0:00welcome to another fiber laser learning
0:02that last time we built a foundation on laser fiber
0:06the color gold today we’re going to try
0:10and consolidate that foundation a little
0:12bit more because we can’t really build
0:15up all the walls of the house until
0:16we’ve got a good foundation and there
0:20are a couple of big questions that I
0:23would like to answer before I go forward
0:25I’ve heard that there are three major
0:27problems with putting color on to
0:30stainless steel there’s a fairly narrow
0:32range of parameters for each color well
0:35I think last time we discovered that
0:37there was a very wide range of
0:39opportunity for gold now I only tried it
0:45for nanosecond pulses but within that
0:47four nanosecond pulse there was a huge
0:50range of possibilities that existed for
0:52finding gold but I want to look at the
0:54other possible problems today as well
0:56one of them is the thickness or the if
1:00you like the thermal conductivity of the
1:02material which will pull heat away from
1:04the actual work surface and it will
1:07change the color so unwarned and
1:09unrelated to that thermal conductivity
1:12is air temperature in other words if
1:15it’s a hot environment you will get
1:17different color results to have it’s a
1:19cool environment so we’re going to test
1:22the stability of the Gold’s that I found
1:24was it fool’s gold or is it the real
1:27thing that will resist changes of
1:30temperature and changes of thermal
1:32conductivity in the material as we saw
1:34last time there are many types of gold
1:38those that are gold but don’t show up
1:41only in a certain light and there are
1:45those sorts of gold here and here which
1:48are pretty good at being viewed in all
1:52sorts of lighting conditions now these
1:54are the goals that I want to look at
1:56today I’ve searched through the color
1:58swatch that I produce last time and
2:00identified or highlighted here those
Transcript for Fiber Laser Marking: Is this Fools Gold? (Cont…)
2:03colors that were sparkling six or seven
2:07of them which are what I call good
2:11quality gold what I want to find out is
2:13are there
2:13any common factors that give us some
2:15clues as to what produces what type of
2:18gold I think the answer is yes there’s a
2:21bit of an odd one there at twelve
2:23hundred and fifty millimeters a second
2:24but most of the sparkly ones if you
2:26notice are up here in the sixteen
2:28hundred to two thousand millimeters a
2:30second range and then we start taking a
2:34look at the gold we had a light gold and
2:37then we had the slightly coppery colored
2:39what I would call rose gold so we’ve got
2:42four three and two point five which
2:44produces light gold and if you remember
2:47when we looked at the pulse per square
2:50millimeter density we’ve got numbers
2:53here which are in that which are a
2:54hundred K now when we went to rose gold
2:58the parameters have tightened up quite a
3:01bit although we had fifteen ninety seven
3:03there that’s basically the same as 1600
3:05and they’re both the same so you would
3:07expect those two to be the same but then
3:09we’ve got this one here at two thousand
3:11with a slightly smaller pitch one point
3:14six microns and that gave rose gold as
3:16well and again when we looked at the
3:18pulses per square millimeter these are
3:20in the hundred and fifty six K so there
3:22appears to be a color difference that we
3:25can identify from pixels per square
3:27millimeter and tie that in with the
3:29microns that we’re using it gets us a
3:32nice rose gold color so we’re gonna
3:34start off today by just reproducing this
3:37result here which should be a nice rose
3:40gold okay so we’ve got a nice solid gold
3:43there okay so the first test I’m going
3:46to carry out is using my thermocouple
3:48here my k-type thermocouple which is
3:51sitting directly under the heated area
3:54now
3:58this will just basically check the
4:00thermal conductivity of the heat zone
Transcript for Fiber Laser Marking: Is this Fools Gold? (Cont…)
4:03through this very thin point five or 0.7
4:06thick stainless steel so probably my
4:09hand heat has pushed the temperature up
4:11a little bit the air temperature in here
