0:14Welcome to another Lightblade Learning Lab today we’re going to do a real task
0:21that involves marking of stainless steel now stainless steel can be marked with a
0:29proper metal cutting laser and I have managed to mark stainless steel with one
0:36of these lasers as well but not very successfully and at the risk of damaging
0:41the lens so please don’t do raw stainless steel let me first of all show
0:49you what we’re going to try and do on this piece of metal behind me which is
0:55stainless steel it’s 1,800 millimeters tall and it’s 600 millimeters wide which
1:01is just about the capacity of this machine now I’m hopeful that I’m going
1:07to be able to slide this through the machine because it is a pass-through
1:10machine and I’m going to be able to mark numbers and letters on this grid of
1:16slots that we’ve got here this is basically a key cabinet that
1:21I’ve designed now the bunches of keys are various sizes they can be anything
1:27from the size of my fist here down to just a simple bunch of keys like mine
1:36you can’t have all these keys at the same pitch so I’ve designed some special
1:42hooks that actually fit into these slots in a solid manner we pop them in the
1:49slot and then you just gently tap them down and they then remain
1:56permanently fixed in the slot I say permanently, but you can knock them out. But then
2:02what we need to do is to mark this sheet up, that’s already happened across the top
Transcript for Thermal Laser Marking Stainless Steel (Cont…)
2:07here with a laser a proper metal laser engraver and you’ll see that it’s been
2:12numbered across the top so all these slots just like a spreadsheet I’ve got a
2:16reference to them so it’s ABC down the side and numbers across the top so every
2:22bunch of keys can have its own reference the problem is these numbers in this
2:28light you could just about see them but to be honest they’re not very distinct
2:33when they’re in a dark cupboard what I’ve decided to do is to overwrite these
2:38numbers somewhere else with itched solid black numbers and letters and that’s
2:45what I’m going to show you today now before we start that process we need to
2:49go through a little bit of theory now there are some fundamental things about
2:53the laser beam which in a way I’ve been slightly misleading you about up to now
2:59Our laser beam is a parallel beam of and this is the important thing
3:06sorry I can’t write sideways and all the light is traveling in one direction and
3:14it runs completely parallel it’s what they call a coherent monochromatic light
3:21it is a light beam but it’s invisible I’ve been referring to it up to now as a
3:27beam of heat that’s where I’ve been misleading you because it isn’t really a
3:33beam of heat it is a beam of light and it’s only when that light hits a surface
3:40and gets absorbed into the surface that it turns from one energy form to another
3:48so it turns from light energy to heat energy when it gets absorbed by a
3:55surface if you can understand that simple principle it will give you a much
4:00clearer understanding of how and why the laser beam works when our infrared beam
Transcript for Thermal Laser Marking Stainless Steel (Cont…)
4:06hits a suitable reflective material and most
4:10metals are a reflective material to some degree there are some metals which are
4:16extremely reflective things like silver gold aluminium copper there are other
4:24metals such as this piece of metal that I have here which is a piece of
4:29stainless steel which is about probably 90 to 95% reflective so when we fire
4:37this beam at any organic material such as wood leather card any of those sorts
4:44of materials what happens is the surface of the material absorbs the energy and
4:50therefore it starts to heat up and if you heat it up enough it will burn and
4:56that is the process by which cutting takes place with organic materials now
5:03with acrylic the absorption into the surface creates heat but immediately the
5:10material evaporates it doesn’t burn if you fire it into water water absorbs the
5:18energy within the first probably less than a millimeter and it heats the
5:23surface of the water up so much that it boils and creates steam now you’ve seen
5:28me demonstrating that probably in some of my earlier videos so all I’m doing is
5:32trying to reinforce the fact that this beam is totally innocuous until it gets
5:39absorbed by an absorbing surface so when we looked at creating marks on our piece
5:44of stainless steel we were doing damage to the surface of the stainless steel so
5:50stainless steel melts at about fourteen hundred and fifty degrees C we’re going
5:55to need a lot of heat to cause damage to the surface of our stainless steel and
6:03we’re not going to get that out of a 60 watt parallel beam like this well two
Transcript for Thermal Laser Marking Stainless Steel (Cont…)
6:10things are going to work in our favour first of all the light in this beam is
6:15not uni.. uniformly distributed across it we’ve talked about it before
6:21and we’ve said that the energy distribution in this beam is what they
