Etching Steel Using a 2.5 watt Diode Laser

Typical over-spec nonsense. I doubt it's even 7W output. Maybe input. Even my 60W CO2 is peak, 50W "real", running it at 60W will blow the tube quickly. It's just how they do it over there. You have to just know that if you are going to buy direct.

You can mark on metal with various compounds, a diode could do that. Stuff like Cermark. It's stupid expensive though. Some people have had luck with dry moly lube, and a few other things. Those are more like powder coating than marking the metal directly. Some of them may have an etching reaction with the metal when combined with the heat from the laser.

I have seen some recent claims that a 40W CO2 with an upgraded lens was able to mark stainless directly. I haven't seen it confirmed though. For all I know they burned an oxide layer or something.
 
ttabbal said:
I have seen some recent claims that a 40W CO2 with an upgraded lens was able to mark stainless directly. I haven't seen it confirmed though. For all I know they burned an oxide layer or something.
Click to expand...

Cermark is a spray product that enables marking on most metals including stainless. Only problem is it's expensive. I have a 40 watt laser and an alternative to Cermark is using a spray dry moly lube. I had mixed but acceptable results with the dry moly on stainless. A little trial and error with amount and proper drying etc.. Never tried the Cermark due to the price and no real need.
 
At work we had a Q-switched YAG laser system that was used to remove epoxy molding compound from integrated circuits. Peak power was at least in the tens if not hundreds of kilowatt range, and it was barely able to directly write on stainless steel. Not an apples-apples comparison to a CW laser (and different wavelength, 1064 vs 455nm) but it gives you an idea of what's needed to direct-write on steel. One of the problems is that a large percentage of the incident beam is reflected. Epoxy absorbs much more of the energy so it's readily ablated with the laser. It also produces some really nasty byproducts so the system came with a charcoal filter + HEPA arrangement to protect personnel from the fumes.

You wanted to stop the process before getting down to the integrated circuits in the molded packages. The laser beam would toast them in an instant. We finished up the decapsulation process by putting a drop or two of fuming nitric acid in the cavity. Surprisingly enough, the IC itself would be OK after being abused that way. Most of the time anyway....
 
Incredible,
The world is passing me by.
I remember we used acid etched plates on the pad press for baseball printing back in the 80's.
Somehow the negative print only allowed the acid to etch the intended design?? The ink would fall in the etched print, the silicone pad would pick it up and over and down it went on the balls.
I don't remember how they did it. It was an outfit in Danvers MA. that set up the machines then they went to Haiti where I set them up for production.
Lasers on Hobby Machinists, very impressive sir.
 
You know, I have one simple request. And that is to have sharks with frickin’ laser beams attached to their heads!
Dr. E.
 
I work with solid state (and tunable dye) lasers too. I have a 40W 808 nm (infrared) behemoth and several less powerful lasers. I will throw in something most people are not aware of. The shorter the wavelength (the closer to UV and the further from Infrared), the more damage a laser does. My lowly 7w 445 nm laser WILL cut through the spring from a ball point pen, IF G2 optics (narrow, very close, tight and low loss) is used. But then, a small spring does not have a good way to dissipate heat. I suspect a printed circuit board would shrug it off like a non-event.
 
We have a 3kW fiber laser at work, Trumpf Tr if laser 2030. It can directly engrave stainless. But RJs quality of etch here is better quality marking in my opinion than direct engraving which is more like cross hatching on the laser.


Sent from my iPhone using Tapatalk
 
What no one has mentioned yet, is dry film photoresist; you can get a double-sided sheet of gooey photoresist
in a clear wrap; pull off one (protective) side sheet, press the goo film against your clean surface, and apply
a warm roller, iron (maybe with a PTFE protective sheet so the iron doesn't stick), and/or bake the
photoresist on.

Then print your pattern onto a transparency negative (some of the coated laser-printer clear sheets work well)
apply the pattern over the spot to be etched, and shine UV lights (LEDs or fluorescent) on it.
The exposed (transparent) parts harden.

