DEVELOPMENT OF PALM OIL-BASED FLY ASH

POWDER-BINDER SYSTEM FOR THREE-DIMENSIONAL PRINTING

NORHIDAYAH BINTI MOHD ZAIN

A thesis submitted in

fulfillment of the requirement for the award of the

Degree of Master of Mechanical Engineering

Faculty of Mechanical and Manufacturing Engineering

Universiti Tun Hussein Onn Malaysia

JUNE, 2010

v

ABSTRACT

Three-dimensional printing (3DP) is one of the techniques in rapid prototyping (RP)

technology which creates parts directly from graphical data computer and it is being

widely used in diverse areas. However, the cost of the 3DP material is high and

limited to a number of choices that can be used due to the restricted capabilities of

the existing binder. This research aims to investigate the potential of the new

powder-binder system for palm oil-based fly ash (POFA) for 3DP applications. The

newly proposed material is a type of powder-binder system containing POFA

powder, maltodextrin and polyvinyl alcohol (PVA) which was prepared thoroughly

by three different techniques; mechanical mixing, ball milling and solution blending

process. Certain mass percentage of POFA powder-binder system was successfully

fabricated as a product of the 3DP of which distilled water was used as the binding

material and followed by post-treatment with the Z Max solution in order to further

improve their mechanical properties. The experimental results show that, by using

solution blending process during material preparation of the POFA powder-binder

system is able to achieve good tensile strength and surface quality with mean values

of 6.65MPa and 12.05μm, respectively. However, the preparation of POFA powder-

binder system by using the mechanical mixing method show good flexural strength

results with mean value of 44.7MPa. Both results of mechanical properties are

allegedly due to the bimodal powder in the POFA powder-binder system which

contains various particle sizes. Further studies are required to improve the quality of

the product printed using the POFA powder-binder system particularly regarding of

the dimensional accuracy. This study believes that the POFA powder-binder system

has the potential to be used as an optional material for 3DP applications.

vi

ABSTRAK

Pencetak tiga dimensi (3DP) merupakan salah satu teknik yang terdapat dalam

teknologi pembuatan deras (RP) dimana produk dihasilkan adalah melalui data

grafik berkomputer dan teknologi ini telah digunakan secara meluas dalam pelbagai

sektor. Walaubagaimanapun, kos bahan mentah bagi 3DP adalah tinggi dan tidak

mempunyai banyak pilihan disebabkan oleh keupayaan bahan pengikat yang sedia

ada adalah terhad. Penyelidikan ini dijalankan bertujuan untuk mengkaji potensi

sistem serbuk-pengikat yang baru bagi palm-oil based-fly ash (POFA) untuk

digunakan sebagai bahan mentah dalam aplikasi 3DP. Bahan baru yang dicadangkan

ini adalah merupakan sistem serbuk-pengikat yang mengandungi serbuk POFA,

maltodextrin dan polyvinyl alcohol, dimana bahan-bahan ini disediakan melalui tiga

proses yang berlainan iaitu mechanical mixing, ball milling dan solution blending

processes. Beberapa peratusan campuran serbuk-pengikat telah berjaya dihasilkan

sebagai satu produk 3DP yang menggunakan air suling sebagai cecair pengikat dan

seterusnya diikuti oleh proses rawatan dengan menggunakan larutan Z Max bagi

penambahbaikan sifat mekanikal produk yang dihasilkan. Hasil ujikaji menunjukkan

bahawa dengan menggunakan proses solution blending adalah dicadangkan bagi

mencapai kekuatan tegangan dan kualiti permukaan yang baik dengan purata bacaan

masing-masing adalah 6.65MPa dan 12.05μm. Walaubagaimanapun, penyediaan

serbuk-pengikat POFA menggunakan proses mechanical mixing adalah disyorkan

untuk mencapai kekuatan lenturan yang lebih baik dengan purata bacaan 44.7MPa.