6:24call Gaussian in other words it looks something like this
6:27where the center of the beam is very intense light and the light dissipates
6:32towards zero as we get further towards the edge of the beam here I’ve got a
6:38lovely little magic pen and it’s a great demonstrator of that principle if we
6:44look at that light there you’ll see that it is very intense in the middle and it
6:48gets weaker and weaker as it goes to the edge well that’s exactly what this beam
6:53of light is doing as well it is not a uniform puddle of energy when I tried to
6:59measure with a thermocouple the temperature in the middle of this beam
7:03here I know that it is more than 1300 degrees C because I’ve melted the
7:09thermocouple and that is in the standard raw beam as I call it but what we would
7:14then do is pass this beam through a lens where it would come down to a very very
7:19small area something that we’ve previously called the spot size a two inch
7:24lens has got a spot size of about naught point one of a millimeter this
7:31concentration of the light becomes greatly amplified and we get very very
7:36high temperatures now at this spot of light because the energy density has
7:41been increased tremendously so now we can do damage to the surface of
7:47stainless steel but of course remember what I said to you, stainless steel is
7:52in fact reflective so whatever you fire at the stainless steel most of it will
7:57be firing back at your lens and this time it will be at a very high
8:01temperature a very high energy density because it’s firing off of a flat
Transcript for Thermal Laser Marking Stainless Steel (Cont…)
8:06surface and so consequently what will happen is it’ll come back up here and
8:10it’s likely to damage the surface of your lens now if I shine my light on
8:15that lens there you can see that little black spot there well look I’ve removed
8:20the coating from the surface of the lens by doing just that reflecting the beam
8:25back onto the lens surface and so that lens is now being completely destroyed
8:29so if I can’t mark the metal surface by firing the laser at it as we do in
8:37most products you know we just fire the laser at it and etches the surface well
8:41we can’t do that with metal because of this reflective property so what we’ve
8:45got to do is adopt a different procedure and the procedure that has normally been
8:50adopted as to buy some expensive chemicals this is a product called CERMARK
8:55this one’s called a metal marking material and this one a glass marking
9:01material and you can normally only get this stuff in the States if you try and
9:05buy in the UK it’s even more expensive because it has to be transported under
9:11very special conditions and those transport conditions hike the price up
9:15even more so from being maybe 10 or 12 pound in the States
9:19it may be real as much as 50 or 60 pounds to buy that same bottle of
9:23material here in the UK now how does this material work well basically you
9:29paint it onto the surface of your steel your stainless steel in particular and
9:33then you fire your laser beam at it as though you’re engraving normally now
9:38although you’ve got a very thin layer of this material sitting on the surface of
9:42your stainless steel this material will absorb all the energy and convert it
9:48into heat and so this material is the thing that heats up and in heating up it
9:55transmits some of its heat quite a lot of its heat into the surface of the
9:59stainless steel underneath and the combination of heating this material on
Transcript for Thermal Laser Marking Stainless Steel (Cont…)
10:03the top surface and the stainless steel beneath causes a bonding action between
10:09some of this material and the stainless steel that’s basically the principle
10:13that we’re going to be using today to mark this stainless steel instead of
10:20this little bottle of material which would have cost me 60 pounds in the UK
10:25I’m going to be using some of this spray which cost me about 10 or 12 pounds now
10:33these two materials are not really the same material but there is sufficient of
10:39this material in this product that it’s probably the active material
10:46we can use this dry film molybdenum disulphide lubricant to actually perform
10:52almost the same task if we get the combination of speed and power correct
10:58we shall get a very good black bond on this surface. Ok, just like any normal spray paint, you have to make sure this
11:08stuff is thoroughly mixed before you spray it and then what we need to do is
11:14just spray the surface fairly liberally
11:28got a reasonably thick coating as you can see and we just get rid of the
11:35excess and there because I’m very impatient I shall use my hot-air gun
11:47that doesn’t need to be rock-hard it just needs to be dry we’ve now got a
11:55nice matte gray surface and that is the surface very thin surface that will more
Transcript for Thermal Laser Marking Stainless Steel (Cont…)
12:03or less 100% absorb the energy from the laser beam I’ve set this up to the
