Some powder coaters use 400 deg or more. I think most use more than 200. The fact a wheel can be welded means nothing. For sure the area around the weld will be annealed. Powder coating heats the entire wheel.
Some wheel makers recommend not powder coating their wheels.

As for weld...the whole wheel would need annealed to guarantee proper molecular structure throughout.

The common alloys used are 356-T6 for cast wheels and 6061-T6 for forged wheels. The common coatings are epoxy, polyester and acrylic powder coatings, which have a cure time of approximately 15 minutes at maximum temp, which is usually less than 275 °F

ASM Handbook Volume 2, Properties and Selection: Nonferrous Alloys and Special-Purpose Materials has the following information:

356-T6: aging at 305 to 315 °F for 2 to 5 hours
Yield stress = 185 MPa
Ultimate stress = 262 MPa
Fracture strain = 0.05

356-T7: aging at 435 to 445 °F for 7 to 9 hours
Yield stress = 165 MPa
Ultimate stress = 220 MPa
Fracture strain = 0.06

Since a good poweder coating company wouldn't do AL in the 400 °F range, and actual aging happens at longer times in the curing temp range, then it shouldn't be a problem if done properly by a reputable company.

I'm sure Brian Carlton will correct my above information, since my current edition is outdated.

__________________
1987 560SL
85,000 miles

I was a little concerned about convection of the heat in a smaller oven. Heating these rims pretty equally by conduction since it is alloy might get past the problem in a smaller oven. At these kinds of temperatures perhaps a well constructed insulated steel box with a couple of elements inside from old stoves and their thermostats might be attempted.

Do you remember how much the electrostatic powder gun set up was? I thought from memory some of them where pretty reasonable.

Craftsman has a starter kit for less than $50... Craftsman Complete Portable Powder Coating System

Use an independent thermometer, as most residential ovens are off a bit. The type that hangs on the rack and can be seen through the glass is good.

An oven can be built pretty cheaply, using regular oven heating elements. I'd caution on using a well built and designed thermostatic system to control the heat. I'd recommend at least 3-4 inches of insulation on all sides of the unit, as well as keeping an eye on the humidity...if it's too humid, the coating won't adhere that well, and you'll end up with a poor quality finish.

Practice on smaller pieces, but please...send the wheels out to be done. They can control hot spots better than a residential oven can. Residential ovens are warmer in the back, away from the door.

__________________
1987 560SL
85,000 miles

You seem to condradict your own post about the weldablity of wheels.
Welding locally anneals any tempered aluminum part. Subjecting the entire wheel to heat neccessary to anneal the entire wheel would require re-heat treating the entire wheel. Such a process would likely introduce distortions to the extent the wheel would need to remachined.
I agree a good powdercoater will not do aluminum at a higher temperature. The trick is to find a good powdercoater.

Not necessarily. Adding localized high heat, such as needed to weld aluminum, changes it on a molecular level in that area, not the whole part. To be able to get it's true hardness and strength uniform, then the part would need to be treated uniformly, such as annealing, or, as my co-worker calls it, heat-treating.

I wouldn't trust a welded aluminum wheel unless it was properly heated after weld. Welding it brings it to near dead soft, at least that's been my experience with it.

I designed and built about 300 aluminum Kaizen carts out of 6061-T6 for Duramax, each cart holding 10 shelves. Each shelf had to hold all components for the engine, so weight handling was a must. The frames on the prototypes were mig welded, then strength tested. Each part failed within an inch of the weld. We sent one test unit out for annealing and it kept it from breaking near the weld. For the production of the carts, we ended up using water jets to cut all the sides as whole pieces instead of welding all 600 sides. (more cost effective that way.)

__________________
1987 560SL
85,000 miles

What do you mean? Of course it's neccessary.
Welding locally anneals any tempered part.

part of a response i thought i deleted...carry on.

Posting through some of these medications is proving to be a bit confusing...even to me!

__________________
1987 560SL
85,000 miles

Still wishing you the best at this time. Getting well is important. Takes a little longer for us younger fellows to bounce back sometimes.

Thanks. They adjusted the medications for dizziness to a lower dose due to the lethargy it was creating for me, and now the dizziness is back as strong as ever. I have an appointment with an ENT doc next week to try to find the cause of the Vertigo.

__________________
1987 560SL
85,000 miles

Just in case nobody has not mentioned it yet - scratched paint is easier to repair than powder coating. Who is going to drive the car?????

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

This is true...but road grime and brake dust wash off of powder coating much easier.

__________________
1987 560SL
85,000 miles

Oh right - I didn't know that. That must be 'cos of the clear coating - is it that different (in terms of wettability) than a polished clear paint coat?

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I'll explain it this way...the brake dust and road grime will impregnate itself into paint much easier than powder coat, because powder coating has a harder finish. Once impregnated, you're screwed.

It's like the difference between acrylic and glass. Both have many of the same properties, but one is harder and will outlast the other.

__________________
1987 560SL
85,000 miles

It think that is backwards. The screwing leads to becoming impregnated.

__________________
1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags