School of Technology and Society
Design of a CAD and Rapid Prototyping
based production process for porcelain
Bachelor Degree Project in Integrated Product Development
C-Level 22.5 ECTS
Spring term 2008
Delia Villatoro Palomar
Manuel Gil Besi
Supervisors: Gunnar Hansson, Rörstrand Kulturforum AB
Thomas Johansson, Iittala AB
Christian Bergman, University of Skövde
Examiner: Lennart Ljungberg
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
The present work has as aim implementing a CAD and rapid prototyping based production
process in a porcelain company. There is considerable interest in ceramic companies in
implementing new digital technologies in an old-fashioned industry, where traditional handscraft
The work is carried out in collaboration with Rörstrand Kulturforum AB, whose current
process is analyzed, pointing out strengths and weaknesses, to define where to set the focus and the
actions to perform. This analysis goes from early stages of product design to slipcasting clay bodies,
the forming process of porcelain that uses plaster moulds.
As a result of this analysis, some alternatives including rapid prototyping and CNC milling
techniques are defined and compared to one another. Eventually, the definitive solution features
CNC milling as the main prototyping system, shaping the mother moulds out of a polyurethane
block. This process skips some initial steps, such as manual modelling and mould casting, resulting
saving in the new product development. Anyhow, the new process is yet to be tested in the
company’s own environment to fully implement it, regarding to various parameters such as the size
of the production and the complexity of the products to be manufactured.
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
Historical background of the company
Problems formulation
Analysis of the problems
First approach
Presentation of RP technique
Subtractive rapid prototyping
Casting materials
3D scanning
Solution 1. From the CAD to the plaster model/ mould
Solution 2. From the CAD to the mother mould
Solution 3. Changing the silicone
Solution 4. From the CAD to the mother mould. CNC
Solution 5. From the CAD to the plastic moulds
Discussion of the solutions
Final solution
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
This project was completed between February and June, 2008. The entire work was done at
Rörstrand Kulturforum AB facilities, in Lidköping, and at the University of Skövde. Apart from the
Bachelor's Degree students, Delia Villatoro Palomar and Manuel Gil Besi, there were other people
who played an important role in the development of the project. Some invaluable information on
the current operations of the company came from Gunnar Hansson, financial manager, and Kristin
Andersson product developer. Göran Fogelqvist also helped in contacting some suppliers for
materials. We would like to thank Christian Bergman, the supervisor of the project, who always
showed great interest on our progress, and Eiler Karlsson, whose first suggestions helped us
constructively from the very beginning.
As the time to complete this project was limited, we limited our work to feasible possibilities,
within the current state of the industry, rejecting those which were too new and not commercialised
yet, let alone the ones that, although seeming to be too good, were little less than impossible to
The bulk of the time for the project was devoted to research, trying to depict in the most accurate
way the state of the art towards porcelain manufacturing, considering all the techniques used in
prototyping, both machine-based and traditional. To do so, we used different methods, mainly
reading (internet searches, books, engineering journals, scientific articles and patents), receiving
feedback by contacting several companies and professionals in various fields and talking with
people involved in the production process. All the above information was processed through
brainstorming sessions.
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
Rörstrand is the second oldest porcelain manufacturer in Europe and was founded in 1726.
Since that time, the company has uninterruptedly been supplying people with top-drawer porcelain
In the past century, the company underwent many changes, the most important being the
relocation of the factory from Stockholm to Göteborg and eventually to Lidköping (1936), where
they have been manufacturing their products until early 2000's. They also underwent several
changes in their ownership, with the Finnish group, Iittala, taking over the company.
In 2005 manufacturing was moved from Lidköping, where products development for
Rörstrand remains. Rörstrand Kulturforum AB was
founded when the relocation of production was
implemented, in order to keep Rörstrand's heritage
alive. One of the main aims of this company is to
support small scale design and production, especially
oriented to developers and craftsmen that cannot
access bigger production ranges.
Figure 1. Source: Rörstrand website
The main issues of this project will be focused on giving as much information as possible. We
will also show what the first approach involved.
Though the problem must be treated as a whole, and an integral solution is required, we will
firstly define three different tasks, making it easier to understand the different angles of the
The manufacturing process does not make the production profitable. There are two main
reasons for this. On the one hand the production method is old, costly and slow. Porcelain is
produced the same way it has been for decades, with a handcraft-wait alternation system. As a
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
general idea that will later be explained in more detail, in figure 2. “Current Production Method” the
current manufacturing process of the company is shown.
Time and
1. Sketches/Drawings
3. Preproduction
2. Manual
model (Plaster)
5. Subsequent
-Very expensive.
-Not profitable unless mass
Figure 2. Current production method
On the other hand, Rörstrand's current scope is mainly short run production, especially to
attract craftmen, designers and small developers who come and use their facilities sporadically. This
could reactivate production in Lidköping and help keep the tradition of porcelain in Sweden. That is
why there is a need for improving the current system. Thus, one of the main aims of the project has
been defined.
The communication between Rörstrand Kulturforum AB and Iittala's production factories
needs to be improved. This is an old problem which exists in every company that has product
development and manufacturing areas separate from one another, and Rörstrand is not an exception.
As mentioned, they still have some product design and development left in Lidköping, which is
mainly drawings and handcraft in their workshop. The problem arises when these drawings of a
product are sent to the place where they will be produced in large scale to become an item for the
real market. In some cases these drawings are misused, either for a lack of information from the
source as a result of misinterpretation by the recipient, thus resulting in products not being produced
according to specifications, which means wasting money and time.
Presentations of new series of products often involve the creation of a product that will never
be sold. These kinds of products are created only for presentation, because they belong to a series
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
with which they share a certain design language and they are expected to be there. We can point out
the coffee pot as one such product. In spite of not being
normally produced, there is a need to create at least one, and
this arises a considerable problem, as it means that they have
to develop (the same way they do other products) a product
which will not give any profit back.
It was the company's suggestion to research RP (Rapid
Figure 3. Source: Rörstrand website
Prototyping) and related technologies as a solution to the mentioned problems. The implementation
of some of these techniques would, in a rapid way, solve some of the deficiencies of the company.
However, the enormous widths of this field, with numerous possibilities and different techniques let alone the perfect integration within the company-, require thorough investigation, procedure
definition and further testing.
For this purpose, and to a larger extent, we will analyse the production method of the company
in the following section. This will lead to the formulation of some ideas on how to perform our
work, as a first approach.
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
The following is an analysis of the way
the company works at present. Referring to
figure 2, 4 and 7 “Current Production
Method”, we see that the first stage is
preparing the sketches and drawings. That is
the main input from which the product
developers in the company start the work an it
can be drawings and conceptual sketches from
an external source or for a product of the
modelling starts (step 1, figure 7), which is
done by hand-carving fresh plaster material in
a completely traditional way. In this, the skills
of the craftsman are the principal factors to
influence both the duration of the work and the
quality of the model. This is a decisive factor
to take into account, as it is much more
difficult and time consuming to educate a
person into craftsmanship than in CADmodelling, the former being the result of many
years and the latter, of months.
This initial stage implies an interpretation
of the drawings when they have not been made
by the craftmen themselves, which can also
Figure 2. Current
Production Method 2
lead to a waste of time and material if there is
any kind of misunderstanding, on the part of
Figure 4. Current
Production Method
the craftsmen, or because of a lack of
information in the drawings. Thus, this part of
the process turns to be the most time and
money consuming, and the major costs are the labour. In the case of Rörstrand this phase involves
an investment in money and time that is half the total expense. We focus on this issue more
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
precisely later, when comparing the cost of the current production
method with the cost of the suggested alternatives.
In the subsequent stage, some plaster moulds (step 2, figure 7) are
cast out of the first model. These moulds are negatives of the desired
shape, and their purpose is to test several parameters for the subsequent
Figure 5. Hand carving-
porcelain casting (slipcasting), such as amount of plaster for the moulds
Homer Laughlin Company
and the number of parts, amount of clay to cast in them, time for the draining and wall thickness for
the clay bodies. These tasks are done quickly, with a low cost in materials, since plaster moulds are
very cheap.
The next step is the creation of the mother mould (name given to the model that serves as a
pattern). Unlike the first model, this is done in silicone rubber (step 4, figure 7). The process is
basically a casting of silicone fluid, mixed with a hardener inside a plaster mould, forming a thin
layer of a very smooth, rubber-like surface. The definitive moulds for production will be cast in a
box with this model, obtaining the negative an accurate surface ( step 5, figure 7). Though this stage
is not always necessary (it depends on the complexity of the object to be manufactured, and in the
number of moulds that will be cast out of the mother mould), most times they build this silicone
model, as this material has some important properties that plaster does not have. Among them, we
can count flexibility, which makes it easier for the decasting of the moulds, and the durability. This
property is essential, as a life lasting silicone model as opposed to plaster models that resist few
castings. The reason for this is the extremely high resistance to humidity of this material, as
opposed to plaster, which absorbs water, becoming dimensionally unstable after some time.
Despite all these favourable properties, silicone has a drawback, and that is its price.
Comparatively it is more expensive than plaster, which makes this step dear. However, the bigger
advantage of not having to make several models balances the extra cost. This step is, anyhow,
almost as expensive as the manual modelling and only slightly shorter in time, making it a step to
emphasise when defining changes in the whole process.
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
After this, the moulds for production are cast and the real porcelain manufacturing starts (step
6, figure 7). The clay is cast in the moulds, and left to stick to the walls to get the proper thickness
through the so called process of slipcasting, shown in figure 6. Firstly, the mould absorbs the water
of the mix, bringing the particles of clay to the walls. If the shape to produce is hollow, the excess
of mix is disposed of (drain casting) when the desired thickness is achieved, otherwise the object
becomes solid (solid casting). After demoulding, the clay is left to dry and fired, then glazed, and
fired again. This part of the manufacturing does not need to be analysed since it is outside our focus
Following on this overview of the production, the conclusion is clear. There are two steps
involving high costs, both in time and money. The first is the modelling stage, with a big investment
in specialised labour, and the other is the mother mould making, which involves a high cost of
silicone material and spare time because of the time required for the model to cure. It is on these
two stages that the main effort should be focused, trying to search for other solutions that, without
involving a big reorganization of the company, may shorten the time to production and to marketing
and thus reduce the cost of the development phase.
Figure 6. Slip casting. SCI
The next figure 7, shows the Current Production Method with real illustration in each step of
the process for the sample piece.
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“Design of a CAD and Rapid Prototyping based production process
for porcelain”
Figure 7. Current process illustrated with real pictures
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“Design of a CAD and Rapid Prototyping based production process
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As mentioned above, it was the company's desire to research rapid prototyping to find solutions,
given that the technologies this comprises have been developing considerably in the last few years,
thus becoming an important source of prototypes, tools (Rapid Tooling) and even finished products
(Rapid Manufacturing) for the industry. Furthermore, the predictions suggest an over growing
tendency in the use of these techniques, FFF (Free Form Fabrication), high-speed CNC-milling and
rapid casting tool making, as T. Wohlers (Wohlers Report, 2003) points out.
Following our first analysis, and to standardize our methods and not to focus too narrowly on a
certain level of the problem definition, we present the process on the basis of the Black Box Model,
as discussed in Nigel Cross' Engineering Design Methods (ed. 94, page 66). Emplosying this
approach there is a constant reconsideration of the level of the problem definition, as it focuses not
on the process itself, but on what is to be achieved.
