CONCEPT TO COLLECTABLE - VOLUME I - A Guide To Understanding The Production Process - Action Figures

As my Luke Bespin focus started to take shape, I began to ask myself questions about all the variations and where they came from. It started with a question I asked myself about a specific lightsaber variation and which figure it belonged with, I educated myself with a basic understanding of the production process of these toys, this gave me a much better understanding of how variations occur and how they fit in.
So I decided to compile these threads to try and help educate fellow collectors and hopefully offer them some knowledge that will help them find the answers they are looking for.

Note : This article is aimed at helping people gain a basic understanding of how figures themselves were produced, allowing for a clearer understanding of figure variations. The packaging process has been left out but will follow in Volume II.

[section_header]Part 1 - The Pre-Production Stage[/section_header]

Design

The first stage of any toy production was the conceptual design. This was handled by the Marketing & Design Department, in the case of Star Wars, the design team would have had Cast photography and stills to work with but there is of course evidence to suggest that sometimes this wasn't the case and descriptions at best may have sometimes been all there was to work with.
Snaggletooth is a good example of this, it's possible that the designer only had pictures or reference to the characters mask, as the rest of the figure was about as inaccurate as it gets the first time round. The same with General Madine, it is common Star Wars Knowledge that the actor Dermot Crowley actually had to wear a fake beard so that he would match the action figure that had already been designed.

Typically the conceptual design would show a drawing of the character from front, back, left & right. The artwork would also feature various measurements and notes on general features, colour and other relevant details for the next stage of production, the sculpt.

Sculpt

The next stage of the production was to create a three dimensional representation of the character. The way in which this was done largely depended on the preferences of the actual artist working on the design, in the same way that some painters prefer to use water colour, while others prefer oil.
The two most common materials used were wax and acetate, how ever clay was sometimes used as a priliminary sculpting method.
Creating the original sculpt was a difficult process for the artist, regardless of the material used. He was required to not only create an accurate representation of the actual character but also consider the process of manufacture, the final creation had to be designed in such a way that it could be successfully released from a two part mold.
The artist would have to establish 'parting lines' to do this, these would usually be drawn on, to represent the line the final mold would have to follow, allowing it to be parted without damaging the figure part.
The most common method used was to create the figure using wax, in this case a specially formulated carving wax was used, similar to that which jewellers use to design jewellery.
The wax was first applied to a 'sculpting buck' this is a piece of material, (usually brass or bronze) which is a small block that has the arm, leg and head holes in it and represented the neccessary torso shape to allow the figure to move correctly. The wax was applied to the buck and then carved, by the artist using various tools, into the likeness of the character.
Small metal or plastic rods were used to allow the limbs to be connected to the torso. The major advantage of using wax was that if an error was made, it could be rectified using the addition of more wax or the removal of it, a process usually acheived using a heated tool.
Acetate was also used by some artists. This didn't require a 'buck' but typically the process was similar, the acetate was carved and sculpted to represent the likeness of the character. The problem with acetate was that if an error was made, it couldn't be altered in the same way that a wax sculpt could, so sculpting with acetate was a delicate job.
Sometimes, clay was used to create a priliminary sculpt, this process took a little longer but certainly had its benefits. The clay would be sculpted into the rough shape, sometimes using a 'buck' of some kind again. Once the general shape was acheived the clay was cast in plaster to produce a mold. This was then subsequently filled with wax which was then shaped and carved to produce the desired result.
It is important to note that sometimes existing wax sculpts were modified to produce other characters, a pratcise which saved time but also meant that some characters original sculpts where lost to time.

Silicone Mold

The next stage was to cast the original sculpt and make the first mold, this was done using silicone. Silicone molds were made of all the components of the figure. As the mold had to be cut in half after casting, it was often detrimental to the originl sculpt inside, causing damage to it.

