aluminium motorcycle wheels - pc'ing cause failure?

[mtnbiker]

Has anyone heard of any stories where powder coating aluminium motorcycle wheels effected the strength.... and caused failure?

[bzer1]

I have never heard of a specific case where that has happened, but it could. It depends on the alloy and method of manufacture. 6160-T6 has a tendency to become structuraly unsound when it's heated to 400f for extended periods of time. Vacume castings and extrusions in most cases will not be an issue. Basically if someone comes to you with a stock wheel from HD or where ever you should be ok. If someone comes to you with a one off CNC cut "billet" wheel you should ask some questions before you heat it up. The most important thing to ask is: What is the alloy? If you can't find that out you should probably not heat it up too much. If you do it anyway you need to ask: How's my liability insurance? There are more powder manufacturers making low cure powders now, so that may be an option for some of the more exotic alloys. I would turn down a job before I took a risk on an unknown alloy. I went and purchased a metalurgists hand book that gives specs on hundreds of alloys including max temp. It was VERY expensive but has come in handy a few times.

if that was the case i put well over 300 rides in harms way... there is not enought effect on the metal to matter the bearings need to be remove or they will be harmed .. but other than that the 300 + set's of wheels i did are racking up miles ... Don't worry about it



FOOTNOTE FROM CASWELL INC

A red flag has been raised here. Please refer to my posting further down

[sdold]

Does anyone know where I can find out at what temperature heat-treatable alloys begin to undergo a change in their structure? I'm concerned not only about strength but also intergrannular corrosion forming later on (from the slow cooling).

[Popeye]

http://www.key-to-metals.com/Articles.htm
http://www.asminternational.org/
How's the fishing been sdold?

[mcaswell]

Attn Customsound

Just before you posted this, another guy was saying that there is scientific evidence to show that some aluminum alloys will fatigue and cause failure when exposed to excessive heat. After you posted this, another guy asked for more information on the subject.

I've been in business selling coatings and resins and repair materials for 30 years, and I've learnt not to recommend any product which may be used in a life threatening situation without scientific evidence that it will perform. All the tech depts of the numerous companies I worked for would squash any such idea immediately. That is why we have standards on all sorts of products.

I doubt you are an expert in this field, and the fact that you have had no problems doesn't mean that it won't happen. I hope you have good liability insurance, although somehow I doubt it.

All I want you to do is moderate the forum, not trailblaze ideas that aren't proven, and hold potential danger. Our terms and conditions absolve us of anything you say, but it could still cause a problem if a hungry lawyer got hold of it. But worse, you and I, would be completely guilt ridden if we discovered that someone died as a result of your most unscientific assumption that just because YOU had painted 300 wheels with no problems to date, it was ok. Maybe testing will show that the wheel will fail in 2 or 3 years?

A customer raised a red flag here, we cannot afford to glibly shrug off the problem.

If someone comes back with specific evidence saying that alumiunum type X is ok to 450 f, then we know what to tell our customers. Whatever the outcome, we need to know the truth. Until then, I hold the red flag high!

Now, if you don't like that, its too bad. I'll be sorry to see you go. I was hoping that you would take some direction and realise that we are trying to protect our, and your, interests. Maybe you'd like to rethink this, but I'll tell you now, our position on these things will not change.


Mike Caswell

Customsounds says:

You know what .. I am done here. there is no problem in the post .. it is the truth .. remove me and i will be gone .. I had it[/quote]

[mcaswell]

http://naca.larc.nasa.gov/reports/1956/naca-tm-1419/naca-tm-1419.pdf check this link for the effects of heating aluminum.

[daveg]

Thanks for the link.

I have to agree with Caswell, better to err on the side of caution and find the correct information from someone who knows rather than find out the hard way. Granted many aluminum alloys you will get away with heating with no ill effects, but there are the exceptions, and without knowing what you're dealing with, you're taking someone's life in your hands and could be ruining any future life you may have. Just something to think about....

David

[sswee]

Just an idea for some. I've worked machine shop for years and dealt with aviation parts some of which were heat treated. If a heat treatment business can be found local give them a ring and check with them on the effects on aluminum. SS

[bzer1]

If you would like I can try to find the pdf format of the metalurgists reference that I bought and you can make it available as a download. It is definately public information and I believe it is used by the military to create their milspec standards(at least that's the claim in the book). If I can find it I will submit the link for anyone who wants to take the time to read it. I must warn you that it's very boring but the charts are easy to understand. However it is incumbent on the coater to coax the info out of the customer or manufacturer before applying any knowledge gained. I recently emailed a manufacturer asking for information on materials used in their product. It took a few days but I got a call from an engineer who gave me the info I needed. Better safe than caught in a law suit or reading about your mistake in the obituaries. With alloys getting more exotic everyday I like to be sure before I cure. Corny but a good policy I think.