Anybody here have experience with CO2 lasers?

I am sorry I can not give you much practical advice on marking and cutting, but as an optical engineer I designed a CO2 laser system in this power range for other material processing purposes, and I have heard a bit about their use for marking and cutting. From what I understand, marking reflective materials with lower powered CO2 lasers need it to first be sprayed with a special coating that absorbs the laser energy and bonds to the metal. I think 40W might be practical to cut thin plastics but not metal.

Have you looked at fiber laser systems? They are much easier to maintain. The technology is advancing very quickly and will probably end up mostly replacing CO2 systems. A Q-switched fiber laser is very good at marking reflective materials. At lower powers, each type have advantages. Here's a table of what each can mark, maybe you have seen a similar one.

I have been reading about fiber lasers. But only about big ones and they are too expensive. The fiber laser made by the linked company above will only cut metal foil. They do sell a CO2 laser that cuts metal though. There is obviously a lot to learn before I buy anything. Eric

Please do keep us up to date with what you find. This is a subject that has been on my mind lately, hopfully to be able to fabricate small prototype c ases for electronics, and (possibly) to fabricate printed circuit boards. I was JUST about to start doing some research when your post came up.

been on my mind lately, hopfully to be able to fabricate small prototype cases for electronics, and (possibly) to fabricate printed circuit boards. I was JUST about to start doing some research when your post came up.

I don't think those little CW CO2 lasers are good for much more than cutting acrylic sheet (up to a few mm, anyway, maybe 6 if you go slow). They can only _mark_ metal if you pre-treat it with an expensive coating. They'll harmlessly reflect off of anything specular.

I have had samples of PCBs fabbed by laser ablation, but that laser is in a whole different class*- pulsed YAG UV running off of 3-phase power. You _could_ cut stencils into thin plastic for printing solder.

• OK, technically they're both Class 4 lasers, but you know what I mean.

been on my mind lately, hopfully to be able to fabricate small prototype cases for electronics, and (possibly) to fabricate printed circuit boards. I was JUST about to start doing some research when your post came up.

There are some good videos out there showing what you can do with one of the affordable 80W CO2 units. They certainly have some uses, but they are probably inadequate for what RCM folks would want to do. Perhaps build a 3D wax printer instead to make cores for investment casting?

Interesting. Does this mean that the laser rod is a bundle of flexible fiber optics -- or even just one instead of a rigid rod like the NdYAG ones which I have used in the past? (Those had a rotating roof prism as the Q-switch, FWIW, and perhaps these days there are electronic shutters which can do the task, to allow more precise control over firing timing.)

Enjoy, DoN.

Well actually the laser "rod" is usually just one very long single mode doped-core fiber. The pump light from many solid state laser diodes is launched into the cladding. These articles will tell you more than I know.

Acousto-optic and electro-optic modulators can be used for active Q-switching, but I think most of these lasers use passive Q-switching with a saturable absorber mirror.

Fiber lasers have several practical advantages for marking and cutting:

1) Very clean beam profile. 2) Near zero maintenance. 3) Shorter wavelengths require less exotic lenses than CO2. 4) Beam can be conveyed where needed with a fiber. 5) More efficient, less cooling needed. 6) Can be passively Q-switched. (There is at least one make of CO2 laser that is q-switched, but I think this is expensive).

The largest commercial CO2 lasers still lead the way in peak average power over commercial fiber lasers, but this will probably change. Here is an article on a 40,000 watt fiber laser weapon being tested:

I built a 40-50 W cw CO2 laser back in the 80's for fun. Using a damaged ZnSe lens (it was free :-)) that gave a spot size of about 1 mm and no gas assist I could cut completely through 1/4" plexiglas at 1-4 inches per second. I managed to drill (well, slowly melt and slag) a hole in a Gillette razor blade about 0.03" thick in many, many seconds (in the very early days of lasers the Gillett was the unit of how powerful a laser was when researchers bragged to each other; how many Gillette blades it could drill through in one second :-)). Mild steel is about the easiest to laser cut, especially with oxygen assist gas, so with the right set up you might, might be able to cut something as thick as 0.01" at say 0.1-.5 inches per second. Forget stainless or aluminum or anything else thicker than heavy foil. Pretty much all the common plastics should cut about the same, so that should work well for you. I never tried marking but at that power level plastics and glass should mark very easily. Reflective metals will need an absorber paint but again, never did that myself. For comparison, at work our 1200 watt cw CO2 laser with gas assist can cut 1/2" mild steel at a few inches per second I believe, I don't get out to the sheet metal shop very often.

Thanks to whomever posted the links to fiber laser details.

I've been looking at 40 and 80 watt CO2 laser engraver/cutters lately. Prices have come way down and one machine I looked at with a 40 watt laser was less than 3000.00 bux. There are even cheaper ones but they were a little too basic for me. The price for a new tube is $300.00 which translates to about 30 cents an hour operating cost for just the tube. But what I am really interested in is what CO2 can realistically cut and engrave. Not what the website says but real world experience. I know I'll be able to engrave black anodized aluminum and black acetal plastic, two materials which I would be engraving and have paid for engraving in the past. But titanium engraving would be nice. And cutting thin metal sheet and maybe thin plastic sheet. And laser sintering Saturn 5 boosters. Well, maybe not Saturn 5 boosters. But is

40 watts even capable of cutting thin metal at any kind of decent feed rate? And how thin is thin? When it comes to that, what kind of feed rates when engraving black anodized aluminum or black plastics? Thanks, Eric

been on my mind lately, hopfully to be able to fabricate small prototype cases for electronics, and (possibly) to fabricate printed circuit boards. I was JUST about to start doing some research when your post came up.

They will mark surfaces that absorb IR well. So black anodize works. I bet clear anodize not as well. I wonder if glasses with anti-reflective coating can't be called "specs"? Eric

Thanks for the info Carl, that's just what I'm looking for. I'll be talking to the guy who does my laser marking now, but I can't ask him too much. It wouldn't be fair because I will be taking away my business from him if I buy a laser. Eric

snipped-for-privacy@whidbey.com fired this volley in news: snipped-for-privacy@4ax.com:

I have a guy right up the road who can cut 1/16" polished stainless with his laser. I'm bettin' it's got a higher output than 40W!

He's got water-jet, too, but that's for the thicker stuff.

Lloyd

Here's a nice discussion with lots of photos: