Laser Marking Steel

[awemawson]

Cheap imported 50 watt laser engraver / cutters won't cut metals, or engrave them without jumping through hoops. There is a hugely expensive spray, meant for marking steel with a laser, that contains exotic ceramic materials that the laser presumably fuses and effectively marks the steel. But it also marks you wallet at £100 per aerosol can 

On another forum John Stevenson mentioned that he'd been using Ambersil 'Dry Moly' for the same purpose and it was effective. As this is far less expensive (I paid £14.99 including postage) I thought it worth a try, and ordered some, which arrived today.

The 'Dry Moly' is resin bonded according to the can - possibly it's the resin rather than the molybdenum disulphide that's doing the work, but hey, it works so I thought I show you the results.

This is a 20 mm square HSS form tool that according to the date I put on it, I've had since at least 9/4/89 as I've marked it with an electric Actograph pen with that date. How things have progress since 1989 in the home workshop 

The result seems quite durable but I've not tried to scrape it off yet !

[edward]

A chap I know runs an engineering company making all sorts of complicated valves and things. He has a machine that fuses glass beads to Stainless to make I.D. plates and instructions using a laser. The results are excellent but I suspect the machine might be pretty expensive. I can find out what it is if you would be interested.

[RobWilson]

Impressive Andrew


Nice and crisp 


Rob

[RotarySMP]

Now you can go into business printing "Laser Metal Etching Spray" labels, sicking them on 15 quid cans of Moly, and selling them on Ebay for 75 quid. Only the Chinese have probably already read your post and cornered the market.

Mark

[Jonny]

I was after something pro 5 years back not wanting the down time sourcing out and came across this link.
http://www.etch-o-matic.com/eom.htm

Several emails to buy, no reply sod him.

[awemawson]

Jonny, yes I saw that a year or two back. There was another version where the stencil was made on a standard type writer using a porous paper with a wax film that got knocked off where you wanted a mark. It's the same process making his stencil as making screen printing stencils.

As I have the laser I can print any graphic or text that I can generate using Windows, for no cost other than a puff of Dry Moly, and the longest part of the process is waiting for the 'Dry Moly' to dry ! No faffing about making stencils, and having 'developer' (which is caustic soda), and special electrolyte, and of course the special stencil film.

[tom osselton]

I just received some photopolymer paper to give etching a try there are a quite  few done using salt water and a      q-tip with a dc charger for knifemaking logos, apperantly a shot of ac will blacken it ( after the initial etch).
I have one of the actograph pen types made by Martindale it is a older unit with 10 heat settings I picked up for $85.00 Canadian, on there site the new one was $700.00!

[PK]

So we use that 'unbelievably expensive' spray. The flavor we buy is called Cermark, and it costs about AU$170 a can! It does a really good job (will post some pics tomorrow), but holy cow it hurts to buy that can.... I once went looking for some dry molly spray but couldn't find any. I'll have another look for that brand, (any chance of a pointer to a web site?)
 It'd be really interesting to compare..

Also interesting is... when you upgrade the tube and power supply in your 40W Chinese laser to >100W, marking metals becomes possible.  It's still not as good as the Cermark stuff, and sometimes we just hit the job with some black acrylic paint it get it to start absorbing, but it does work...

Cheers
PK

[awemawson]

I got it from my local convenience store eBay 

[PK]

 
Found some at Farnell. Will post comparison pics when it gets here....

[raynerd]

Well impressive results!! I didn't know the real stuff cost that much.

[PK]

So I said I'd do a comparison when the dry moly spray got here.  Well it never did. After about a month, a can of PCB lacquer turned up from Farnell! WTF?

Anyhow, I found this other stuff at the local nut and bolt shop, it appears to be MDS in an acrylic binder. I figure the binder isn't going to last more than a milisecond under the laser so I grabbed a can at AU$36


Sitting next to it is a can of CerMark LMM-6000. this is the stuff we use on our products and it comes in at the bargain price of only AU$165 per can.

The test

I did 2 tests on each spray, both at max power, one at 20mm/s one at 60mm/s (which is the speed we normally mark at) on a 120W CO2 Laser.
The substrate was some 0.8mm stainless sheet.



The top to are the MDS spray, the bottom two the CerMark.
Nb, by the time of the last test (60mm/s on the CerMark) the steel was quite warped

So it didn't turn out quite as well as our production work.

So it looks like the statement "Dry Moly spray gives results that are almost as good as the expensive marking compound for a fraction of the price." holds true. Unfortunately for us we're always chasing a high quality mark so we'll be sticking to the CerMark...

