Powder coat question

[OTHGbronco82]

I'm thinking about having my mountain bike frame powder coated and was just wondering if a low temp powder coat will affect the frame. It's 6061 T6 aluminum if I remember correctly. I've seen a lot of threads on other forums questioning the strength of the welds after powder coating. I just don't want to end up in the dirt with a broken frame.

 

[HyperMark]

Not sure how it would affect the Aluminium, but I can't imagine it would hurt it. It is quit a low temp bake, 350 to 400°F.
The problem I foresee is the powder coat is easily scratched as it's quit soft.
I would go for a 2 pack wet spray myself.

I found this, It may help you decide.

Where did you read that powdercoating changes aluminum structure? Was it the interwebz? Bad interwebz!

Powdercoating is a process where a power is electrostatically stuck to metal then baked on. The baking procedure is done at around 390°F, the melting temperature for 6061 is 985°F and the annealing temperature for 6061 is 775°F for 2-3 hours. Unless you drastically mess up the cure cycle on powdercoat, you're not going to even touch the temperature where the aluminum structure changes. You might get into a precipitation hardening temperature, but you'd need to hold 320°F for 12 hours or more to see a difference.

Quote from here.

 

[OTHGbronco82]

I've actually already read all that. I had read that about five minutes before posting. :lmao: I'd just like something that'll last since it'll be going on a downhill bike and it's going to see lots of rocks and really small pebbles. Eh, maybe I'll just have it sand blasted and then clear coated. Raw aluminum doesn't look to bad.

 

[wings_of_fire]

Don't powdercoat since aluminium has a low melting point and hence low heat treatment temperatures.

Use PU paint. Its used on industrial machines and its hard to even scratch.

 

[bryco13]

I've had countless frames powdercoated with no issues over the past 20+ years.

 

[binaryterror]

Powdercoating aluminum is perfectly fine.

Doesn't affect the welds, or the temper of the aluminum as Powder Coat ovens usually never go beyond 400* and bake times will never get longer than 1 hour. To Anneal 6061 you need 775* for 2-3 hours.

 

[Peaker]

I have powedercoated a lot of ALU stuff in the 4 years i worked with it, but there havent been any bicycle frames in that.

But motorcycle frames en mass and wheels too, even done up a lot of dynaudio speaker frames, so i cant see any problem in "pulverizing" a MTB frame.

I would put a sparkly silver bottom on it and cover that with a coat of colored transparent topcoat, and if i feel like a pimp i might add another coat of clear with just a little bit holo flake in it.

Or drive 150 KM and borrow my old friends paintbooth, and then slap some automotive paint on the damm thing.
That is if i can find a time when he dont have a car in there :mrgreen:

 

[OTHGbronco82]

Don't powdercoat since aluminium has a low melting point and hence low heat treatment temperatures.

Use PU paint. Its used on industrial machines and its hard to even scratch.

Depending on the price I might just go that route.

Powdercoating aluminum is perfectly fine.

Doesn't affect the welds, or the temper of the aluminum as Powder Coat ovens usually never go beyond 400* and bake times will never get longer than 1 hour. To Anneal 6061 you need 775* for 2-3 hours.

That's what I had read in a couple of other forums.

I have powedercoated a lot of ALU stuff in the 4 years i worked with it, but there havent been any bicycle frames in that.

But motorcycle frames en mass and wheels too, even done up a lot of dynaudio speaker frames, so i cant see any problem in "pulverizing" a MTB frame.

I would put a sparkly silver bottom on it and cover that with a coat of colored transparent topcoat, and if i feel like a pimp i might add another coat of clear with just a little bit holo flake in it.

Or drive 150 KM and borrow my old friends paintbooth, and then slap some automotive paint on the damm thing.
That is if i can find a time when he dont have a car in there :mrgreen:

:lmao: Pimpin.

 

[TexasSP]

Powdercoating aluminum is perfectly fine.

Doesn't affect the welds, or the temper of the aluminum as Powder Coat ovens usually never go beyond 400* and bake times will never get longer than 1 hour. To Anneal 6061 you need 775* for 2-3 hours.

Have extensive experience in metals and powder coating, I agree with BT on this. I also work with metallurgists and have studied and know quite a bit about this.

Even at annealing temperatures, it is not hot enough to cause weld issues. A lot of welded aluminum pipe is annealed after welding for industrial purposes. At 400 °F you're not even getting close to changing any physical properties of the metal or the weld. The only issue would be if the weld was bad in the first place.

 

[OTHGbronco82]

Have extensive experience in metals and powder coating, I agree with BT on this. I also work with metallurgists and have studied and know quite a bit about this.

Even at annealing temperatures, it is not hot enough to cause weld issues. A lot of welded aluminum pipe is annealed after welding for industrial purposes. At 400 °F you're not even getting close to changing any physical properties of the metal or the weld. The only issue would be if the weld was bad in the first place.

As long as it isn't to expensive I might do it. Most of it comes down to price. Plus, I have a couple of surfaces that can't have any paint or anything on them like the head tube and all the bearing locations. Painting would be easier but I think powder coating might last longer.