Lately in my online research to see what some of the most common questions and misconceptions about powder coating are, I have come across many people inquiring whether or not powder coating wheels was safe and reliable. Unfortunately, while I like to make most things as simple as possible for people to understand, since after all, this is a beginner/intermediate introduction to powder coating, this is a not so clear cut answer on this one.
By now everybody should be aware of how powder coating works and how to properly use powder coating equipment. Furthermore, people must really understand how the curing process works.
To start with, and a very important detail in powder coating wheels, a manufacturers powder coating cure time is not simply bake for 20 minutes like that turkey you bought from the grocery store is. The powder coating is not bonding to the air inside of the oven, but rather the piece that it is sprayed on, and therefore it is this part that must reach, and maintain the temperature for the manufacturers cure time, for the powder coating to really flow out nicely and attach to it. Obviously for small thing parts, you're not going to be far from that 20 minutes the manufacturer stated, however when getting into larger items, like when powder coating wheels, you will really have to pay attention to the part you're working with before you start the timer on that cure time. This is a very key part of this powder coating system, but really not the most important job either in this setup.
Secondly, preparing the part is crucial and many people overlook this with "You can't see the outer edge of the rim so I don't need to mask it" syndrome. Fact is, powder coatings strength comes in the fact that is a shell, completely encompassing the part and sealing it within. The catch here is that powder coating the entire outside of the rim can make tire sealing problematic, and also add significant weight while powder coating wheels. The item should be properly masked just past the area of the rim the tire bead sits up against, but not the entire outside rim of it. Furthermore, detail must be placed inside of the lug holes as well too, leaving the base, or conical section clean while powder coating wheels, otherwise the lug nuts will damage it during installation and can lead to flaking of the powder coat in the effected area. You would then proceed further with masking off or plugging the item in areas like the valve stem hole, or possibly the lip of the rim if it were to stay polished and not have powder coating applied to the rest of it.
Now that we have tackled those two problems, this is where the key, and the heavy debates come in on powder coating wheels. Does the heat from the curing process effect the integrity of the alloys in the wheel. Long story short, and sparing you of all the nitty gritty metallurgy aspects of it all, yes it can and it's possible to be quite detrimental to the part. This is where the main ingredient comes in to success in powder coating wheels, and it can be a long and time consuming setup.
One of the most important things to remember is that metal just simply doesn't like to change temperature fast. While powder coating wheels, it is very important that you slowly and steadily raise the temperature of the part to it's curing temperature, and furthermore, that part needs to come back to ambient temperature very slowly as well too. Quick flashing of heat can make the metal brittle, and can result in powder coated wheels cracking under stress. This is not only very detrimental to your reputation as a powder coating professional, but it is also a big safety concern and potentially deadly. If you found this site while just searching about powder coating, I only hope you read this and take the moment to speak with whoever will be completing your work to make sure proper procedures are followed to insure the structural integrity of your rim. If you merely mention this to them and they laugh and say it will be fine, do yourself a favor and take your work elsewhere. It's not worth risking a harmful situation because some idiots are powder coating wheels and have no clue what they're doing.
This sites activity is picking up, so if you have any questions, please leave a comment and I will reply within a day or so. I'm always happy to help out, and frankly, powder coating wheels is a beautiful modification for any car, I just want you guys to make sure it is done right :)