Marking or Scribing on 6061-T6 Aluminum with a YAG

[Richard DiMaggio]

Can anyone tell me what wattage YAG I need to engrave a .025" deep by .025" wide line on the surface of a 1/4" thick piece of aluminum? CW, pulsed or Q-switched? I have a 30" x 30" X/Y flat bed setup with a CO2 in it now, but I find that using the Cermark solution for this application not as "permanent" as I would like for doing motorcycle parts. I really want to "ENGRAVE" the parts.

Thanks..
rj

[Chuck Thomas]

From all I've been able to find out, a 20W would be able to do it however the time it would take would make a hammer and chisel seem faster. I've had samples run with a 20W and I wasn't impressed. The 50W I'm looking to get has a lot more punch to it, but a .025" deep gouge will still take multiple passes at slow speed. I'll be happy if I can get .008" in 7075 ALU. Granted I've been looking at the standard machines Epilog and Trotec offer so there isn't a whole lot you can fiddle with. The laser head that both companies sell is considered a YLP style, Q-switched marker. If you contact IPG (the maker) look for Tony Hoult, he's helped me a lot with selection and general information about the unit I'm looking at.
Is there a specific reason you want to go so deep?

[Bruce Boone]

I would think at least a 50 watt machine. I have an 80 watt and it still takes several passes and beam wobble to get that deep. It seems to take an exponential amount of power to get deeper. That's because some of the cone shaped beam gets blocked as you go deeper. I can cut right through .085" titanium, but it takes LOTS of passes.

[Dan Hintz]

It would seem to me that a CNC with a V bit would be a better fit for this.

[Richard DiMaggio]

Thanks Chuck, and all...
Well, maybe my requirement of the .025" deep was a bit much, but I was just grabbing at a number that seemed "doable" and I guess it's just asking for too much. In actuality, I guess less depth would be acceptable. Some graphics cannot be applied with a vbit Dan...especially if you are rastering.. I have various artwork to do on different motorcycle parts and doing it milling style with mechanical cutters isn't always the best solution, not to mention how much time it would take to do a "pocketing routine" and the problem with the radius of the cutter and losing definition. I'll keep searching tho. I wish building a YAG was as easy as throwing together a CO2 unit.
And I hate that Cermark stuff too.
rj

[Dan Hintz]

Are you simply looking for a color change on the surface, or do you truly need an engraving? If you can live with a color change, the YAG can provide that if you get the correct wavelength. I'll also add that if you're having problems with CerMark coming off, are you sure you're marking properly? Applied properly, the only way to remove it would be to remove the metal underneath it's attached to. Scraping with a Brillo pad won't even touch it.

[Chuck Thomas]

If I'm remembering correctly the color change is only on Stainless and not so much Aluminum. By color change I'm talking about reds, blues, and blacks among others. If you can get away from deep etching then a YAG or Fiber would be the answer and I can't imagine being all that difficult to set up. At least not the Fiber unit since there are no mirrors. Don't give up yet. I've been working on getting my machine and starting a new business for a year now and I'm finally getting close to launching. Keep looking around and talking to people.

[Dan Hintz]

If I'm remembering correctly the color change is only on Stainless and not so much Aluminum.
You're right, my bad... jumping between threads and I forgot we were talking about aluminum. Takes carbon to get a color change...