Powdercoat wheels = Weak rim strength?

[Jack Rabbit]

Does powder coat = a weak rim??

Apparently you need to be in charge of the whole powder-coating process from start to finish to make sure it's done right.

Supposedly high temperature over 200° can anneal & weaken some aluminum/alloy rims. And powder coats are usually baked on at 350 to 450° ... though there might be low temp powder coats out there.

But the shop could tell you one temp and bake it at another.

Also, some say sandblasting ruins the rims and causes microscopic cracks. Unless they blast with walnuts...apparently walnuts are safer.

Has anyone successfully ran powder-coated cast (low pressure cast) rims with no problems and no rim cracking, etc.?

Did they use walnut blasting and did they use low temp/bake powder coat ?

and were they OEM or aftermarket rims?

Just found out the local place doesn't use walnuts and they cook at 375°. At least it's not 450°. Heard 450° will completly destroy an alloy wheel.

And can't get bi-color rims or the machine flanged look. They only do one(1) color so need to make sure it's a color goes well with machine gray.

 

[ColtX-5]

Aluminum anneals at 650F to 775F depending on alloy. That's permanent. It also may take 2 - 3 hours at temperature.

How to Anneal Aluminum: The Beginner’s Guide | Make it From Metal

Lots of people are surprised when they hear that aluminum can be annealed. Since it's already a soft material, why do you need to make…

makeitfrommetal.com

Aluminum loses about 50% of its strength at about 525F, but that is not permanent and is will return to normal at room temp.

Overview of aluminum alloy mechanical properties during and after fires - Fire Science Reviews

Aluminum alloys are increasingly being used in a broad spectrum of load-bearing applications such as lightweight structures, light rail, bridge decks, marine crafts, and off-shore platforms. A major concern in the design of land-based and marine aluminum structures is fire safety, at least in...

firesciencereviews.springeropen.com

 

[hal2]

A good shop, as with any trade, should know how to do it, as well as know what they can and can't do. - maybe I'm being naive

 

[Jack Rabbit]

Aluminum anneals at 650F to 775F depending on alloy. That's permanent. It also may take 2 - 3 hours at temperature.

How to Anneal Aluminum: The Beginner’s Guide | Make it From Metal

Lots of people are surprised when they hear that aluminum can be annealed. Since it's already a soft material, why do you need to make…

makeitfrommetal.com

Aluminum loses about 50% of its strength at about 525F, but that is not permanent and is will return to normal at room temp.

https://firesciencereviews.springeropen.com/articles/10.1186/s40038-015-0007-5[/URL

Interesting.

I'm confused.. some research papers say aluminum alloys molecular structure can start to change at as little as 200° F and starts to accelerate change at 250° F.

And that it depends which alloy your wheels are made of...alloy 1100, 1200, 1500, 1700 , etc. Certain alloys will be weakened.

Gonna be hard to even find which alloy the stock rims are made of ..doubtful even aftermarket rims publish the alloy type.

Apparently the forged rim alloy is the toughest and able to withstand powder-coating.

All cast or flow-formed rims are apparently aged by the process & weakened with increased brittleness.

But then again I've never seen anyone with Powdercoat have problems. But maybe just haven't met those folks yet.

I really want to get Powder-coat but don't want to ruin the rims either.

 

[Gaspar]

I believe that would be 200c.

 

[Jack Rabbit]

So went to the engineering boards...

Apparently most cast wheels use
Alloy 356-T6 aged @325°F

While forged is 6601-T6 aged @ 350°F.

Any exposure (even 10 minutes) above their aged temperatures can age the wheel further, weaken the wheel & increase it's brittleness factor.

Usually Powdercoat is done at 375° to 400° F for an hour or more.

Supposedly it will weaken the wheel, maybe not significantly but will change it from a T6 to T7 condition.
Not sure how much affect this would have on an already 20 year old OEM high mileage wheel. But apparently some manufacturers like Enkei void the warranty if Powdercoat.

Need to re-think this and maybe find shop to get sandblast and painted instead.

Or since it's a cast alloy, inquire if they can only bake the powder @325° F and no higher. and then hope they actually do it @ 325°.

They were only $160 for the OEM rims but want them to last..

Probably should have gotten the new Montegi's instead.

 

[Jack Rabbit]

Decision has been made...

The few different engineering and metalurgical forums have seen say that powder-coating heat process weakend most alloy rims.

So am going to do something different.

Since rim stripping/ cleaning can be time consuming & tedious.

Instead of DIY stripping/ cleaning the rim,
will be searching for sandblaster company that uses walnut media.

Then instead of Powder-coat, will be DIY painting & clear-coating the rims myself.

