The Fiber Laser Learning Lab Series with Russ Sadler
In this Series, Lotus Laser have lent Russ a MOPA 20 watt fiber laser to “play with”. Although Russ has a moderate understanding of laser technology (his words) and how constant power glass tube systems work, pulsing fiber laser marking machines are shrouded in a deeper mystery than the glass tube machines. In this session, Russ investigates fiber laser marking and tries to figure out how to achieve a black mark onto clear anodizing.
They have been designed for high speed marking and the technology has been well tried and proven. There are limited “tricks” that the pulsing laser technology can perform. You enter predefined parameters for each marking “trick” you wish the machine to deliver , then stand back in amazement. Most correspondents tell Russ that they have bought their machine direct from China and received a machine and EZCAD software, preloaded with a few default parameters. No other instructions beyond the EZCAD manual are forthcoming.
Russ states “I am neither a teacher or expert in this field so you join me in my learning adventure with the warning that I have a simple but inquisitive mind and will probably make mistakes on my way to discovering the truth. I WILL oversimplify and maybe distort the scientific detail in my quest to build a simple picture of why and how this technology works. I am not trying to reverse engineer anything, just to break through the seemingly impenetrable ‘techno cotton wool’ that surrounds this amazing piece of science.”
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Transcript for Fiber Laser Marking – Black Marking Clear Anodizing
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0:00welcome to another fight the laser
0:01learning lab um we focused last time on
0:06the lens no pun intended because the
0:11lens is actually the most important part
0:14of this machine I know that without the
0:17fiber laser itself it wouldn’t work but
0:19equally well you wouldn’t have to do
0:21anything with this machine without the
0:24ability to amplify the power through the
0:26lens so last time we checked out the
0:29focus on this machine and we now
0:31understand that we can if necessary use
0:34the focus as a mechanism for controlling
0:37the softness of the heat that we put
0:40down onto the surface it’s just one of
0:42the many parameters that we can play
0:44with to try and do this now that’s quite
0:48an important factor for today’s session
0:50because what we’re going to do today is
0:53something that I know can be done
0:55because I’ve heard and seen of other
0:57people doing it but I’ve got no idea how
1:00it’s done
1:00maybe they don’t either as an engineer I
1:04know quite a lot about some of the
1:06material processing that you have to do
1:08to get materials up to their finished
1:11state you know something I don’t have
1:13much in the way of to play with is clear
1:17anodized material because that’s the
1:20day’s challenge we’re going to try and
1:22find out if we can black mark clear
1:26anodized aluminium now technically where
1:29you think about it
1:29there’s nothing in there to cause it to
1:31go black we’ve got an aluminium sub
1:34structure there with a very thin layer
1:36of aluminium oxide sitting on the
1:38surface which has been created by an
1:40electrolytic process and then the micro
1:43granular structure which is being
1:45created by that process is then in field
1:47by assailant we have to look at the
1:50question and say well what is that
1:51sealant because whatever that salient is
1:54must be the thing that’s allowing us to
1:58make the mark black mm so I did a little
Transcript for Fiber Laser Marking – Black Marking Clear Anodizing (Cont…)
2:03bit of research and it turns out that
2:06the ceiling
2:08material that’s used for anodized is
2:11usually based on something called a
2:13nickel acetate formula we need to
2:16understand how to control the machine
2:19itself but the fundamental problems that
2:21we’re going to encounter all to do with
2:23materials and this is the first example
2:25we’ve got to understand what and how
2:28this material reacts the light so that
2:31we can apply the right sort of pulses to
2:33the surface to create what we’re after
2:36now the fact that it is a surface
2:40process means that probably we haven’t
2:44got to break through so we’re not going
2:46to be using powerful closes to pierce to
2:48pierce through the surface we’re somehow