Kedua-dua keputusan sifat mekanikal ini dipercayai disebabkan oleh serbuk bimodal

yang terdapat dalam sistem serbuk-pengikat POFA yang mengandungi pelbagai saiz

zarah. Kajian lanjut perlu dilakukan bagi memperbaiki kualiti produk yang

dihasilkan melalui 3DP menggunakan sistem serbuk-pengikat POFA terutamanya

dalam ketepatan ukuran dimensi. Kajian ini berpendapat bahawa sistem serbuk-

pengikat POFA mempunyai potensi untuk digunakan sebagai bahan altenatif untuk

aplikasi dalam 3DP.

vii

TABLE OF CONTENTS

TITLE PAGE

TITLE

DECLARATION

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

TABLE OF CONTENTS

LIST OF TABLES

LIST OF FIGURES

LIST OF SYMBOLS AND ABBREVIATIONS

LIST OF APPENDICES

i

ii

iii

iv

v

vii

xi

xii

xv

xvii

CHAPTER 1

INTRODUCTION

1.1 Background of study

1.2 Statement of problem

1.3 Objectives of study

1.4 Scope of study

1.5 Significant of study

1.6 Expected results

1.7 Organization of thesis

1

1

2

3

4

4

4

5

viii

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction

2.2 Overview of rapid prototyping technology

2.2.1 Rapid prototyping techniques

2.2.2 Rapid prototyping process

2.3 Three-dimensional printing (3DP)

2.3.1 3DP basic operation

2.3.2 3DP process parameters

2.3.3 3DP powder materials

2.3.4 3DP binder materials

2.4 Canon desktop printer

2.5 Palm oil-based fly ash (POFA)

2.6 Previous study on the development of new

material for 3DP

2.7 Summary of literature review

6

6

6

7

7

10

10

14

17

17

19

20

21

27

CHAPTER 3

METHODOLOGY

3.1 Introduction

3.2 Material used in this study

3.2.1 POFA

3.2.2 Maltodextrin

3.2.3 Polyvinyl Alcohol (PVA)

3.3 Material characteristics

3.3.1 Microscopy physical characteristics

3.3.2 Particle size distribution

3.4 Material preparation

3.4.1 Powder preparation

3.4.1.1 Pulverizing process

3.4.1.2 Sieving process

3.4.2 Optimization of material composition

3.4.3 Powder mixing techniques

3.4.3.1 Mechanical mixing process

3.4.3.2 Ball milling process

3.4.3.3 Solution blending process

29

29

31

31

32

33

34

34

36

37

37

38

39

39

41

41

41

43

ix

3.5 Experimental work on 3DP machine

3.5.1 Sample preparation

3.5.2 Sample infiltration

3.6 Sample testing and analysis

3.6.1 Mechanical properties

3.6.1.1 Tensile test

3.6.1.2 Flexural test

3.6.2 Dimensional accuracy

3.6.3 Surface roughness measurement

3.7 Summary

44

45

46

46

46

47

48

49

50

52

CHAPTER 4

RESULTS & DISCUSSION

4.1 Introduction

4.2 Material characteristics

4.2.1. Microscopy physical characteristics

4.2.2. Particle size distribution

4.3 Optimization of material composition

4.4 Powder mixing techniques

4.4.1. Mechanical mixing process

4.4.2. Ball milling process

4.4.3. Solution blending process

4.5 3DP characteristics

4.6 Mechanical properties

4.6.1 Tensile strength

4.6.2 Flexural strength

4.6.3 Fracture surface morphology

4.7 Dimensional accuracy

4.8 Surface quality

53

53

53

54

57

58

59

59

62

63

64

66

66

68

70

72

75

x

CHAPTER 5 CONCLUSIONS

5.1 Conclusion

5.2 Recommendation for future work

5.2.1 Determination of the optimum printing

parameters

5.2.2 Improve the material preparation

78

78

79

79

80

REFERENCES

81

APPENDICES 87

xi

LIST OF TABLES

2.1 The percentage weight chemical composition of 18

ZCorp binders

2.2 Influence of binder content on dimensional error, 23

strength and modulus

2.3 The control factors and levels recommended from 25

ZCorp Inc.