Hard Copy

The purpose of the silicone mold was to produce a Hard Copy. Hard Copies were so called because the plastic used to make them was Urethane, a dense and hard plastic. Different types of Urethane where used like Carbalon and Dynacast, Carbalon was a common Urethane compound used at Kenner in the early years of production, Dynacast was more commonly used in the later years of Star Wars production.
The Hard Copy is the most accurate representation of the figure in terms of detail, with the exeption of the original sculpt and is often classed as the first 'true' prototype of a figure.
The primary purpose of the Hard Copy was to serve as a Tooling Master for the production of the steel molds in Asia, that would ultimately be used to create the final production figures.
Although multiple hard copies where produced from the silicone molds which would be used for other purposes in-house at Kenner.
One use of Hard Copies was to produce Kirksite molds at Kenner. Kirksite or Zamak 2 is a metal alloy, mainly consisting of Zinc, Aluminium, copper and magnesium. It allowed Kenner to produce short run molds cheaply so that they could produce figures to test the mold before the costly task of having the production molds made in Asia. Prototypes produced from Kirksite molds are often referred to as protomolds or bench shots and often served as test subjects for early paint designs.
Hard Copies were also used as paint masters, these could be used to create the spray masks that would be used on the production figures.
Hard Copies were also used on many occasions for catalogue and packaging photography. Good examples of this are the Hard Copies used on the early 41 back cards, the same ones can be seen better on the Palitoy 30a and 30b cards.

Production Mold

The final production molds where made in the factories in Asia, the primary metal used for these was steel, although other softer metals were sometimes used. The molds for the limbs would most likely have been made from a softer metal as the plastics used for the limbs was softer and therefore less abrasive and unlikely to cause as much wear to the mold.
The molds were usually created using a pantograph. The technique involved a stylus, which would follow the contours of the hard copy, this information would be copied by the milling machine, which would cut the reverse cavity into the metal mold.
Another method for producing molds was by using an electrode to melt away the metal. This technique is called Electronic Discharge Machining. (This subject will be further explained in Volume III.)

First Shot Prototypes

Once production molds were created, they were tested. The figures that came out of these were known as first shots and were essentially the final stage of pre-production. The term first shot is a reference to the first injection in to the molds a process referred to as shots. First shots were identical to the production figures, in most cases. Except they lacked any copyright information (some do have this) The primary job of a first shot was to test functionality, primarily  the functionality of the mold it's self, to make sure that the plastic was injecting correctly into all the parts. Secondly, the functionality of the figure. This was the first opportunity to put together an actual production standard figure and make sure everything moves and fits together correctly.
The functionality of the figure didn't require asthetics. First shots can sometimes be found molded in odd colour plastics. The factory would produce so many first shots, usually 100 - 200 which would be sent back to Kenner for evaluation before giving the green light for production to begin. Once this was given, the molds where stamped with the copyright information, date and country mark and production began.
First shots where also used for various other things; safety tests, paint tests etc. They can be found hand painted, machine painted or damaged through stress testing.

Engineering Pilot

The term Engineering Pilot can be confusing and so for the sake of this article, I will explain what this means in terms of the collecting world.
The problem in many respects is that technically an Engineering Pilot is a first shot prototype. This is actually the correct name for a 'first shot'. The 'Pilot' part is referring to the first in the same way that a T.V. program airs its Pilot Episode. The 'Engineering' part is a reference to the actual machine, in this case the mold, so by common definition, the term Engineering Pilot means Mold First Test.
In the collecting world of pre-production, the term Engineering Pilot is now usually associated with early production figures that are used in-house at Kenner for various tests and sometimes packaging photography. These figures usually have full copyright markings and are identical to production figures. They often have numbers on their feet or letters written on them which where used by the integrety staff at Kenner to reference the purpose of the figure. The problem with these figures is that without a full provenance history they are identical to production figures.
It is also important to state that first shot prototypes were also used for various tests as well, which is why the two can often be confused. Typically though in the collecting world the two are as described here, first shot being the prototypes, and engineering pilots being the integrity test figures.

