DESIGN OF SCREW EXTRUDER FOR THREE-DIMENSIONAL CERAMIC PRINTING

CERAMIC PRINTING
WU PENG
Lee Kong Chian Faculty of Engineering and Science
Universiti Tunku Abdul Rahman
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DECLARATION
I hereby declare that this project report is based on my original work except for
citations and quotations which have been duly acknowledged. I also declare that it
has not been previously and concurrently submitted for any other degree or award at
UTAR or other institutions.
APPROVAL FOR SUBMISSION
I certify that this project report entitled “DESIGN OF SCREW EXTRUDER FOR
THREE-DIMENSIONAL CERAMIC PRINTING” prepared by WU PENG has
met the required standard for submission in partial fulfilment of the requirements for
the award of Master of Engineering (Mechanical) at Universiti Tunku Abdul Rahman.
Approved by,
Date : 02/04/2021
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The copyright of this report belongs to the author under the terms of the
copyright Act 1987 as qualified by Intellectual Property Policy of Universiti Tunku
Abdul Rahman. Due acknowledgement shall always be made of the use of any
material contained in, or derived from, this report.
© 2020, WU PENG. All right reserved.
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ACKNOWLEDGEMENTS
Thanks to Dr Tey Jing Yuen, the superviser of this thesis. This thesis was completed
under his careful guidance. From the topic selection, simulation and theoretical
analysis, Dr Tey gave me specific and detailed guidance. His profound professional
knowledge and rigorous academic attitude have deeply influenced me and benefited
me for life. Thanks again to Dr Tey for his serious guidance!
Finally, I want to express the deepest gratitude to the family who have supported
and encouraged me for many years. Without the support of my parents, there would be
no life today. I want to pay my highest respects to my parents!
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CERAMIC PRINTING
ABSTRACT
3D printing is a rapid prototyping technology based on additive manufacturing. It
uses plastics, ceramics, metals and other materials based on digital models to
construct objects through layered printing and layer-by-layer stacking. This method
has brought great innovation to the manufacturing field and is considered as a
significant production tool for the third industrial revolution. And 3D printing
technology has emerged as early as the 1980s. Because the technology was not
mature at that time and the price was too expensive, it was not promoted and
popularized. However, after more than 30 years' development, 3D printing
technology has become more mature with more consumable prices, which creates
favorable conditions for the popularization and use of this technology.
At present, 3D printing technology is relatively mature. In contrast, 3D ceramic
material printing technology has less research and application. As known, ceramic
materials have the advantages of high strength, hardness, temperature resistance and
corrosion resistance, and high-tech ceramic materials with complex designs and fine
structures have very important applications in the national economy and national
defense fields. Nowadays, there are all kinds of methods for ceramic 3D printing,
like light curing, Fused Deposition Modeling and inkjet printing. But the methods
mentioned above have some drawbacks, which has the limitations on the ceramic 3D
printing. So a proper method for ceramic 3D printing is very necessary. In this topic,
the idea of designing a screw extrusion for ceramic 3D printing will be come up with.
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As the key of this method, the slurry extrusion device is so critical that it has a
crucial impact on the molding accuracy and printing efficiency of the printed product.
Therefore, the design of a ceramic 3D printer slurry extrusion device with a
reasonable structure is the key to study ceramic 3D printing technology. So the
design and improvement of screw extruder has been developed in this topic. And by
the use of CAD, the models and parameters of components of screw extruder
designed such as motor, screw, hopper, barrel and hopper can be exactly determined
and after designing, by the use of CAE, the printing performance of screw designed
will be developed, such as pressure of ceramic slurry and screw, temperature
distribution and printing speed of screw.
