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**X-Link** · 02-26-2009, 12:45 AM

Re: Misinformation and misguided "sources"

Not up on the wheel debate, but I know for a fact that aluminum Compressed gas cylinders MUST be scrapped if they are heated above 350* That info comes directly from the cylinder MFG's

**redlinecustomsms** · 02-26-2009, 03:02 AM

Re: Misinformation and misguided "sources"

someone stated earlier that alcoa said the 6000 and 7000 series alloys were ok at our temps for a minimum of 30 minutes. that's pretty bold coming from alcoa. i'd say they are just about THE authority when it comes to aluminum. and that would only alter them 5%. 5% in my opinion is not enough to hurt anything. if your product isn't built with enough safety margin to accommodate that, then it shouldn't be built. I was telling a guy the other day, i bet these cheap chinese built wheels vary in strength more than 5% because they're quality control sucks.

One thing about the comment that if you drop both wheels, the PC'd one will bend. that is completely backwards if PC'ing did indeed hurt the wheel. When you get tempered alloys at or over the temperature they were aged at, they continue to age. what this does is make the alloy stiffer(brittle), doesn't flex as much. the more it is aged, the less it can bend/flex without cracking. so, in all actuality if you were to leave a tempered alloy wheel in the oven for a couple of hours so it has continued to age enough to have adverse effects....it should be harder to bend than the unaltered wheel. but, one it is bent it is more likely to crack when bent than the unaltered wheel.

**Guest** · 02-26-2009, 03:49 AM

Re: Misinformation and misguided "sources"

Check out the forged wheels thread info by streetwerks.I remember while doing some autocross talking to a guy who said some tracks/organizations only allowed them to run steel wheels. No aluminum coated or not! These places I'm sure are looking at worst case senarios. I've also heard you won't pass tech with a pc'ed chromoly frame. I don't know if they're concerned about the frame itself or maybe pc's flexibility makes it harder to spot stress defects? That response from alcoa seems pretty clear though. Unless there is a way to get a rim up to temp and cured in 30 min. I know my oven won't.5% is'nt that much but what about longer cure times multiple coats [prime,color,two tones,clear]? If it follows a linear increase thats 20% pretty easily[not saying it does so don't yell at me]! Not for nothing but I think I will be wet painting my triple clamps! Will pc everything else including rims as I think factory bike wheels are reasonably over engineered and don't get much latteral stress. Spindly aftermarket car rims I might pass on atleast till someone proves it won't be a liability.

**redlinecustomsms** · 02-26-2009, 04:10 AM

Re: Misinformation and misguided "sources"

well you don't count the whole time in the oven, only the amount of time over the temp the alloy was tempered at. which varys but somewhere in the 300+ degree range is common. so basically 10-12 minutes per coat. 3 coats and be fine by they're standard. but, in this day in age if alcoa says 30 minutes is ok, you're probably good for an hour or two. they're not gonna cut it that close, they're gonna leave themselves plenty of "lawsuit" room.

Here's a good question since people didn't just start PC'ing aluminum parts yesterday... Are there any documented, legit cases where an aluminum part failed because it was PC'd? i'm sure there are people crying wolf quite often, but i bet everytime there is a better reason...like the part not being used the way it was designed, etc.

**Guest** · 02-26-2009, 08:17 AM

Re: Misinformation and misguided "sources"

interesting.... Well ive done 2 coats on my Motorcycle wheels and havent had a problem yet next year I will do another color. I reach speeds of 180mph. wheels are in tact and solid.

Any rim will bend if dropped in the correct spot/angle/degree/height/weight theres always a weak point just have to find it.

**Streetwerkz** · 02-26-2009, 08:27 AM

Re: Misinformation and misguided "sources"

Originally posted by redlinecustomsms

Here's a good question since people didn't just start PC'ing aluminum parts yesterday... Are there any documented, legit cases where an aluminum part failed because it was PC'd? I'm sure there are people crying wolf quite often, but i bet everytime there is a better reason...like the part not being used the way it was designed, etc.