A basic representation of this model is shown in figure 8. There are certain 'inputs' that turn into
'outputs' after passing through the 'black box'. The 'black box' contains all the functions which are
necessary for converting the inputs into the outputs. (Source: Engineering Design Methods, Nigel
Cross, 92)
Figure 8. Black box
The advantage of this model is that it broadens the possibilities, and if applied to our
investigation, causing us not to focus only in RP technologies, since there could be other options.
The next aspect to define in this model is what the inputs and outputs are, which can be done or
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“Design of a CAD and Rapid Prototyping based production process
for porcelain”
classified as flows of either materials, information or techniques. In our case it is not a difficult task
to define them. As we already know our process starts with some sketches/drawings of the product,
CAD files or ready-made models, sent by people who want them to be produced. Of course, the
output of all this has to be porcelain goods ready to be sold in the market, but as we mentioned
previously, our area of investigation does not cover glazing and decorating the product. For this
reason we can take the green bodies (greenware, unfired articles coming from the slipcasting
process) as our output. Figure 9 shows the development of our idea.
Figure 9. Developing the Black Box
As can be seen in the figure 9, what is shown inside the 'black box' is to be broken down into
sub-tasks or sub-functions. The developer of the model recognizes that "There is no real objective,
systematic way of doing this; the analysis into sub-functions may depend on factors such as the
kinds of components available for specific tasks, the necessary or preferred allocations of functions
to machines or to human operators, the designer's experience, and so on." Consequently, we are
basing our first ideas on the sum of our previous knowledge in the field and some intuitions as a
result of discussions with people who are knowledgeable in the field. Next figure 10 , represents
the first general ideas of how to undertake the new processes.
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“Design of a CAD and Rapid Prototyping based production process
for porcelain”
Figure 10. First general ideas
In a first attempt, we will investigate ways of rapidly manufacturing (whichever technique
there might be) porcelain products, that means try to find out if there are commercialised machines
that are able to manufacture these clay bodies via FFF processes. The main idea is to shorten the
steps in the production of the porcelain goods, and that is why direct manufacturing , unless being
extremely expensive, would be the best option. If this turns to be impossible, we would move back
one step, where the faster achievement of the moulds for production is the main objective. If
unachievable, the same goes for this option, then all the effort will be put on the previous step, the
construction of the mother mould. In a more general way, figure 11 shows the whole process with a
summary of the possibilities.
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“Design of a CAD and Rapid Prototyping based production process
for porcelain”
Figure 11. First brainstorming
The following section will provide the details of our investigation, giving an overview of the
possibilities of the industry for porcelain production, emphasizing on RP technologies (kinds and
applications) and properties of the materials involved.
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“Design of a CAD and Rapid Prototyping based production process
for porcelain”
The term rapid prototyping (RP) refers to a types of technologies that can automatically
construct physical models from Computer-Aided Design (CAD) data. These "three dimensional
printers" allow designers to quickly create tangible prototypes of their designs, rather than just twodimensional pictures. Such models have numerous uses. They make excellent visual aids for
communicating ideas to co-workers or customers. In addition, prototypes can be used for design
testing. Designers have always utilized prototypes; RP allows them to be made faster and less
As mentioned previously, RP techniques can also be used to make tooling (referred to as rapid
tooling) and even production-quality parts (rapid manufacturing). For small production runs and
complicated objects, rapid prototyping is often the best manufacturing process available.
At least six different rapid prototyping techniques are commercially available, each with
unique strengths and some weaknesses. A software package "slices" the CAD model into a number
of thin (~0.1 mm) layers, which are then built one on top of the other. Rapid prototyping is an
"additive" process, combining layers of paper, wax, or plastic to create a solid object. In contrast,
most machining processes (milling, drilling, grinding, etc.) are "subtractive" processes that remove
material from a solid block. RP’s additive nature allows it to create objects with complicated
internal features that cannot be manufactured by other means.
Although several rapid prototyping techniques exist, all employ the following basic five-step
1. Create a CAD model of the design
2. Convert the CAD model to STL format
3. Slice the STL file into thin cross-sectional layers
4. Construct the model one layer atop another
5. Clean and finish the model
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“Design of a CAD and Rapid Prototyping based production process
for porcelain”
The main Rapid Prototyping techniques are:
Stereolithography (SLA)
Selective Laser Sintering (SLS)
Fused Deposition Modelling (FDM)
Laminated Object Manufactured (LOM)
3D Printer
Patented in 1986, stereolithography started the rapid prototyping revolution. The technique
builds three-dimensional models from liquid photosensitive polymers that solidify when exposed to
ultraviolet light. It uses epoxy or acrylate resin. A low-power highly focused UV laser traces out the
first layer, solidifying the model’s cross section while leaving
excess areas liquid.
Next, an elevator incrementally lowers the platform into
the liquid polymer and the laser keeps on tracing layers atop
the previous ones. The model is then placed in an ultraviolet
oven for complete curing.
Figure 12: Schematic diagram of stereolithography. Princeton
Highest quality surface and accuracy
Possibility to build transparent models
Residual machining possible
Strongly allergy-provoking subjects evolves in case of uncompleted curing
During curing, changes in dimension can occur
It is among the most expensive: $180,000- $800,000
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“Design of a CAD and Rapid Prototyping based production process
for porcelain”
We cannot mention any specific case where SLA prototypes have been used in the field of
porcelain manufacturing.It is considerably expensive, but gives good results regarding to accuracy
and dimensional stability. Being the most widespread of all RP techniques, it is easy to find some
RP bureaus to outsource the prototypes. Their role in our process could basically be a mould to cast
some flexible material (eg. Silicone
rubber) for making the mother mould.
There are some applications outside
porcelain manufacturing in which SLA
is used to cast such material.
Figure 13. SLA process for microceramics
prototyping- RP process chains
Laminated Object Manufacturing
In this technique, developed by Helisys of Torrance, CA, layers of adhesive-coated sheet
material are bonded together to form a prototype. The original material consists of paper laminated
with heat-activated glue and rolled up on spools. A first layer is cut, then the platform lowers out of
the way and fresh material is advanced. The platform rises to slightly below the previous height, the
roller bonds the second layer to the first, and the laser cuts the second layer. This process is repeated
as needed to build the part, which will have a wood-like texture. Because the models are made of
paper, they must be sealed and finished with paint or varnish
to prevent moisture damage.
No shrinking and internal stress
Cheap materials
Fast building time
Hard too clean the support structure
Risk of dividing into two parts
Tendency to become softer in wet conditions
Figure 14. LOM process-Rapid product
development resource centre
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“Design of a CAD and Rapid Prototyping based production process
for porcelain”
Abandoned technique
The main disadvantage this technique has is that it is out of use. It is very rare to find a
company that builds prototypes with such machinery. This is mainly because of the softness of the
prototypes that need special treatments after being built. Otherwise they easily loose dimensional
stability and break apart. This results in LOM not being useful in most fields that might require RP
This contradicts somewhat the fact that there have been some experience with LOM and
ceramics manufacturing, and more specifically porcelain products development. There is a variant
of the original LOM machine that works with ceramic sheets, being able to build prototypes diverse
engineered ceramics, including alumina, zirconia, silicon carbide, aluminum nitride, silicon nitride,
aluminum silicates, hydroxyapatite, and various titanates.
Furthermore, there are some cases in which the technique has been used to make pottery, but
they remain more as unique experiments and tests than some real close-to-be-commercialised
One of them was performed by Tavs Jörgensen, expert in industrial ceramic production
techniques and researcher on how traditional pottery crafts merge with digital technologies, at the
Autonomatic Research cluster, in the UK. In his experiment, called 'Binary pottery project', he
made some first models of the jars and dishes to be produced in a LOM machine, but as he
acknowledges, the process turned out to be inefficient, CNC machining being the best alternative
for such a task. The main purpose of LOM in this operation was the achievement of really unusual
aesthetics in the pieces. (Picture of 'Binary pottery project') (Source: Binary tools, Tavs Jörgensen).
Another situation in which the terms LOM and pottery blended was in an experiment carried
out at INEGI (Instituto de Engenharia Mecânica e Gestão Industrial), Porto (Portugal). In this case,
the researchers used some LOM oversized vacuum epoxy infiltrated and painted prototypes with an
'as ceramic' finishing to subsequently cast plaster moulds. As they point out: “For non-complex
geometries, this approach seems to be good enough to change the old methodologies, maintaining
the necessity of the skilled experienced technicians.” The surface finishing and wall thickness were
good enough for the tooling to be used for mass production. They also used some other approaches
with the same technique, concluding that, in a general way, when the prices are fundamental, and
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“Design of a CAD and Rapid Prototyping based production process
for porcelain”
high accuracy is required, the mass production tooling must be performed by finishing with CNC
(CAD/CAM) high precision machining. However, they claim some Portuguese companies to be
using the above mentioned RP technique as part of the production. (Source: Rapid Prototyping and
Rapid Tooling Applied in Product Development of Ceramic Components, F. Jorge Lino and others)
Figure 15. LOM moulding
Figure 16. LOM model
Figure 17. LOM simulating porcelain
To conclude with LOM, we have to say that we do not advise using it because of all the above
factors. Even if there is an already accepted use of it for porcelain manufacturing, the difficulty of
finding a source (machine, RP company...) would make it unfeasible for use. As we will see later
on, there are no companies in Sweden providing LOM services. Then, the only alternative would be
purchasing a machine of a technique that is almost out of the market.
Selective Laser Sintering
Developed by Carl Deckard for his master’s thesis at the University of Texas, selective laser
sintering was patented in 1989. The technique,
shown in Figure 3, uses a laser beam to selectively
fuse powdered materials, such as nylon, elastomer,
and metal, into a solid object. Parts are built upon a
platform which sits just below the surface in a bin
of the heat-fusable powder. A laser traces the
pattern of the first layer, sintering it together. The
platform is lowered by the height of the next layer
and powder is reapplied. This process continues
Figure 18. SLS Morread State university
until the part is complete. Excess powder in each
layer helps to support the part during the build. SLS machines are produced by DTM of Austin, TX.
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“Design of a CAD and Rapid Prototyping based production process
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Material varieties
No post-hardening needed and auxiliary support
Residual machining possible
Functional parts with the same material as the final product
Large space to house it
High power consumption
Poor surface finish about 250 RMS.
It takes time to cool down before working with it (24h)
Dimensionally of lower quality than SLA patterns
Prices: $ 300,000
SLS is not the appropriate technique to use for our purpose for several reasons. It is quite dear
yet it does not give a good enough surface finishing. Moreover, the prototypes are porous, requiring
a sealing in case of being used in applications where the SLS material would be in contact with
water. If used as the mother mould, the prototype would require a much better stability and higher
performance than what the technique is able to achieve, as opposed to the silicone mother mould,
able to withstand numerous castings. In the case of using it as a mould for casting the previously
mentioned mother mould, the main requirement would be, once again, the surface finishing.
Fused Deposition Modeling
thermoplastic are extruded from a tip that moves in
the x-y plane. Like a baker decorating a cake, the
controlled extrusion head deposits very thin beads of
material onto the built platform to form the first layer.
The platform is maintained at a lower temperature, so
that the thermoplastic quickly hardens. After the
platform lowers, the extrusion head deposits a second
Figure 19. FDM. Xtrem 3D
layer upon the first. Supports are built along the way, fastened
to the part either with a second, weaker material or with a perforated junction.