This appears be best option to have quality prepped base rim to start with, and be able to control the color choice as well as the priming & painting process without potentially weakening the rim by Powdercoat.

Added bonus is should save some $$$.

 

[186746]

It’s always funny when someone who isn’t an expert tries to read things on the internet and then makes a bunch of poorly thought out statements. I would suggest educating yourself better, but your posting history points to the fact you like to type a bunch of non-sense around your ill informed ideas and concerns.

For others reading the thread, no, the temperatures and length of time at those temperatures used in the powder coating process will not impact the structural integrity of an aluminum alloy wheel. If you want actual facts, do your own research and don’t read Jack Rabbit’s statements which are fraught with incorrect values and false assumptions.

 

[Jack Rabbit]

It’s always funny when someone who isn’t an expert tries to read things on the internet and then makes a bunch of poorly thought out statements. I would suggest educating yourself better, but your posting history points to the fact you like to type a bunch of non-sense around your ill informed ideas and concerns.

For others reading the thread, no, the temperatures and length of time at those temperatures used in the powder coating process will not impact the structural integrity of an aluminum alloy wheel. If you want actual facts, do your own research and don’t read Jack Rabbit’s statements which are fraught with incorrect values and false assumptions.

1st off I never said I'm an expert and always post the positive and negative as accurately as possible.

I try to post what I find that is as factual as possible.

If it's from first hand experience, I post my actual findings(weights, mpg, rim clearance, etc.). Those are factual postings.

I haven't found metallurgical opinion that it is a good idea to re-bake wheels at a higher temperature than what they were aged at. All highly recommend against it as they state anything above 300°/325° F will weaken the cast alloys. Unless can find a low bake powder-coater... As there are some low baking processes.

Even Enkei and some other manufactures void warranties for powder coated rims.

And some of my posts usually do tell people to do their own research. Should we all write disclaimers on every post to " do your own research" ?

My question to you...is are you a metallurgist engineer ? to make your above statement "powder coating process won't impact the structural integrity of aluminum alloy wheel" ?

If you are then I will take your experience under advisement and seriously consider your post that powder coat won't weaken the rims.

Otherwise I'll assume your posts are fraught with hypotheticals and guessing game with my rims. I'd rather be on the safe side.

Before I post anything else on this subject, I'll check with some rim manufacturers, and Mazda corporate as well as see if I can find a metallurgist...

And just like you say to others on your posts, do you have any facts to back up your opinions ? that Powdercoat heat above 300/325° F won't damage rims and can you please post them?

From your posting history you like to question others without providing your own facts.

Update: have sent one inquiry to rim manufacturer and am awaiting answer.

 

[Jack Rabbit]

Ok. One large well respected manufacturer has already responded.

They only paint their rims for a reason. The powdercoat heat can alter/weaken both cast and forged rims and actually be extremely detrimental to the forged. They recommend against powder coat and will void warranty if a rim is altered/ powder-coated.

Of course this is only one manufacturer and maybe some are ok. You will need to check with your own manufacturer.

And this is disappointing to me as really wanted to get them powdered.

I apologize to the board as I thought it would be easier to get answer from the board while sharing information. Maybe I need to inquire of the manufacturers from now on.... Instead of being heckled?

 

[murky]

Some links would be nice, to provide the context for the assertions.

 

[Jack Rabbit]

Some links would be nice, to provide the context for the assertions.

Myself? Its hard to provide Links from mobile but will login from computer over weekend.

Still no response from any more manufacturers but will post once get response.

Would be nice if those claiming that powder-coating was ok/safe provided links as well.

One thing to say and dispute gas mileage or cargo shelfs.
Quite another to claim something is safe when it might not be.

Best case is nothing happens or a weak rim breaks offroad gets you stuck. Worst case is weakened brittle rim falls apart on daily driver at highway speed and cause injury/ fatality.

I started this not knowing anything about the powder-coating process and thinking it was safe...but didn't make any wild claims regarding rim structure integrity without some research and always err on the caution side. When buying rims one always check the load rating to make sure it is sufficient for the vehicle... Why wouldn't one also make sure nothing weakens or reduces that load rating?

And there might very well be some aftermarket rims who are not compromised by Powdercoat. Am waiting to hear back.

 

[Jack Rabbit]

Ok..
large highly reputable manufacturer #2 responded.

Apparently they prime(prime only) with powder coat(assuming at low temp) some of their rims, then liquid paint finish and clearcoat.

Customer powder coating voids warranty and also, per their response causes/compromises structural integrity.

So far 2 of 2 wheel manufacturers say powder coat voids warranty & compromise structural integrity of rim.

And to be fair, I really wanted to powder coat my wheels.