[section_header]Part 2 - The Production Stage[/section_header]

Understanding The Production Process

To me, understanding the actual production process is the real key to understanding the variations and answering many of the questions that arise through collecting. In this next section I will do my best to highlight the actual creation process used in a working factory.
At this stage it is important to know that Star Wars figures didn't just come from one factory, but from numerous factories across Asia, even if it says 'Made In Hong Kong', this doesn't neccessarily mean that there was one factory in Hong Kong that produced the figures, infact there was at least three Hong Kong factories producing figures; Kader Industries, Smile and Unitoy. It's also important to note that these where all operating at the same time producing figures. Multiple factories increased productivity and also allowed for distribution to other countries.

The Production Molds

With the exception of some of the foreign sub licsense holders, production molds did not produce one figure at a time. They would usually produce 2, 3 or 4 figures at a time. It's important to note that the limbs and head were produced in different molds from the torso parts. There would be one mold block which would have injection points called gates which had tracks that lead to the figure cavities allowing the molten plastic to fill the cavities.
The mold is set with in an injection molding machine, these are large pieces of industrial equipment.

Injection Molding

The injection molding process is of course the most significant part of the production process of the actual toy. The injection molding machine is a complex piece of equipment. Taking the time to look into the detailed process is worth the effort if you want to understand more, but I will keep it to the absolute basics here.
Plastic comes in the form of plastic resin pellets which are placed in a hopper and super heated. These pellets can be a specific colour or sometimes the pigment is added during the molding process to create the correct colour.
The 2 piece mold block closes and the plastic is injected at high pressure (through the injection gate into the mold). This is connected to the runners which are then connected to the  figure mold cavity via the sprue. The easiest way to understand this is to think of an Airfix model kit. The Outer rim of plastic that all the pieces are set with is the runner, the little bits of plastic that connect the runner to the actual model part is the sprue.
Once the plastic has cooled the mold opens and the figure parts are released from the mold by the ejector pins which are rods within the mold, that push the plastic out when the mold block retracts.
At this point an operative opens the machine and removes the plastic and closes the machine and the process is repeated. The plastic part is placed in a container and sent off to the next department.

Note : The torso parts,limb parts and head parts are created in three different mold blocks in three different injection machines, but the process is the same for each, although the plastic used for the limbs and head is often a softer plastic.

Cut and Clean

This stage is simple, the figure parts are removed from the sprue, this is done by cutting them free, the points that are cut are then sanded off and cleaned up. The individual parts are then put into seperate containers (left leg, right leg, torso front, torso back etc. ) The parts are then sent off to be painted.

Paint Application

There are several different methods of paint application used in industry, but in the case of Star Wars toys, there is only really three that need to be discussed and only two of those that are relevant to the actual action figures, these are Electrostatic Painting, Spray Masking and Tampo Printing.
Electrostatic Painting is a method of painting metal die cast toys. This method would have been used for the Star Wars die cast range. The process involves electrically charged paint particles being sprayed out into an electrically static enclosed area, where the toy parts are hung from lines or 'trees'. The paint particles are attracted to the metal toy parts and cover the entire area evenly.
Spray Masking is responsible for the vast majority of paint application on Star Wars action figures. The process involves a 'mask' which is usually made of a copper sheet and is  roughly molded to fit a specific figure part into it. There are numerous different designs and styles used, it depended on the figure part. Sometimes they can be like a pair of tongs which you open place the part into the cavity and then close them. With a certain part exposed e.g. a boot, an airbrush is then used to spray this entire area, the tongs are then opened and the leg is released with only the boot painted.
Sometimes more complex mask are used, say for example you have a toso front that require a paint application to one area on the front. For this, a kind of mold cavity mask is used. The part is fitted into it and the cavity simply has the neccessary area cut out so when the paint is sprayed over the mask, the only part of the figure exposed is the area required to be painted.
Tampo Printing is method usually used for more detailed paint application, in the case of Star Wars figures, this method was used mainly for the eye prints. This is a machine printing process. The heads are placed into a cavity which holds them in place, they are then moved into the printing machine which has a silicone press with a metal printing plate with the eye pattern or detail etched into it. This is lowered into a paint resevoir and then applied to the head, the machine moves the cavity strip along for the next head and the process is repeated.
The colours used on the figures are usually established way back in the early design stage, although sometimes, changes where made along the way for example Luke Bespin started life with blonde hair, but sometime around the 41 Back era, the decision was made to change this to brown.
The factories were sent plastic colour Swatches with all the correct pantone codes on them so the correct colours as desired by Kenner could be correctly applied.