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“Design of a CAD and Rapid Prototyping based production process
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Materials include ABS (standard and medical grade), elastomer (96 durometer),
polycarbonate, polyphenolsulfone, and investment casting wax.
• Residual machining possible
• The model can be produced in various colours
• Minimal wastage
• Easy to remove support structure
• Easy to change material
• Minimal set-up time
• Small space to house the machine
• Restricted accuracy
• Slow process
• Unpredictable shrinkage
FDM is definitely not the technique to be used in Rörstrand's process. Firstly, its materials are
not flexible, and the accuracy is not the best. The unpredictability of the shrinkage of the parts is a
big drawback for parts that should be working as tooling patterns.
3-D Ink-Jet Printing
Ink-Jet Printing refers to an entire class of machines that employ ink-jet technology. The first
was 3D Printing (3DP), developed at MIT and licensed to Soligen Corporation, Extrude Hone, and
others. The ZCorp 3D printer, produced by Z Corporation of Burlington, MA (www.zcorp.com) is
an example of this technology. As shown in Figure 6a, parts are built upon a platform situated in a
bin full of powder material. An ink-jet printing head selectively deposits or "prints" a binder fluid to
fuse the powder together in the desired areas. Unbound powder remains to support the part. The
platform is lowered, more powder added and leveled, and the process repeated. When finished, the
green part is then removed from the unbound powder, and excess unbound powder is blown off.
Finished parts can be infiltrated with wax, CA glue, or other sealants to improve durability and
surface finish. Typical layer thicknesses are in the order of 0.1 mm. This process is very fast, and
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“Design of a CAD and Rapid Prototyping based production process
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produces parts with a slightly grainy surface. ZCorp
uses two different materials, a starch based powder
(not as strong, but can be burned out, for investment
casting applications) and a ceramic powder.
Figure 20: Schematic diagrams of ink-jet techniques for
different companies.
Easiest, cheapest and faster
Enable various coloured models
No wastage of materials
Quick green bodies
Fragile models
Poor surface finish
There is much to say about this technique. Nowadays it is the technique which is developing
faster, gaining a bigger market share within RP techniques every year. Thus, there are some exciting
developments involving porcelain manufacturing.
Nevertheless, they are not commercially
available yet. For instance, there are some examples of direct manufacturing of ceramics via RP,
and more specifically clay greenware.
The 'Slip Jet Printer' is an apparatus developed as an experiment by
David Herrold, DePauw University, USA. Briefly, the machine uses a pump to
extrude a heavy clay slip through a nozzle. An object is built up by depositing
layers of clay along a rim. The machine produces geometric shapes from a
combination of functions that include: extrude, offset and twist as well as
lathe forms of the potters wheel. Objects produced by the machine can be
altered and finished using conventional ceramic methods.
Figure 21. Slip Jet
Printer. DAvid Herrold
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“Design of a CAD and Rapid Prototyping based production process
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However the Slip Jet Printer is an analogue device using mechanical methods of control, the
idea was inspired by contemporary efforts to produce a three dimensional
printing machine that is controlled by a model held digitally in a computer. The
“Slip Jet Printer” is conceptually a half step between the potter's wheel and a
digital three dimensional printer. This machine introduces mechanical precision
and geometric complexity but as a hand powered, analog device, it still fulfills
the “hands-on” criteria of craft. It is likely to be improved converting it into a
digitally driven device.
Figure 22. Slip Jet Printer
Another attempt at direct manufacturing ceramics is being carried out by Heinrich and coauthors, presently trying to produce directly in RP machine tableware ceramic prototypes, but the
process is still under development and is only suitable for small prototypes (J. Heinrich, J. Gunster,
S. Engler: L´Industrie Céramique & Vérrière Vol. 977, 2002).
The fact that in his famous annual worlwide report from 2003 (Wohlers Report, 2003).,
T.Wohlers does not mention any work that uses RP processes and ceramic and plaster moulds for
the development of ceramic parts shows how new these attempts are to the field we are dealing
Apart from this case, already commercialised techniques like Zcorp's 3D-Printing, use a
plaster-based composite to build the models. Though it is possible to rapid prototype the plaster
moulds and slip cast in them, the quality is very rough and the material, as it is not common plaster,
is expensive. Moreover, the life of the moulds is limited by their low strength. Parts typically have a
rough, porous surface not well suited to making silicone tooling. They can be impregnated with a
liquid resin such as an epoxy to achieve a smooth finish, but the additional post-processing cost is
unattractive for this application. There are also some developments in terms of coatings for Zcorp
models, in which Tavs Jorgensen, mentioned above, is involved. Due to the fact that these findings
are not fully patented yet, we could not get any further information, but it seems that they have the
potential of significantly widening the use of RP in the ceramic and glass industry. MIT 's 3DP
laboratory (Massachussets Institute of Technology) is also involved in several projects aiming at
the development of materials for specific applications of 3D-Printing machines.
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Figure 23. Parts made of zp140/ zb 60
(plaster). ZCorp
The clearest case of the use of this technique in a porcelain company is Denby's. It is an
international pottery manufacturer that uses Zcorp's machines to make their prototypes in plaster
material. They purchased some Zcorp device and they recognized to have improved their times to
market and efficiency due to several reasons:
2 hours printing instead of ¾ weeks for manual model carving.
In their case, purchasing the machine was more cost effective than outsourcing the
prototypes building.
Company typically detects manufacturing problems four weeks earlier, resulting in shorter
time to market. Problems are solved much earlier.
New product lines launched in half the time.
Prototypes enable the use of customer focus groups, resulting in more profitable design
decisions reflecting true customer tastes.
Accurate models better communicate design intent internally, with customers, and with
suppliers. Testing of the models both internally and externally.
Production prototype times reduced by half since properly scaled patterns are printed instead
of hand-carved.
Customers are impressed by Denby’s use of advanced technology like 3D printing, elevating
the Denby brand.
Partners in Portugal and Thailand, in charge of the production have their own 3D printer,
which leads to perfect understanding between product designing and production areas.
Repetitively of the models, as they cost around 10 $ in material consumption and machine
working time.
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In Denby's case the use of these RP prototypes remains in early stages of the process, with
testing and communicative purposes. Yet it quickens the process because of the improvements it
brings, it does not influence the production itself. This approach could be used together with some
other improvements later in the process, shortening and improving a big deal the whole flow from
designing to marketing.
Erik Adolfsson, Keraminstitutet's expert in Direct Casting and Rapid Prototyping argues that
Zcorp's techniques are the ones to use in this market.
To this point, and emphasising this case study, it shows the importance of prototypes, that
enable complete design iterations to be undertaken until an optimized design is reached. How this
process of iterations and customer involvement works is successfully presented in Campbell and
Co-Authors, “Design evolution through customer interaction with functional prototypes”. It argues
that “the provision of fully functional prototypes can also act as the catalyst for stimulation of
further ideas and development”.
To sum up, we can say that there is no possibility in the market that can create porcelain
straight out. This statement has been a constant aspect throughout the whole research, and it is
verified by different professionals in the field. In fact, this idea is shared by G.P. Tromans, renowned
expert in RP processes, working for the RP Consortium at the facilities of the University of
Loughborough. Said Tavs Jörgensen is also of the same opinion, although his work is focused on
developing new possibilities in the field. Even so, the incredible easiness of RP machines to build
whichever shape you can imagine could be an invaluable help in the development of new porcelain
products, with improved and limitless aesthetics.
At this stage, the question arises again with
renewed urgency: Is there a way to dramatically
improve the porcelain manufacturing process at the
company, shortening times to market and making it
more cost effective? To answer this question we will
have to examine other possibilities, such as subtractive
fabrication, which is not, as expected, so much an
opposite to additive fabrication, but complementary technology, and
other porcelain forming techniques different than slipcasting. The
Figure 24 . Source:
Denby company’s dossier
expected process might arise from the blending these and the previously explained RP techniques.
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This term refers to the use of traditional NC cutting for prototyping purposes. The source of
info for making a prototype in a CNC-milling machine is the same than for FFF techniques: CAD
and CAM files. Subtractive Rapid Prototyping (SRP) is even a lower cost prototyping and parts
manufacturing process than additive techniques, let alone the speed, which in most cases is bigger,
and the accuracy, much more precise.
A large drilling/cutting tool is used to shape the model removing large quantities of material.
Subsequently finer tools (smaller diameters) take care of the profile, passing over and over until the
work is close to be completed. Finally, a small tool is used to
provide with a surface finishing in accordance to the required
standard. Various size and shape cutters are used depending on the
materials and the cutting speed. The capability of the machine is
defined by its number of axis. There are machines with 3, 4 and 5
axis, the latter being the most capable, nevertheless requiring deep
specialisation in using them.
Figure 25. Raku-tool CNC
What is more important, some CNC-milling processes can be somewhat used for ceramics
manufacturing. Firstly, we will describe the general advantages and disadvantages of both CNCmilling and RP techniques.
The choice between CNC milling and RP is not easy. Both have their own strengths and
weaknesses. In our case, the company's skill base both in terms of IT and conventional
modelling/moulding techniques is also crucial. The following are some considerations about them
(all in the context of ceramic products development).
CNC pros:
Very good surface quality
Lower running cost
Generally larger build envelope
Much faster than RP
Figure 26.
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Possible to make mother moulds directly
CNC cons:
Demands a more skilled operator
Limitations to the geometry that can be created
RP pros:
Very easy to use
No limitation in geometry that can be created
Can create functional prototypes ( example;
teapots that pours)
Can make very realistic prototypes/mock-ups
RP cons:
Figure 27. 3D PrinterDimension
Quite expensive running costs
Limited build envelope, rarely over 250mm squared
Surface quality not as good as with CNC
SRP machines mill a wider range of materials that cost less and do not require chemicals or
post-finishing work. Among these materials there is a group of polyurethane foams, called
modelling boards. They all share a number of performance characteristics including: ease of
machining, excellent dimensional stability, good edge definition and low levels of residual particles
for easy clean-up. They are well-suited mother moulds, producing very stable, dimensionally
accurate tools with well-defined edges and surface detail when prepared, handled, and worked
properly. In addition, CNC-milling machines can also work with pottery plaster.
There are cases of ceramic companies using such polyurethane boards plus CNC-cutting
techniques to build mother moulds in which plaster moulds are subsequently cast. The mentioned
properties of the material and the precision of the machines make this option attractive, the easy and
quick demoulding after casting being crucial to the process. This way, a considerable amount of
time could be saved, as from the CAD data the company could be getting the moulds for production
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in just two steps, avoiding the fairly laborious step of manual modelling and casting the silicone.
Moreover, here is a point where traditional craftsmanship and brand-new technologies wave hands,
as long as some of these milling boards can be even hand-carved. As a matter of fact, a prepared
person in both old and new crafts could create shapes joining the straightness and accuracy of
digitally controlled machining and the complexity and “uniqueness” of hand-made products.
The only drawback to this possibility is the fact that it requires specialised people, as big
CNC-milling machines are not easy to use. Machining takes skill, creativity and the ability to
develop solutions to problems in both an engineering and imaginative way of thinking. From
designing tool paths and machining strategies to operating and monitoring the cutting, machining is
a work for considerably experienced craftsmen. Investing in this kind of machines would involve an
investment in know-how, in human resources who are able to manipulate them. Nevertheless, more
and more they are becoming user-friendly, with examples of desktop CNC-machines. In this group
of machines we can name Roland MDX series, from Roland Company, that delivers desktop CNCmilling machines. They are at the same time milling centres and scanners, and their prices are easily
affordable. The disadvantage is that the working area is limited (x=400 mm, y=400 mm, z=155 mm
for the largest machine of the series, with a cost of aprox. 180,000 SEK), but once again the
formidable properties of the modelling boards can help fix this problem. These boards can be cut
and glued together easily, allowing the user to build a prototype out of several slices milled
separately. In a sense, there is no size limitation to the parts you can build.
