Stripes/Streaks/Y-axis banding on stainless steel tumblers with Cermark

[robert solis]

Hello all engravers, I am at my wits end with this horrible problem that my department has been working around for months.

First off, we have 7 Epilog Laser Helix machines, all 50W, all relatively new (under 6 months), only 2 of them can print thick filled logos.

The other 5 machines seem to produce striped results like so:


Attachment 357295

IMG_6695.jpg


The only way we've worked around it is by using the Auto-Focus feature, adjusting the focus to -80 and -90 and running at a very high speed of 50-55.

Now all the techs at Epilog highly suggest not using the Auto-Focus feature and urge us to use the Manual Focus Gauge, however when we do this, our results come out either streaky or bronze/golden instead of solid and black.

Epilog has had us do many many tests but to no avail. These tests include aligning the laser, tightening our optics, engraving at low dpis and high dpis, checking the resolution on our CorelDraw and matching it with the dpi on the machine, lowering speeds, manually focusing and manually adjusting the focus up or down, switching rotary attachments.

We've also tried printing a 1inx1in block at 75dpi on a piece of acrylic to compare it to the lasers that the techs are using. They haven't gotten back to us about any solutions unfortunately.

The engineer that works with our company has checked the voltage to make sure they are all pumping out 220-240. He has also checked the fans and other mechanical aspects of the machine such as bearings, railings, belts, etc.

Has anyone else run into problems like this?? It seriously feels like our company is the only company in the world that has these issues seeing as I can't find anything closely related to this.

Any help would be very much appreciated. We are suffering at the moment seeing as we have a large order with a rather thick logo that can only be printed on 2 of our machines.

[Kev Williams]

Nope, you're not alone. Horizontal banding. Not sure what causes it but it's a pain-
Awhile back we had a laser-engraved photo contest. This is a pic of our boat harbor, laser engraved on some non-laserable Rowmark-
I was amazed at how well it turned out,
banding-sky1.jpg

but I didn't enter it because of the same exact banding you're having in the upper right, in the clouds...
banding-sky2.jpg

This was in pure photo-mode, which I've normally found is somewhat immune to this problem, but obviously, not always...

All I can offer as suggestions is to lower the power- you're bronze-ish engraving is indicative of too much power- and play with the res settings.
Not sure if I'm alone, but I rarely have my X and Y settings the same. I run Cermark almost always at 600 lines per inch, and 1000 dpi-X on my LS900 (my GCC has no X adjustment, but it does great at 600 lines...)

I run my 2 machines at 16 and 18 speed, which probably won't correspond to yours, but my LS900 will sweep a 6" X path, left to right in almost exactly 1 second. That speed, 40 watts, 600 lines, I get great results.

[Scott Shepherd]

That's a hard one to solve over the internet. Plenty of unknown questions.

How are the files sent? All from same computer? Each one have a different computer? Are you sending it from the same computer to 1 machine that works and 1 that doesn't work? What are the color management settings in CorelDraw for each computer (if more than one, or just the one)?

[John Kleiber]

What type of UPS is connected to the lasers?

UPS with integral Voltage Regulator?
UPS with integral Power Conditioner?

Voltage may be good at the moment of testing, however that does not mean its steady over time.

-John

[John Lifer]

And you aren't the only one with Epilog that has this problem. Defocus, run lower power, run faster, make sure cermark is dry are all suggested by Epilog users.... Good luck

[Joseph Shawa]

Is this different than the banding one gets when not matching the DPI of the image and the Scan Gap?

[Keith Downing]

If speeding up reduces it or makes it go away, then it could be heat building up. As others have mentioned, there are lots of variables. However, the only time I've consistently battled this problem was when I was running too slowly and with little or no air. Now I crank up the air and run at a "normal" speed and never see it.

So, if you have an external air assist, I'd crank it up to 30psi and see if that helps. If not, then I'd try to go at the fastest speed you possibly can where you still get a solid black mark. If they cup is coming out hot to the touch, or if you can see or feel any warping at all after you're done, then it's getting too hot IMHO.

Oh, and +1 on making sure the Cermark is completely dry when you start. That has also made a big difference for me.