Strip off the film from the top, and apply developer (it'll dissolve the protected bit, representing your
line art). Then, a cotton swab and some ferric chloride will etch your letters in. Remove the resist
by some brisk scrubbing.

Assuming you've got a laserprinter (inkjet ought to work, too) and not an X/Y laser, the extra work doesn't
seem too bad. Near-UV LED modules in 3 to 10W sizes, and modest precautions (UV lenses like for
welding should protect your eyes) suffice for exposing the film. Developer can be washing soda/water.
There's materials in the usual (Amazon, eBay, AliExpress) places, 'dry photosensitive' or 'dry photoresist'
will find it.

p.s. if you want crisp images, the laser-print ink will be DOWN on the surface, so you want to print the
image mirror-reversed
 
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whitmore said:
What no one has mentioned yet, is dry film photoresist; you can get a double-sided sheet of gooey photoresist
in a clear wrap; pull off one (protective) side sheet, press the goo film against your clean surface, and apply
a warm roller, iron (maybe with a PTFE protective sheet so the iron doesn't stick), and/or bake the
photoresist on.

Then print your pattern onto a transparency negative (some of the coated laser-printer clear sheets work well)
apply the pattern over the spot to be etched, and shine UV lights (LEDs or fluorescent) on it.
The exposed (transparent) parts harden.

Strip off the film from the top, and apply developer (it'll dissolve the protected bit, representing your
line art). Then, a cotton swab and some ferric chloride will etch your letters in. Remove the resist
by some brisk scrubbing.

Assuming you've got a laserprinter (inkjet ought to work, too) and not an X/Y laser, the extra work doesn't
seem too bad. Near-UV LED modules in 3 to 10W sizes, and modest precautions (UV lenses like for
welding should protect your eyes) suffice for exposing the film. Developer can be washing soda/water.
There's materials in the usual (Amazon, eBay, AliExpress) places, 'dry photosensitive' or 'dry photoresist'
will find it.
Click to expand...
vtcnc said:
We have a 3kW fiber laser at work, Trumpf Tr if laser 2030. It can directly engrave stainless. But RJs quality of etch here is better quality marking in my opinion than direct engraving which is more like cross hatching on the laser.


Sent from my iPhone using Tapatalk
Click to expand...
Photoresist is a good alternative for etching metal. I used it in my business for 22 years to make printed circuit boards. I started with Eastman Kodak KPR and KPR liquid resist, progressing to Kepro laminated circuit board using dry film resist.

Originally, my artwork was laid out on transparent film which was used to make a negative photomask for exposing the photoresist. With the advent of computers and printers, I could print photomasks directly on transparencies. Another process that worked was to print on regular paper and bond the print side to the photoresist and gently wash the the paper away to leave the artwork in place. For a time, there were special kits available from DigiKey which used a similar process.

For exposure, I made a light box using four fluorescent tubes with a timer. For controlling exposure, I used a gray scale which had a range of different densities painted on a transparency. I would expose to a particular level which would provide a proper resist mask. Lacking a light box, exposure to sunlight is a good way to get a uniform exposure. The work is oriented so that it directly faces the sun which prevents undercutting astound the edges of the art. Some test pieces should be tried first to determine the correct length of exposure. Obviously, you are limited to cloudless days.
 
I always found light sources which were most nearly a "point source" provided edges with the best definition. This was important when doing small font on panel legends and 1mm traces on circuit boards. I did it back in the day when you would apply your artwork to a clear mylar sheet, to do small production runs. Later, I would use Programs by Orcad to do the artwork, print out a black and white copy, create a large negative, and overlay the negative on the board with Kodak KPR4 photoresist. The per-use cost with the Kodak product was much cheaper than the applied resist film.

I also used a photo-reactive silk screen coating. For large production I would use that, with a resist which was silk-screened onto the surface for direct etch. As I recall, the resist washed off with Xylene. I really liked doing black anodized aluminum panels, which were etched with Sodium Hydroxide. This gave really nice silvery-white marks/letters against the black anodized finish.

In the really early days of making panels, I used a Gorton Pantomill to do marks and legends on panels.. but the fineness of details was driven by how fine of a rotary engraving tip you were using.
 
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