The implementation of digital technologies in the production process does not necessarily
mean perfection. The time and effort spent in the 3D-modelling phase, which can turn to be an
arduous task if the model is complex, in conjunction with the programming of whatever machines
you may use and any post-processing work can change what seems to be an easy automated process
into a long laborious work. Therefore we also have to look at smaller, but perhaps more effective
changes than just relying on the purchase of a big machine.
One possibility could be changing the casting material for the mother mould. There are some
materials that can be cast to make this model instead of silicone. Polyurethane resins are formed,
similarly to silicone, by a mix of powder material and a hardener. Their properties and applications
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are the same to those of silicone. Both kinds of materials belong to what are called Room
Temperature Vulcanization (RTV) rubbers, which means that they cure at room temperature.
Generally, there is an equivalence relation between silicone and
polyurethane rubbers regarding their application and their properties, and
for a same standard the latter are slightly cheaper. There are several
commercial names for them, such as RenCast and Raku-PUR.
Figure 28. RenCast.
When it comes to a variation in the material of the moulds for casting the clay, polymeric
moulds for pressure slipcasting should be mentioned. The material is normally PMMA. Monomer is
mixed with a PMMA powder and water and then the mix is poured in a mother mould, just as if
making a plaster mould. The monomer is polymerized (hardened) and the porosity is created by the
water. Despite being porous, moulds made of this material have less capillary force than plaster, and
external pressure is required to make the mould absorb water efficiently. Channels within the mould
for applying air, vacuum and water are also created during the casting process.
Pressure casting is very common today, especially in the field of sanitary porcelain but also in
houseware making. It is more efficient than conventional slip casting, with faster casting cycles and
less water content after casting.
In more detail, the pressure in these moulds is much higher, in the range of 40 bar, than in
normal slipcasting, where it is around 2 bar. This involves faster cycles (consecutive castings are
allowed, without the necessity for the moulds to dry) and completely dry parts, that can be
immediately post-processed, unlike conventional slipcasting green bodies. Furthermore, the
durability of polymeric moulds is also higher, being able to withstand thousands of castings,
whereas plaster moulds can be used up to several dozen times.
This technique is experiencing some radically new improvements, with the development of a
new material for the moulds that can be CNC worked. This brand new feature is not
commercialized yet. It was developed under the project FLEXIFORM, performed mainly by
CERAM, British research centre for ceramics, in collaboration with several European companies,
Iittala group and Portec (developer of the material) among them. The project underwent all the steps
from formulation to testing, and as Graham Small, CERAM's coordinator for the project with whom
we corresponded, the technology proved “to work in the demonstration phase but there
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was not sufficient interest from the ceramic manufacturing industry to put it
implementation of the technology if anyone wants to put it into production. It
would involve the following companies: Lippert (developer of the demonstration
machine), Portec (producer of the aluminium-epoxi porous material) and Goodalls
(company that milled out the shape from the blocks of material)”.
Figure 29. Pressure casting.SCI
The Swedish Ceramic Institute (SCI), in Göteborg, possesses a pressure casting machine, a
small production unit, suitable for casting pieces up to about 1 dm3 in pre-studies for large-scale
pressure casting (Source: www.keram.se/eng/pdf/slam_eng.pdf).
However, the company showed little interest in this industrial process, this being the reason
for us not to go further into this possibility. The focus, as stated in the beginning, is to be put in the
early stages of the product development.
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There is much to say about 3D-Scanners because of the wide variety of scanning systems and
their different applications. Rapid Prototyping technology uses 3D-CAD models, but sometimes
these models are not created directly in 3D software packages, but come from the scanning of a
part, in the form of a cloud of points or a mesh which can be used to develop the virtual model. The
contribution of a 3D Scanner in the factory would consist of two main tasks: The first one is to
reproduce an object or piece in the computer more easily than manually using a 3D-modelling
software to create it with the same features; and the second one is to attract craftsmen that might be
interested in manufacturing their previously hand-modelled models. A physical object is always the
best way to communicate shapes, purposes and feelings. Thus, the scanner works as a
communication device between designers and Rörstrand, and also between the company's
development area and the production facilities: an automatic translator of the other's desire into
CAD data, ready to be worked through the manufacturing process.
3D Scanners are generally classified, depending on they perform the scanning, as follows:
Contact: These scanners work though physical touch. Although they are very precise, the act
of scanning could involve damages or changes of the model if it is delicate, and it is much slower
because the arm supporting the probe has to be physically moved. Examples of this type of scanners
are the Coordinate Measuring Machines (CMM) and Hand Driven touch probes.
Non-contact: A radiation or light is used to build the model into the computer, where millions
of data points are captured. Applying talc powder helps minimize resolution problems because of
the environment (darkness, brightness, transparency…).
They are divided in 3 types:
1. White light scanners (Interferometry) use an optical method for measuring physical parts.
It obtains measurements of an object by determining changes in the fringe and distortion of a
pattern of white light projected on an object.
2. 3D Laser Scanning is a 3D scanning device that uses a laser to reflect off the part and
triangulate with a camera lens, allowing the scanner to determine and create XYZ coordinates. The
scanner then uses these points to form a 3D digital model of the part.
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- Laser triangulation is accomplished by projecting a laser line or point onto an
object and then capturing its reflection with a sensor located at a known distance from the laser's
source. The resulting reflection angle can be interpreted to yield 3D measurements of the part.
- Time of flight laser scanners emit a pulse of laser light that is reflected off of the
object to be scanned. The resulting reflection is detected with a sensor and the time that elapses
between emission and detection yields the distance to the object since the speed of the laser light is
precisely known.
- Phase shift laser scanners work by comparing the phase shift in the reflected laser
light to a standard phase, which is also captured for comparison. This is similar to time of flight
detection except that the phase of the reflected laser light further refines the distance detection,
similar to the vernier scale on a calliper.
3. Stereo vision based: A method of capturing three dimensional data based only on cameras.
An algorithm of stereo vision involves receiving inputs from two or more different cameras oriented
at different angles and analyzing the differences between the images to obtain 3D information. This
3D information is easily read as a 3D point cloud.
After a thorough search, we have chosen three of the most representative scanners in the
market, from well-known brands. They belong to different ranges in quality and price.
Scanner/ Features
ZScanner 700
Non-contact, Laser
50µm XY,0.1mm Z
Size of the
160 x 260 x 210
Scan area
Points per
Laser Roland LPX 600
Direct Dimension
Contact, digitalized
with laser
±o.o15 mm
150 mm square
Non contact, Laser
±0.05 mm
630 [W] x 506 [D] x 761
[H] mm
Rotary scanning:
1270 mm sphere
18 000 measures / s
37 mm/sec
From 314235 Kr
From 29771 Kr
From 96647Kr
Figure 30. Scanners
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Roland LPX 600
MicroScribe G2-RSI Laser System
Figure 31. Source: Roland
Figure 32.Source: Microscribe website
ZScanner 700
Figure 33. Source: Zcorp’s website
It is certain that Zcorp's laser scanning systems are much faster and effective than the rest, but
at the same time more expensive. Zcorp's scanners are more adequate to make complex figures
without size limitation. ZScanner 700 is a portable scanner which is able to take references itself in
relation to the part, so establishing a coordinates system is not needed. Microscribe MX uses a
flexible articulated arm technology. It belongs to the contact scanners group, which is not as fast
and accurate than the previous ones. It is necessary to determinate the points to model the part into
3D-CAD. To save this disadvantage MicroScribe digitizers and portable CMMs are joined together
with the RSI 3D laser system that compiles data points that appear in real time in the screen of the
computer to show where the density of the points should be increased. Then the software aligns the
scanned profiles to give as a result an accurate scanned object. Roland LPX scanners are automated
3D scanners at the touch of a button. If the object is not larger than the dimensions shown in the
comparison chart, LPX-600 is the one to use, being relatively cheap and easier to use than the
others. The rotating table allows the system to quickly scan the objects. Otherwise, we recommend
MicroScribe system. 1
Through the figure above, with the main performance characteristics of the scanners and after
discussing it with the company, Roland LPX-600 is the chosen solution. It has enough accuracy for
objects like the ones being produced at the company, since Zscanner exceeds this point, with a
much higher accuracy than needed. The main factor upon which the company decides to choose this
scanner is the fact that it is completely automatic. There is no need for monitoring the work, that
can even be done outside working times.
Brochures attached in Appendix 1. Scanners
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In summary, in the latest years the industry has seen a bigger tendency into the automation
of the manufacturing process of porcelain goods than into cutting steps out of it. Major companies
have been purchasing either pressure casting machines or slipcasting plants, consisting of rollers
and/or conveyors, with automatic filling and robot-based glazing and processing. These machines
and chain processes are completely focused on the manufacturing itself (from the mother mould
until the clay products ready to be sold, with all the intermediate steps of casting, firing, glazing and
so forth), but have little impact on early stages of the product development.
As mentioned previously, there is little investigation specifically focused on adapting RP
techniques to porcelain production. Mostly, the influence of RP in ceramics have more to do with
engineering materials, with rapid manufacturing of small parts and some other purposes different
from our scope. However, the great opportunities rapid prototyping (in the broadest sense of the
term, including both additive and subtractive fabrication, and rapid casting) have a way into the
world of porcelain fabrication. Apart from some very interesting experiments being performed,
which may lead to further developments that might be used in the industry, there are some activities
already put into practice that join RP, porcelain and production to market.
In the following section we will use all the information gathered in this study of the State of
the Art to define some alternatives to the current process in Rörstrand, that will later be compared
with each other and channelled through some decisional techniques to choose the most appropriate
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This solution is based on the 3D-Printing technique. It skips the process of making the initial
model by hand, which is expensive and takes much time. A rapid prototyping model made of plaster
replaces it. In this stage of the process, it is possible to test the model, which is built in CAD and
printed, just as it would be done with a hand-modelled prototype, and correct the possible mistakes.
When the shape is perfectly clear and the casting with the number of moulds and the channels to
pour the slip into the mould is designed, the next stage is making the plaster moulds. This could be
made by: a) RP technique, like the part; b) casting plaster, as it is being made nowadays.
Denby pottery is using Zcorp's printing machines for the first stage of the process, as it is
said in a previous section of the report, so we know with certainty that this innovation can be
introduced in Rörstrand.
Figure 34.
Solution 1 sketch
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The first stage of the process currently takes 1 week for manufacturing the first model and it
is worth 50% of the whole process. The sequence after having introduced this implementation
would be:
1. Scan the model (Optional)
2. Build the 3D-CAD file for the part or/and the moulds 2
3. Test the moulds and the part in order to check if everything works for the final
4. Use the model for casting the plaster for making moulds
5. Cast the silicone model
6. Create the plaster moulds for production
7. Production
As long as the moulds made via RP are not as hard and accurate as the ones made by
casting, the implementation of this technique for making the moulds is merely experimental, as a
support for the design of the casting process and as a way to share ideas. Slipcasting with these RPmade moulds is very crude, and the binder of the plaster material tends to dissolve when in contact
with water, making the moulds break apart soon. Nowadays, the introduction of the 3D-Printing
technique to directly reproduce moulds made of plaster for production is in an early stage.
