Powder Coating Hubs and Cylinders

[inxs]

- this was interesting... powder coating for motorcycles

- Powder Coating Course Workshop-2 day

 

[inxs]

- had this on file..no idea where it comes from, perhaps from here.. eastwood.com powder coating forum f=9

Powder coating aluminum.


Q. I have a small powder coating shop and I have some customers that want their rims powder coated. Some of them are cast aluminum and others are milled out of billet. Do I need to use a special powder and cure temperature for these types of aluminum ? The powder I currently use cures at 400 [degrees] F for 20 min. Would this temperature have an effect on the properties of the aluminum? K.P.

A. I don't know why I get so many metallurgy questions. It makes you think that just because someone puts a powder coating over something that all of a sudden the powder magically transforms all product problems into powder coating problems. Just because you sprinkle sugar on your oatmeal doesn't mean that the "sugar expert" knows anything about the growing of oats or the making of the breakfast cereal. Anyways, now that I vented a little, I will offer some sage advice.

Let's first review some facts. Aluminum products are often powder coated, especially wheels. Some aluminum products are temperature sensitive, especially those that have temper or heat-treated properties. It is a well-known fact that aluminum can loose those temper properties when heated above a predetermined threshold (this is called annealing). How much the properties are affected depends upon the alloy of aluminum, the temper rating, the exposure temperature and the time the aluminum is exposed to that temperature.

You asked specifically about cast and billeted aluminum wheels. This is not enough information for me to give an accurate answer. You should check with the wheel manufacturer for temperature limitations before coating. At least obtain the alloy and temper rating, if any, for these products. Then you can look up the information online or check with a Metallurgist. You will probably need to use a low-temperature cure powder material and cure it for a longer time at the lowest possible temperature on the cure curve to ensure some safety margin.

 

[mule]

I would say there is no relationship between powdercoating and aluminum breakage. Where I get my stuff done, and I've had at least 250 frames done, probably 75-100 sets of mag wheels(aluminum) and at least 20 sets of wire wheel hubs, I've never broken a single hub or wheel. And that includes crashes! The ovens are generally at 350 degrees and it's only about 15 minutes. Could be an hour of pre-heating prior to coating. But I heat hubs up all the time in the oven or barbie to over 350 just to drop in bearings!

Maybe somebody broke a hub somewhere once, but that would definitely be the rare exception and most likely unrelated to powdercoating!

If you paint your engine black and it's dark out, how will the heat know what to do?

Aluminum dissipates heat because of it's metal properties and the fact that microscopically, it's porous. It looks like a mountain range under a microscope. Fill it all in with nice smooth paint or powdercoat and it's got much less surface area resulting in decreased cooling.

Look at all the motogp engines. NONE are painted black. And I would bet you could cook a steak on one of those engines during a race! If black was better, they'd be black.

Exhaust systems are ceramic coated to keep IN the heat to make more power.

 

[big al]

I checked with my powder coating guy and he does it at 400 deg as well and there;s been no problem and he's been at it for years.

 

[mwzephyr]

mwzephyr here. 1st post.
25 years in powdercoating ~ran a shop, painted, stripped- did my own work and trained painters, and ran production for all types of metal substrates. Also ran production wet paint lines, including robots, for OEM automotive parts suppliers to Toyota, Gm, and Mitsubishi. I did the time and learned the stuff right.

Powdercoating under normal circumstances is not recommended for cylinder heads. Temps on low cure powders won't hurt alum cylinders, but probably will burn off at higher temps. Also who wants to hold the heat into their heads? Thats why they are aluminum ...

Average powder coating temps are from, 325* average to 450*f.
Pre cleaning is the most imporatnt key to sucess. A good phosphate rinse in the cleaning process will help to prevent corrosion and improve the bond between the part and the powder.

Wheels are ok- rims ok.

Hubs, not a good idea, plating is better or anodising. Plating~ Strip, acid copper, copper, nickle then chrome. Also worked at a plater for a year.

Save the powder coating for tanks, bars, housings, fenders, frames are a natural.
There are high heat tolerant powdercoatings for engine related parts- Dupont makes them.
They work best for Automotive ( did several engines most parts on my own rods). But never never cylinder heads. Manifolds only if bolted -torqued down to custom made plattens so they don't warp or to old blocks if you're into production. Gotta torque em down dudes or you'll be crying later...
Valve covers are a natural... But I'm getting off topic.

