[LotusManDan]

I have had my rims done over 4 times. Each time they take them back down to metal. Excellent prep work and cleaned each time the in between the spokes comes out barley coated and the middle is supper heavy and orange peals. I had 2 different company's give it a try both looked like $hit.

Has any one else had this issue or have an alternate solution to finishing these rims?

 

[LostPawn]

I’m not sure about these rims and the temps used to powder coat. You could also try just paint or anodizing.

 

[LotusManDan]

The dishes look perfect the last time the face of the rims were perfect and the dish looked like garbage. The orange peal is not every were just on the center most part.

 

[Doge]

Wow, those do look bad. I had mine powdercoated along with a set of evora wheels and both came out great.

 

[chris2pher]

Mine were professionally powder coated and look perfect. Another member here had them done and we swapped. They were done by Restock Wheels in Southfield, Michigan. You may just want to give them a call to understand what their process is for getting this type of finish.

 

[LotusManDan]

i wonder if theirs some sort of a dipping process that is more efficient i was told that some of these rims could be anodized form the factory.

 

[LotusManDan]

any body know any thing about electrostatic wet spray?

 

[KWYK]

thats a bad job for sure,ive had plenty of wheels powdercoated for clients and none ever looked like that
Most powder cures at ~200C for 15-20min (depending on color),looks like they were done at 400C,the common reason for orange peel in powdercoat is too higher temperature or pre heating the item
Its also not oil or grease,that gives fisheyes

 

[mr.woolery]

That's a really bad powdercoating job, and KWYK is right. It looks like they cooked it at too high temperature.

Another point:
I hate to be a downer, but why are you powdercoating these forged wheels?! You should realize that the heating process used in powdercoating affects the molecular structure of the aluminum and weakens the forged strength of the wheel. If these wheels were powdercoated multiple times, especially at temperatures that were too high to properly cure the powdercoat, I wouldn't trust them structurally at all anymore.

 

[Ziker]

Looks like it was too hot to me as well. I have had done and done many wheels and never had that much peel. typically 20 minutes after flow out at 400 is all you need. Looks like its hammerfinish powder .

 

[Nessal]

I hear powdercoatimg wheels compromises their structural integrity.

 

[bjbubble]

Here's a graph pulled from NASA. Yield and ultimate strength along with elongation at break will all go down ever so slightly if baked at 200°C/400°F, but only ever so slightly.

I would much rather use a set of powdercoated OEM forged wheels over some gravity cast aftermarket wheels with who knows what temper.

 

[LotusManDan]

WOW do you think it decreases the strength enough to worry about it?

 

[Vulcan Grey]

Powdercoating temperatures should be low enough that the heat treatment and the strength of the aluminum alloys are fine. Unless the powdercoater doesn't know what they are doing, or doesn't have good controls on their oven temps.

 

[Doge]

WOW do you think it decreases the strength enough to worry about it?

No, not with powdercoating.

 

[LotusManDan]

I don know you need crazy equipment to get above 400 and form what iam told 400 is to hot for powder coating anyway.

 

[Glen]

There are low-temp powder coating materials available (about 250 F cure IIRC). I had some OEM VW pressure-cast wheels aluminum wheels refinished using low temp powder coat. They were redone twice for a total of three heat cycles. The first two jobs resulted in yellowing of the clear coat over the silver so much that the silver underneath also looked yellow. Some wheels were yellow, some not, so I had to have them redo the entire batch to get all the wheels the same.

Despite the use of low-temp powder coating, I'm reasonably sure the result was soft aluminum. After the wheels had been refinished, I ended up driving up over a snow-covered curb to avoid an accident and bent two of the wheels. I've had similar excursions in the past with no damage to the same rims (the hardpacked snow makes a pretty good ramp). I ended up selling the wheels for scrap aluminum and buying some (better looking) aftermarket wheels.

I suspect the yellowing of the powder coat clear was due to poor temperature control. For my money, I'll stick with catalyzed spray finishes and have them redone as necessary. Remember that powder coat paint isn't magic...there are catalyzed finishes just as durable.

Glen

 

[Glen]

Here's a graph pulled from NASA.

This is interesting info, but the graph is for 6061, a very different material than alloys used to cast aluminum parts. Relatively low heat is used to anneal aluminum, and it doesn't take a lot to change the material's properties. I've used my home oven or a propane torch to anneal cast and sheet aluminum many times...in my experience, as little as 500F will affect cast parts. That could easily be a hot spot in an oven running at 400-450F.

I'd be interested in a similar graph for aluminum alloys designed for casting.

Glen

 

[MaineLotus]

Powder coated my wheels a couple times and they turned out glossy with very little orange peel. It looks like the powder may have been applied too heavy - too much powder will cause orange peel. When doing wheels, they should apply the powder coat to the 'hard to spray' areas first. For really difficult wheels, they can heat the part in the oven first, it helps the powder to adhere without over coating.

I'm not a metallurgist, but I don't believe 400 degrees for 20 minutes has a negative impact on wheel strength.

Here's how my Elise wheels turned out -

 

[MaineLotus]

PS - another technique is to apply the powder from the back of the wheel first, to cover the areas between spokes. Then coat the face of the wheel last. Coating the area between the spokes from the front will cover the face of the wheel will too much powder.