- Direct moulding
- Fragile
- Shortened production cycle
- Less quality in surface finishing
- Save time and money
- Low durability of moulds
- Early testing and corrections
- Less water absorption
- Size of the parts
Figure 35
B) Casting the plaster:
Although RP is just used in the firs step, it shortens the time considerably and at the same
time reduces the errors when creating the first model and helps make the changes earlier and more
3D CAD-file attached in Appendix 2-1
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- Acting over 2 steps
- Saving time in the beginning
accurate as the manual model ones.
- Need for coating and polishing in
investment- Only RP machine
the RP model (Time consuming)
- User testing
- Easy early-errors fixing
Figure 36
Introducing this solution does not mean that the process is dramatically reduced comparing
to the current one, as there has to be an investment of time in the CAD designing and in the curing
and post-processing of the printed part. Anyhow, it can be a complement to some other techniques
in order to computerize all the process.
Even if this technique does not revolutionize the process, it perfectly solves one of the other
tasks of the project: the one concerning the communication between the factories. Thanks to the use
of CAD files (drawings and 3D models), the manual drawings turn to be unnecessary, and the
interpretation becomes easier. The best way to know how the final product has to look like is
handling a replica of it, instead of thousands of drawings and views with the dimensions, and the
best way to achieve that is having a 3D-Printer in the manufacturing facilities.
Figure 37. Millenium tower
made of plaster. ZCorp
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ZCorporation offers several plaster materials depending on the needs. Appendix 2-1 shows
that it is necessary to take into account different parameters due to not all the machines can work
with all offered materials. Regarding to our purpose, the chosen material has to be resistant, with
good surface finishing…The printed parts are not good enough for being used as a final model,
what make necessary to use a composite or infiltrate to improve or tailor the final properties of the
In our case the material which fulfils the demands is zp 1313. The next table 1 shows that it
has the best qualities of surface finishing and toughness. These characteristics make the material the
most appropriate within all the zp range.
Figure 38. Material comparison chart ZCorp
Figure 39.Green strength-time grapic.ZCorp
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The fastest machines within this technique are ZCorp's. There are several machines that are
able to build models in plaster, with differences between them, the size of the working envelope
being the most significant. While Z310 can build in a 203x254x203 mm area, the Z510 works with
sizes up to 254x365x203 mm. Most of the models of the company (pots, dishes, and decorative
goods) can be built with Z310 printer, but the problems come with the moulds, of a bigger size. 3
Figure 40. ZCorporation 3D Printer machines
Technical data ZCorporation materials and systems attached in Appendix 2-2
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SOLUTION 2. Flexible mother mould
In this case, we have thought of the possibility of making the mother mould by means of
rapid prototyping.
Figure 41. Solution 2 sketch
Some suitable materials for this purpose are epoxies, elastomers, (poly)urethanes and some
flexible polymers. The problem is that only flexible polymers and elastomers can be manufactured
in RP machines, while the others have to be cast.
From the 3D-CAD file4 and using Zcorp's elastomer material (Zp15e), a flexible mother
mould can be built, with some important advantages, but also considerable drawbacks.
- Saves three steps --> saves time
- Faster than manual
- Accurate
- No testing first model or moulds
- Humidity resistance
- Durability
- Size of the part
- Generally needs coating
(Por-a-mold) and polishing.
Figure 42
The material being used currently for mother moulding is silicone Elastosil M 46434. It takes
about 3 or 4 days to cure and the step of creating the mother mould with it costs around 40 % of the
entire process, taking into account the price of the material, the time and the labour. The thickness
of the casting is usually 8-10 mm. It is easy to cast silicone because of its high viscosity
Elastosil datasheet Appendix 3-1/ .STL part for this solution Appendix 3-1
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and low density. Once cured, the demoulding of the part is easy, since it deforms to let the mould
out, yet it recovers the shape.
As an example, we have calculated the price of the mother mould for a specific model, in
order to obtain exacts the amount of silicone and money that it costs, so we can compare it with
possible solutions.
We have constructed the part in 3D with Pro/E software, which has a command that allows you to
calculate many parameters, such as volume and weight5. This file has been used for these
calculations, as well as for getting quotes from companies to which we have sent the model.
The silicone price for this specific model is ~ 2040 Kr 5. All initials steps should be added
which means about:
First model + Plaster moulds for testing: ~ 10000 kr (1000 material + 9000 worker)
The following chart shows some RP materials that might be used in this solution. They
belong to different companies in Sweden and abroad, from which we tried to get a quote.
Material /
Tango Plus
FullCure 930
Flex plastic
3D System
3D printer
Cellulosebased powder.
Extremely soft rubberlike
Excepcional elongation
Used in
place of
silicone or
rubber parts
Somos 9120
- Accurate
-Rigid &
Figure 43
Volume calculated in Appendix 7-1
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Analysing the solutions in depth:
ZP15e 6
General properties:
This material allows the user to create parts with rubber-like properties by means of
infiltrating the printed part with an elastomer, called Por-a-Mold. Zp15e absorbs the elastomer and
becomes tough and flexible.
Zp15e can be used by ZPrinter 310 and Spectrum 510. The differences between them the
binder and the printhead. While Zprinter 310 is using one HP printhead, Z510 uses four, making the
printing faster.
The next figure shows a comparison between ZCorp's materials:
Manufacturing this material in ZPrinter
310 could involve a great advantage, as
the machine not only produces parts
with Zp15e, but also parts with Zp100
or Zp102, plaster materials. The same
machine works with both plaster
material (as in solution 1) and the
elastomer, making it possible to
combine both solutions. In a first stage,
a model made of plaster from the CAD
could be done for testing purposes and,
if approved, the next step would be
building the mother mould with the
elastomer material, saving time and
Figure 44. Zcorp’s material comparison
If this becomes the chosen solution the company would have to purchase a Zprinter machine, as we
have not found any company supplying parts in the elastomeric material in Sweden. Of course,
another possibility is outsourcing it with a company outside Sweden, but in that case there would be
more expenses for the delivery.
Somos 9120 7
Somos 9120 produces accurate functional parts ideal for master patterns
in rubber applications. In contrast, the technical properties make it not very
suitable for our purpose, because of low humidity resistance and lack of
dimensional stability. Furthermore, from a quote from AME prototypes, rapid
prototyping company in UK, we concluded that this option does not save much
Figure 45. Part made of
Somos 9120.M/J-CC
Datasheet refecence in Appendix 3-2
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Tango Plus, FullCure 930 7
It is also a rubber like material which is flexible, durable, tough and resistant to tearing and
Comparing this material to Elastosil there is some divergence in
properties, but they share a long elongation at break. However, it is also
very expensive, while it does not assure the same performance as the
casting resin.
Figure 46: Part made of Tango
Plus. ProtoCam
Duraform Flex plastic 7
The advantage of this flexible material is that it can be used for end-use parts because of the
good surface finishing, even with small parts though the properties are worse than silicone's.
Therefore this option can be quickly ruled out.
Below is a quote from Amalgam, British company supplying RP prototypes. We contacted
them to get a quote for the 3D-CAD file above, to build a flexible mother mould, but their
suggestion was to CNC mill a mould to be used to vacuum casting a resin (7150 7) in it. Although
the mother mould is not created via RP, the quote just gives an idea of how expensive it can be.
Datasheets references in Appendix 3-2
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Figure 47. Solution 2 diagram
It comes about 11800 kr just to the annotated steps. It is not much expensive that the current
one, but the disadvantage is that it is not possible to test the first model, which is a very important
step for the company, as we will see in the Pugh matrix afterwards.
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SOLUTION 3. Replacing the silicone
The idea of this solution is to replace the silicone with a cheaper material, without a loss in
properties and performance, reducing the price of this step. As we have already explained, these
materials are RTV resins with similar properties to Elastosil, the durability being the most
In the market we can find a wide range of polyurethanes for different purposes like abrasion,
temperature, oils,…Their machinability makes them to adopt any shape easily.
RenCast series. (Supplier: Abic Kemi AB, Sweden)
RenCast is a series of polyurethane resins whose properties are quite close to
silicones, but slightly cheaper.
It was Abic Kemi, the supplier, who recommended RenCast FC 528 for our application. It is
low viscosity polyurethane with excellent properties compared to RTV silicone. One of its
applications is flexible moulding, allowing easy removal of complex parts.
As it is showed in the Appendix 4-1 all the properties can be compared.
Freeman 1040 polyurethane elastomer 8 (Supplier: Freeman, USA)
As we said before is an alternative to RTV silicone rubber mold making materials
what makes it ideal for plaster casting and prototypes.
PU 342 A/B 8 (Supplier: Alchemie, Denmark )
PU 342 A/B is another flexible polyurethane resin used for mould making that can
also replace Elastosil.
This Danish company gave us a quote, resulting in a lower price than Elastosil, even when
the delivery expenses have to be paid.
195 Kr/ Kg + 25% VAT + 200 kr (delivery)
Technical datasheet Appendix 4-1
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- Very similar to the silicone
- Cheaper
- Complementary used with the
- No automation advantage, it just
minimizes the expenditure
rest of solutions
Figure 48
Whereas the rest of the solutions imply some kind of investment, just changing silicone for
polyurethane cuts the price of the process. This change of material is more a complementary feature
than an integral solution itself, since its incidence is reduced to a mere and slight reduction of the
price. It does not cope with the roots of the issue.
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In the same way that it is possible to get moulds via RP, they can be built by milling the
shape out of blocks, as it was stated in the section State of the art. This process skips the three first
stages and takes us directly to the mother mould.
This option is, as we see it, the most feasible. It was suggested by Tavs Jörgensen. This
solution was somewhat depicted in the section mentioned above. The material is low-medium
density polyurethane board, that can be milled with a good surface finishing and precise shapes and
edges. They can also be hand-carved, being both machining and craftsmanship mixable to get the
desired shapes. A commercial brand for this material is RenShape9.
Figure 49. Solution 4 sketch
There are two sub-options within this alternative. One is building the positive out of the
block, as the mother mould's shape, for casting the plaster moulds in the next step. The other would
be milling the negative form, to later cast the positive, either in silicone or some other polyurethane
casting resin (explained in solution 3) and so get the mother mould. Even plaster could be cast to
get a sample model.
Datasheet of RenShape 5460- Appendix 5-1
** Render of the parts- Appendix 5-2
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Below is an estimation of the price made upon the modelled file, calculating the amount of
material needed (we also wrote down the price of a whole block of the material, that should serve
for several works). There is also a quote from Suncab AB ( CNC), company located in Lidköping.
Figure 50. CNC estimation
This alternative has many advantages, such as the quickness in the achievement of the
mother mould -straight from CAD data- and the low price of the material. There is only one
drawback, that after all can also be saved, and it is the problem with negative draft angles. An
intelligent design of the casting process, with the right number and a correct definition of the parts
of the moulds and some expertise in CAM there should not be any unachievable shape.
- Quickness from CAD data to
- Has to be outsourced (investing
requires much money and skilled
- Saves several steps
- Material workable with both
- Special considerations with the
machinery and hands
- Cheap material
Figure 51
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SOLUTION 5. To the plastic mould
In this solution the mother mould is built, like in the current process, by casting silicone (or
polyurethane resin) in moulds prepared for such purpose. The difference is that, unlike the moulds
that are currently made by casting plaster, these ones are made by SLA. The figure below shows the
flow of the process.