Agreed, that was my point with the forged wheel post, I would like a definitive "yes or no" , and results directly related to powder coating alloys (mainly aluminum).
This is something that we should all look into, as it's potentially a HUGE liability.

Don't get me wrong, I have powdered tons of aluminum, never a complaint, but it only takes one accident, for your grandkids to be paying someones attorney.

I ordered a book by Alcoa about process heating Al, has not got here yet, maybe when it does it will help clear things up a little.

**rbroker** · 02-26-2009, 09:13 AM

Re: Misinformation and misguided "sources"

As a former heavy autocrosser, I can assure you that the comment on aluminum wheels is obsurd and 100% completly false. They don't care what you run as long as it passes a tech inspection which involves shaking tires to make sure suspension bolts aren't loose. I'm willing to bet most tracks dont care either... but cannot confirm.

You won't change peoples mind about things like this. Start surfing another forum, lol. Some people just beleive anything from anyone, regardless of facts.

**Guest** · 02-26-2009, 10:43 AM

Re: Misinformation and misguided "sources"

Now I remember what I wanted to say? Takes me a while

Am I wrong or right? Some wheels all types are coming powder coated from the factory. Now I think its called E coating but you have to bake it also?

So what are they using and at what temps do they do them?

Ok PBTP what can you find out for us? Some one out there in the powder making world is supplying mfg with powder and I would say its the big boys I guess. So what powder at what temp I guess would be the question?

**Guest** · 02-26-2009, 11:09 AM

Re: Misinformation and misguided "sources"

This was just posted on the wheel thread in the cycle forum:

From Dymag in the UK - "We have been powder coating our wheels for over 20 years now..."

Jay

**Guest** · 02-26-2009, 11:17 AM

Re: Misinformation and misguided "sources"

I know Gm,Ford & Chrysler Have Been Powder coating There Factory aluminum wheels since 1984...

**Guest** · 02-26-2009, 11:38 AM

Re: Misinformation and misguided "sources"

Originally posted by Hppowdercoating

I know Gm,Ford & Chrysler Have Been Powder coating There Factory aluminum wheels since 1984...

I need a photo or something that I can post that will confirm it.

I stated that European manufactures have been coating wheels for decades, and need some sort of proof.

Thanks.

Jay

**Guest** · 02-26-2009, 12:36 PM

Re: Misinformation and misguided "sources"

Some reading info...

http://www.p2pays.org/ref/01/00659.pdf

**Guest** · 02-26-2009, 12:39 PM

Re: Misinformation and misguided "sources"

Below is a reply I received from a Metallurgist when I asked him about powder coating aluminum or magnesium wheels.

"The short answer is �it depends�. No one is going to tell you that �it�s safe� without full knowledge of the substrates and process, because there is much that can go wrong. I suggest you hire a metallurgical consultant to render opinion on your specific situation.

What can go wrong? Many alloys of aluminum will become more brittle upon heating. If the loss of elasticity on heating is detrimental to the end use of the product, there could be catastrophic failure. For example, high pressure air scuba tanks made of aluminum cannot be heated to 400 F for any length of time (as in the case of a decorative powder coating cure, for example), since the induced embrittlement will cause the tank will rupture, rather than expand, upon pressurizing.

Much speculation about the tendency for the aluminum wheels to crack or fail after such heating has also taken place. I am not aware of any metallurgical testing in this regard, but the auto companies are no doubt investigating due to the potential liabilities.

I have no current experience with coating magnesium, and am unaware of the changes upon heating that metal may undergo."

Jay

**Guest** · 02-26-2009, 12:49 PM

Re: Misinformation and misguided "sources"

Originally posted by Hppowdercoating

Some reading info...

http://www.p2pays.org/ref/01/00659.pdf

Thanks HP.

Jay

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