2:50trying to get very accurate heating to
2:53the surface to modify the chemical
2:56they’re in some way so let’s just have a
2:59look a little bit further into the
3:00chemistry of what’s going on so we know
3:03that it was nickel acetate that was used
3:05there to create that final sealing
3:07process and here we got the data sheet
3:11for nickel acetate when I look further
3:14into the chemistry of nickel acetate
3:17toxic gases and vapors such as nickel
3:20carbonyl may be released when nickel
3:24acetate is heated it loses its water of
3:27crystallization and then decomposes to
3:30form nickel oxide okay so we’ve now
3:34gotta go hunting further what’s nickel
3:37oxide nickel monoxide is a green to
3:41black colored inorganic compound that
3:47then turns yellow and produces toxic
3:49gases upon heating so now we’ve got to
3:52decide the best parameters on this
3:54machine to create a very soft heating
3:58effect the point I’m really making it I
4:00could spend ages chasing around
Transcript for Fiber Laser Marking – Black Marking Clear Anodizing (Cont…)
4:01parameters but now what we’ve done we’ve
4:04narrowed down two things number one it’s
4:06a chemical process and number two it
4:08doesn’t require a great deal of e so we
4:10can now try softly T okay so here’s my
4:14almost my total stock of anodized
4:16aluminium it’s a piece of an angle
4:19which I then cut back into flat so
4:21they’re easy to work with and a piece of
4:24anodized aluminium – now from what I’ve
4:27seen there’s mainly only surface marking
4:30not depth cutting into the material
4:33looking at my parametric chart here I
4:36would suggest that we’re not going to
4:39start off down here look we’ve got lots
4:42of burning down here that means that
4:44although we’ve got a lot of range of
4:46pulse power across the top here that we
4:49could play with all of them down here at
4:51these low frequencies are very heavy
4:54burning what we need to do is go up the
4:57frequency scale and I know peak power is
5:02supposed to be at 850 I think if my
5:05memory serves me right two milliseconds
5:07two nanoseconds 850 is peak power why
5:11not use what are numbers I’ve got here
5:13which is a thousand and two nanoseconds
5:16so I think we’ll start off with that
5:19this is 500 millimeters a second well we
5:23could start off at that I don’t have a
5:26great deal of material to play with but
5:28what we’ll do we’ll draw a little square
5:30which is 4 millimeters square I will
5:33just put a fill in that line spacing
5:362.03 that’s basically half the width of
5:41the spot so we should get a 50% overlap
5:43on every spot we’ve got the loop count
5:46to one speed let’s try the 500 because
5:50we know that that’s roughly in the right
5:53sort of ballpark power hundred percent
5:56frequency a thousand kilohertz and pulse
6:00width – okay so at 6.15 not 6.25 so let
Transcript for Fiber Laser Marking – Black Marking Clear Anodizing (Cont…)
6:06me set the part height down here 6.15
6:14okay
6:22very dark gray as opposed to black every
6:25will slow it down a little bit give it a
6:27little bit more time to be tired
6:28here’s where my little chart comes in
6:30handy because we’re running this at 500
6:35millimeters a second
6:37so that means I’m producing 1700 pulses
6:43or 1700 dots per millimeter now if I
6:48change the speed to 200 or 250 look I
6:54can go from 1700 dots per millimeter to
6:57four thousand two hundred and fifty dots
7:00per millimeter so the heating effect
7:02will be greater if I run at 200
7:04millimeters a second now I’m going to
7:07note down all the data for this because
7:09I don’t want to lose this valuable data
7:11to be fair there probably looks to be no
7:21difference in the density of that black
7:23in this light it could be construed as
7:27gray it’s actually not bad it’s a pretty
7:31a pretty good matte black if I fail it
7:35with my fingernail there is just a small
7:40amount of depression in that cut well I
7:43did say that the material that we’re
7:45trying to blacken goes down into the
7:47material maybe that can maybe that
7:50counts for why we’ve got slightly very
7:52slightly gray so will now be a little
7:55bit brutal and we will reduce the power
7:57to 50%
8:00[Applause]
Transcript for Fiber Laser Marking – Black Marking Clear Anodizing (Cont…)
8:05the fingernail press tells you that
8:07we’ve got very little depression on the
8:10surface now I could definitely feel
8:12something there
8:16feel it here so let’s see how low you go