Figure 52. Solution 5 sketch
There are several materials that can be used in this solution, all of them belonging to the
group of materials with which SLA works.
Here is a list of different materials used in RTV moulding, arranged by company:
3D Systems10
Accura 25 plastic
Duraform PA&GF
Duraform Flex
Accura 60
Accura 25
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Accura Xtreme plastic
Watershed 11122XC for RTV patterns
14120 White
Somos 9120 epoxy
Figure 53. Solution 5
The figure 53 shows an estimation of the price this technique would have if trying to create
our 3D-model. It becomes expensive as the creation of two moulds is needed. The main problem is
that, in order to make it cheaper, the parts have to be shelled out and the thinner the walls, the
weaker and less durable the moulds.
Datasheet Appendix 6-1
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- Easiness and rapidity to get the
- Mostly expensive
mould for casting the
- Limited size (building in parts
silicone/flexible material
becomes extremely expensive)
- It skips the first step which is the
- Less durability than current
most expensive
mother moulds
- High accuracy in the parts
Figure 54
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The solutions defined in the previous section need to be discussed and assessed, and in the
end one (or a mix of several) of them will be selected as the process to be implemented in the
company. For this, and so as to follow a more precise and objective approach, we will use the
decision-matrix method, also called concept selection matrix and Pugh's matrix.
Basically, it is a process of narrowing the set of concept alternatives under consideration. As
an overview of the methodology, and in a first stage, a matrix with the different concepts to be
evaluated is done -in our case this refers to the solutions we have given to the problem-, taking one
of them as a reference. For us, the current process will be the axis of coordinates with which all the
rest of the concepts will be compared. Consequently, this reference concept will be given points standard values- for all the criteria involved in the decision-matrix.
Subsequently, points are given to the rest of the concepts accordingly to how they satisfy
each criterion in comparison to the reference. Criteria are given a weigh, depending on how relevant
they are to the final decision, so as to make it more accurate and objective.
Once all the solutions have been rated, there is a value, result of the sum of the different
criteria, that shows what solution is the most appropriate or, at least, clearly enlighten what the
strengths and weaknesses of these solutions are. In subsequent stages solutions can be blended to
get a more integral solution with the strengths of all the others, covering the weaknesses.
In our case, we presented to the company a matrix with some criteria that we thought to be
most important to the manufacturing process in order to discuss with them whether they agreed or
not, or if they could think of any other criteria that should be presented in the matrix. Furthermore,
we wanted them to weigh up the criteria according to their experience and expectations.
Firstly, these were the criteria we included in the matrix, defined upon the problem
formulation made in the beginning, capturing the real objectives of the project:
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Model & casting design time: This criterion measures how quick the early design stage is
done, from the original source -drawings/sketches or CAD-files- to the first physical model
and moulds.
Time to pattern: This criterion measures how quick the solution is being evaluated achieves
the mother mould -ready for production- after the first stage.
Materials cost: This one takes into account the amount of material used in the solution and
its cost, involving complementary expenses such as coatings and/or post-processing.
One-time model (for exhibitions): This criterion is more qualitative than quantitative, as
what it defines is how a solution helps solve the problem of the unique models for
presentations that will never be produced.
Specialized knowledge on technique: This compares what the investment in know-how must
be in every solution.
Quality/quantity of the moulds: This evaluates how the different solutions perform when it
comes to making the moulds for production -number, cost and quality of them-.
Communication: This criterion measures how well each solution fixes the problems of
communication between the development and the manufacturing areas.
Salaries: This is what the cost of the labour is in every solution.
CAD/CAM licenses: The cost of the software required to introduce the solutions in the chain
In our reunion with the people from the company we discussed the criteria and they decided that
they were representative of the factors involved in the production process. Weighing the criteria
took a long time, in which they discussed about the issue, and the final matrix, with our rates to the
concepts, is as follows:
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Current process
Selection Criteria
Polyurethane casting
Rating Notes Wtd Rating Notes Wtd Rating Notes Wtd Rating Notes Wtd Rating Notes Wtd Rating Notes Wtd
Model & casting design time
Time to pattern
Materials cost
One-time model (for exhibitions)
Specialized knowledge on technique
Quality/Quantity of moulds
Total Score
Figure 55. Pugh´s matrix
Though CNC is the most rated solution, an analysis of the matrix is needed, as there are some
other factors that are not represented in the chart that must be taken into account. For this, we can
check all the criteria separately:
Model & casting design time is not a crucial criterion, as the rating is the same for all the
concepts, given that all of them are CAD based, the time spent in modelling being the same.
The only one that does not have such a rating is solution 3, as the process is completely the
same than the current one.
The time to pattern is short for 3D-Printer used with elastomeric material and CNC, since a
mother mould can directly be made out of the CAD data. However, CNC still has
advantages over the others, with a larger working envelope and much higher accuracy.
Polyurethane materials, both boards and RTV-resins are cheaper than RP materials.
Nevertheless this criterion was given little weight by the company -only 2%-, so its
influence is almost negligible.
One-time model is considered the worthiest criteria in the matrix with 40 %. Despite 3Dprinters build quickly models in plaster, surfaces require polishing and coating. Both CNC
and SLA techniques make it expensive due to it is necessary to build moulds for casting the
model. However it is cheaper and faster than the traditional way.
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Whichever technique, there is a need to invest in know-how, and this can be mostly time,
money or both. Anyhow, this criterion was given so little weight because the company
pretends to outsource the prototyping works, this depending on the difficulty of the
technique. Even 3D-Printers require some learning to be used properly.
The quantity of the moulds, or more precisely the ratio of quantity/quality of the moulds to
price of them is a crucial point in the process. This criterion shows that the best the solutions
can perform is as good as the current process. CNC, SLA and polyurethane casting provide
the best moulds because of the accuracy of the mother moulds, as good as current silicone
mother moulds, whereas 3D-Printers provide patterns nor accurate neither durable enough.
3D-Printers have, unlike in the previous criterion, the highest rating in communication. This
is because these machines are the easiest to use, with very fast speeds when building visual
models. With a 3D-Printer the interaction between designers and manufacturing can be
considerably improved, just as in Denby's case, eliminating the traditional drawings and
sketches from the process. Once again, a physical object is the best way to communicate,
and 3D-Printers create models inexpensively.
The other two criteria we had included in the matrix -salaries and CAD license- were
discarded because the board of the company gave them a weight of 0%.
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After the discussion with the company, which gave us a new and more profound perspective
of the issue, we used the output of the matrix to develop a new solution that would join the
strenghts of the different concepts, enhancing the process sifnificantly. The result is a new process
that blends solutions 1 and 4, as the figure below shows.
Figure 56. Final solution sketch
Firstly, the modelling is done with CAD software. This modelling involves the object that is
going to be produced and, depending on the complexity and communication factors, the design of
the casting, with the moulds and their channels to pour the clay in. This is basically to help visualize
the whole process from the very beginning. Furthermore, this parts can all be printed, to handle the
phyiscal models and discuss over them and test how the casting process might work. This serves as
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a channel of communication between the product design developers and the manufacturing area,
and also with directors in the company, or even customers and testers. If the moulds are too large
for the ZPrinter machine, the parts can be scaled, as they serve only for testing purposes.
The main advantage in this stage is the flexibility when making changes in the modelling. If
a virtual model is printed and finally not approved, it just takes minutes to move back to the 3Dmodelling and make the appropriate changes. After this, the part can be printed again, thus having
an iteration until the model is tested and approved. These changes in the CAD file are easy to carry
out, unlike traditional modelling with plaster. Depending on the changes a plaster model may
require, the process of hand-modelling must be started all over again, which does not happen with
Secondly, once the design has been approved, the shape of the product is milled out from a
block of milling board to get either a negative -if a plaster positive is required- or a positive -mother
mould-. The advantage of this entire process is that CNC works with the same digital input than RP
machines, so that changes in the 3D-CAD files are not needed.
Subsequently, the moulds for production can be cast in the mother mould, leading to a
quicker and more efficient production. The polyurethane milling material has very good
dimensional stability and humidity resistance, being able to withstand hundreds of castings.
To ascertain that this solution is better than the solutions it comprises and the discarded
ones, we assess it with the same matrix we have used for the others.
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Current process
Selection Criteria
Model & casting design time
Final solution
Rating Notes Wtd Rating Notes Wtd
Time to pattern
Materials cost
One-time model (for exhibitions)
Specialized knowledge on technique
Quality/Quantity of moulds
Total Score
Figure 57
As can be seen, the final solution gets a rating of 3.94, compared to 3 for the reference.
Though it may seem that the gap between this solution and the early solutions -CNC, for instance,
with 3,90- is not very big, there are some considerations that increase the value of the former.
Concerning the first and the second criterion, the final solution does not seem to improve
anything with regard to the CNC solution. On the contrary, there is the advantage mentioned
previously of having a physical model, that serves as a communication device and helps fix errors.
In the CNC solution the mother mould can be achieved with much velocity, but this alternative
skips the possibility of a physical model.
About a possible implementation and investment, the board of people with who we
discussed acknowledged that there is no will in the company to invest in a big machine that would
demand new skills within the personnel. The CNC milling step would be sourced out to any
company, since the operations to mill a block of material should not take more than 1 or 2 days, and
the prices are lowering everyday. Contray to CNC, they would be willing to purchase a 3D-Printer
because these machines are easily affordable and they do not require high skills beyond knowing
how to use standard CAD software.
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In summary, the process joins 3D-Printing and CNC milling in one solution that solves all
the problems that were defined in the specification of the project.
The manufacturing process is greatly improved, with much shorter times to market thanks
to a quicker design phase. While in the current process the first stage takes half the time and cost of
the process, in this solution the time is shortened and the need for skilled personnel in traditional
crafts is reduced. The same goes to mother moulding, now done via CNC milling, that saves the
laborious and time consuming step of casting rubber inside the moulds and letting it cure for several
days. This process cuts time, therefore reducing costs.
The communication becomes more fluid and honest, as models can easily be printed in the
RP machines and sent to several departments in the company to get the approval. In the case of the
manufacturing area, physical models can be sent with their corresponding CAD files, which are a
source of exact information about the product. Errors and misunderstandings should decrease and
drawings and sketches would be no longer necessary.
The presentations of new series should never be a problem any longer because of the need
of a one-time model. 3D-CAD modelling and 3D-Printing solve this issue in a simple way, being
able to produce functional prototypes, such as pouring teapots, with whichever shape that can be
imagined. Some post-finishing work is required though -coating, sealing and polishing the part-.
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“Design of a CAD and Rapid Prototyping based production process
for porcelain”
1. Wohlers, T. (2003). “Wohlers Report 2003: Rapid prototyping,Tooling & Manufacturing,
State of the Industry, Annual World Wide Progress Report”. Colorado: Wohlers Association
2. Ulrich & Eppinger, “Product Design and Development”, 4th ed.
3. Campbell, R. I., De Beer, D. J., Barnard, L. J., Booysen, G. J., Truscott, M., Cain, R.,
Burton, M. J., Gyi, D. E. and Hague, R. (2007) “Design evolution through customer
interaction with functional prototypes”, Journal of Engineering Design, 1
4. Cross, Nigel (1994). “Engineering design methods”. 2nd edition, John Wiley & Sons.
5. Delpech, J.P., Figueres, M.A. (2001). “The mouldmaker's handbook”. Ed. A&C Black.
6. F. Jorge Lino, Rui J. L. Neto, Ricardo Paiva, Ana Moreira (2004). “Rapid Prototyping and
Rapid Tooling Applied in Product Development of Ceramic Components”. Materials
Science Forum Vols. 455-456 (2004) pp 835-838
7. Jorgensen, Tavs. (2004) “Binary tools”. 3D Digital Production Research Cluster, University
College Falmouth (UCF), UK.
