Electrostatic painting question (layer too thin near hook)

[321GO]

Hello guys.

Maybe one of you can help us with a problem we are having on our electrostatic painting line.

The problem is the part isn't getting enough paint thickness near /around the hole that is used to hang it(rest of the part is fine).

Basically the charged paint particles seem to 'avoid' the region near the hole/hook.

The problem region is flat and readily accessible, so i don't think this would be due to a faraday effect or 'electrostatic pathway effect' or something similar(although i could be very wrong).

Anybody dealt with something similar before?

Any advice more than welcome as usuall.

 

[telecomguy]

I've seen this on many parts in the past. I'm honestly not well versed on the process. I assume the hook could be sapping some of the electrostatic charge in the area resulting in reduced coverage. Looking forward to the real answer for others in the know. <tg>

 

[Compositepro]

The hook will affect the electrostatic field in a way that will thin the paint around it.

 

[321GO]

Yes compositepro,

it seems the hook will act somewhat as a 'lightning pole' for the electric field.

Google comes up with some interesting links on:
"electrostatic field concentration powder coating"

It seems this effect is quite common for corona based systems(the one usings high voltage).


That's a bummer.

 

[telecomguy]

Anti-static hook? Or a dedicated/strategically placed hook point?

Side note: I recall a story about the hole in old PC slot filler panels. Everyone designing new IO panels kept the hole because they weren't sure what it was for. Turns out it was for hooking the part and dipping it into the plating tank, but you'd see the hole on panels that had various connector cutouts that could have just as easily served as hook points. D

 

[Ron]

Holes in thin materials will create eddy currents that can actually repel particles.