8:19is a power okay so we’re now gonna run
8:22this one at 20% power I think
8:34well it might be considered running
8:36before we can walk but hey I’m going to
8:40try scanning across a piece of Jew we’re
8:48looking at twenty three point three
8:50twenty three point three which is the
8:55maximum height and as it goes over the
8:57edge there it’s going to drop off so
8:59that’s actually going to test the focal
9:01accuracy of this process as well as we
9:05established in the previous session
9:06focus has got a very large range on it
9:09so we shouldn’t actually notice any
9:12effect at all as we go around this
9:14surface the focus is correct on the edge
9:17of the mark and it’s going to drop away
9:19by maybe one millimeter this does
9:21another check as well first of all we’ve
9:23got a different anodizing or we’ve got
9:25anodizing on a different type of
9:27material it shouldn’t make any
9:28difference
9:29but hey let’s see what we get definitely
9:35fifty material
9:39no this is not the F theta lens off the
9:43machine this is a macro lens I’m going
9:46to plug onto the front of this camera in
9:49the hope that you might be able to get
9:50some idea of what I’m seeing under the
9:52microscope
9:53now I managed to put this into some
9:55bright sunlight and the sunlight is over
9:58to the right-hand side of the camera and
10:01I think you’ll be able to see by virtue
Transcript for Fiber Laser Marking – Black Marking Clear Anodizing (Cont…)
10:04of the small shadows on the left hand
10:06side how raised up this surface is and
10:09how relatively speaking how rough it is
10:12so the first question is how do we
10:14reduce the surface temperature we’ve
10:17already got the power turned down to 20%
10:21we could go the other extreme and we’ll
10:24go right from 200 millimeters a second
10:26up to a thousand millimeters a second
10:29let’s try that because that means that
10:32we should be getting a lot less power
10:34five times less power per unit area now
10:43the one on the right is the second one
10:45that’s done a thousand millimeters a
10:47second and it does appear to be a
10:51slightly smoother finish and to be fair
10:54it does look to be slightly darker in
10:58this bright sunlight but when I look at
11:02it with the naked eye there really isn’t
11:03any difference so we’ve almost only got
11:07to turn the machine on or pick some
11:09lottery numbers and hey we’re going to
11:12make this material white knowing that
11:15I’m working on black marking of anodized
11:17aluminium notice later have been very
11:19helpful this morning and they sent me
11:21across their parameters for the black
11:24marking that they use let’s have a quick
11:28look loop one speed 400 power 42% that’s
11:35a bit exact frequency 825 Potts width –
11:40so they’re more or less using maximum
11:45power pulse like I am so their
11:48parameters
11:48not far off those that I was using for
11:51the first samples we tried on the tube
11:54first because I’m already set up for the
11:57correct focus height so we delete the
11:59Lotus Laser logo and we’ll just work
Transcript for Fiber Laser Marking – Black Marking Clear Anodizing (Cont…)
12:02with this little cue code after all my
12:04failures on this material let’s see how
12:07the Lotus Mart program works
12:32so here at 45 because a little bit slow
12:35on the stopwatch
12:59why the edge where it’s going out of
13:02focus we’ve got color so what I’m going
13:06to do now is to actually lift the focus
13:09up to see if we can bring that out of
13:12focus on to the top here to make it
13:14darker millimeter
13:16let’s try millimeter
13:27the fifties at the color very long its
13:29who play sthis you so I’ll increase the
13:32focus a bit more golf another elevator
13:36it is the localizable
13:40Oh
13:41start moving along here
13:48we’re gonna try those same settings
13:50right down the centre now
Transcript for Fiber Laser Marking – Black Marking Clear Anodizing (Cont…)
14:11there’s something different about that
14:12because I can feel your subducting that
14:15we’re now back to the Lotus later q-code
14:18settings
14:27apart from taking a long time
14:31none of those work we’ve now raised the
14:34focus hike up to 27 from its nominal 23
14:38point out that these are the Lotus Laser
14:42settings see we’ve got a lot less power
14:48there now because we’re using a lower
14:51part of the food
14:58not tucking into the surface and that
15:01looks pretty but whichever way I’ll
