Powder coating my wheels.

[highonthai]

Very nice work!

Thanks,
I've powder coated allot of wheels over the years, including the wheels on my bikes and my off road race cars. (Baja500/1000) never had a failure due to powder coating. Tons of other stuff has broken though that were not powder coated or anodized.
Thanks for the compliment.

 

[mzflorida]

Thanks,
I've powder coated allot of wheels over the years, including the wheels on my bikes and my off road race cars. (Baja500/1000) never had a failure due to powder coating. Tons of other stuff has broken though that were not powder coated or anodized.
Thanks for the compliment.

Honestly, though I've never looked to see if a diy er could powder coat, this is the first time I've seen it. Probably better that way as I would have powder coated everything and the dog. I've also broken a lot of crap over the years, most of it through my own faults!

 

[hulkss]

Around 400F tends to be the worst temp for most aluminums for degradation (except during artificial aging immediately after heat treat, but once the max properties are achieved, things drop off pretty quick). Time-at-temperature is going to play a major role, but where wheels have relatively thin spokes, I'd imagine there's a strong chance that strength is reduced. I've seen claims of between 30% and 55% reduction in strength for different alloys from 400F temperatures.
It's entirely possible the relatively short baking time had negligible impact, or that the wheels are so overdesigned that the reduction in strength is acceptable, but there isn't an easy way to know how much reduction and if it's still good. I'd be particularly concerned with fatigue
I'd recommend finding a lower temp cure coat for aluminum, but that's just me.

Using safe temperatures for the wheel alloy will prevent any problems.
My main concert would be a reduction in fracture toughness. The wheels may then fracture from an impact as in this powder coated example:

 

[Rabbit]

I had no idea aluminum alloys were so temperamental. I work in steel and 400f isn’t enough to wake the dog up for.

 

[Rapturee]

wow, i too have TIG'd a lot of aluminum and even "Cerakoted" a ton of parts over the years at/close to 400f myself(though i have never tried to powder coat anything, nor has the thought even cross my mind to do so) and i have never had any problems or herd of them until the aforementioned post... good to keep in mind.

 

[highonthai]

Well for starters, who ever did the powder coat on those wheels was a hack. Take a look at the globs from the spray. Who knows what they did as far as temp and oven time. And who knows what they did to that wheel to make it fail. (some kind of boy racer?)

Also I'm not sure why your so against powder coating and what your back ground is? ( metallurgist?)
Without trying to be a brag, and I didn't even want to to there. But, I have been a factory R&D rider for Honda Japan (RSC/HRC), and a designer for Yamaha GYTR USA, also a Baja Racer for years. And you?
Let it just rest. Point taken.

 

[potter0o]

Very interesting topic. I would not have thought of this issue without the associated posts. If you research the subject you can make up your own mind.

 

[hulkss]

Well for starters, who ever did the powder coat on those wheels was a hack. Take a look at the globs from the spray. Who knows what they did as far as temp and oven time. And who knows what they did to that wheel to make it fail. (some kind of boy racer?)

Also I'm not sure why your so against powder coating and what your back ground is? ( metallurgist?)
Without trying to be a brag, and I didn't even want to to there. But, I have been a factory R&D rider for Honda Japan (RSC/HRC), and a designer for Yamaha GYTR USA, also a Baja Racer for years. And you?
Let it just rest. Point taken.

The globs are road debris stuck to the wheel. I'm not against powder coating. I'm against making a wheel potentially unsafe. Powder coating can be done at temperatures below 400 F.

My background is in Mechanical Engineering including Material Science of metals.

 

[TheIronWarrior]

I had no idea aluminum alloys were so temperamental. I work in steel and 400f isn’t enough to wake the dog up for.

At work (international aerospace technical and maintenance organization, primarily military contracts) we can HT aluminum all day long no problem, but have to sub-contract out steel treats because our ovens aren't hot enough.
We also have to sub out aluminum welding because it's fairly highly specialized (read: you can really fuck it up). At least for aerospace grade welding.

The globs are road debris stuck to the wheel. I'm not against powder coating. I'm against making a wheel potentially unsafe. Powder coating can be done at temperatures below 400 F.