8. Herrold, David, DePauw University, USA. “Slip Jet 3D Printer”. Challenging Craft,
International Conference 8th - 10th September 2004.
9. Bunnell, K., Falmouth College of Arts. “Craft and digital technology”. World Crafts
Council, 40th Anniversary Conference (2004).
10. Prof. D. Dimitrov, Dr. K Schreve, N. de Beer (2004), University of Stellenbosch, South
Africa. “Advances in Three Dimensional Printing – State of the Art and Future
Perspectives”. 10èmes Assises Européennes de Prototypage Rapide – 14 & 15 septembre
11. Prof. D. Dimitrov, Dr. K Schreve, N. de Beer (2005), University of Stellenbosch, South
Africa. “Investigating the achievable accuracy of three dimensional printing”. Rapid
Prototyping Journal 12/1 (2006) 42–52.
12. Moréus, P., Löwdin, M. (2004). “Time reducing actions with Free Form Fabrication and
Rapid Prototyping” Master Thesis, Örebro University.
13. Nikam, P.E. (2005). “Application of Subtractive Rapid Prototyping (SRP) For RSP
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Tooling”. Bachelor of Science in Mechanical Engineering, Cleveland State University.
14. Evans, M.A., Campbell, R.I., (2003). “A comparative evaluation of industrial design models
produced using rapid prototyping and workshop-based fabrication techniques”. Rapid
Prototyping Journal Volume 9 · Number 5 · 2003 · pp. 344–351.
15. Rak, Z.S. “Advanced forming techniques in ceramics”. Polish Ceramics 2000 conference,
29-31 of May 2000.
17. ZCorp. 3D-Printing systems. 27th February 2008. <www.zcorp.com>
18. Porcelain: information on how it is made. 24th February 2008.
19. Pottery: information on how it is made. 24th February 2008.
20. Pottery: list of terms. 4th March 2008. <http://en.wikipedia.org/wiki/List_of_pottery_terms>
21. Cebex. Swedish supplier for materials related to ceramics industry.
22. Crocker, B. “Plaster isn't so hard to use”. 29th March 2008
23. Rapid Prototyping: Information on the techniques. 17th March 2008.
24. Curtis, G (2005). “Automated Rapid Prototyping of 3D Ceramic Parts” 3rd April 2008.
25. Sherman, L.M. “Close-up on Technology – Rapid Prototyping 3D Printers lead growth of
Rapid Prototyping”. 2nd April 2008. <http://www.ptonline.com/articles/200408cu3.html>
26. Autonomatic Research Cluster: digital manufacturing technologies. 25th April 2008.
27. Ogando, J. “Intelligent Subtractive Manufacturing”. Design News, July 26, 2007. 22nd may
28. Portec. Material supplier (CE 100 White) for project FLEXIFORM. 24th May 2008.
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29. Dickin, P. “Tradition accelerated” (2006). 13th May 2008.
30. “Early Success for Pressure Casting Machine being Developed for Tableware and
Sanitaryware” (2004). 17th May 2008. <http://www.azom.com/details.asp?ArticleID=2502>
31. “Process for making ceramic mold”. US Patent 6180034 (January 30, 2001).
32. SCI (Swedish Keramin Institutet). Differences between slipcasting and Pressure slipcasting.
2nd May 2008. <www.keram.se/eng/pdf/slam_eng.pdf
33. 3DScanco. Scanning terms. 26th April 2008. <http://www.3dscanco.com/about/3dscanning/glossary.cfm#w>
34. Wikipedia. 3D Scanner. 25th April 2008. <http://en.wikipedia.org/wiki/3D_scanner>
35. The Mechanical Engineering Dictionary: General overview of RP. 26th March 2008.
36. The Learning Factory. Rapid Prototyping information. 26th March 2008.
37. Texcast: Rapid Prototyping and Rapid Manufacturing. 25th March 2008.
38. Renssealer. Rapid Prototyping services. 30th March 2008.
39. Stereolithography. SLA prototyping company. 6th April 2008.
40. 2Objet. 3D-Printing systems. 1st March 2008. <www.2objet.com>
41. 3DSystems. Rapid Prototyping machines. 3rd March 2008. <www.3dsystems.com>
42. Polyurethane.org – Polyurethanes for industry. 12th May 2008. <www.polyurethane.org>
43. ProtoCAM. RP services. 15th April <www.protocam.com>
44. Denby Pottery case study. 2nd April <http://www.zcorp.com/documents/121_CaseStudyDenby-FINAL.pdf>
45. Hassold, R. “CNC machining as a Rapid Prototyping technique”. 28th April 2008.
46. Schuett, Todd. “Rapid milling for prototypes”. 28th April 2008.
47. Polytek. Mouldmaking Catalogue. 3rd March 2008. <www.polytek.com>
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Appendix 1. Scanners
Appendix 2. Solution 1
Appendix 3. Solution 2
Appendix 3-1. Elastosil Datasheel
Appendix 3-2. Materials Datasheet
Appendix 3-3. Renders
Appendix 4. Solution 3
Appendix 5. Solution 4
Appendix 5-1. Materials Datasheet
Appendix 5-2. Renders
Appendix 6. Solution 5
Appendix 6. Material Datasheet
Appendix 6. Renders
Appendix 7.Volume Calculations
Appendix 8. Glossary
Appendix 9. Software
Appendix 10. Brainstorming
Appendix 11. Contacts
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
The technical data of the scanners can be found in the following links:
MicroScribe G2
Roland LPX-600
Scanner 700
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
Part.stl built with Pro-Engineer. This piece is ready to be manufactured via 3D printer since
it is refered to .stl formal, which means that the piece is divide in layer/slices through it can be
built with this RP technique.
“Design of a CAD and Rapid Prototyping based production process
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“Design of a CAD and Rapid Prototyping based production process
for porcelain”
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
Materials solution 2
All datasheet can be found in this links.
Somos 9120
Tango Plus, FullCure 930
Duraform Flex plastic
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
The next figures show the .STL render parts refering to the solution 2. The grey part is has to
be made of flexible material which joins with the plaster box in order to construct the mother
mould for casting the moulds for production. The part also possess the gate of a mould to cast the
clay when the mould is done.
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
Material Datasheet:
RenCast series
Freeman 1040 elastomer
Pu 342 ab (Alchemie)
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
Techical brochure of RenShape 5460
“Design of a CAD and Rapid Prototyping based production process
for porcelain”
The renders corresponding to the solution 4. The mother mould is made in one polyurethane
Figure 1. 3D-CAD file for polyurethane mo
ther mould
Figure 2, 3. 3D-CAD file for polyurethane moulds.
In the second option, polyurethane moulds, the point is that we can get the first plaster model just
casting the plaster in these moulds.
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Material Technical Datasheet
SLA, 3D System
DSM Somos
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Mould upper
Mould lower for casting the silicone and
get the mother mould
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Volume calculation with Pro-Engineer tool
- Solid piece
V= 5,25388 105 mm3
Surface area= 5,2715655 104 mm2
-Silicone part in the mother mould
The estimation is done for a 8 mm wall
V= 2,505718,58 cm3;
D= 1,35 g/cm 3;
M = D*V;
M = 3382718,9 g = ~ 3,4 Kg
- Shell part with 8 mm thickness
V= 2, 3061955 105 cm3;
Surface area= 9, 3399216 105 mm2;
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“Design of a CAD and Rapid Prototyping based production process
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The following is a list of common terms related to RP, ceramics manufacturing and 3DScanning:
CAD - Computer Aided Design. CAD is a standard term defining a group of software that aides in
design. CAD software is what is used for 3D modelling and to create 2D drawings. It is typically
used in manufacturing or other engineering disciplines. For example: An engineer designs in
SolidWorks, Pro-E, AutoCAD, CATIA, or Unigraphics; all of which are CAD.
3D Modelling - 3D modelling refers to the creation of three-dimensional objects that are defined
mathematically and geometrically (i.e. a circle extruded to a certain value to create a cylinder
defined by its location, radius and length). 3D modelling can be aided by the use of scan data (see
Reverse Engineering).
3D Scanner - 3D scanners come in many forms, but the purpose of every one of them is to capture
the shape, and sometimes colour, of real-world physical objects or environments. This captured data
is typically stored as a list of xyz-coordinates in a point cloud file. 3D scanners can be categorized
as contact (CMM arms) or non-contact (white light, 3D laser scanners, or stereo-vision based).
Some can even capture internal features. "3D scanner" is sometimes misspelled as "3D scaner".
Accuracy - The accuracy is the closeness of a measurement to the actual feature. The opposite of
accuracy is uncertainty, which is an inverse perspective of the same value.
Scan - Measuring the part, capturing data, and transferring the measured points to the computer. It
also refers to the computer file that is based on the physical part, i.e., xyz coordinates that represent
physical measurements taken by the scanner.
Resolution - Refers to the minimum increment in dimensions that a system achieve. It's one of the
main determining factors for finish, appearance and accuracy, but certainly not the only one.
Pattern - An object or part which possesses the mechanical geometry of a final object or part, but
which may not possess the desired mechanical, thermal or other attributes of the final parts. Patterns
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are used in secondary processes to form tools to make parts for end-uses. In the report, following
the company's terminology, they are called mother moulds.
Rapid manufacturing - Refers to the process of fabricating parts directly for end-use from a rapid
prototyping machine. A synonym is direct manufacturing.
Rapid prototyping - Computer-controlled additive fabrication. Commonly used synonyms for RP
are: 3-Dimensional Printing, additive fabrication, freeform fabrication, solid freeform fabrication,
stereolithography. Note that most of these synonyms are imprecise.
Rapid tooling - Most often refers to the process of fabricating tools from a rapid prototyping
process. Rapid tooling may utilize direct or indirect methods: In direct methods, the part fabricated
by the RP machine itself is used as the tool. In indirect methods, the part fabricated by the RP
machine is used as a pattern in a secondary process. The resulting part from the secondary process
is then used as the tool.
Reverse engineering - The process of measuring an existing part to create a geometric CAD data
definition of the part. In common non-technical usage, reverse engineering may also refer to
measuring or analyzing a part or a product for the purpose of copying it.
Solid freeform fabrication (SFF) - A synonym for rapid prototyping. The term is more precise and
wider in scope, and somewhat favoured by the academic community. A variant is freeform
fabrication (FFF).
Subtractive fabrication - Term used for all the fabrication technologies that, unlike RP additive
techniques, eliminate material from a block.
CNC machining - Computer numerically controlled machining. It can be categorized as a
subtractive fabrication technology. The input data for CNC machines is CAD/CAM files.
Slipcasting - Slip casting is a forming process used in ceramics, in which a powder suspension is
poured into a plaster mould, which by its porosity creates capillary forces and removes liquid from
the suspension (slip). Because of this, the powder particles are forced towards the mould walls and
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a consolidated layer (filter cake) is gradually built up. When a desirable layer thickness has been
obtained, the casting process is stopped. After a certain period of time the shaped piece can be
released from the mould for further drying and firing (sintering).