2.4 Summary of research on development new material 28

for 3DP process

3.1 Percentage of powder mixture 40

3.2 Material formulation with distilled water 43

4.1 Mean size of particle distribution for raw materials 57

4.2 Material formulation results 59

4.3 Tensile strength of all mixing methods 67

4.4 Flexural strength of all mixing methods 69

4.5 Data of dimensional error 72

4.6 Value of roughness (Ra) 75

xii

LIST OF FIGURES

2.1 (a) Surface are presented by triangles, 8

(b) Faceted stl file translated with coarse tolerance,

(c) File translated with fine tolerance

2.2 Five steps of rapid prototyping 9

2.3 Z310 3DP machine 11

2.4 Schematic diagram of Z310 3DP machine 11

2.5 The printing process 12

2.6 Comparing the strong and weak axis for print heads 13

2.7 3DP process parameters 14

2.8 Binder setting saturation value description 15

2.9 Definition of shell and core 16

2.10 Canon IP1880 printer 19

2.11 Thermal inkjet schematic diagram 20

2.12 Scaffolds (a) compressive stiffness and (b) initial 22

yield strength

2.13 Influence of (a) ratio of maltodextrin to water on 24

green strength (b) green strength on sintered strength

and (c) pre-coated particle size on green strength

2.14 Effect of different composition ZP102/ wood materials 27

at (a) maximum stress, (b) surface quality,

(c) dimensional accuracy and (d) SEM image of wood

powder at 150x magnification

3.1 Methodology flow chart 30

3.2 Photograph images of (a) A sight of POFA being 31

discarded from the Kluang Palm Oil Factory and

(b) POFA

3.3 Photograph image of maltodextrin 32

xiii

3.4 Photograph image of PVA 33

3.5 Schematic operation of SEM 35

3.6 Fison sputter coater 35

3.7 Schematic setup of particle size analyzer, Cilas1180 36

3.8 Photograph images of (a) Auto Mortar Grinder 38

(b) Pulverissete 6 machine (c) Pulverized POFA

(d) Pulverized PVA

3.9 Photograph image of Sieve-shaker machine 39

3.10 Modified Canon desktop printer IP1880 40

3.11 Labkorea, ball mill machine 42

3.12 (a) Ceramic beaker (b) Ceramic balls used in 42

ball milling

3.13 3DP setup for default setting 44

3.14 Photograph images of 3D components produced 45

for samples testing and analysis

3.15 Universal testing machine (AG-1, Shimadzu) 47

3.16 Tensile test sample 47

3.17 Tensile test experiment setup 48

3.18 Three-point bending test sample 48

3.19 Three-point bending test experiment setup 49

3.20 Mitutoyo digital calliper 50

3.21 Direction of x, y and z-axis 50

3.22 (a) Mitutoyo SJ-400 surface roughness test machine and 51

(b) Measurement placement

4.1 SEM images of raw materials at 100x of magnification 54

4.2 Element distribution map of raw materials for (a) POFA, 56

(b) maltodextrin and (c) PVA

4.3 Particle size distribution of POFA material 57

4.4 Samples of each formulation 58

4.5 SEM images of raw material prepared using 60

mechanical mixing process

4.6 Elements distribution map of raw material of 61

mechanical mixing process

xiv

4.7 SEM images of raw material prepared using ball 62

milling process

4.8 SEM images of raw material prepared using solution 64

blending process

4.9 Single samples printing 65

4.10 Slippage error in multiple samples printing 65

4.11 Stress-stroke graphs for tensile strength 66

4.12 Mean and SD values of tensile strength 67

4.13 Stress-stroke graphs for flexural strength 68

4.14 Mean and SD values of flexural strength 70

4.15 Image of fracture surface 70

4.16 SEM images of fracture surface of (a) mechanical 71

mixing process, (b) ball milling process, (c) solution

blending method and (d) ZP102 materials

4.17 Mean dimension for all specimen at (a) length 74

(b) width and (c) thickness

4.18 Mean roughness value (Ra) at (a) left, (b) middle and 76

(c) right side

4.19 SEM image of (a) mechanical mixing process 77

(b) ball milling process and (c) solution blending

process and (d) ZP102 materials

xv

LIST OF SYMBOLS AND ABBREVIATIONS

cm Centimeter

kg Kilogram

kV kiloVolts

mm Millimeter

μm Micrometer

% Percentage oC Degree Celcius

ASTM American Society for Testing and Materials

BSE Backscattered Electron

CAD Computer Aided Design

CIM Computer Integrated Manufacturing

CMM Coordinate Measurement Machine

CT Computerised Tomography

DM Desktop Manufacturing

EDX Energy Dispersive X-ray

2D Two Dimensional

3D Three Dimensional

3DP Three Dimensional Printing

FDM Fused Deposition Modeling

FFF Freeform Fabrication

IGES Initial Graphics Exchange Standard

Inc Incorporated

ISO International Organization for Standardization

IT International Tolerance

LM Layered Manufacturing

xvi

LOM Laminated Object Manufacturing

MIT Massachusetts Institute of Technology

MJM Multi Jet Modeling

PMMA Polymethyl Methacrylate

POFA Palm Oil-based Fly Ash

PVA Polyvinyl Alcohol

RT Rapid Tooling

RP Rapid Prototyping

SE Secondary Electrons

SEM Scanning Electron Microscope

SFF Solid Freeform Fabrication

SLA Stereolithography Apparatus

SLS Selective Laser Sintering

STL Stereolithography

Z Corp Z Corporation

xvii

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Work progress for research project 87