My background is in Mechanical Engineering including Material Science of metals.

I've read of some coats that bake at 250F or less. These might be more appropriate for Al.
I'm an aerospace mechanical engineer, but we have a whole (separate) materials and process engineering department (it's been a long time since I've had to look in detail at many "materials" related issues). I'm sure they would have more insight than I would into the properties of aluminum, but based on the references I have access to, the aluminum casting that responds "best" to higher temperatures still loses about 30% of it's strength if heated to 400F. Other alloys and tempers lose over half their strength. Something tells me that they wouldn't select the alloy for the wheels based on it's response to high temperatures, especially when cost and ease of manufacture are at odds.

Just like everything, it will be fine right up until it's not, so saying "I've done it for years and it always worked out fine" doesn't inspire much confidence in me. I've had some pretty major problems to solve from something that's been "done this way forever" when the luck runs out. For example, an aircraft had the boost pack removed from the elevator, so the bell cranks were ratchet strapped to prevent movement. The wind picked up and snapped the straps. The elevators got beat to shit. This isn't the first time straps were used in this way, but it sure as fuck was the last.

It's entirely possible (but nearly impossible to calculate) that the wheels are still serviceable after baking, but without test coupons and pull tests, or MAYBE some NDT of the wheel, you can never know for sure, especially without knowing the design load cases.
Schrodinger's wheel, it's both serviceable and unserviceable until it fails.

 

[CapeMan]

At work (international aerospace technical and maintenance organization, primarily military contracts) we can HT aluminum all day long no problem, but have to sub-contract out steel treats because our ovens aren't hot enough.
We also have to sub out aluminum welding because it's fairly highly specialized (read: you can really fuck it up). At least for aerospace grade welding.


I've read of some coats that bake at 250F or less. These might be more appropriate for Al.
I'm an aerospace mechanical engineer, but we have a whole (separate) materials and process engineering department (it's been a long time since I've had to look in detail at many "materials" related issues). I'm sure they would have more insight than I would into the properties of aluminum, but based on the references I have access to, the aluminum casting that responds "best" to higher temperatures still loses about 30% of it's strength if heated to 400F. Other alloys and tempers lose over half their strength. Something tells me that they wouldn't select the alloy for the wheels based on it's response to high temperatures, especially when cost and ease of manufacture are at odds.

Just like everything, it will be fine right up until it's not, so saying "I've done it for years and it always worked out fine" doesn't inspire much confidence in me. I've had some pretty major problems to solve from something that's been "done this way forever" when the luck runs out. For example, an aircraft had the boost pack removed from the elevator, so the bell cranks were ratchet strapped to prevent movement. The wind picked up and snapped the straps. The elevators got beat to shit. This isn't the first time straps were used in this way, but it sure as fuck was the last.

It's entirely possible (but nearly impossible to calculate) that the wheels are still serviceable after baking, but without test coupons and pull tests, or MAYBE some NDT of the wheel, you can never know for sure, especially without knowing the design load cases.
Schrodinger's wheel, it's both serviceable and unserviceable until it fails.

A well-made case ... you've convinced me, at least.

But I'm most impressed by "Schrodinger's wheel, it's both serviceable and unserviceable until it fails." Wordsmithing at its finest! My helmet's off to you, sir.

 

[showkey]

Just a word of caution…….there are 10’s of 1000’s of broken rims in cars and trucks. Many of which had low profile tires and sharp edge pot holes, rough rail road tracks, curbs and other large road defects. Low profile tires often play a very large part of the rim damage. So making engineering decisions based on internet pictures has its own problems.

Yes…….. powder coating vehicle rims and the potential issues is a very common topic on many forums.
Aluminum wheels are almost always painted at the factory.

 

[hulkss]

Just a word of caution…….there are 10’s of 1000’s of broken rims in cars and trucks. Many of which had low profile tires and sharp edge pot holes, rough rail road tracks, curbs and other large road defects. Low profile tires often play a very large part of the rim damage. So making engineering decisions based on internet pictures has its own problems.

Yes…….. powder coating vehicle rims and the potential issues is a very common topic on many forums.
Aluminum wheels are almost always painted at the factory.

Yup, a good reason not to make things worse than than they already are.