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1.3 Problem Statement 7
1.5 Scope and Limitation of the Study 9
2 LITERATURE REVIEW 10
2.1.1 Inkjet Printing 11
2.1.2 Stereolithography Apparatus 14
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2.3 The Review to Extruder Screw 23
2.3.1 The Three Sections of Extruder Screw 23
2.3.2 The Diameter of Screw 24
2.3.3 The Clearance 25
2.3.4 The Helix Angle of Screw 25
2.4 The Review of Other Components of a Screw Extruder 26
2.5 The Optimization of Screw Extruder 26
2.5.1 Printing Accuracy 26
2.6 The Properties of Alumina Ceramic 29
2.7 The Review of the Rheological Behavior of Alumina Ceramic 30
2.8 The Review to the Process Ceramic Sintering 33
3 RESEARCH METHODOLOGY 36
3.3 The Design of Extruder Screw 39
3.4 The Design of Hopper 43
3.5 The Design of Barrel 46
3.6 The Design of Nozzle 47
3.7 The Design of Heating Block 48
3.8 The Calculation Involved in the Design 50
3.8.1 Output Flow Rate Model 50
3.8.2 Max Output Pressure 52
3.9 The Assembly of Screw Extruder 53
3.10 The Simulation to the Screw Extruder 56
4 RESULTS AND DISCUSSIONS 61
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4.1 Introduction 61
4.2 The Static Pressure of Screw Surface and Ceramic Slurry 61
4.3 The Analysis of Heat Transfer 63
4.4 The simulation to Flow Trace and Speed 64
4.5 Outlet Pressure Measurement 66
5 CONCLUSIONS AND RECOMMENDATIONS 67
5.1 Conclusion 67
REFERENCE 70
Table 2.1: Comparison of 3D printing technologies .......................................... 11
Table 3.1: The specifications of gearbox stepped motor .................................... 38
Table 3.2: Extrusion variable definitions .......................................................... 51
Table 3.3: Critical parameters of the screw ....................................................... 52
Table 3.4: Summary of the results when extruding at different temperature ...... 58
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Figure 2.2: Schematic diagram of SLA light curing process ..............................14
Figure 2.3: Selective Laser Sintering ................................................................16
Figure 2.4: Fused Deposition Modeling ............................................................18
Figure 2.5: The 3D printer in Missouri University of Science and Technology .20
Figure 2.6: The screw extrusion process ...........................................................23
Figure 2.7: A typical screw design ....................................................................24
Figure 2.8: Average outlet flow rate at different speeds.....................................27
Figure 2.9: Average outlet flow rate at different gaps ........................................28
Figure 2.10: Outlet flow rate of optimized screw extrusion devicein the
stop-start state .........................................................................29
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Figure 2.12: The rheological curves of Alumina slurry with different contents..31
Figure 2.13: The relationship between the viscosity of Alumina slurry and
shear rate ....................................................................................32
Figure 2.14: The curve about change of alumina slurry viscosity with solid
content ........................................................................................33
Figure 2.15: Shrinkage of alumina ceramic sintered with different holding
times. ..........................................................................................34
Figure 3.4: Parameters of the screw ..................................................................41
Figure 3.5: The pitch and diameter of the screw ...............................................43
Figure 3.6: Angle of Repose .............................................................................44
Figure 3.7: The determination of angle of repose in the hopper design..............44
Figure 3.8: The position of hopper relative to the screw....................................45
Figure 3.9: The model of hopper ......................................................................46
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Figure 3.11: The parameters of filament ...........................................................48
Figure 3.12: The design of heating block ..........................................................49
Figure 3.13: Flow coefficient for a given channel geometry .............................51
Figure 3.14: The cross section of screw extruder designed................................54
Figure 3.15: The model of hopper designed ......................................................55
Figure 3.16: The assembly of the fans and plates ..............................................55
Figure 3.17: The model of screw extruder designed ..........................................56
Figure 3.18: The model after being simplified ..................................................57
Figure 3.19: The setting of Analysis Type, and Initial and Environmental
Condition ....................................................................................58
Figure 3.20: The setting of boundary conditions and analysis grid ....................59
Figure 4.1: The pressure on ceramic slurry during extrusion .............................62
Figure 4.2: The pressure on the screw surface in the barrel ...............................63
Figure 4.3: Temperature distribution of the model ............................................64
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Figure 4.5: Outlet pressure measurement ..........................................................66
CHAPTER 1
1.1 General Introduction
As one of the three pillars of today's social development, materials are the basis for
human society to survive, and at the same time it plays a foundation and guiding role
for the development of high-tech. With the rapid development of human society and
the acceleration of economic globalization, a large number of high-tech products
have continuously emerged on the market, the pace of updating new materials has
been accelerating, and the technological era of material-led innovation has arrived.
In order to gain a place in the fiercely competitive society, most companies will not
hesitate to invest a large number of manpower and material resources in order to
achieve greater breakthroughs in the technology, process and application of new
materials in the various technical fields. In the history of material development,
ceramic materials are one of the oldest materials manufactured by mankind. (Jin
Zhihao, 2000) In the context of the development of ceramic molding technology and
raw materials, ceramic materials have achieved rapid development from traditional
ceramics which are generally made from rocks, minerals and clay, to the new
ceramics made from artificially synthesized high-purity inorganic compounds. New
ceramic materials, due to their stable chemical properties which are high hardness,
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special optical, electrical, magnetic, acoustic, thermal and sensitive properties, are
widely active in the area of aerospace, national defense, machinery, electronics,
chemical engineering, medicine, and construction hygiene. (Guan Zhenduo, 2011)
3D printing technology is a new kind of manufacturing technology which is
speedily developing in the manufacturing field. Compared with traditional
preparation methods, in the process of 3D printing and preparing parts, the computer
controls the 3D printer to directly generate objects of any shape without any molds,
which greatly simplifies the manufacturing process and shortens the production
cycle, at the same time it greatly improves efficiency and reduces production costs.