4:13is around about probably 10 degrees C so
4:16I’m a few degrees higher than the
4:18ambient but let’s not get too concerned
4:21about that
4:29and hey you saw what the temperature
4:31went up to 70 degrees C okay so let’s
4:36turn this little cold workshop into
4:38summer should we turn this piece of
4:41metal into something about 40 degrees C
4:45it’s a pretty
4:52there we go one warm summer’s day
5:05warder 65 color change what do you think
5:14so there’s myth number two blown out the
5:16water it’s not very temperature
5:18sensitive at all
5:19let’s go myth number three which is
5:23thickness of material now haven’t got
5:25any really thick stainless steel but for
5:27the purpose of this very very small test
5:29we’ve gone from 0.5 to something like
5:32about 1.6 so we’re more than three times
5:35the thickness and what I’m going to do
5:37I’m going to do the test right in the
5:38middle right in the middle of the piece
5:40of material so I’ve got the maximum
5:42amount of heat being sucked away this is
5:44basically the heat being pulled away
5:46from the surface by a much larger
5:48thermal mass so let’s see whether this
5:51has an effect on the color that I’m
5:53producing it’s also a mechanically
5:55polished stainless steel this time as
5:58opposed to a piece of bright annealed
6:00maybe slightly redder than these first
Transcript for Fiber Laser Marking: Is this Fools Gold? (Cont…)
6:03two so it is possible that there is some
6:06small degree of variation with
6:10temperature or with heat sinking so
6:14we’re not going to dismiss it completely
6:17but what I would say is it looks as
6:19though it’s fairly resilient to the two
6:21extremes that I’ve just tested so it
6:24takes my fear away from the possibility
6:27that I may have discovered fool’s gold
6:30now I think it’s pretty real and that we
6:33can work with general workshop
6:35parameters and not worry too much about
6:37the color and we have just shown that at
6:392 microns it’s a pretty durable color
6:43resisting both heat sinking and
6:46temperature rise but what these results
6:50seem to indicate sparkle over here and
6:54color over here because here we’ve got
6:58the first four results between four
7:00three and two and a half giving us a
7:02light gold and then we’ve got these
7:05second three results here which are
7:08giving us a rose gold two and 1.6 micron
7:13pitch so the indication here is that if
7:15we go from say
7:17- which is what we’ve seen our nice rose
7:20gold s 2.05 in other words half a micron
7:26pitch that’s a fairly significant change
7:28in the heating effect that we’re going
7:30to see into the material are we going to
7:33push this rose gold towards a purple or
7:35a moe let’s give it a try that’s a
7:38pretty nice powder blue sparkly powder
7:44blue
7:44so my first shot will be to calculate
7:47quickly how many pulses per square
7:49millimeter it took to achieve that and
7:52then we’ll try a few more variables to
7:56see whether we can repeat that color
7:57with different parameters I’ve just
8:00calculated post density for powder blue
Transcript for Fiber Laser Marking: Is this Fools Gold? (Cont…)
8:02and it’s six hundred twenty-five
8:04thousand so I’ve done a quick
8:06calculation and to check the extremes of
8:09what we found before for spark cleanness
8:11roughly two thousand and twelve hundred
8:14the pitch becomes naught point four
8:17microns and naught point six six microns
8:20we’ll try those two numbers and see
8:22whether we can replicate powder blue now
8:25that is weird because that’s sixteen
8:28hundred millimeters a second half a
8:31micron two thousand millimeters a second
8:34point four of our on twelve hundred
8:38millimeters a second point six sixth of
8:41a micron a thousand millimeters a second
8:44point eighth of a micron nine hundred
8:48millimeters a second twenty nine of a
8:51micron and eight hundred millimeters a
8:54second one micron the rule seems to hold
8:58up except that one there’s nothing wrong
9:01with my calculations these are all done
9:03with exactly the same calculation in a
9:05spreadsheet I really don’t understand
9:07why that should be different the
9:09principle involved here is very simple
9:11we’ve got exactly the same number of
