in under 20 minutes.

 

Caswell, a popular powder supplier, has cure times/temps hovering around 10 minutes at 350F depending on color

http://www.caswellplating.com/powder/powder_colors.html#

[BAC5.2]

Again, I very well could be wrong. But I see nothing that grossly points to an assurance of failure as the result of proper powdercoating.

 

Now, you could do it wrong, baking at WAY too high a temp, or the right temp for WAY too long a time. But that's ignorance on the operators part and not the fault of powdercoating.

[amp583]

I know quite a few people in Chicago that powder coat their rims and rims of their "clients" - which isn't scientific but how else are Anthracite, silver gloss, etc available for the same rim style - they're powdercoated im pretty sure, after they are cast or forged or made.

[BrooklynBoy]

I know quite a few people in Chicago that powder coat their rims and rims of their "clients" - which isn't scientific but how else are Anthracite, silver gloss, etc available for the same rim style - they're powdercoated im pretty sure, after they are cast or forged or made.

 

Any color is possible.......at the factory. I personally would not trust ANY aftermarket shop to do the wheels that transport my 11 month old son.

The temperature , timing of application and dissipation of heat is too easy to screw up. (and you would not know it until it failed) I am not able to ignore the possibility that the factory temper and ageing of the rim would be altered and my families safety compromised as a consequence.

(Just me guys.....I guess I'm just the nervous type)

[BAC5.2]

You sound overly cautious, but there isnt any fault in that. You have an 11 month old, no one can blame you!

 

To ease your mind, regardless of whether or not powdercoating is of interest to you. Aging of aluminum isn't something that occurs in 10 minutes. The times required to achieve T6 levels of temper are nearly 50 times longer than the powdercoat time. In fact, aging does not even begin to occur until you reach the ~2 hour mark. I'm fairly certain that absolutely no quantifiable aging will occur during proper powdercoating processes.

 

Next, the temperature required for powdercoating isn't even close to half the anneal temp of the wheel.

 

I'm also quite sure that the colored wheels on one of the variations of the F350 were powdercoated from Ford.

 

You'd have to REALLY mess up to have any alteration of factory temper or age.

[jedraz]

I had my S2000 on powder coated wheels for 6 years and never had a problem, very durable finish. I also did my forged BBS's on my LGT and have had the same experience, sorry no pics, I will get some.