So 3D printing technology is regarded as a forming technology with significance of
the industrial revolution. (Berman B,2012)
The introduction of 3D printing into ceramic component manufacturing provides
new probabilities for solving various problems like good surface quality and
dimensional accuracy. The scientists Marcus and Sachs first reported the 3D printing
of ceramics in the end of 20th century. So far, with the greatest developments in
computer science and material science, 3D printing technology has been definitely
developed for ceramic manufacturing. (Chen Zhangwei et al, 2019) As a general rule,
3D printing technology can be easily divided into slurry-based, powder-based and
bulk solid-based method due to raw material form after pretreatment, which is shown
in Table 1.1 below.
Table 1.1: Ceramic 3D printing technologies
Nowadays, ceramic 3D printing is widely used in the areas of aerospace,
medical science and industrial manufacturing. For instance, the flexural strength of
3D printed alumina ceramic sintered products can reach 300Mpa and the Mohs
hardness can reach 9, coupled with excellent wear resistance and good high
temperature resistance. Ceramic precision parts are widely used in occasions where
there are special requirements for wear resistance, hardness, and high temperature.
(Liu Houcai et al, 2008)
Figure 1.2: Nut, Jewelry core, Bolt and Fan blade made by 3d ceramic printing
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With continuous breakthroughs in aerospace technology, the development of
aerospace vehicles is coming into the stage of high temperature, high altitude, and
high speed bit by bit. Lots of aerospace sensors need to work in extremely harsh
actual working environments which are severe vibration, high temperature, high
pressure, and corrosiveness as the examples. It causes that the production of sensors
will face great challenges and difficulties. In order to insulate and fix the sensitive
components and conductive lines in the sensor, a bushing is usually added to the
metal shell. Due to the limitation of the processing technology, the bushings are all
polymer injection parts used before. As the temperature rises and insulation
performance requirements increase, polymer materials are difficult to meet the harsh
working environment requirements.
Ceramic materials have great characteristics like high compressive strength,
temperature resistance, and corrosion resistance, and they are regarded as the poor
electrical and thermal conductors. They are the best choice for manufacturing the
aerospace sensor bushing. However, the aerospace sensor bushing has a small size
with high precision and complex shape. If using the traditional method to prepare the
aerospace sensor bushing, the cost will be high with the complicated process and the
long development cycle. To solve this problem, the researchers from the company
iLaser utilized the method of ceramic laser printing to produce the aerospace sensor
bushing which met the requirements of smooth surface and stable insulation
performance. (Liu Houcai et al, 2008)
The ceramic 3d printing is also widely active in the field of medical science.
The ceramic material used in this area includes bio-inert ceramics like Alumina
ceramic, Zirconia ceramic and Silicon Nitride ceramic, and bio-active ceramic such
as Hydroxyapatite ceramic and Tricalcium Phosphate ceramic. Alumina, zirconia and
silicon nitride ceramic materials usually can not be easily degraded, they have high
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wear resistance and biocompatibility, so they can be used to make long-lasting
implantable medical devices, such as artificial caput femoris, acetabular cup lining
and dentures.
The ceramic material used in 3D printed dentures is usually zirconia, which
is processed by digital scanning and modeling to the dental cast, three-dimensional
design, 3D printing, degreasing and sintering, and glazing. In China, some
companies have used ceramic 3D printing technology to produce zirconia ceramic
dentures that have undergone mechanical and biological tests, and obtained
marketing approval. The zirconia denture has high precision and permeability.
