MOPA fiber laser, where to start?!

[Scott Watson84]

Hello all,

I run an engraving business for the last 25 years, we have been laser engraving for the last 15, in that time we have only ever used Trotec Speedy C02 machines. I have been toying with the idea of adding a fiber engraver to mark on stainless steel and clear anodized aluminum. I spoke to Trotec about a machine and they recommended a MOPA laser, they said it's the only way to get a black mark on these materials consistantly, I was quoted $55,000 for the machine, now being a Trotec user for the past 15 years I understand the value in their machines, However after checking with a few Chinese manufactures, There is a significant price difference,

Our use for the machine would be mostly to engrave on industrial tags and such, we currently use stainless steel with cermark, or use a black anodized aluminum. however we are getting more and more requests for aluminum tags with black text. Add to that, we don't have the ability to sheer stainless steel in house and rely on an outside vendor which at times have caused us to miss deadlines.

After doing quite a bit of reading online, including these forums, I'm still confused, is it correct that a MOPA laser is the way to go to get a nice consistent black mark on stainless and clear anodized aluminum? My idea is to purchase a well reviewed Chinese machine to test the waters, if I find that it is helpful to my business I can look at replacing it with a Trotec machine in the future.

Does anyone have any insight into the world of MOPA?

[Kev Williams]

Best advice against buying a $55,000 Trotec Mopa is supplied by Trotec themselves:
Watch this video: https://www.youtube.com/watch?v=uJnufscnAMs

fast forward past the nonsense to the 3:20 mark and hit play... watch the machine in action. Looks like it's moving along pretty good-- that is, until he removes the plate from the machine, at which point you'll see how small the plate is compared to his hands... The Achilles Heel of Mopa lasers is, doing colors is excruciatingly SLOW... Now, just as the timer hits the 3:49 mark, HIT PAUSE-- And give close scrutiny to, and this is my opinion, the light, inconsistent engraving.

I have 2 better ways to get black on aluminum, one of which may not work ...

1st option: get some outdoor black aluminum from Johnson's, both sides are engraveable, it's intended to engrave to silver, but here I 'relief engraved' this, burnt off the entire plate, leaving black lettering:
DSC07460.jpg
now, this isn't perfect because the silver is a little on the dark side because of the UV resistant coating, it more resembles SS than anodized aluminum. Took my 40w Gravograph exactly 1:02 to do this. I would wager the MOPA would take longer than that to engrave just the black. And anodized aluminum isn't particularly weather resistant, this stuff is!

2nd option, which I've been going to try but haven't yet-- Cermark engraving raw aluminum, which I do a lot of with my Triumph, THEN having it clear anodized after the engraving. What I'm not sure is, is if the Cermark will tolerate the anodizing process... but, I'm not sure why not either...

Anyway, I love Trotec machines, but I'm not a fan of MOPA fibers, and personally, I think the engraving in that video is atrocious-- I couldn't sell that to anyone...


.

[Bert McMahan]

FYI on Youtube, you can move to a point in the video then right click on it and select "Copy URL at current time" to get this link:

https://youtu.be/uJnufscnAMs?t=200

that takes you right to 3:20

[Scott Watson84]

Thank you for the very informative reply! I have tried cermark on raw aluminum and gotten mixed results at best.

I like your idea of relief engraving the black aluminum, however I don't know how it would hold up in an industrial environment, which is where most of our tags end up, power plants, water treatment facilities, naval ships etc.

With a standard fiber laser, is it possible to engrave aluminum and stainless to a depth deep enough to allow paint filling? If so would the edges be smooth enough to allow easy clean up after the paint dries?

[Kev Williams]

If you're willing to paint fill aluminum, just tool engrave it. It's faster and cleaner, much better suited for paint filling. And aside from aluminum AB, Cutler-Hammer etc legend plates, virtually all of my 'industrial environment' customers use stainless or Rowmark Lasermax. And for truly indestructible tags, Rowmark Ultramatte (or equivalent) is what your customers should buy from you... But there is a catch with Ultramatte, the top cap is so thick it must be tool engraved

That outdoor black is very good at repelling the weather, but it's not particularly scratch resistant... however, any acids that will attack these plates will likely attack raw and anodized aluminum too.

