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View Full Version : Ultra thin line widths for lab application- 0.0015"?



Bert McMahan
12-12-2018, 5:44 PM
I have a (potential) application that needs some 0.0015" (~0.038 mm) lines marked in anodized aluminum, spaced 0.0015" apart. The application is related to microscopic measurements of small things. I'm seeing fiber laser minimum line widths as 0.01 mm, which seems to indicate it's doable.

What's the smallest size you guys have been able to mark? I spoke with Keyence and they suggested their UV wavelength laser for this, but they haven't been very responsive with getting me samples.

The customer has used some type of printing process that has worked in the past, but would like to directly mark some of their metal pieces.

Wojciech Szul
12-12-2018, 6:36 PM
It is around 670dpi (what is more handy for laser users/manufacturers). I suppose it will be not easy, as energy which destruct anodized aluminum can be transferred to adjacent areas and destruct them (even partially) as well.
Blue laser: 500nm=0.0005mm (what is 76 times bigger than you need theoretically).
Fiber laser: 1000nm=0.001mm (38 times bigger than you need theoretically) (this depend of fiber, there are few technologies and wavelengths)

Just to comparison this 76 and 38 "times":
In practice form CO2 laser (which wavelength is a ~10000nm=0.01mm) We can easily(!) got real resolution low as... 0.2mm (127dpi) which is 20 times bigger than theoretically possible. Better are possible, but are not straight forward. Range as 0.1mm (254dpi) - quite easily with just replacing lens to shorter one, higher resolutions - way harder.

Kev Williams
12-13-2018, 1:57 AM
I'm going to go out on a limb here and proclaim that while you CAN engrave those lines you need with a fiber, the problem you'll find is that the more lines you have to do, the more out of tolerance you're going to be. It's simply because of the nature of steering a laser beam thru a lens with mirrors and focusing 11" from those mirrors; a slight mis-focus will change the size of everything- never really noticeable doing simple words & such, but sure is when engraving accurate scales, even 'big' scales. Right now I'm engraving a 40mm long scale on some anodized, and to get the my new laser to make the engraving white, I have to de-focus the beam upwards 'half a crank' on the tower handle. That half crank makes the engraving great, but I have to reduce the size of the scale from 40mm actual to 39.82mm to compensate for the enlargement caused by the longer focus distance. And then there's the pincushion effect- most fibers are probably not even engraving boxes with straight lines! My triumph with the 240 lens showed me that! And even to draw a straight line anywhere but dead-center, both mirrors have to move to compensate for the arc of the lenses...

Fiber on a gantry, might be more do-able for such small tolerances...

Scott Shepherd
12-13-2018, 7:59 AM
Totally agree with Kev. I don't see you doing that on a galvo with a lens that flattens the engraving out as it does. You'll have a whole host of errors.

Bert McMahan
12-13-2018, 12:09 PM
The entire artwork is very small- an inch or two across in most cases. It's also not a variable mark, so it could be "calibrated" out if the line widths were physically possible. I'm just having a hard time determining if a fiber laser can do it at all- many manufacturers claim 10 micron spot sizes, but I spoke with Keyence (who know a LOT about their lasers) and they said a standard fiber won't do it, but their UV wavelength would be able to. Unfortunately I can't get them to do a solid test for me since I'm a "little fish" :)

And I don't actually own a fiber laser at this point, neither gantry nor galvo, so whichever fit the bill for this job would be the one to get. The print solutions I'm working to replace are around $10 per unit, so if the quantities get into the 2000's (easily doable) then the laser starts to make a lot of sense. (I'm also doing this more as a consultant to the company looking to set up their laser process, not just doing this as a gig.)

Scott Shepherd
12-13-2018, 1:46 PM
I would think some sort of photo-etching process would be the ticket.

Bert McMahan
12-13-2018, 1:57 PM
That is possible, but the locations of the marks on the components are going to be hard to photo etch. Laser marking would be great... if it is physically possible :)

Kev Williams
12-13-2018, 6:47 PM
I just tried this with my ebay laser and its 150 lens, tried several versions of anodized aluminum I have laying around, the anodizing chips and flakes at lower power, and higher power just smooths everything out. So I tried a piece of polished stainless. Ran it at zero power to start, got some smoke was all ;)
Next I did 20 power, speed was 200, 30kh, one-way 0 hatch at .038mm, 1/8" wide strip 1" long...
Just going to 20 power was way hot---
398698

-and while you CAN make out- barely- the separate hatch lines--
398699
--they won't be of much use for measuring anything.

My 72mm lens might do a snick better, but

Bert McMahan
12-13-2018, 10:28 PM
Oh wow, thanks Kevin- I really appreciate it. Looks like a UV laser may work for this but not a regular fiber. I really appreciate you giving it a shot for me.

Gary Hair
12-14-2018, 9:23 AM
Here are lines spaced .108mm apart, that's about the closest I could get them without touching. The width of the engraved line is definitely wider than .01mm but I don't have an accurate way of measuring it. I used 200 speed, 40 power and 40 frequency, that seemed to give the best quality line without blowing out around it. FYI - this quality of line carried all the way across a business card size piece of material so something close to an inch would be no problem with this spacing and line width.

Bert McMahan
12-14-2018, 1:52 PM
Good to know Gary, I appreciate you running that test for me!