Assembly

There are several methods of bonding plastic parts together that were used on Star Wars toys. Glueing, rivetting and screw fixing or a combination of these, for example, glueing and then screw fixing. These methods are self explanitory.
The most common method of bonding used though was Ultrasonic Welding. This is a process that is used in industry to accurately bond two pieces of material together. It can be used to bond metals but is most commonly used on plastics.
In the case of Star Wars action figures, the torso front and back parts where bonded by Ultrasonic Welding.
First the figure is assembled, sometimes a buck is used to hold the parts in place. The arms, legs and head are placed into place on the back torso part and then the front is placed on top and clipped together via the central pin and socket located on the interior of the front and back torso parts. The figure is then welded.
The Ultrasonic Wedling process works by pressing the two parts together between a specially designed 'Anvil' and 'Horn' (Sonotrode) at which point a low amplitude acoustic vibration is emitted (usually between 20kHz - 70kHz) The contact points basically melt together.
This process is actually suprisingly quick taking only a second or two.

And there you have it, the Production Process involved in the manufacture of an action figure. In Volume II I will try and explain the process involved in the packaging design and production process.

Thank you for reading.

Some light reading before bed

Excellent thread Alex Great info Many thanks for taking the time and effort to do this mate

Cheers Andy, I'm working on Volumes II & III

Alex, Awesome article. Thanks for making the process clear and easy to read. I've finished part 1. I'll have to leave the rest for bedtime reading.

Great read, thanks! There can never been enough sources for this info. Do you consider lettered sabers "EPs" ? I have seen some people sell and showcase them that way.

That's a fantastic article Alex, which is clear and easy to understand.
I will certainly look forward to volumes II & III.

Thanks guys

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No I do not consider the lettered sabers as EP's simply because they are not. It is widely regarded that the letters where for some form of reference concerning the mould in the same way that the torso parts pretty much always have either letters or numbers stamped inside, and the LL Biker Scout has them on his legs.

Thanks! I thought the same! I am finding mold numbers on the outside on a few figures: S Crumb, Stormtrooper, Gammy and Gonk's can be seen without taking apart. I also have Short mouth scouts with no numbers on feet.

a fantastic guide to the whole production process General, thanks for putting this together

Great article, thank you for sharing (:

Thats Bleedin' ace. Really well explained and a fascinating read. Thank you.

Great article Sir Alex Magraw! Thanks for taking the time for making it!I am very looking forward to read the other two parts!

However this, i have to point out a couple of things i would say are not  accurate. I am used to molds development as a part of my restoration formation, but of course any modeler  involved in the model -hobby could know it. Anyway,here are a couple of thoughts about the this matter.

1.
SCULPT SECTION:
"He was required to not only create an accurate representation of the actual character but also consider the process of manufacture, the final creation had to be designed in such a way that it could be successfully released from a two part mold."

However the artist should keep in mind the manufacturing process, he never did the division between parts at the same time he made the sculpt details, that would be near to impossible and uneccesary at that early stage . If you take a look to an original Chief Chirpa(page 64) dynacast sculpt or a Greedo early sculpt(page 35) on Gus and Duncan book, you will realize the sculpt do not have "the line division" you mean. That "line" you can actually seen on figures is produced when you are making the first soft mold, either rubber or silicone, by the molds engineer and not the sculpter, despite they can be same person  

2.
SILICON MOLD SECTION
"The next stage was to cast the original sculpt and make the first mold, this was done using silicone. Silicone molds were made of all the components of the figure. As the mold had to be cut in half after casting, it was often detrimental to the originl sculpt inside, causing damage to it".