B Particle measurement data 89

C Tensile strength profile 96

D Flexural strength profile 99

E Surface roughness profile 102

F Patent Application 105

CHAPTER I

INTRODUCTION

1.1 Background of study

Rapid prototyping (RP) is a special class of machine technology that rapidly produce

models from three-dimensional (3D) data using an additive approach to form the

physical models [1]. There are numerous terms to describe RP including Solid

Freeform Fabrication (SFF), Layered Manufacturing (LM) Technology or Desktop

Manufacturing (DM). The techniques are all based on the principle of creating 3D

components directly from computer-aided design (CAD) in two-dimensional profiles

on layer-by-layer process without using moulds or tools as used in conventional

manufacturing techniques [2]. The RP processes have been used to produce physical

components for various purposes such as patterns for prototyping, fit/assembly

components and also functional models.

There are a variety of RP techniques available which one of the type is 3D

printing (3DP). Z Corporation (Z Corp) manufactures the Z series of 3DP systems

based on the technology originally developed by the Massachusetts Institute of

Technology (MIT) [3]. The 3DP process uses a technology similar to ink-jet

printing, but also uses a binder material to selectively join particles on the layer

where the object is to be formed.

The 3DP has the advantage of producing parts from any powder material

including polymer-based, metal-based and ceramic-based [4]. Despite being

proficient in the selection of raw material, the production cost of using 3DP also

appears to be significantly less than any other RP techniques, particularly when

compared with selective laser sintering (SLS), stereolithography (SLA) and fused

2��

deposition modelling (FDM) process [3]. This suggests that 3DP holds the upmost

potential to be further developed in many ways, enhancing the production of

prototypes and any other components.

1.2 Statement of problem

Researches have been continuously done on the 3DP technology for many purposes

inspired by the idea to increase its capacity in all aspects. Until today, problems

related to 3DP are well defined and are being constantly studied, improved and

resolved completely, if not partially.

This study attempts to solve some of the most common problems faced by

3DP users and material researchers. Studies have shown that by using 100% newly

proposed materials, particularly developed for 3DP applications, do not produce

good combination with the existing binder [4, 5]. As the binder was made for ZCorp

materials, there are high possibilities that it can never be easily compatible with any

other material. This is proven by the numerous unsuccessful and failed products

made by several previous researchers [4, 5]. Errors of sample being failed to be

layerly-bonded, failed to shape, easily damaged during extraction from machines,

break when touched, too fragile are all common problems faced by new material

tested by researchers. Based on this foundation, it is assumed that the limitation of

currently used binder is significant towards future studies related to new 3DP

material development.

In addition, existing 3DP materials such as Z Cast, Starch, and Plaster, are

expensive especially if were to be consumed for educational purposes which are non-

profitable. Researches have been done to find cheaper materials able to be used as an

alternate replacement for these costly powders.

Further researches have been done on mixing new materials with the

commercialized ZP102 (commercial Z Corp material) which the study showed

unsuccessful fabrication being made by using 100% new materials [4, 5]. Materials

used on the study are wood-based composite powder [4] and fly ash-based composite

powder [5], and results have shown that a material mixture composed with up to

50% of the commercialized ZP102 is required for a successful fabrication of

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samples. It has been assumed that the cause of this requirement is because of the

usage of the original liquid binder, ZB56 which was made to suit the ZP102 in

particular. Therefore a study to find a suitable binder for this newly developed

material is needed to maximize cost reduction by fully eliminating the use of the

high cost ZP102. In this study, palm oil-based fly ash (POFA) is used as the raw

material since POFA has an encouragingly good prospect in terms of hardness,

surface quality and dimensional accuracy [5]. POFA is produced as waste products

by palm oil processing factories making it easily obtainable, unwanted and therefore,

currently, can always be acquired at no cost at all.

Furthermore, previous studies have shown that the polyvinyl alcohol (PVA)

and maltodextrin are able to form good binding ability with the parent material when

distilled water is added [6]. As it is easily available and cheap, it will be used for this

study to replace the original binder to further test its potential.