12:09correct focal distance I’ve got a 2-inch lens in there and I’m gonna run this
12:14initially at about 100 millimetres a second but I’ve got maximum power coming
12:20through the lens and what we’ve got to try and do is to develop enough heat in
12:25a single spot to produce this chemical bond if we run too fast we shan’t get
12:31enough heat into a single spot to produce that bond so I may well have to
12:35slow it down if I don’t succeed in the first pass I’m gonna close the lid down
12:41because this stuff produces some rather strange smelling fumes and I’m not sure
12:47what they are so I want to make sure that I will extract them safely into my
12:52Purex unit now for this first attempt I’ve just done outline letters so that
12:58we can see the relative density of the letters themselves okay now for the
13:04second test I’ve rearranged the programme
13:07so I’ve got a small amount of air assist on there so that it doesn’t come up and
13:11damage the lens the fumes don’t come up and damage the lens and you can see 100
13:16millimeters a second is actually quite a leisurely speed we’ve got our letters
13:20that have been hopefully chemically bonded into the surface of the stainless
13:26steel the next process is a bit like magic painting
13:34we need some of this stuff Acetone and today I’m wearing my protective PVC
13:42gloves
13:49we just go for a final cleanup
13:56and there we go you can see how nice and crisp and clean those letters are and
Transcript for Thermal Laser Marking Stainless Steel (Cont…)
14:01now well what I want to show you is this
14:13yeah I’ve scratched the surface but I’ve not taken the letters off those letters
14:19are chemically bonded into that surface okay so I’ve scratched the surface but I
14:25haven’t erased the letter but it produces nice crisp black letters that
14:32was just a test now before I start on this rather large
14:37wide sheet of material I’ve got some slightly narrower sheets here that are
14:44probably only about 300 millimeters wide requires the same type of lettering
14:49different lettering different numbers but I’m going to do this easy one first
14:55because if I make a mistake on here I can turn it over and I can use the other
15:02side
15:05because this sheet is not yet bent when it’s bent there’ll be a front and a back
15:10but at the moment both sides are exactly the same so I have two shots at getting
15:16this job correct to be honest I’m very confident I should
15:20do it in one but there is an escape route that makes me more comfortable now
15:26it’s all very well me showing you what I’m going to do and how I’m going to get
15:31these numbers and letters into exactly the right place against the slots in
15:37both planes well obviously I’m not going to do it all in one go because there’s
15:42no way that I can make the unit pass through the machine but what I’m going
15:47to do now is we go back to RDWorks and I’ll show you how I program these
15:51numbers this is how I’ve imported my sets of numbers as you can see I’ve got
15:57two sets of numbers here well we don’t need both those sets of numbers and I’ve
16:01also shown you the slots that I’ve imported as well so what the first thing
Transcript for Thermal Laser Marking Stainless Steel (Cont…)
16:08I’ll do we’re going to do let’s just say we’re going to do 21 to 29 to start with
16:12I would delete that set there and we’ll work on this set here now the first
16:19thing I need to do is make sure I can I know where I’m going to put my head to
16:24start with the important thing for me to do is to accurately position these
16:28numbers relative to my slots and the way that I plan to do that is to mess around
16:33with this green dot so we’re go into config and system setting and here we’ll
16:41change the position of the green dot which is the start point for the head to
16:45the bottom center, close. Now watch what happens to the green dot now it goes
16:53down to there but look what happens when I remove the slots
17:04so that basically means the head is sitting at the top of the center slot
17:09and that’s where I’ve got to locate the head to get my letters into the correct
17:16position and the reason why I’ve drawn a rectangle around the letters like that is so
17:20that I can put that particular feature onto a different layer and let’s put it
17:24onto a blue layer and on this blue layer up here we’ll set is output no in other
17:33words I don’t want that rectangle to print but I do want the green square on
17:38the center of that rectangle for location and so now what we’ve got to do
17:43is go to the black letters which is the parameters up here is output yes speed
17:50100 is blowing yes scan and max power that’s all we need so now I shall output
17:58that to a memory stick and now we can be a little bit clever save yourself some
Transcript for Thermal Laser Marking Stainless Steel (Cont…)
18:04time by pressing by pressing ctrl + Z several times and there we go we’re back
18:11to our original so now we can delete this one and we can delete these we can
18:26call that