The very first molds were made either silicone (cream white color as you can see on page 78 on G&D book) - or rubber (with a orange reddish-brown color as you can see in page 44 on G&D book. I guess you took the information about the necessity for  cutting in a half the whole silicone mold block form there. I would say thats not accurated. The silicone mold development is a bit complicated at first sight, it is a long process...

If you take a close look at how a silicone mold have to be made( you have a good example on page 78), you will realize that there is a inner  thin "trench" carved surrounding the original sculpt piece you need to mold. The "trench " could be sculpted raising over the surface as well, and  is used to avoid the movement between the two parts on the mold when handling or casting the piece . There will be, also, a good amount of "rounded humps" surrounding the outer part too, those use to have semi-spherical or cylindric  shape and they are used as the carved trench. The mold NEVER is cut in half! That would be the worst scenery when it comes to make a silicon mold because you CAN´T see the piece inside,  you will 100% fail for sure when cutting the mold in a half. Sometimes when you are making the mold, the two silicone parts gets stuck! and you have to cut that part indeed, but should be considered as a fail when you are making the mold, and therefore you will need to repeat the whole mold if you are not luck enough to cut the wrongly joined silicone part.This is a explication i allways wanted  to say to Gus and Duncan for a revised issued on their book, which btw is a great book about SW collecting.

I don't know if i was able to explain it as well as i wanted LOL! there are a lot of silicone mold information on the net, will be easy to figure out how to making a proper silicone mold if someone is interested in know it.

It just took me 1 minute to find a good tutorial in the net, this will give you a good vision about how a two-part silicon molds are made, its worth to spent a few minutes to check it out:

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Hope this help a bit!!

Again it was a great article, i would like to share it in ma FB wall, if possible

Cheers!
Javier

Thanks for the help Javi, much appreciated. I have to say I did find the silicon mould process a little off when writing and yes in this section sourced from Gus and Duncans book. Especially as the silicon moulds that have survived are clearly two piece designs.
It's possible this could maybe, be a reference to the the even earlier stage when clay was sometime used where cutting it clean in half wouldn't have damaged the interior part because it's much harder than wax?
Either way, yes cutting into it would be a bit silly especially when dealing with wax.

Cheers for chiming in my friend

There is another good video of how to make a two part silicone mould in this thread.

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Alex thank you so much for writing this review article.
A must read for every collector who takes his or her hobby seriously.

I found two videos that visualize the use of spray masks a bit more.
In the first video you see a spray mask which is used to paint the blue hair of what seems an attractive Manga action figure.





I have one questions concerning the production of steel moulds. I understand that these were made from hard copies using a pantograph, faithfully transferring the contours of the hardcopy to the steel mould.
But at what stage were the subtle differences in steel moulds introduced, i.e. the differences which characterize the different mould families. For instance long V vs short V on Power Droid, or more subtle differences like hollow and solid eyes for IG-88?
1) At the stage of the hardcopy: send two slightly different hardcopies A and B to two factories (e.g. Hong Kong and Taiwan) to make their own steel moulds and there you go >>> two slightly different steel moulds giving rise to two mould families for one figure
2) Or at the stage of copying a steelmould: copy a steelmould (using pantograph) once there is need to allocate manufacturing to a different factory and manually adapt the part which needed some finetuning, giving rise to two mould families for one figure?
3) Other ideas?

Oh one other question. At some stage Lili Ledy obtained steel moulds from other factories to produce their own figures. And so did PBP. .
Were these the actual steel moulds, or copies thereof?