9:14pulses per square millimeter which
9:17technically means we should have exactly
9:20the same heating effect per square
9:22millimeter the only difference is we’ve
9:25changed the relationship between the
9:28pulses across
9:29and the lines down in general it looks
9:33as though it doesn’t make any difference
9:35but in this particular instance for some
9:37strange reason it does
9:40that’s a bluey green that’s a nice
9:41powdery blue I suppose and these are I
9:45suppose edging towards a green rather
9:48than a blue I can see clearly that that
9:51one has got a smoother effect to it as
9:55we decrease the speed we’re putting more
9:57pulses in in the horizontal direction
9:59and we’re producing a smoother effect it
Transcript for Fiber Laser Marking: Is this Fools Gold? (Cont…)
10:02would appear that the roughness or the
10:04texture on the surface comes from
10:06running at the higher speeds as I
10:08anticipated before I mean to get blue
10:10we’ve got actually got to drive right
10:12through this color range here to get
10:15towards the hotter part of the spectrum
10:18and obviously by closing up the pitch
10:20we’re putting more heat into the
10:22material I mean logically it does make
10:24sense that I should move from here to
10:27blue although I didn’t didn’t think that
10:30it was going to be as Extreme as that I
10:31thought it would move from there from
10:34that to rate first as we start moving in
10:36towards the hot razón we won’t know
10:38until we really go and have a look at
10:39these under the microscope okay so
10:42here’s a puzzling image it’s a sort of a
10:44a purpley gold so that was when we
10:48changed to say point five five look a
10:53half a micron and there’s no apparent
10:57difference so let’s go down half a
11:00micron it looks like the same picture
11:02because that’s what the color is on the
11:04surface it’s it’s exactly the same
11:06colour when you look at it in normal
11:08light okay so let’s go back to this
11:12image which is the starting image and
11:15this time instead of changing the pitch
11:18we’re going to reduce the speed to 1900
11:21which means we’re going to reduce the
11:23number of pulses in this horizontal
11:25direction we’re giving a little less
11:28mode and a little more blue so now we
11:32reduce it to 1800 though we’re getting a
11:36lot more blue and a lot less pink
11:39although the yellow hasn’t changed very
11:40much
11:41so now we reduce it to 1600 a little
11:44less pink we’ve got some green coming in
11:47a bit now but it’s still rough as you
11:51could see from the texture now we’re at
11:531600 and we’ve virtually lost all the
11:56yellow and we’re just in two shades of
11:58blue and green now and sure enough the
12:01color is coming out as a very nice blue
Transcript for Fiber Laser Marking: Is this Fools Gold? (Cont…)
12:03now we’re at 1500 still a nice sparkly
12:07texture more green less blue no yellow
12:12now we’re going out to 1400 ah now look
12:16what’s happening now 1400 can you see
12:20all these sort of blotches coming in and
12:24these blobs we’re getting much more of a
12:28flatter surface now this is what this
12:30indicating although we’ve still got some
12:32spark cleanness in there we’ve got areas
12:35where the surface is basically flat and
12:39now we come down to the final test which
12:42is 1,300 still got a moderately rough
12:45surface there it is sparkly now what you
12:50must remember is there is no green in
12:53these temporary colors so these colors
12:59that we’re seeing here there must be a
13:01combination of light rays which are
13:03creating colors that are not really
13:07there and these are the colors that we
13:09can see at high magnification once they
13:13get drawn away and get to your eye
13:15these colors don’t exist what you see is
13:18an amalgam of these colors I haven’t
13:20done the calculations at the moment to
13:22see what degree of variation we’ve got
13:24in the pulses per square millimeter
13:26count across this range of colors I will
13:30go and do that shortly
13:31we’ve just come across coppery gold
13:34again okay so let’s run again with two
13:39microns or I have to say it’s a bit
13:42difficult to say what that color is it’s