(Manicone, 2007)
Silicon nitride has very high fracture toughness and it is a super hard ceramic
material. A US biomaterials company took the lead in the world to develop medical
silicon nitride materials. The company used the 3D printing technology of automatic
grouting to manufacture the complex silicon nitride Spine Fusion Implant and
verified its performance, confirming that 3D printed silicon nitride implants have
certain property of corrosion resistance in the human bone, which meets the
requirement of manufacturing implants. (Chen Li, 2002)
The chemical composition of tricalcium phosphate and Hydroxyapatite is
similar to the component of bone, which has good biocompatibility, osteoinductivity,
osteoconductivity, and degradability. In China, a medical team from the National
Additive Manufacturing Innovation Center used Stereolithography Apparatus, digital
light processing, selective laser sintering and melting, and inkjet printing to create
movable artificial eyes with complex structures, and they opened up a new chapter in
the application of ceramic 3D printing technology in the field of personalized
medicine. In the future, more new processes and new materials will be applied to the
medical field, bringing new treatment options to patients. (Zhang Wenyan, 2013)
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At the same time, the commercialization of ceramic 3D printing technology
has to overcome the difficulties like manufacturing speed, material properties of
products, machine and material costs, printing accuracy and quality. There are some
issues like how to effectively accumulate ceramic objects with accurate size and
complex structure, how to decrease the residual stress in the sintered body during
sintering, and how to prepare more stable ceramic inks, which the scientists have to
face and solve. (Liu Wei et al, 2017)
The ceramic extrusion process is one of the steps for ceramic 3D printing. It
is similar to the FDM process of plastic materials. They both extrude the materials
and stack them layer by layer on the platform, and finally print and shape according
to the designed model. However, the mass production of ceramic hot-melt
filamentary materials is not mature enough, and the performance is not stable enough
by using FDM technology. (Wang Di et al, 2011)
The extruder is a critical part of the additive manufacturing process based on
extrusion. The structure design of the extruder and the selection of the extrusion
method are directly related to the smooth progress of the forming process and the
quality of the ceramic parts. The extrusion methods of the extruder are divided into
screw extrusion, pneumatic extrusion and plunger extrusion. Screw extrusion is the
process of extruding ceramic slurry or paste through the shearing force of a rotating
screw. The biggest advantage of screw extrusion is that it can realize continuous
feeding of materials. (Harold F. Giles et al, 2004) So combining the technology of
FDM with the screw extrusion, a new method of ceramic printing is proposed, which
will overcome the difficulties in FDM. In the process of ceramic 3D printing, the
ceramic 3D printer slurry extrusion device plays an important role. An extruder with
the proper structures will benefit for the reliability and efficiency of the extrusion of
ceramic slurry, which is also the purpose in this project.
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1.2 Importance of the Study
This project will focus on a novel approach to design and develop a compact single
screw extruder for ceramic 3D printing. It will overcome many drawbacks of the other
ceramic printings, which are the high cost, the tough requirements, occurring many
issues after the ceramic printing. By using the single screw extruder for extrusion, it
will expand the flexibility and capability of a 3D printer.
1.3 Problem Statement
At present, powder injection molding which is an advanced molding technology, is
developing at a rapid rate of 22% annually at home and abroad, and the injection
molding of ceramic materials has also been applied in some fields. (Li Xinjun et al,
1999) But there exists an issue that the particle size distribution, specific surface area,
particle size and particle shape of the ceramic powder used in ceramic injection
molding have a significant impact on the entire process, which means that ceramic
injection molding has special requirements for the properties of the powder. (G
Bandyopadhyay et al, 1994)
The research has shown that due to the addition of a large amount of binder
in ceramic injection molding, the size shrinkage after sintering is much greater than
that in compression molding. In order to prevent the problems of deformation and
decrease in dimensional accuracy, it is important to raise the powder loading, and
reduce the shrinkage of the product in ceramic injection molding, which means that
ceramic powders with extreme obturation density should be used in ceramic
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injection molding. For the shape of the powder, spherical powder is more ideal, but
the meshing force between the spherical powders is poor during the degreasing
process, and there is a risk of deformation. If selecting the powder with the irregular
shape, there will be an agglomeration caused by the friction between the powder
particles, which will affect the full mixing between the powder and the binder, and
reduce the powder loading at the same time. And another issue is that there may be a
high initial tooling and machinery cost for injection moulding. (R M German et al,
1992)
Compared with ceramic injection molding, the ceramic 3d printing has some
advantages which are that there is no need for the molds during the manufacturing
process and ceramic 3D printing does not require a centralized and fixed
manufacturing workshop, which reduces production procedures and greatly saves
production costs. (Cong riyuan et al, 2019) Therefore, it is so popular that it has been
extensively used in the area of ceramic preparation at the moment. But there are some
drawbacks in the methods of ceramic 3D printing, which are shown below as the
examples. At early stage, researchers GRIFFITH M L et al (1996) used Stereo
Lithography process to make alumina ceramic parts, and used photosensitive resin to
configure photosensitive alumina ceramic slurry during the experiment. However, the
study showed that the photosensitive resin used in the experiment was expensive, it
had extremely high environmental requirements, and it was not conducive to
long-term storage. The most important point was that the material was toxic, not only
harmful to humans, but also polluting the environment. Therefore, the application in
the field of ceramic preparation is limited. Another group of researchers used alumina
powder as the raw material and mixed polymers as the binder to prepare alumina
ceramic bodies through Selective Laser Sintering, and then debinded and sintered to
obtain ceramic parts. However, the ceramic parts manufactured by this method were
loose and porous, they had low bending strength and poor product performance, which
basically did not meet the current requirements for ceramic products.…