I had the same issue with my Rough Country winch plate. Rust underneath the coating caused it to flake off. I just wire-brushed it and applied some One-Step rust converter. No more issues.

 

Part of the issue, as noted, is lack of metal prep. The best approach is to get the part bare metal, clean, sand everything with an orbital sander, clean again with a pre-painting solvent, and then tack cloth. If you use a good powder coater, it is very unlikely to flake. However, you will still face potential rust issues. Powder coat does a poor job of getting into tight spaces. You'll often get rust in areas of welds, or where joints meet together. No biggie though. Clean with a nylon brush and dab some rustoleum that matches. Should keep the rust away for a long time.

The best solution is to get it dipped in zinc first (e.g. like MetalCloaks control arms). That is some amazing stuff.

Or, rattle can it

 

I've had this issue on 2 sets of rails: Ace and Evo.

With the Ace, I ended up taking them off and selling them (not because of the powder coating). So I just sanded them down and rattle canned with Rustoleum flat black. Use the same stuff on my Evo rails after getting scratches from wheeling. I don't even bother sanding it anymore. Just wash them and spray.

Pretty sure Evo ships stuff un-finished now because too many were complaining + damage from shipping, etc.

 

I've had to send back 2 sets of the Poison Spyder ( Rigid ) light bar mounts because the powder coat chipped off during shipping.

I'm now getting the aluminum version and bedlining it myself. It's sad really...

 

Seriously consider having it all sprayed with linex or any other truck bed material. That's how my stock 10A sliders came from the factory. Your bumper would look 10 times better also. Good luck.

Sent from a nearby galaxy...