Powder painting a flywheel

[Brian Rupnow]

A few years ago I designed and built this i.c. engine, and at the time I painted the gas tank and the flywheel with red spray on enamel. As time went by, the enamel paint on the flywheel got chipped, scratched, and generally buggered up. To redo this flywheel with powder paint, the enamel paint will have to be totally removed (sandblaster). Then the powder paint (which is applied as a dry powder) will be sprayed onto the flywheel and baked in an oven until the powder melts and flows out smoothly. This results in an almost bullet-proof coating, which is very resistant to scratches and chipping away. In order to hold this part securely in place while applying the powder paint and baking it will require some simple fixturing which I will show as I go along. This will be the first thing I have ever powder painted, so stay with me and we'll see what the results will be.---Brian

 

[Brian Rupnow]

This is the flywheel after sandblasting. 99.9% of the paint is blasted away. I didn't realize it, but this flywheel is made up from three different pieces which have been pressed or Loctited together. Powder paint has issues with this as any oil trapped between the pieces tends to "boil up" during the baking process and this affects the paint finish. I may just re-spray this flywheel with enamel and pick on a one piece flywheel to powder paint.

 

[Brian Rupnow]

Okay---we'll try something different. These flywheels are one piece, and I'm sure of that because there is no paint on them to hide things. They will not have to be sandblasted, but will be wiped down with thinners and cleaned up with a lint free rag, then straight into the powder paint booth. I have built so many engines over the years, that once paint is on the flywheels, I don't remember if they were one piece, two piece, or three piece. The flywheel I sandblasted that turned out to be three piece will be repainted with spray can enamel and reinstalled on the engine it came off of.

 

[dsage]

Probably too late this time, but I would recommend that you sand blast bare metal lightly to give the powder coat some grip. Powder coat, although tough in it's own right is only as good as the prep as far as sticking to the base metal.

On another note. Good thing you didn't paint the flywheel that's loctited together. The loctite would cut loose at less than the 400 deg or so require to cure the paint.

Also cast material takes some special care. The part should be preheated first to above the curing temp. I can be cooled to say 200deg or so while being painted. What happens (as me how I know with cast aluminum) is you'll paint it and the finish will get rice crispy like bubbles popping in the finish. Air trapped in the castings expands out when it's heated bubbling through the liquid paint.
One hell of a mess requiring re-sandblasting and then proper treatment.

 

[Brian Rupnow]

dsage---Thank you. I did know most of that. I've read a lot of write ups about the application of powder paint, what it sticks to, what it doesn't stick to, and what screws up the finish. I didn't do anything today. Today my left knee, the one not operated on was giving me all kinds of Hell---wouldn't bear any load on it. My good wife had gone out for the day, so I laid in bed until 2:00 in the afternoon waiting for my wife to come home and save me. I'm up and about now, but not up to doing any real work.----Brian

 

[dsage]

BTW. If you need to mask portions. You can use tin foil or better, Kapton tape and (reusable silicon plugs and caps.
(Caps and Plugs company in Mississauga has everything you need).

 

[dsage]

I figured you might know all of that but posting is as much for others that might be reading.

 

[dsage]

BTW. I should add that I had no problem with the cast aluminum using the pre-heat first. I believe I pre-heated to 450 and cured to 400.