Fiber Laser question

[Kenny Davis72]

Hi, Is it possible to get a deep black using a fiber laser? I have a Chinese 20W fiber laser and all I can get it brown/rust to gray burn marks. I'm looking for something similar to Cermark black.

Kenny

[Mark Sipes]

I'm sure the first question most members will ask is "what material are you attempting to mark?" Since you are looking for a Cermark Black "I" would assume Stainless/Steel but that is what I use Cermark on...



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[Gary Hair]

If your laser is a MOPA then you can easily get black marks from what I have read. If not, you can still get black marks on stainless but it's fairly slow going. For small graphics and text it's still faster than Cermark, but for anything large it will probably be a lot longer. For my 30 watt machine I used 225 speed, 28 power, 80 frequency, .01mm hatch at 45 and 135 degrees, 2mm out of focus. You can start there with your 20 watt machine and adjust power until you get a good mark. Before you ask, I have no idea why MOPA marks better or what is different about it, I'll leave that answer up to the tech pro's!

[Kenny Davis72]

I am trying to mark stainless steel. How do you know if your laser is a MOPA laser? I've noticed that my laser has an additional setting under mark parameter in EZCad that I don't see in others on youtube...Q Pulse Width(ns). The manufacture told me to leave it at 100. I've tried adjusting the setting and it doesn't seem to do much, if anything, when changed.

[Kev Williams]

I've found it depends on the stainless. On 20 gauge-ish SS I can turn 4x4" plates into cereal bowls before I get a "black" mark. Dark brown is all I can muster.

I posted some pics I did on some SS 'wallet' bottle openers. The settings were pretty bizarre for engraving SS to black, very high freq and out of focus, but it turned out almost as good as today's Cermark (not to be confused with 'yesterday's GOOD Cermark).

The other day I engraved some SS tubes, got a very nice mark---- in the pic, the bottom is Cermark, top the fiber. While they're almost identical, the fibered still shows a hint of brown. I believe the settings were around 200 speed, 100 power and 40 freq, with a .01 one-way hatch.
DSC05467.jpg

Funny thing, when I was done with the tubes, using the same exact settings on a piece of 20 gauge, all I got was burnt brown, not even close to black. And lots of warp.

I've come to the conclusion that my fiber will NEVER replace Cermark.

[Gary Hair]

How do you know if your laser is a MOPA laser?

That's a good question... I would assume it would have said something in the specs or maybe on the invoice, but you know what they say about assuming.

[Kev Williams]

Hit the F3 parameters, check the "hardware info" tab -- fwiw, mine says "USB LMC - IPG Laser"...

[Kenny Davis72]

Looks like I'm supposed to have a JPT M1 fiber laser installed which is a MOPA laser.

http://www.jptelectronics.com/en/pd_302_302_372.html

The above links says "the pulse repetition frequency(PRF) and pulse width can be controlled independently in MOPA configuration". My EZCad does have an additional marking parameter Q-Pulse Width which makes me think it is a MOPA fiber laser.

It also says the application advantages are black marking on aluminum (I get a good gray) and black marking on stainless steel (I get mostly brown). I'm still looking for that black mark.

Does anyone own a MOPA laser that can maybe provide additional information on how to properly use it?

Kenny

[Bert McMahan]

Hate to necro-post on a several months old thread, but Kenny did you ever get your black mark on Stainless going? I'm researching a laser that comes with the JPT MOPA head and I can't find many people talking about it. Google is returning mostly Alibaba results lol.

I'm just wondering on an update on your experience after having the laser for several months now.

[Darren Wilson]

I think what they mean by black mark on aluminium, is black oxide on to a anodised aluminium surface much like back of iPad/Phone. I have a MOPA fiber and it can make black mark on anodised ali, but I have not been able to mark much better that dark grey on bare Ali. Does black pretty well on Stainless along with colours, although it is very small window for colour marking and varies between types of Stainless. I've only had the machine since Jan, and have not had as much time to free time play experiment with different settings and material, only as needed when as a job comes up. Those of you with fibers already know hatch, speed, power, frequency now add pulse width to the mix, can be a bit daughting...

[Neville Stewart]

Hate to necro-post on a several months old thread, but Kenny did you ever get your black mark on Stainless going? I'm researching a laser that comes with the JPT MOPA head and I can't find many people talking about it. Google is returning mostly Alibaba results lol.

I'm just wondering on an update on your experience after having the laser for several months now.

In Gary's description, the most important part is "out of focus". Focus about 2mm into the material, you will barely see any flash or at least you shouldn't, if you do go a touch deeper. Gary's numbers are good ( and thank you for sharing Gary ). You have a little extra capacity with a mopa but it should work.

[Kev Williams]

And just to be different, I get great results with the same (or slightly tweaked) settings while perfectly IN focus...

I was playing with an old Browning knife recently (diamond etched by pantograph back in the '70's, still have a half dozen of these!)..

I ran a 2-pass at .008 hatch, I THINK around 200sp 30p and 80f --
Then I made some changes, I think I went to 35p and 60f, and I started getting light sparks, it was engraving slightly-
Before it was done engraving the second pass, I stopped the machine, which is clearly visible on the "K"-
Then I went down in power, speed an up in frequency and ran a final pass, and it turned out sweet!
knife1.jpg

You can see the up-left tail of the K matches the rest of the lettering.
The rest of the K is slightly shallower and lighter. I like the deeper, but the edge of the shallower is much smoother.
knife2.jpg

but only magnified, to the naked eye it all looks the same, except that the K isn't as dark.

I annealed a bunch of surgical parts not long ago that required the metal not be affected at all, I ran those in focus.
I should experiment with out of focus settings, but so far so good.

[Ulisses Garza]

Hello have a same machine with same problem you have solved ?


Regards