 

[186746]

1st off I never said I'm an expert and always post the positive and negative as accurately as possible.

I try to post what I find that is as factual as possible.

If it's from first hand experience, I post my actual findings(weights, mpg, rim clearance, etc.). Those are factual postings.

I haven't found metallurgical opinion that it is a good idea to re-bake wheels at a higher temperature than what they were formed at. All highly recommend against it as they state anything above 300°/325° F will weaken the cast alloys. Unless can find a low bake powder-coater... As there are some low baking processes.

Even Enkei and some other manufactures void warranties for powder coated rims.

And some of my posts usually do tell people to do their own research. Should we all write disclaimers on every post to " do your own research" ?

My question to you...is are you a metallurgist engineer ? to make your above statement "powder coating process won't impact the structural integrity of aluminum alloy wheel" ?

If you are then I will take your experience under advisement and seriously consider your post that powder coat won't weaken the rims.

Otherwise I'll assume your posts are fraught with hypotheticals and guessing game with my rims. I'd rather be on the safe side.

Before I post anything else on this subject, I'll check with some rim manufacturers, and Mazda corporate as well as see if I can find a metallurgist...

And just like you say to others on your posts, do you have any facts to back up your opinions ? that Powdercoat heat above 300/325° F won't damage rims and can you please post them?

From your posting history you like to question others without providing your own facts.

Update: have sent one inquiry to rim manufacturer and am awaiting answer.

Again, just like with your facts, your reading comprehension of my post shows how you either don’t take the time to fully read or can’t understand what’s being said. You stated inaccurate values for aluminum annealing, mixing Fahrenheit and Celsius, you stated most cast wheels are formed at 325 degrees Fahrenheit. In order to cast, the metal is melted and poured. Aluminum melts around 1220 degrees Fahrenheit (660 Celsius), so that’s just wrong even if you used mixed values and scales.

Sure, here’s an example: Multiple well known aftermarket wheel manufacturers powder coat their wheels from the factory: Forgestar, Forgeline, Lexani as a few of the bigger names.

Manufacturers who warn against powder coating wheels are simply absolving themselves of any liability in a case where someone does something stupid to their wheel during the process. It’s standard corporate legal practice. The discussion about weakening wheels seems to only exist on forums when someone brings up the topic, and real world examples never seem to be produced.

 

[Jack Rabbit]

Again, just like with your facts, your reading comprehension of my post shows how you either don’t take the time to fully read or can’t understand what’s being said. You stated inaccurate values for aluminum annealing, mixing Fahrenheit and Celsius, you stated most cast wheels are formed at 325 degrees Fahrenheit. In order to cast, the metal is melted and poured. Aluminum melts around 1220 degrees Fahrenheit (660 Celsius), so that’s just wrong even if you used mixed values and scales.

Sure, here’s an example: Multiple well known aftermarket wheel manufacturers powder coat their wheels from the factory: Forgestar, Forgeline, Lexani as a few of the bigger names.

Manufacturers who warn against powder coating wheels are simply absolving themselves of any liability in a case where someone does something stupid to their wheel during the process. It’s standard corporate legal practice. The discussion about weakening wheels seems to only exist on forums when someone brings up the topic, and real world examples never seem to be produced.

Again you seem to misunderstand.. .
Two manufactures have responded and could have left it at saying 'it voids warranty." but went on to caution that structural integrity would be compromised and wheel weakened.

Your fairytale land would have people believe a big mac a day doesn't cause heart-attacks and smoking doesn't cause cancer. At least let people know the possible negatives and take the risk themselves. People still eat bigmacs and smoke and will probably powder coat rims but it appears it does weaken the rims .

 

[Jack Rabbit]

Alloy Wheels - Painted or Powder Coated? Which is best?

Alloy wheels painted or powder coated from the factory? Should you paint or powder coat your wheels when you refurbish them? This articles explains the pluses and minuses and which method to avoid.

strikeengine.com

See attachments below.

Also, Inquired of six different manufacturers and received two(2) responses that recommend against powder coat and the rim companies noted that powder-coat heat ranges WILL ALTER the structural integrity of the wheel.

One has to remember that alloy wheels are not just aluminum but combined with other metals like silicon(7.5 %) and magnesium(approx. 1/2 to 1 %) which might be weaker. The rim is only as good as it's weakest link. it sounds as if not only is the aluminum altered at powder coat temps, but apparently something happens to the silicon crystallization when reheated, especially at powder-coat temps and magnesium, well hey its magnesium.

Also, from what am learning so far, it appears that some wheel manufacturers may powder the prime process @ low temps(that is key), but then liquid paint(am assuming they mean spray paint as well) and clearcoat the rims without any further heating process.

