engraving off powder coat

[Graham Taylor]

Hi guys,

After some advice please.

I have been asked to do a sample for a possible ongoing job engraving off powder coat so that it leaves a clean metal surface to use as an earth bonding point. When I did some 10mm square tests it came out cool but when I did the main piece it left a reddish mark/residue on the engraved area - see pic below. They need the whole area nice and clean back to the metal. I have tried giving it a good clean but it doenst seem to shift the residue.

I am using the following settings on an 80W Speedy 300 - engrave P=90, speed=50, PPI/Hz=500, passes=2, air assist on and Z-offset=0. Does this look about right (I thought it was ok during the tests).

powder coat 1.jpg

As always, any help or advice greatly received

[Gary Hair]

Your settings are similar to mine, I use 100% power and 60% speed, 600 dpi and usually two passes. I do tons of hydroflasks and this almost always leaves a very clean result. Worst case, I might have to wipe with acetone to get what little residue remains. The picture looks like the metal under the powder isn't very nicely finished, could that be it?

[Dennis Watson]

Looks like poorly prepped steel before coating.

[Keith Downing]

Is it the powder coat being blown and fused to the metal as it's lasered off? I don't have much experience with powder coated metal, but I've had something similar happen with freshly painted wood. The entire area came out light blue from the dust settling onto the material.

Try upping the air assist if you can and see if that helps. And wiping clean with DNA or a comparable solvent right after lasering; maybe with a metal scouring pad.

Also it's a longshot, but does it help to engrave from the center out instead of the outside in?

[John Kleiber]

Have you tried more passes? 3,4,5,6,7,8 until bare metal.
Automated powder coating is usually more consistent. Possibly poor prep, but then too thickly applied.

All they want is a clean surface for ground, why wouldn't you just make a little mask template and hit it with a sand blaster?

-John

[John Lifer]

Different metal and different machine, but I've been engraving Powder coated mugs today at 75% power and 225mm/s. Most had two layers (base and clearcoat) and laser blasted thru them all. Probably could have used 75% or sped up a bit, but it worked well. I did have to wipe off residue. Used Simple Green and a cheap white magic eraser to make the base metal shine. I'd expect you'll have to clean a bit...

[Graham Taylor]

All sorted - a good wipe with some nail varnish remover (being careful not to go over the powder coat) and its nice and clean. Customer is happy so hopefully the job will be mine.

thanks for the help and suggestions -allways appreciated.