But it's not a laugh when you pay big bucks for a coating that burns off when the parts get hot... Covers and cowlings are a damn beautiful sight if you work with progressive masks and powdercoatings. Need to find an artist for that kind of work. I am out of the business,
but it is similar to airbrush work if the painter/coater is an artisan who understands, materials, heat, and has a steady technique.
The expensive automotive quality powders are avalaible but can cost better than 500$ a box. But you can't beat the results.
Main thing is to make sure layers are of compatible powder materials, and that the layer thicknesses are are very thin or they will chunk out and look like shit.

Thin layers are durable, heavy layers will shatter and lift.
I don't recommend more than three layers, the clear coat being one of them.
Don't go for high gloss. Pebble, flat and semi gloss look best.

Dwell time in the oven also is important because thin substartes will soak up heat differently than cast parts, billet parts, tubes etc. Each different type of material should be baked seperately. If you were a baker you wouldn't cook cookies with bread and pizza at the same time in the same oven...
ALWAYS do a sample mockup of the pattern and layers on some scap sheet before,
you work on the actual parts. Powder coating needs to be removed usually by methylene chloride- badd ass shit-media blasting, or by putting in a burn off oven- not good for bike parts.
Tanks are better left to wet paint, as fuels usually discolor and lift even with the best materials.
We used to do side jobs on farm equipt, motorcycles, rod parts and trucks too.
Take your time and ask all the questions. It's too expensive to make a mistake.

Find a dude who has experience with the media, it takes a lot of failures to get it right. Let some other guy pay. Find the right dude and watch him work.
Powder coating needs to be extremely clean, no oils, silicones, lint, dust, no finger prints.
But this is what the big boys use so there should be someone out there who can help.
Electronics enclosure on the expressways are powder coated. A good job lasts for decades. A cheap shoddy job will look like shit in one season.

mules got it right.

If you have an imperfect part or it looks like shit, the powder coating will only make it look worse. Powder coating hides nothing; it magnifys the imperfections.

Any tech questions,
serious only,
I will help. Just pm me.
Zep

 

[mule]

Very good stuff!

 

[71XS1B]

Well... Here goes my 2 cents...

I am fairly certain that the hubs are cast aluminum alloys.

Heat treatment of cast, extruded and forged aluminum alloys is accomplished at temperatures between 850ºF - 1050ºF. This process allows alloying elements to diffuse evenly throughout the metal. The process takes anywhere from a single minute for thin sheet to 24 hours for large cast items.

Precipitation Heat Treatment or Artificial Aging of aluminum alloys is accomplished at temperatures as low as 250ºF - 350ºF. Artificial aging enhances the structural properties (Yield Strength) of the alloy.

Annealing of aluminum alloys is accomplished at temperatures between 300ºF - 600ºF and dependent on the the alloy and mass of the item being annealed, can require heat soaking for as much as 24 hours. Annealing softens the alloy to make it workable.

Conclusion: There is the possibility that the powder coating process can alter the structural properties of your hub.

I suggest trying to find a powder-coater that uses the lower curing powders or repaint the hub using conventional painting processes. (Alodine, 2-part epoxy primer & polyurethane enamel)

Cheers... Dan

 

[xstwin]

Powder coating both 6060 and 7005 can be done safely if you use a powder that melts at 300 or less. Aluminum molecule will start to change shape at 410 degrees causing brittleness to occur. Cast becoming the weakest after a heating there's pictures on the web of powder coated cast rims with the whole hub cracked right out of the spokes.I"m not to common with the lower temp powders,usually 325-450 is the range I"m familiar with. There"s a billion company's using and selling powder coated rims out there,I would say there's a good bet some of these could be faulty due to the fact there's no watchdog for such industry.
,

 

[txpowdercoater]

I bake at 350-375 with rims, and hubs, I also do tons and tons of cylinders and heads and I bring them up to temp and back down when done very slowly to allow the different metals to expand and contract w/o unseating valve seats or steel cylinder sleeves in aluminum cylinders. That being said I havent had one customer come back and say anything about temps, that would lead me to conclude the issue hasnt been a real issue at all.