13:45it’s almost just a blank brown it’s
13:49certainly not sparkly
13:52so I think we’ll try and put some
13:53Sparkle into that by increasing the
13:55speed which is the formula for spark
13:58leanness so far we’ll push the speed up
Transcript for Fiber Laser Marking: Is this Fools Gold? (Cont…)
14:03to 1600
14:04okay now by pushing the speed up we’ve
14:09decreased the heat and we’ve got our
14:14copper color back again which is
14:17virtually the same as these two here
14:20let’s see if we can lighten the gold by
14:22putting the speed up leaving the picture
14:252 microns well yeah we’ve gone lighter
14:28and we’ve also gone spark Leah and those
14:32two there were done with a for
14:35nanosecond pulse but this time we’ve got
14:37our nice coppery gold rose gold at 6
14:42milliseconds as opposed to 4 nanoseconds
14:44so I wonder what happens if we go two
14:48thousand and something like point five
14:54point five of the micron well the answer
15:00is it gets us back to this strange brown
15:03color that we had here it’s not sparkly
15:07it’s it’s a dull brown so I’m not
15:11interested in that really I mean it’s
15:12obviously part of the color spectrum
15:14it’s going to take a long time to
15:15produce it at point zero at point five
15:19of a micron so I’m trying to see if I
15:21can get nice color and relatively high
15:25speed let’s jump up to another power
15:27band let’s try eight nanoseconds which
15:31will be at two hundred and fifty
15:32kilohertz and we’ll start off again what
15:36should we say 1200 let’s say 8 microns
15:41well we got a a sparkly coffee color
15:46there that’s nearly gold but not quite
15:48it’s like a a white coffee and we’ll do
15:53two things we’ll first of all put the
15:55speed up to 2000 and see what happens
15:59so we’re decreasing the power which
Transcript for Fiber Laser Marking: Is this Fools Gold? (Cont…)
16:01means we might move too
16:03- sparkly gold again yeah
16:06that’s actually not bad that’s even more
16:10that’s a bit of a copy but this one or
16:12some of these here and these down here
16:16so we found rose gold again at another
16:20set of parameters yeah we’ll take the
16:23vertical lines down to 6 micron 6 micron
16:26spacing so we’re adding some heat now
16:31which might drive us towards blue yeah
16:36there’s definitely a blue tinge in there
16:37it’s no longer copper so let’s push it
16:41one more down to 4 microns which
16:46increases the power permit per square
16:48millimeter and that’s done something
16:50really weird we’ve got a sort of a green
16:54on the ends and a gold in the middle now
16:58that must create that must be created by
17:00some really weirds heating effects
17:02because we are scanning like this so it
17:09means we’re getting double a heating
17:11effect at each end like that hot there
17:18turn round hot there so this is very hot
17:21this area and then as we scan across
17:23this middle area here we’ve got a cooler
17:26zone and that’s exactly what that
17:31pattern there seems to be showing I’m
17:32sure you could see that in this light
17:34let’s just zoom in on that
17:35there we go look you can see that
17:37clearly there now gold in the middle and
17:39green at the ends so does that mean if I
17:42go down to 2 microns I might be finding
17:45a sort of a peppermint green well the
17:48answer to that question is no we’ve
17:50we’ve gone to a very nice coffee color a
17:55very nice sort of a but you’ll notice
17:58something else in here as well look
18:00we’ve got the same effect that we had
Transcript for Fiber Laser Marking: Is this Fools Gold? (Cont…)
18:02here we’ve got the ends which are a
18:06different color to the center well
18:10although this is very interesting and
18:11we’re getting further and further away
18:13from gold but we are
18:15effectively trying to see if there are
18:18any patterns in the data that we’re
18:21getting I’m still trying to see whether
18:23or not there are any rules for colors
18:26and this one here again it’s a color
18:30that’s at two microns
18:32that’s a nice coincidence that we’ve
18:34come across many times before and at two
18:38thousand millimeters a second with a
18:40different pulse now we came across this
18:44lovely but very positive meter brown and