And last one: PBP erased the COOs for the set of steel moulds they obtained. And later some of these were sent to Lili Ledy to produce the Tie Fighter Pilot, Stormtrooper?
Too many questions, I feel the need for another Skype team session.

Thanks again for your effort!
Keep on the good work brother.

Marco

I will try and answer some of those questions Marco.

Funnily enough I'm working on a couple of threads which may actually answer some of those questions a little clearer

First of all let's discuss why there are different sculpts, like you said about Power Droid, IG-88 etc. It actually incorrect to say 'different sculpts' as I just did to be honest because there was most likely only ever one original sculpt for each character, although it is possible that two artists worked on one character, just seems a bit silly to do that really. The differences where created from the mould machining process.

Let's look at the three different 'sculpts' for Luke Bespin:


Now if you compare in detail the far left and far right figures (Unitoy & Kader) you will actually notice that they are almost identical, the Unitoy figure just has slightly more defined detail, to me this suggests that these where both produced using the same technique.

All factories would have received hard copies that where the same. Take for example the pantographing machine, if both Unitoy and Kader used this technique then the figures would come out pretty much the same which they are, the slightly more defined detail is probably just the simple result of a better pantographing machine. Think of a stylus on a record player, a brand new stylus is going to play the record better than an old one that wont pick up all the detail. Alternatively just look at it as, no too machine are the same so they will produce different results.

Now take a look at the middle figure, you will notice that it is totally different (unless you can't see all those difference... like for example on a Lili Ledy Mock Up )
There is no way on Earth these difference cames from the same hard copy. Funnily enough it's always the figures from the Smile factory that have the very noticeable differences, IG-88 hollow eyes for example.
To me there was a different technique used to produce the mould. One of the artist who worked on the figures originally said that it was suspected that not all factories used the pantographing technique and that some produced the moulds from sight.

Now this is impossible, someone, cutting into steel, a negative impression of a figure from sight???? Not gonna happen, how ever what he was probably referring too was this which I mentioned in the original post but didn't go into detail about.....

General Kahn wrote:Another method for producing molds was by using an electrode to melt away the metal. This technique is called Electronic Discharge Machining. (This subject will be further explained in Volume III.)

Well what this is, is a different method used to produce moulds. There are three main types of Electronic Discharge Machining (EDM)

Conventional Die Sinker EDM
CNC Die Sinker EDM
CNC Wire EDM

Convential Die Sinker EDM is most likely the method used for Star Wars figures. Basically how this process works is by using Tool Electrode which creates a spark to burn into the mould. The mould which is referred to as the Work Piece Electrode is submerged in a special fluid called Dielectric Fluid The process repeatidly creates a spark charge which burns the impression to create the mould although no actual contact between the two surface ever happens. The fluid contains microscopic Particles which are attracted to the area between the Tool Electrode and the Work Piece Electrode when an positive electrical current is applied to the Tool Electrode and a negative electrical charge to the work piece electrode. When particles gather together in the magnetic field created between the two electrodes they create a conductivity bridge which allows a spark which then burns and vaporises a small part of the work piece electrode. This process is repeated until the correct indention is create in the work piece electrode to create the mould.

Think of it as similar to how lightning happens.

Conventional Die Sinker EDM uses a Tool Electrode that is the actual same shape as the desired mould. So the actual Tool Electrode would look like an actual figure figure part. The Electrode is usually made from Graphite. The process keeps repeatedly burning into the metal until and exact negative impression is left thus creating the mould.
The point is that the Graphite Tool Electrode has to be made first and it is the construction of this that is probably why the figures are noticably different and probably the reason why the artist said 'made from eye' he was probably referring to the Electrode not the actual mould it's self.

I believe that the Smile factory used this technique to create there moulds which is why they are different, or of course it could be the other way round

Next question

In the case of PBP and Lili Ledy having moulds, this is discussed in a thread I'm working on so I wont elaborate to deeply and will insert a link here once it's done.