[Pete49]

mmm pictures didn't show here.
Pete

[awemawson]

Not sure what we are seeing here PK. In your first picture both upper and lower tests look to have come out well, and in your second picture both seem to have been erased 

[PK]

Not sure what we are seeing here PK. In your first picture both upper and lower tests look to have come out well,

The bottom pair are noticably darker in the flesh. It's more pronounced at the 60mm/s speed.

and in your second picture both seem to have been erased 

The bottom picture is of the back of the sheet showing the distortion caused by the amount of heat that went into it.

[sparky961]

Did you test the durability of the marking at all? Maybe take some steel wool or similar to it?  I'm curious how much this is etching vs. just converting something in the spray to carbon.

[PK]

Did you test the durability of the marking at all? Maybe take some steel wool or similar to it?  I'm curious how much this is etching vs. just converting something in the spray to carbon.

Its pretty good. You can sand it off, but it takes quite a lot of work and you can still see the mark on the bare metal. I'll go over half that test piece with some scotch bright tomorrow and post a pic.
The CerMark stuff is well and truly good enough for our applications (industrial electronic enclosures, and sensors). We use it on 316 stainless, nickle plated steel, and anodised aluminium. Many of the items operate outside and the marking is good after years of weathering.

[sparky961]

Its pretty good. You can sand it off, but it takes quite a lot of work and you can still see the mark on the bare metal. I'll go over half that test piece with some scotch bright tomorrow and post a pic.
The CerMark stuff is well and truly good enough for our applications (industrial electronic enclosures, and sensors). We use it on 316 stainless, nickle plated steel, and anodised aluminium. Many of the items operate outside and the marking is good after years of weathering.

I used to program and run multi-kW industrial lasers at a job a couple of years ago.  With both CO2 and diode/fibre machines, we'd just "etch" at a low power setting, and usually just outlines rather than fills.  The results were usually quite nice in terms of resolution and consistency but the contrast was always poor.  I wish I'd have known about this while I was still there, as I'd have a ton of things around here still that were laser marked.

[PK]

So here's the abrasion test. I used some OOO steel wool and scrubbed as hard as I could for a minute or so.
All the tests Held up about the same and pretty well I reckon.

[sparky961]

That's pretty impressive.

[awemawson]

I'm reviving this thread as I've been doing a bit more work on the subject.

I needed to make a label for my Flail Mower - chose to use Aluminium, and totally failed to produce a result. Ended up using non-optimal settings on Stainless Steel resulting is it taking over 6 hours to scan / laser a label. Hence wanting to see what's what and find some optimal conditions to use in the future.

Now my Laser Engraver is a 60 watt model so if you are using a different one you'll need to scale things accordingly.

First I produced a set of twelve sets of text, defined with power ratings ranging from 25% to 100& and travel speeds of 25 mm/Sec up to 75 mm/Sec

Then I prepared a sheet of aluminium, sprayed it with a good coat of 'Dry Moly' by Ambersil and lasered it. The theory is that the Moly bonds to the underlying surface when hit by the laser and any unbonded remnants are cleaned off with acetone.

The results confirmed my suspicion that this process does not work with Aluminium  As you can see NONE of the Moly bonded to the aluminium - zilch, nowt at any of a wide range of settings

[awemawson]

So now to repeat the process with Stainless Steel.

Good results this time - only a finished photo - sorry I forgot to take a pre-acetone cleaning one but it looked just like the Aluminium.

From my tests it seems that a travel speed of 75 mm/Sec with a laser power of 50% is the optimum for laser life and time taken - overall a good test and one I should have done years ago !

The resulting bonding seems VERY tough - I cannot scratch the 'blackness' off the substrate.

[John Stevenson]

No the moly only seems to work with ferrous materials.

The Cermark will work with anything but the idea is to find something cheaper.

If you want to so aluminium then just get some anodised plate and laser the coating off.
You will always get silver letters though so you need a good contrast colour like black or blue.

Like this:-



Not mine stole it off a web site but that is typical.

Good thing nowadays is that the lasers are getting so popular that a whole industry has spring up to supply materials. One of the better ones in the UK is www.908ltd.co.uk

On a different note I did read lately where some people have had decent results sticking a layer of Kapton tape that is used as bed substrate on 3D printers.

Not having any I haven't tried it, I did ask if it would do brass which is one of the hardest common material I have found to mark but no reply yet.

So Andrew seeing as you are at least 17s and 6d in front of me, that's your next project ?   

[John Stevenson]

Forgot to add, don't use plain silver anodising as with the silver letters it will look like an Italian flag

[awemawson]

Thought I'd give the anodised aluminium a try - seems ok on a first test using the same varied settings as before

[John Stevenson]

Told you not to try silver, now you have an Italian flag.

Have you tried the Kapton tape yet ?