Laser struggling to etch glass any longer

[Danny Arthur]

I have a Mantech 4060 machine with a 60w laser
Details below
Up until now it has been brilliant for doing glasses for prize giving even on very small detail. I have been using the same glass and supplier for 2 years with no issues. I now find that it wont really etch onto glass even at a low speed on 100% power, sometimes leaving a very faint image.
It will still etch wood happily all day long.
Lenses and mirrors all clean and chiller happily running at 22 degrees with deionised water.

Any ideas before I go to Mantech and pay out on a tech to come out as it's no longer under warranty.
Any help most appreciated



Laser power

60W



Engraving speed(mm/min)
0-75,000


Cutting speed(mm/min)
0-40,000


Minimum letter
English: 1 x 1mm


Location precision
≤0.01mm


Resetting positioning accuracy
0.01mm


Power supply
AC 220V/50Hz


Driving system
Stepper


Cooling mode
Water-cooling and protection system


Auxiliary Devices
Exhauster and the Exhaust Pipe


Software
Lasercut 5.3


Graphic format supported
BMP, CIF, JPEG, TGA, TIFF, PLT, AI, DXF, DWG, etc.

[Kev Williams]

Before drastic measures, especially considering it's engraving wood nicely-- try engraving some other glass first...

I've been running into this issue to some extent lately myself. I etched a couple of champagne flutes for a wedding about a couple of months ago that my LS900 would barely mark. Subsequent passes at ridiculously slow speeds barely helped. And not long ago a beer mug (from a dollar store) didn't 'take' all that well. I've been wondering what's up, and the words "Chinese glass" jumps into my head-- but other glass I've done since engraves as nice as always...

[Joseph Shawa]

Can't wait to hear how you resolve this one. It's amazing how many different problems crop up when using these machines.
My plastic cutting has come to be a breeze and now I have been focusing on learning engraving as of late. My son wanted his baseball bat engraved. Tough getting it into the machine but got it done.


I have some question for you or anyone else since it sounds like you have been doing a lot of glass. I'll post it as a new topic.

[John Blazy]

I'm going to apply some science to this, since lasers don't truly engrave or cut glass the way it does other materials, by vaporising or ablating the material. Glass melts at over 3000 F, so melting or vaporising the glass is out. The laser is only super heating a tiny area (only really heating impurities within the glass), and its the heat contrast between hot and cold within immediate proximity that causes the glass to micro-fracture, which is how it "engraves".

So my hypothesis is that pure borosilicate (lab, Pyrex) glass (which has high heat resistance) likely will not engrave with a laser due to the lack of impurities within the glass, which might be why cheap glass engraves. So is it possible that your glass that is not etching is too pure? Maybe its Low Iron (Starphire).

So before I embarrass myself with this cool techno-babble, I'm going to try my laser on Low-Iron vs common float glass, and some other pure glass thats laying around.

We engraved some lead crystal a while back and maybe it engraved well because of the lead content.

[John Blazy]

Ok, so I might be of **** with the above explanation. I just ran my 80 watt in a straight line across a pc of regular glass and Low-Iron Starphire glass, both 1/4" thick, and ran the beam over both pcs in same "cut". I smeared dirty grease from my forklift on a section of the Starphire to test my hypothesis about the laser super-heating impurities to create more heat/thus fracturing. Ran at 33 mm / sec @ 100% power, and the "line" looked identical all across both pcs, even over the grease. The micro-fracturing was at least 1/32" deep, as viewed from the edge of the glass.

Then I ran over the regular glass at 11 mm / second @ 100%, and the fracturing was deep enough (1/16") to run a crack right under the line.

Couldn't find any Pyrex in the shop, so still inconclusive.

So I got nothin for ya Danny, sorry. I tried.

[Ron Hamilton]

I have had this problem wit glass that contains crystalline, IKEA sell some of them that are terrible. I find the cheaper the glass the better it etches.

Ron
Accuris powersharp 30 w

[Danny Arthur]

Sorry been on other projects for a while,
Thanks for your help guys, seems to be a bit of a mystery I think I'll try the same settings and design on a range of glasses and see what the results are.

[Kev Williams]

I've engraved probably 2 or 3 dozen Pyrex casseroles the past few years as Xmas and wedding presents. They engrave wonderfully!

And I know the heat fractures the glass, and I know that different laser frequencies (fiber v C02) are absorbed, or not, by different materials. But knowing that is still weird when my C02's will etch glass and cut thru paper, but hitting a piece of glass with the fiber engraves whatever's BELOW the glass, and if you put a piece of paper on a piece of stainless, that paper acts like lead to Superman's x-ray vision. The paper smokes a bit, and that's it. Just doesn't seem right! ;)

But if crystalline is a reason the laser won't etch it, it would be nice to know how to avoid it...

[david minnery]

Have you looked at the laser, perhaps it's on the downside of it's lifespan.