If there are any aftermarket manufacturers that do a full color powder coat, it would be interesting to find out what temp and time they bake at. Most likely it's a low bake.

Be aware that a manufacturer Powdercoat at controlled temps/times which has a vested interest in limited liability is different from taking your wheels to a shop for a Powdercoat re-bake where you have no control over what temp and time they bake your wheels, nor how lax their quality control is(f.e. baking at higher temp or leaving in longer)

My original post was concerned with having my wheels re-done not a factory powder-coated finish.

From metallurgy boards, Aging temperatures for alloy 356-T6 is between 310 and 325 F. Going above those temps(which most powder-coaters do) can alter/weaken the wheels. Some research even suggest that any temp above 200 F can start to cause changes in the alloy. Again you would need to consult a metallurgist.

Can wheels be powder-coat? yes

Can it alter/weaken the alloy structural properties? Yes, it appears so, especially dependant on cure temperature & length of cure. Higher, hotter and longer may mean less strength and more brittle.

How much will rim be weakened with increased brittle? A metallurgist would best answer your question as it depends on the alloy and what it was combined with, the curing temperature and the for how long it was heated.

Will it be unsafe to drive on? Depends, so far two(2) of the manufacturers appear to think so and have advised against it.

Will I powder coat? probably not. Will get professional sandblast and paint.

Local shop here powder coats at 375 F. Seems alot of shops, at least in USA powder @ 375, 400, 450 F, etc. Found a shop in Australia that only powders @ 180 F so the alloys aren't altered/weakened but still achieves a decent powder-coat. *;Powdercoat can cure at as little as 160 F. Don't understand why shops here can't powder at lower temps. Think it has to do with $$$, quicker in, quicker out.

It appears that powder coat itself isn't the issue, it's the high temps that shops want to bake them that causes potential issues.

Sadly if you want powdercoat, you may be better off buying an old stove, keep it outside, spray/powder the wheel yourself and bake it at 180 F.
At least you can low bake & control the process. Please be advised there could be ramifications from breathing any gases , consult the powdercoat msds and wear appropriate PPE masks, etc.

Again do your own research and contact your own wheel manufacturers, etc. and take your own risks.

 

[Jack Rabbit]

Out of six(6) inquiries, three(3) have responded .

The tally

Two(2) - No to powdercoat. Alters/weakens the structure of rim.

One(1) - Avoidance. Wouldn't provide the temps they powdercoat at nor a response as to if alters/ weakens the rim. Tried the sell me rims but didnt answer any questions.

Zero(0) - yes. No responses that it is ok to powder coat.

Waiting on three(3) remaining responses.

 

[Mazdiod2]

Some people use that Plasti dip stuf. I don't have experience with it.

 

[sm1ke]

I apologize to the board as I thought it would be easier to get answer from the board while sharing information. Maybe I need to inquire of the manufacturers from now on.... Instead of being heckled?

No need to apologize - we are all here to share information and learn about our shared interests.

Usually this is exactly what happens, but sometimes passion and misunderstandings get in the way.

It’s always funny when someone who isn’t an expert tries to read things on the internet and then makes a bunch of poorly thought out statements. I would suggest educating yourself better, but your posting history points to the fact you like to type a bunch of non-sense around your ill informed ideas and concerns.

For others reading the thread, no, the temperatures and length of time at those temperatures used in the powder coating process will not impact the structural integrity of an aluminum alloy wheel. If you want actual facts, do your own research and don’t read Jack Rabbit’s statements which are fraught with incorrect values and false assumptions.

It's perfectly fine to disagree with someone else's posts, but please at least be civil about it. You can provide counterpoints without making assumptions about someone else's character. Again, we're all here to share information and learn.

 

[186746]

No need to apologize - we are all here to share information and learn about our shared interests.

Usually this is exactly what happens, but sometimes passion and misunderstandings get in the way.




It's perfectly fine to disagree with someone else's posts, but please at least be civil about it. You can provide counterpoints without making assumptions about someone else's character. Again, we're all here to share information and learn.

Yes, by all means encourage the blatantly incorrect information that was shared, and then call me out for bringing that to light and telling others to do their own research rather than use this shared “information”. Someone in the thread did say the below…. Oh wait that was the guy you’re encouraging….

Your fairytale land would have people believe a big mac a day doesn't cause heart-attacks and smoking doesn't cause cancer.

You moderators here run one of the worst forums going, with a dreadful level of activity. I’ll move on and let you pat everyone on the back for posting incorrect information and using the forum as their personal blog to blather on and on to themselves. I’m sure you’ll remove this post soon enough, but thought I’d write it anyone in hopes you might improve the forum for the very few active posters.