18:48if we take a look here look at the
18:50texture of the surface we’ve got all
18:52these little blobs on the surface here
18:54little raised portions so let me just
18:57bring one of them into clear focus and
19:02that’s 41 microns let’s just see how
19:07that relates to the background right
19:09there and that’s 39 38 so that’s about a
19:16three micron difference in depth which
19:22is substantially more than the thickness
19:25of the film itself so we must be
19:27disrupting the surface of the metal to
19:30make that amount of distortion so I did
19:34the calculations for that mid Brown and
19:35found it was sixty-two thousand five
19:37hundred pulses per square millimeter now
19:41I changed from two thousand at two
19:45microns to one thousand at four microns
19:50okay now that looks like a modern
19:54artwork but even though that is
19:59different it still comes out looking the
Transcript for Fiber Laser Marking: Is this Fools Gold? (Cont…)
20:03same mat made of brown now is a huge
20:08change in terms of the speed going from
20:11two thousand two one thousand and the
20:14line width from two microns to four
20:17microns we get no apparent change of
20:19color even though you can see that it is
20:22significantly different down at this
20:24level so here we are at three microns
20:27and thirteen hundred and thirty three
20:30millimeters a second again that we’ve
20:33got these little raised blobs here but
20:36they’re not as pronounced as they were
20:37in the first one but we still got lots
20:39of yellow in the background and we’ve
20:42still got the same apparent meat brown
20:45despite this different slightly
20:46different surface texture so we up the
20:50speed again to sixteen hundred
20:51millimeters a second and dropped the
20:54pitching to 2.5 microns
20:57we’ve got blocks here with modes and
21:00browns and we’ve got yellow in the
21:03background and gold and red the net
21:07result of this is still a meat brown so
21:12we’ve got a very very wide range of
21:15opportunity to get this lovely meat
21:18Brown blank color I think I’m going to
21:21have to produce a separate swatch with a
21:23record of each one of these colors on it
21:26so that we can see what our progress is
21:28and what the lovely range of colors that
21:31I should be able to put onto this
21:33palette so although I’ve been supplied
21:35with a recipe of colors from Lotus laser
21:39I have to say I’ve not opened the files
21:41at all I’m going my own way at finding
21:45colors with my method because I’m
21:48looking for a different sort of color
21:50that normally you see on these pallets
21:53now I’m feeling fairly happy with that
21:56swatch because even in this white LED
21:59light we’ve got some nice colors this is
Transcript for Fiber Laser Marking: Is this Fools Gold? (Cont…)
22:03not daylight this is this is a thing
22:05that was defeating other systems that
22:09should be green those should be I think
22:15that’s pink and that one’s gold
22:19that one’s gold I think these are
22:24supposed to be a pub a purple and I
22:27think these are silver this one is
22:29supposed to be like a sky-blue and it’s
22:32come out as a sort of a bit of a grey
22:33here the color recipe that I’ve been
22:36given is nothing like the recipe that
22:40I’m
22:40yet here no we accidentally came across
22:45this setting doesn’t look particularly
22:48different to some of the golds that
22:50we’ve seen you know it’s it’s got like
22:53pieces in it yellow pieces a little bit
22:56of pink in it some blue what color do
23:00you think that’s gonna come out to look
23:02at that isn’t that beautiful
23:04cuz look I can get that I can get the
23:07top of that lock into focus now let’s
23:10call that 90 well the bottom is just
23:13here somewhere I’ll just bring that
23:15little bit of brown into focus there and
23:18that’s only 88 so that’s only 2 microns
23:22difference what color would you think
23:24that that is going to come out at okay
23:32you’ve had enough time the answer is
23:34matte black don’t ask me why just
23:42mention it in your prayers tonight see
23:44if you get an answer so thanks again for
23:48your time and patience and I’ll catch up
23:50we’re doing the next session