15:03catch it in the light let’s go back to
15:07my settings now
15:11so Tarragona doesn’t disappear I think I
15:14put more parity that’s looking more
15:18promising that is it cutting to the
15:20surface
15:24the answer is No so they’ve managed to
15:27get color five times the speed that the
15:31locust Llosa setting was so we’ve now
15:34change the line spacing to point zero
15:36one
15:45it’s got some quite nice text so most of
15:49that control is gained through messing
15:52around with the focus and softly not the
15:55power I found some more silver anodized
15:59aluminium from a job that I do for
Transcript for Fiber Laser Marking – Black Marking Clear Anodizing (Cont…)
16:01somebody else I have these as a surplus
16:04product now I’ve already done a little
16:06bit of experimentation because this is
16:08boring watching all this stuff for
16:10catchiest in the right light we’ve got
16:11black marks for some of them and as we
16:14turn it around some often go black and
16:17so off them go and disappear so they are
16:21light-sensitive this one at the bottom
16:24here was the first one that I did think
16:29it was that way up and that is the Lotus
16:34laser standard black marking it’s pretty
16:37good but then again that on there as the
16:43Lotus lasers standard black marking and
16:45it’s absolute rubbish the only
16:47difference is the position that I am at
16:50on the material as you can see some of
16:54these if we take a look here this has
16:57got a little black spot right on this
16:59corner but everywhere else it’s pretty
17:02dull and gray so from that I have to
17:04conclude that there’s a varying
17:06thickness across this surface in the
17:07anodizing that’s what we were finding
17:10with this product although it was
17:11anodized it was very very thin anodizing
17:15the thicker the anodizing the deeper
17:17these pores and the further into the
17:20material we can engrave and still hit
17:23this nickel acetate that certainly
17:26appears to be proving by these tests you
17:28know i’m now going to check what the
17:31anodizing is like on this outside
17:32surface here so if you catch them in the
17:34right light the difference between one
17:36and three isn’t all that great but one
17:41takes three minutes 45 and two and three
17:45take about 15 seconds
17:50now that works on this surface but of
17:53course it’s pretty rubbish on the bottom
17:58surface I mean this was the latest laser
17:59mark on the bottom surface and it’s
Transcript for Fiber Laser Marking – Black Marking Clear Anodizing (Cont…)
18:01lovely and black so I’m not I’m not
18:05arguing with that as a set of settings
18:07all I’m saying is it depends on the
18:10quality and the depth of the anodizing
18:12what you can actually do with it now you
18:15can clearly see the difference there now
18:17look I mean those marks hardly show at
18:19all but the locus layer mark settings as
18:23slow as it is it is durable no matter
18:27which way I fire the light at it I mean
18:31here we can clearly see that it makes
18:33the little or no difference as to which
18:36one of these that one is too weak but
18:38those these here were equally as good as
18:41this one which is the Lotus laser mark
18:45but we’ve also seen if we can get a
18:47fairly thick layer of anodizing then the
18:50nickel acetate penetrates into the
18:52surface deeply and even if we engrave
18:55away a small amount of the surface we
18:57still get this lovely black marking and
19:01we do this in something like about 15 or
19:0320 seconds whereas this one as I said is
19:06taking something like nearly about three
19:08and three-quarter minutes well I think
19:10we just have a quick 20 minutes sum up
19:12of what we’ve seen today sorry I’m
19:15joking um very quickly I think we’ve
19:18established that there is no one magic
19:21formula that gives us the opportunity to
19:24black mark on clear anodized aluminium
19:27we’ve established what the mechanism is
19:30and it’s a chemical mechanism of
19:32converting nickel acetate into nickel
19:35oxide and it only happens on the surface
19:38or to a depth that the nickel oxide can
19:41penetrate into the surface of the
19:43anodized material but what we’ve
19:45established is the region in which
19:47you’re going to have to work very very
19:49short pulses may be backed off with
19:52something like about 60 or 70 percent
19:55power and speed is not that important
19:59but I’ve been using speeds of around