18:29a blue layer and it should already contain the properties that we want just
18:36check output no that’s all we need to worry about all the rest is unimportant
18:42okay and we’ve got our position in the center and now we’ll just check the
18:46black parameters hundred output yes blowing yes scan yes maximum power okay
18:55now we can save that to an output file back to the machine
19:02okay well I’ve set myself up the easy one to deal with which is a set of numbers
19:08right across the middle of the sheet but that means I’ve got to hang one end right
19:13out of the machine and to support it to stop it drooping I’ve had to use one of
19:17my tripods now what I’ve also done is set the table so that it’s completely
19:22level with this and I can pass right through the machine so I’ve removed the
19:28plate on the back so that this material can pass through the machine okay now if
19:33you remember the idea was to line the head up with the top of this slot so
19:39we’ll do that now because that’s where we’ve got to set the origin point what
19:41I’ve also done is I’ve made sure that my sheet is running square to the edge of
19:47the machine set that to 5.5 I’ve got air assist on, we don’t want too much air
19:57because we’re not trying to cool the surface down we basically want to keep
20:01as much heat in the job as we can extraction on and we’re ready to go
Transcript for Thermal Laser Marking Stainless Steel (Cont…)
20:15but now you may think we’re going to do these letters individually but as you
20:19can see I’ve copied a slot with a letter beside it now I don’t need the slot
20:24other than I’m going to use the slot as a means of setting up this rectangle and
20:30the rectangle will then be where I start from in other words I shall start
20:35putting my letter from the top of a slot so to do that what I shall need to do is
20:40first of all where should we start we can start at the end s and work our way
20:47up the sheet yeah let’s do that so I shall remove those slots and I shall
21:00remove those then I come up here to config system setting and I’ll change my
21:08location for The Head now to top right
21:15okay so that’s where my head will start on a slot and then I shall basically
21:23engrave four letters in one program so the first thing we’ve got to do if we
21:30remember is to get rid of the we don’t get rid of it we need it there so we
21:35change it onto a different layer and then we’ll make that blue layer if it’s
21:39probably still there is output no that’s okay that’s good and then P well if we
21:47look at the black letters we should find the black layer it’s still set output
21:55yes engraving at 100 millimetres a second is it blowing yes scanning yes
Transcript for Thermal Laser Marking Stainless Steel (Cont…)
22:02maximum power fine and we’ll have an interval of 0.15 so we can save that to
22:09a Ufile control Z and we’ve got everything back again we can delete that
22:17hold down the shift key and delete those and at the same time we can delete those
22:26slots delete we’ve already got our little
22:31green square at the top right hand corner all we’ve got to do is to mark
22:36the outside shape put it onto a blue layer and hopefully the job is OK
22:42let’s go and do those and here we are with the program working four letters at
22:48a time
22:51that’s not too tedious just got to keep loading the program
23:04okay well now I’m stumped because here we’ve got a 600 wide sheet on a 600 wide
23:12machine which I thought was a 600 millimeter pass through machine it turns
23:17out not to be the case
23:21the aperture at the back is 600 over 600 the bridge
23:28is only 560 and there are pillars in the way that hold up the backplane that
23:36limit you to something around about 500 so in reality this is only a 500 pass
23:43through machine so the maximum you can get is 560 if you were to take the
23:49pillars out that basically means I can’t engrave the letters down the side the
23:54best that I can do is engrave the letters at the top and turn my program
23:59round and run them upside down from the bottom and just run with two sets of
Transcript for Thermal Laser Marking Stainless Steel (Cont…)
24:05numbers well we are managing to do the letters across the top and I’ve now
24:10turned the sheet around and we’re doing the doing the bottom row numbers upside
24:15down as you can see so yeah, we’ve 20% done the second part of the job
24:23there’s a central row there’s a central row of numbers that are missing and all
24:27the letters down the side but hey I’m sure we’ll make do without them because
24:32we’ve got adjacent doors with the numbers on and the letters on as well
24:38well it’s sad that we couldn’t complete the job because as you can see behind me
24:42here this stuff does a very good job of producing black letters very durable
24:50black letters on stainless steel without any fear of damaging your machine well
24:56thanks for your attention I hope that’s been of some interest to your practical
25:01demonstration of something that’s real and not just an experiment and I’ll see
25:06you next session so bye for now
