Lasering Aluminum?

[Jin Lee]

So, I'm trying to figure out how to laser mark a sheet of aluminum for a customer. I've been sent a sample of the aluminum sheet and it's 1/32" thick and apparently has a lacquer coating on it. Customer wants to see if I can mark (using Thermark or a similar product) a logo onto the sheet of aluminum.

My question is: should I do this in multiple passes? Arrange the sheet of aluminum then do the first pass with just the laser to "burn-off" the lacquer coating? Pull the sheet out, spray down with Thermark and then laser again? Or is there another way? I was thinking possibly, using vinyl stickers and then sandblasting the logo area before applying the Thermark and lasering?

Anyone out there have experience working with lacquer coated aluminum and marking with Thermark before?

Any help would be greatly appreciated.
- J.

[Rodne Gold]

Dont waste your time and effort if its got a laquer coating , you will have to jump thru hoops to mark it properly.

[Joe Pelonio]

So, I'm trying to figure out how to laser mark a sheet of aluminum for a customer. I've been sent a sample of the aluminum sheet and it's 1/32" thick and apparently has a lacquer coating on it. Customer wants to see if I can mark (using Thermark or a similar product) a logo onto the sheet of aluminum.

My question is: should I do this in multiple passes? Arrange the sheet of aluminum then do the first pass with just the laser to "burn-off" the lacquer coating? Pull the sheet out, spray down with Thermark and then laser again? Or is there another way? I was thinking possibly, using vinyl stickers and then sandblasting the logo area before applying the Thermark and lasering?

Anyone out there have experience working with lacquer coated aluminum and marking with Thermark before?

Any help would be greatly appreciated.
- J.
Thermark LMM14 Black should work. Chances are good that sandblasting lightly first will work well. I have done it by lasering one pass at low speed and high power to remove the clearcoat, then without moving it, apply the thermark and laser again. Unfortunately there's no way to tell if one pass will be enough without some experimentation since all clearcoat products are not the same, plus the laser power varies, mine is 45 watts.

[Keith Outten]

Blast with glass beads then engrave. If you cannot get the surface perfectly clean to bare aluminum don't waste your time. If you blast first you will have a perfect engraving every time.

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[Gary Hair]

Would it be less trouble to get them to supply a sheet without any coating? If it needs to be coated how about coating after you laser it?

Gary

[Ed Parkyn]

Your customer should be able to provide a bare sheet and have it clear anodized after you're done with it.

[Rodne Gold]

Anodising or any finishing involving linishing acid dipping , satinizing , brush finishing or any other chemical/mechnical operations will probably destroy the markings or damage em. Test a marked scrap first to see that further finishing is ok. It's likely the markings are a resist as well, tho we found satinising or passivating brass in a chromic acid solution removed markings , dunno if ally is any better?

[Richard Rumancik]

It would probably be better to put on a clear coat, polyurethane or lacquer over the Cermark rather than anodize. That would protect the bare aluminum from oxidation and is less aggressive. But testing is advisable regardless of what you choose.

[Jason Roehl]

I'm curious how many of you guys have actually lasered aluminum and how it turned out. I don't own an engraver, but have a close friend whose family business owns 2 of them (I forget wattage, but they were $500K and $750K--maybe 350W and 500W?)), and he said they couldn't laser aluminum because the melted aluminum pool around the laser was too reflective and would damage the diode/tube/laser, whatever.

Sorry to hijack, I'm just wondering aloud.

[Richard Rumancik]

The lasers your friend is referring to are probably more like 3500 watts. None of the people on this forum worry about melting the aluminum. It can't happen with the wattage that awards-and-engraving laser systems are capable of.

What you are being told is probably correct. CO2 lasers aren't that good for reflective materials, but you can still cut aluminum. (I had some done for me.) I think copper and copper-based allows are worse than alumimum. If the laser energy reflects back into the optical system it can cause damage.

[Mike Hood]

Not to mention a water jet would do a much better job at a considerable cost savings :)

[Jason Roehl]

Thanks, Richard. They mainly cut stainless steel parts for custom heavy truck accessories. I know the cheaper laser (their first one) was capable of something like 500 in/minute in 26-gauge stainless.

[Keith Outten]

Engraving aluminum with a low power CO2 laser works well if you prepare the surface properly. You must have bare metal and use a chemical agent like Thermark or Cermark which is brushed or sprayed on the surface before engraving.

The contrast between the aluminum surface and the dark mark left by the chemical agent provides lots of contrast and detail. This is an excellent technique that eveyone who owns an engraver should try their hand. Developing techniques with various materials is part of owning an engraver. You never know what a customer will ask for and learning to use as many materials and techniques as possible increases your knowledge and confidence with your machine.

.