Pressure slipcasting - Forming process that is similar to slipcasting, but instead of plaster moulds
uses polymer moulds with an external pressure to increase the water absorption from the slip. It is
much more efficient, but also costly.
Bisque – Unglazed, fired clay.
Ceramic Change – The point at which, during firing, the clay becomes ceramic.
Coefficient of Thermal Expansion – The measurement of the length change of ceramic materials
under temperature change. Ceramics expand while heating and contract while cooling.
Firing – The act of maturing the clay by heating inside a kiln.
Glaze – The liquid covering that is applied to bisque or greenware, which produces a hard, glassy
Greenware – Clay objects that have not yet been fired.
Kiln – A high temperature furnace or oven, which is used to fire ceramics.
Maturity – The point at which ceramics have had the correct amount of firing.
Mould (US English, mold) – A permanent form that is used to press clay into a shape in
preparation for firing.
Porosity – A term for the amount of pores, or empty spaces, within a material. Porosity should not
be confused with permeability.
Sintering – Heating clay to the point at which it will no longer break down when exposed to water.
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Slip - Clay mixed with water with a mayonnaise consistency. Used in casting and decoration.
Slurry - A thick slip.
Porcelain - White stoneware, made from clay prepared from feldspar, china clay, flint and whiting.
Drying shrinkage - Contraction that occurs when parts cool down. All clays shrink as they dry.
After a pot has been made, it is left to dry before firing; the water of plasticity evaporates from the
surfaces of the vessel and the clay particles are gradually brought into contact with one another. The
finer the clay, the greater will be the shrinkage on drying.
Glaze - Glazes are vitreous coatings consisting of a glass former (usually silica) with the addition of
a glass modifier, or flux, to lower its melting point.
Most of these definitions have been taken from the following sources:
Rapid Prototyping glossary. 30th May 2008. <http://home.att.net/~castleisland/glos.htm>
Introduction to ceramics. Ceramic terms. 30th May 2008. <http://www.jnevins.com/glossary.htm>
Glossary of ceramic terms. 30th May 2008.
3DScanCo. 3D Scanning terms. 30th May 2008.
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All the solutions given in the Project involve 3D software for creating new parts or
managing and using data from scans, which can be used as a basis for making changes or adding
new shapes.
The Company asked us for suggestions about what software to use and the prices of the
licenses. We are looking for an easy, general and complete programme that allows building and
modifying parts from data introduced via scanning. This would allow to scan and work with parts
provided by other craftsmen; both final designs and frame-shapes to be develop in depth with the
The main point to bear in mind is the compatibility of the scanners when transferring files to
other programs. Scanned data has the form of a 3D polygonal mesh (stl file) and can be imported
directly in CAD programs, such the ones we will mention shortly, and the object can be modelled
again from the mesh. This is because you do not get surfaces from the scanning, and in order to
work with them in CAD programs there must be reverse engineering software in between, like
Geomagic Studio, Rapidform X or Rhino Reverse. This software converts the 3D mesh into 3D
The next list shows different programs that are normally used in CAD/CAM applications:
3D Modeling/Animation/Rendering Software
3ds max
LightWave 3D
Form Z
Rhino 3D
Autodesk VIZ
Delcam PowerSHAPE
Photomodeler scanner
Rapid form
CAD/CAM/Inspection Software
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Immersion Software
MicroScribe Utility Software
Software Development Kit
(PC and Mac)
MicroScribe Utility Software supports:
Compatible Software
Mechanical Desktop
AutoCAD Mechanical
Studio Tools
The most commonly used design software packages in ceramics industry are Powershape,
Deskartes and Rhinos.
PowerShape: is a total modelling program which allows to integrate surface, solid and
triangle modelling. It is also possible to capture renders, making it easier to understand the final
shape in 3D. It includes textures, shadows and many options that create images to be integrated
in an environment with the aid of the assembly tool. Although it is about 3D, drawings can also
be created to have a general idea of the part's measures.
Figure 1: Designer from Homer
Laughlin Company with
This software is used, for instance, at Homer Laughlin Company, one of the main porcelain
manufacturers in the US. One of the main features of the program is the Mould Wizard that
automates some of the things needed for creating the moulds. A model is drawn on the computer
and then PowerSHAPE is used to create two mould halves, as this software has built-in features to
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help generate complex parting lines and split the molds in half, as well as other things that have to
be done for every mould.
This program was also used in the project FLEXIFORM (pag 27) to create the moulds for
pressure casting. The company VJ Goodall milled the shapes of the moulds with the data that came
from this software.
The license cost for the standard version of this software is around 15400 SEK. There is a
freeware version of the program called PowerShape-e 7350 that allows the user to use all the
features, but does not have compatibility with any other CAD/CAM program, not even with
PowerShape's commercial version. Whenever a consumer wants to export a file or manufacture it,
this has to be done with PS Exchange, with a price of around 400 € per transaction.
DeskArtes: 3Data Expert is utilized for different functions of 3D CAD data for Rapid
Prototyping, 3D printer and simulation in companies like Z Corporation.
All the models can be efficiently modified, until achieving the desired surface, and getting colours
and textures for making the model more realistic becomes an easy step.
It can also convert 3D models into drawings and analyze errors and number of components.
Here we have some features according to the software information extracted from Nest
Technologies Inc., DeskArtes website:
Visual inspection and measuring
Visual model inspection with textures and
Clipping and viewing with grid lines
Take 3D measures to estimate the size
Point value, angle, distance, radius
Calculate areas and volumes
2D Dimensions and drawings
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Verifying the model
Verify both surface and triangle models
Analyze errors and number of components
Gaps, inverted normals, overlapping surfaces, intersecting shells etc.
Generate good STL
Fix Models Automatically or manually
Auto Repair for fully automatic fixing
Help Text to aid the repair work
Interactive Editing for triangle data
Flip triangle normals
Connect separate componenents
Reshape triangles for simulation
Prepare for 3D Printing
Split models for separate or lower build
Add pins to connect the ready parts accurately
Hollow models for faster build
Add Drain Holes to remove non processed material
Offset solid models form open surfaces
Positioning part for RP
Define platforms according to the size of your RP system
Move parts to correct platform area
Output STL or ZPR files with correct topology and colors
for 3D Printing
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DeskArtes software is used, for instance, by Denby pottery (Pag 22) in the building of their
prototypes, because as it is said above, this program works perfectly with Zcorp's 3D-Printing
The license cost for Design Expert standard version is around 7200 SEK, with an amount of
1800 SEK for annual upgrading. There are plenty of extra tools and plug-ins that cost more money.
Rhinoceros: is a very popular design program with a large variety of supported import and
export interfaces that make it flexible and compatible.
Rhino can create, edit, analyze, document, render, animate,
and translate NURBS curves, surfaces, and solids with no
limits on complexity, degree, or size. Rhino also supports
polygon meshes and point clouds.
It can directly outputs STL, the language of 3-D printers and
prototyping include: model analysis, model repair tools, and
accurate STL mesh control.
Another point to take into account is that it has 3D
digitizing support with MicroScribe. It also has some
enhancing plug ins, Claytools being one of the most powerful,
especially when working with artistical free form products.
This plug-in enables designers to use their sense of touch to
rapidly create organic shapes and add sculptural details,
handcrafted modifications and complex blends. The system
uses a virtual clay metaphor that removes the constraints of
technical modelling, strengthening the feel of creative
Rhinos' standard license is 6000 SEK. This quantity may be
increased by adding plug-ins. For instance, Claytools plug-in
Figure 2. Modern bathroom.Source
costs even more than the program itself, with a cost around
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“Design of a CAD and Rapid Prototyping based production process
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16500 SEK.
As long as the company has already had some contact with Rhino, we advise them to
continue using this program. It has a great advantage, which is that incredibly photorealistic renders
can be done, which helps improve the name of the brand when showing them. Furthermore, the
basic license is not expensive, and this standard version is quite enough to manage the models the
company is doing.
Information in this appendix partly comes from the following sources:
- Product Development Inc. Information on Roland LPX 600. 1st June 2008.
- MCAD Online. Information on PowerShape-e. 1st June 2008.
- PowerShape homepage. <www.powershape.com>
- Nest Technologies Inc. DeskArtes 3D-software. 1st June 2008.
- Rhinoceros official website. 31st May 2008. <http://www.rhino3d.com>
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“Design of a CAD and Rapid Prototyping based production process
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“Design of a CAD and Rapid Prototyping based production process
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The following is a list of companies and individuals that have been asked along the working
process, participating with answers and quotes.
Rapid Prototyping Companies
WE DO – 3D-Printing ZCorporation
Västmannagatan 66
113 25 Stockholm
08-313 744
[email protected]
CAD CREATION AB – 3D-Printing ZCorporation
Storängsvägen 26A
184 32 Åkersberga
Tel: 08 519 712 30
LOOM A – 3D-Printing Zcorporation - 3D-Scanning
Excercisgatan 2
211 30 Malmö
040-630 70 77
PROTOTAL AB – 3D-Printing ZCorporation, SLS, SLA
Instrumentvägen 6
E-553 02 Jönköping
[email protected]
phone:+46(0)3638 72 00
fax:+46(0)3638 72 40
Smedstorpsgatan 18,
532 37 Skara
Telefon: 0511-166 08
Fax: 0511-165 11
E-post: [email protected]
SOLIDMAKARNA – Zcorporation machines supplier in Sweden
Slottsvägen 14
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“Design of a CAD and Rapid Prototyping based production process
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Tel 036-16 68 70
[email protected]
Cenneth Lindkvist
Hammarby Allé 3
120 32 Stockholm
08-694 76 60
[email protected]
Tistelvägen 2
+ 46 510 54 50 90
+ 46 510 50 62 7
[email protected]
Polyurethane suppliers
ABIC-KEMI AB – Casting resins & milling boards (RenShape products)
Fjärilsgatan 3
Box 6131
600 06 Norrköping
Telefon: 011-14 90 30
Telefax: 011-14 92 37
e-post : [email protected]
CNC Companies
JIMEC AB – CNC Milling of files
Plastgatan 12A
S-531 55 Lidköping
Phone: +46 (0)510 239 06
Fax: +46 (0)510 239 96
Cellphone: +46 (0)705 72 39 06
E-mail: [email protected]
SUNCAB AB – CNC Milling of files
Skeppareg. 1-3
Box 863
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“Design of a CAD and Rapid Prototyping based production process
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Växel: 0510 27260
FAX: 0510 66920
UNNARYDS MODELSNICKERI AB – CNC Milling prototypes for casting
Österlånggatan 14
310 83 Unnaryd
Tel. +46 371 622 60
Fax. +46 371 602 32
[email protected]
Protech AB – 3D-Printing Dimension & CAD/CAM software & MicroScribe Scanning systems
Girovägen 13,
175 62 Järfälla
08 - 594 708 00
[email protected]
Tavs Jorgensen (Research fellow, Autonomatics Research Center, UK). Expert in ceramics
design and development and digital technologies. Consultancy tasks for ceramic companies.
[email protected]
Johan Nystrom (Solidmakarna, Zcorp supplier). [email protected]
Ola Lyckfeldt & Erik Adolfsson, Keraminstitutet (Göteborg). Experts in slipcasting and
rapid prototyping, respectively. [email protected]; [email protected]
Graham Small (Manager of CERAM Research Center, UK). Coordinator of the project
FLEXIFORM. Researcher and consultant. [email protected]
G.P. Tromans (RP Consortium Manager, Loughborough University). Rapid Prototyping
Research center. [email protected]
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