Transcript for Fiber Laser Marking – Black Marking Clear Anodizing (Cont…)
20:01about two or three hundred millimeters a
20:03second but the most important thing and
20:05difference between my settings and those
20:09of Lotus later oh that Lotus later we’re
20:12using 1 micron line spacing and I’ve
20:14been using 30 micron line spacing so by
20:18default my speed is going to be
20:20substantially greater than their speed
20:22hence I can get to 15 seconds for one of
20:25those cue codes with the right material
20:27that I’m going to use for my product I
20:29might even be able to get it down to 10
20:31or even 5 seconds it really depends on
20:34the quality and thickness of the
20:36anodized aluminium that you’re using ok
20:38so it took 4 minutes not 20 minutes
20:41until the next time cheerio
20:44well I think you better settle down for
20:46another few minutes because I’ve got a
20:48little bit footnote to add to this video
20:50now a couple days ago I went to visit
20:52the guy that does my anodizing and I had
20:56a word with him about the chemicals he
20:58used for finishing off his product for
21:00sealing the anodized I often if he used
21:03at nickel acetate or no-mates is no no
21:07no no no that is it Regis use boiling
21:09water now boiling water is a process
21:12that can be used to seal anodized
21:16aluminium okay he’s only a small guy and
21:19he may be an exception but what he’s
21:22done he’s given me a little piece of
21:24material here that has been water
21:26boiling water sealed as opposed to
21:28nickel acetate sealed I’m wondering
21:31whether the weak results that we’re
21:32getting is because the product has not
21:34been finished with Anik acetate I know
21:37that this particular product has been
21:38boiling water soon so we’re going to
21:41give it a try with a few settings and
21:42see what we can find
21:44[Applause]
21:47so that gives us a shiny one
21:53something like discovered in my purse
21:55the colors
21:58there’s an interesting technique which
22:00I’m going to describe
Transcript for Fiber Laser Marking – Black Marking Clear Anodizing (Cont…)
22:01[Music]
22:07that’s it no I
22:09and so
22:15I’m getting yeah
22:21we confirmed it
22:30locate after a little bit of fiddling I
22:32think we found some results that work on
22:34this material there must be other
22:36chemicals in the surface of this oxide
22:40which are allowing it to turn black
22:43because this is quite a decent black
22:46mark and it must be just the thickness
22:50or the quality of the anodizing
22:52that’s caused the other problems the
22:54inconsistencies that we had in the other
22:56material but we’ll just test those same
22:58settings on the piece of angle that I
23:03had which was a good nice black mark
23:11[Applause]
23:28we’ll just test the same ku code on the
23:30piece of aluminium bracket that I had
23:41so there’s the time in the parameters
23:43for black marking clear anodized
23:45aluminium in some ways we’re still not
23:48all that close to absolutely finding out
23:51what that black mark is we don’t know
23:53whether this particular product has got
23:55nickel acetate in it we do know
23:58absolutely that this piece of clear
24:00anodized material has not got any nickel
Transcript for Fiber Laser Marking – Black Marking Clear Anodizing (Cont…)
24:03acetate in it and so where does the
24:06black mark come from on this one it can
24:08only be coming from some sort of
24:10alloying element within the aluminium
24:12itself now one of the candidates could
24:16be manganese there’s always somewhere in
24:19the reach of a half to one percent of
24:21manganese in aluminium alloy now my
24:25basic knowledge of chemistry and
24:27metallurgy suggests that that the mix of
24:31oxygen and manganese is a possibility
24:34because we’ve got the right ingredients
24:35on this machine eight oxygen in the air
24:39and after one percent manganese in the
24:42aluminium now although that surface does
24:45not feel in any way rough or ablated we
24:50won’t really be able to take a close
24:52look at that until I get my microscope
24:55so I think we’re going to have to leave
24:57this is a bit of an unanswered question
24:59I think the only conclusion we can come
25:02to is that we found a way of black
25:05marking clear anodized aluminium very
25:08quickly and now I’m really going to say
25:12goodbye to you and I’ll see you in the
25:14next session thanks for your time
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