 

[txpowdercoater]

Zep, I have to say I disagree with a lot of what you have said here, and seriously not trying to start any crap, but my work and results definately make a lot of your statements false.
I can produce amazing multi layered work, sometimes over 30 different layers of powder and effects and I wont explain how its done due to the effort it took to solve and discover.
I also can hide all kinds of material imperfections with a little powder and some wet sanding time.
also, there are tons and tons of powders on the markets that are happy on engines, not the exhaust manifolds, but basically, most of the powders on the market are very happy on engines, heads etc etc, the cure temp is at the 325 range and the motor runs at 200 range, its definately not an issue, the issue is whether its sealed properly with a good fuel resistant clear topcoat where applicable, like intake manifolds where fuel spillage might occur. Dupont has a great high gloss fuel resistant clear called Diamond Dust.
I have done tons and tons of intakes and engine parts, even super thin trim pieces, grill shells etc etc etc and never had warpage of any kind due to heat, none, FACT.
I do agree with the "prep is the key" statement, the initial prep I do and also the between layer prep is the key to my powder success.

why not go for the high gloss look with powder? that statement doesnt make sense...There is definately an art to making it right, but totally do-able with ease and done on a daily basis in my shop... again, please see my web listed in my sig for further proof of my statements.

I do a lot of motorcycle tins, lots of show cars and such, many moto tanks still on the road and looking as new as day one, thats 5 years in the sunlight and weather and occasional fuel spills.

Again, not at all trying to start a war here, just trying to get the correct information about powder coating out there, everything I said is documented in my previous work and what is done on a daily basis.
I also am here and willing to answer questions.
Timothy
www.TxPowderCoating.com
832-818-3905

mwzephyr here. 1st post.
25 years in powdercoating ~ran a shop, painted, stripped- did my own work and trained painters, and ran production for all types of metal substrates. Also ran production wet paint lines, including robots, for OEM automotive parts suppliers to Toyota, Gm, and Mitsubishi. I did the time and learned the stuff right.

Powdercoating under normal circumstances is not recommended for cylinder heads. Temps on low cure powders won't hurt alum cylinders, but probably will burn off at higher temps. Also who wants to hold the heat into their heads? Thats why they are aluminum ...

Average powder coating temps are from, 325* average to 450*f.
Pre cleaning is the most imporatnt key to sucess. A good phosphate rinse in the cleaning process will help to prevent corrosion and improve the bond between the part and the powder.

Wheels are ok- rims ok.

Hubs, not a good idea, plating is better or anodising. Plating~ Strip, acid copper, copper, nickle then chrome. Also worked at a plater for a year.

Save the powder coating for tanks, bars, housings, fenders, frames are a natural.
There are high heat tolerant powdercoatings for engine related parts- Dupont makes them.
They work best for Automotive ( did several engines most parts on my own rods). But never never cylinder heads. Manifolds only if bolted -torqued down to custom made plattens so they don't warp or to old blocks if you're into production. Gotta torque em down dudes or you'll be crying later...
Valve covers are a natural... But I'm getting off topic.

But it's not a laugh when you pay big bucks for a coating that burns off when the parts get hot... Covers and cowlings are a damn beautiful sight if you work with progressive masks and powdercoatings. Need to find an artist for that kind of work. I am out of the business,
but it is similar to airbrush work if the painter/coater is an artisan who understands, materials, heat, and has a steady technique.
The expensive automotive quality powders are avalaible but can cost better than 500$ a box. But you can't beat the results.
Main thing is to make sure layers are of compatible powder materials, and that the layer thicknesses are are very thin or they will chunk out and look like shit.

Thin layers are durable, heavy layers will shatter and lift.
I don't recommend more than three layers, the clear coat being one of them.
Don't go for high gloss. Pebble, flat and semi gloss look best.

Dwell time in the oven also is important because thin substartes will soak up heat differently than cast parts, billet parts, tubes etc. Each different type of material should be baked seperately. If you were a baker you wouldn't cook cookies with bread and pizza at the same time in the same oven...
ALWAYS do a sample mockup of the pattern and layers on some scap sheet before,
you work on the actual parts. Powder coating needs to be removed usually by methylene chloride- badd ass shit-media blasting, or by putting in a burn off oven- not good for bike parts.
Tanks are better left to wet paint, as fuels usually discolor and lift even with the best materials.
We used to do side jobs on farm equipt, motorcycles, rod parts and trucks too.
Take your time and ask all the questions. It's too expensive to make a mistake.

Find a dude who has experience with the media, it takes a lot of failures to get it right. Let some other guy pay. Find the right dude and watch him work.
Powder coating needs to be extremely clean, no oils, silicones, lint, dust, no finger prints.
But this is what the big boys use so there should be someone out there who can help.
Electronics enclosure on the expressways are powder coated. A good job lasts for decades. A cheap shoddy job will look like shit in one season.

mules got it right.

If you have an imperfect part or it looks like shit, the powder coating will only make it look worse. Powder coating hides nothing; it magnifys the imperfections.

Any tech questions,
serious only,
I will help. Just pm me.
Zep