Therefore, this research is made as a platform to study the potential of the

new POFA powder-binder system for 3DP applications. As suggested above, since

the cost of the existing material is high and the choice of the material powder is

limited due to the restricted capabilities of the existing binder, this study was done to

further analyze the potential of POFA usage with the proposed PVA and

maltodextrin.

1.3 Objectives of study

The objectives of this research were focused on:

(i). to identify the characteristics of POFA and binder material.

(ii). to develop new material based on powder-binder system which can be used

as a raw material for 3DP process.

(iii). to analyze and compare the new material based on powder-binder system

with the existing material, ZP102 in terms of mechanical properties,

dimensional accuracy and surface quality.

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1.4 Scope of study

The scopes of this study were focused on:

(i) Materials studied were POFA, maltodextrin and PVA.

(ii) Distilled water was used as an optional binder for the existing binder.

(iii) Studies were made on dimensional accuracy and surface quality of the

sample.

(iv) Studies were made on mechanical properties of tensile strength, flexural

strength and structure morphology.

1.5 Significant of study

The significant of this research is to identify the potential of the new powder-binder

system in respect towards the binding ability of the new system itself with distilled

water for 3DP applications. This study will provide information and results on

mechanical properties of tensile strength, flexural strength, structure morphology,

dimensional accuracy and surface quality of the new material produced by the 3DP.

With this in order, hopefully it can be used to establish a ground on the new

material’s potential and capabilities and thus be further improved or identified to its

suitable application in the RP process.

1.6 Expected result

This research will reveal the knowledge on the potential of using the new powder-

binder system in 3DP applications. Comparison analysis can be successfully made

between the new material and the existing ZP102 material when their mechanical

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properties of tensile strength, flexural strength, dimensional accuracy and surface

quality are directly compared. Hopefully at the end of this research, good results can

be achieved and compared at its best quality in order to achieve the study objectives.

1.7 Organization of thesis

This thesis was organized into five chapters. Chapter one is the introduction to this

study which includes background of the study, objective, scope, and purpose of the

study. Chapter two is where the literature review and the case study of the related

works were discussed. Chapter three covers the experimental equipment and

procedures used in conducting the study. While, chapter four presents the results and

discussion of the study. Lastly, chapter five presents the conclusion and

recommendations for future work.

CHAPTER II

LITERATURE REVIEW

2.1 Introduction

Understanding previous researches are important because it can be made as a guide

to help this study move on. This chapter reviews the literature on existing RP

technologies, POFA and powder-binder materials. A basic RP operation and

processing technique are discussed herein. More detailed information on the 3DP

process was also presented, as the technique has been used in this research.

2.2 Overview of rapid prototyping technology

RP technology is a process of rapidly fabricating a model by using CAD data. RP

was largely used for clarifying Three-Dimensional (3D) CAD data during the

1980’s, but has been through a lot of evolutions since then [1]. This technology is

used to evaluate a design before expensive mass production takes place, also known

as the entry-level. The process of verifying and evaluating a successful design

contains several aspects which include: correct shape, correct size and adequate

strength [7]. These aspects are often referred to as form, fit and function. Form deals

with those aesthetics of the part that are essential to capturing the design’s intent. Fit

deals with the shape and dimensional accuracy of the part to ensure proper mating of

surfaces or features. Function is the ability of the part to be used and function as well

as a production part [8, 9].

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2.2.1 Rapid prototyping techniques

RP technologies are also often referred to as layered manufacturing technologies

[10]. The technique is also known by other names such as freeform fabrication

(FFF), solid freeform fabrication (SFF) and additive processes.

Generally, there are five most common RP technique that are commercially

available in the market [11] which are SLA, SLS, FDM, laminated object

manufacturing (LOM) and 3DP.

According to Kruth et al. [2], the RP process can be divided by the state of

the part material before part formation (type of raw material). It also can be

described by the building strategies [12, 13]; photopolymer, sintering,

gluing/lamination, and deposition (filament and inkjet). The basic operation of these

processes can be found from various publications including [14, 15, 16, 17].

2.2.2 Rapid prototyping process

Basically, the RP techniques are divided by the type of raw material including solid,

liquid and powder materials. Although several RP technologies exist, the systems

have same basic process which is the procedure can be divided into five steps [18].