As to Cermarking aluminum, only my 80w Triumph will do this consistently, my 40w machines just plain won't, and fwiw 6061 is all I've ever used Cermark on... 70 series should work, but 50 series bleeds so badly I'm not sure Cermark will fuse to it...

[Scott Watson84]

Thanks Kev.

Is it possible to get a nice black mark on stainless with a standard 30 watt Galvo fiber laser without the use of cermark or similar?

[Bill George]

Thanks Kev.

Is it possible to get a nice black mark on stainless with a standard 30 watt Galvo fiber laser without the use of cermark or similar?

It depends on the stainless. Most of my marks are brown or dark brown. I just purchased something new and the markings on it were fiber lasered and brown. looked pretty nice. Have you asked your customer if they really want black or would the brown work?

[Kev Williams]

Like Bill says, depends... I've hit on a nice annealing setting that gives me consistent results, which means consistent within a particular batch of material. Sometimes the mark is quite black, most times it's more of a dark gray, and there's always the 'hologram' effect, different lighting angles show a lighter mark, and sometimes in a variety of colors, like this plate- This is the same plate, just took pics at different angles. The first pic, you'd swear a MOPA did it, but the second pic reveals the truth
an1.jpgan5.jpg

But the problem with annealing is, it's the same process as a MOPA getting colors: tight hatch fill, low power and slow speeds, emphasis on SLOWWWWW..

If you go the faster-hotter route with a fiber, as Bill says you usually get a brown charred/burnt mark, sometimes you get lucky and not so brown, sometimes you good results, always a crap shoot...
One of my marketing customers brings me these not cheap titanium bracelets that I Cermark engrave on the top sides. The insides come with the name and logo already fiber lasered ( WASN'T ME!! )
bracelets.jpg
The top bracelet is a satin finish, bottom is polished-
Top is annealed, and to the naked eye looks pretty good, but (ahem) it could be better ...
But the bottom has been hit hard and IMO, even though it's black, the char makes it look terrible, and it's worse to the naked eye...

As for the lucky times, a young guy brought me a handful of these SS bottle openers (groomsmen gifts),
black1.jpgblack2.jpg
and I swear, this is NOT Cermark, my fiber did this! -- But I've never been able to quite duplicate it; this is as close as I've gotten:
fiber v cermark.jpg
-this is thick-walled SS tube, top is fiber, bottom is Cermark. I think part of the reason it came out good is the material thickness was able to absorb much of the heat that chars thin stock. But even as good as it looks, it's dark brown, not black... I'm not sure what grade SS these are, or the bottle openers, could be that has something to do with it? But 99.9% of the stainless I engrave is 304 or 316...

Now this is an extreme case of all things fibering SS gone wrong!
-rotary wouldn't line up, and I kinda had the speed a bit too slow I think! SHOULD be black, but nope!
burntcup.jpg
not this extreme obviously, but this is typical of the color when fibering SS, brownish-grayish, not so black-ish...

Fibers are wonderful, but putting black markings on stainless nicely and quickly, not their suit. BRIGHT markings on stainless, oh yes
invicta.jpg

--I've convinced several customers to try bright rather than black etching, most of them like it, but some will always want black!

[Neville Stewart]

I’d have to differ on stainless. I haven’t found any I can’t get a really good black mark with no surface marring and very quickly too. Id say about 20 seconds each on those openers.
19053233-2D93-4180-8EB1-0D9A4C2ECE97.jpg0F20CBA0-2EC9-4F82-A469-A0BF8A1E2E57.jpegE6821D0F-0912-4BB6-8CAA-C5818F6C777A.jpeg

[Kev Williams]

MOPA or the Raycus?

[Darren Wilson]

Hello Scott,
MOPA will produce a beautiful black mark on anodised alumnium, such as iPad.

ipad.jpgThe marks are indistinguishable from the factory marks, and smooth to the touch. As far as I know they are durable as the anodised finish.

[Darren Wilson]

I have found that making a black mark on anodised ali, is a very repeatable process. Color marking is another story, slightest change to the material will change the color of the mark. If you plan on marking materials provided by the customer you will have to take on a sacrificial sample to dial in settngs for color marks. Focus is critical and I have found that 254mm lens works best for me.

[Scott Watson84]

Thanks for the info, I have no interest in colour marking, only in black.

[Kev Williams]

interesting learning experience, need to experiment

[Neville Stewart]

Q switch raycus

MOPA or the Raycus?