The short answer is that I believe that some times moulds where duplicated. There is several piece of evidence to suggest this. Example: PBP produced the Luke Bespin with the smoothed COO and they where still producing it at the same time as Lili Ledy where producing Luke from the altered version of the same mould??? In my opinion the China factory received a duplicated version of the PBP mould, added the raised bar, produced some figure before sending that mould to Mexico for Lili Ledy. Certain other elements of that mould where also altered which adds to the evidence butI'll explain that later.

So yes, I do believe moulds where sometimes duplicated and there is sound evidence to back this up.

Hopefully this help

After seeing the paint mask video's that Marco posted. It got me thinking, because of how small the parts are. Would they have made paint masks that were capable of painting multiple sets of legs (lets use legs as the example), at one time?

It just seems unlikely, they would paint one leg at a time.

Alex, this is a great resource to understanding the process. Thanks for putting it together.
These 2 videos below show exactly everything Alex has pointed out, and if you are like me the pictures make it easier to understand.

The first shows the steel mold making process, and I would say that the star wars figures would have been made using the edm process to achieve the fine details of the figures parts.
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This second one is a modern toy factory in operation, and shows every step mentioned above to produce the action figures, injection, trimming, sonic welding, gluing, painting etc.
These processes are exactly how it would have been done back in the vintage assembly days. Even gives an idea how the diecast toys would have been made also.
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This thread is really turning into a wealth of information

Thank you Alex , Javi , Marco , Oscar and Clint for all the input

Thanks for the video's Oscar, very interesting I've seen the second one before, it actually helped in the original draft of this thread.

I agree with you that EDM was the most likely style used, although Pantographing was also used in some factories apparently. It's this use of two different techniques that in my opinion is how the different 'sculpts' ended up existing for the figures.

@Commander Clint

It's difficult to say about the spray masks. The video that Oscar has posted shows only one part, despite the small size been sprayed at a time and the speed in which it is done. I guess it would actually end up been a much slower process having to fit multiple parts in to the mask and then remove them after as well. So it's likely that the parts where sprayed one at a time I guess.

Oscar, Thanks for posting those video's.   After watching Marco's video, and seeing the guy having difficulty putting the large part into the paint mask, I would have thought smaller pieces would harder to handle.  But after watching your video's, and seeing the paint masks they were using, it might have been easier to paint the smaller pieces one at a time. Thanks Alex, this is a great discussion thread.

Loving this thread as well.

Oscar, thanks for posting those very informative videos!
Also interesting to see the production of die cast toys.
The only disadvantage is that the background music used for the second video is not leaving my head anymore.

Alex: your explanation of different mould families originating from different techniques for making steelmoulds from (the same) hardcopies, is very plausible.
PBP/Lili Ledy: I understand the case for Luke Bespin. However when comparing Ledy and PBP TIE Fighter Pilots and Stormtroopers, it seems that the exact same steelmoulds were used. Or could you copy a steelmould in such a way that even very subtle details would be faithfuly reproduced, think COO typography, scars etc.
Let's discuss this in a different thread at a later point as not to distract too much from the main focus in this fantastic thread.

Cheers

Some videos showing the process of ultrasonic welding.





The energy of ultrasonic sound waves is dissipated along the boundary of two contacting surfaces, thereby causing local melting and immediate assembly of plastic parts.

On a side note (sorry can't help it ): I have this small theory that the melt marks as seen in Early PBP (Poch) figures are due to suboptimal settings of this sonic welding process in the Spanish factory (and not due to the plastic injection process, which took place in South East Asia anyway).
I can imagine when the back and front parts did not fit exactly (which would be likely when using parts from different mould families, which is indeed often the case for Poch figures), that the sonic welding yielded only a weakly assembled figure >>> cracks along the parting lines.
Maybe the factory workers observed this as well sometimes and submitted the figure then to an extra round of sonification, creating an additional energy input, and causing local melting at spots further away of the contact area / parting lines >>> melt marks on the butt etc.
Does this make sense?