(i) Create a CAD model of the design

First, a 3D representation of the part is created by a solid modelling computer

software package such as IDEAS, Unigraphics, ProEngineer, SolidWorks, etc. In

some cases, the 3D model can be created from 3D digitizer devices such as

coordinate measuring machine (CMM) and scanning devices such as 3D scanner or

computerised tomography (CT) scan. This allows the model to be created from a

physical object by collecting data from it’s original shape.

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(ii) Conversion to STL format

The second step is to convert the CAD file into STL format. This format represents a

3D surface as an assembly of planar triangles. The file contains the coordinates of

the vertices and the direction of the outward normal of each triangle [18]. The

various CAD packages use a number of different algorithms to represent solid

objects. To establish consistency, the STL (stereolithography) format, developed by

the Albert Consulting Group, has been adopted as the standard of the rapid

prototyping industry.

Because STL files use planar elements, they cannot represent curved surfaces

exactly. Often the STL file can be termed "bad" because of translation issues [19]. In

many CAD systems, the number of triangles that represent the model can be defined

by the user. If too many triangles are created, the STL file size can become

unmanageable. If too few triangles are created, curved areas are not properly

defined, as shown in Figure 2.1.

(a) (b) (c)

Figure 2.1: (a) Surface are presented by triangles, (b) Faceted stl file translated with

coarse tolerance, (c) File translated with fine tolerance [19]

(iii) Slicing STL file

In the third step, a pre-processing program prepares the STL file to be built. Several

programs are available, and most allow the user to adjust the size, location and

orientation of the model. The pre-processing software slices the STL model into a

number of layers from 0.1 mm to 0.25 mm thick, depending on the build technique.

�

The program m

during the build, depe

processing program i

Further review on slic

(iv) Layer-by-lay

The fourth step is the

The machines build o

needing little human

(v) Cleaning/ po

The final step is post-

and detaching any sup

materials need to be f

cleaning and surface t

Briefly, these steps ca

may also generate an auxiliary structure to su

ending on the requirements of the RP system.

s normally associated with a particular type o

cing procedures can be found from [20].

yer construction

actual construction of the part, using one of

one layer at a time, and most machines are fai

intervention.

st-processing

-processing. This involves removing the part

pports (applied only for certain processes). So

fully cured before use [12]. The part may also

treatment, depending on the specific fabricati

an be demonstrated by Figure 2.2 below:

Figure 2.2: Five steps of RP

Create a CAD model of the design

Conversion to STL format

Slicing STL file

Layer-by-layer construction

Cleaning/ post-processing

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upport the model

. The pre-

of RP machine.

several techniques.

irly autonomous,

from the machine

ome photosensitive

o require minor

ion process.

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2.3 Three-dimensional printing (3DP)

3DP is one of the RP process which falls under powder based categories [11]. The

3DP technology was developed at the MIT [14]. Z Corporation (Z Corp)

manufactures the Z series of 3DP systems, based upon technology originally

developed by the MIT [11]. These technology refers to a range of techniques

characterized by the method of delivering build material or build adhesive a series of

nozzle that are translated across the build platform. The basic build process is the

laying down of a layer of powder 0.1 to 0.25 mm of thickness. As the powder

supports the part, no support structure is required therefore allowing complex parts

to be built [21].

The ability of 3DP includes it’s potential in quickly produce a part and

evaluate it for form, fit and function which can reduce manufacturing lead time of

product up to 30-50% [20]. Yet, 3DP has limitations including size envelopes,

limited material properties, varying accuracies between x, y and z-axis and poor

surface finish [22]. These limitations are less significant when using 3DP to evaluate

a design particularly on form or aesthetics of a part. However it could be vital when

evaluating designs on fit and function or application for end-use products [23].

2.3.1 3DP basic operation

There are several models of 3DP machine available in the market such as Z310,

Z406 and Z810 which are manufactured by Z Corp. Basically, 3DP machine used

drop-on-demand jetting (thermal inkjet), which is one of an inkjet printing

technology [24].

The Z310 3DP machine as shown in Figure 2.3 is the entry-level concept

modelling solution that delivers great models quickly and inexpensively by using a

variety of materials. This model operates as mono device referring to single print-

head that can be used to print models with single colour [25]. Instead of feeding

paper under the print-heads like a 2D printer, a 3DP moves the print-heads over the

bed of powder upon which it prints the cross-sectional data from the CAD file which

has been slice into appropriate build layers.

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Figure 2.3: Z310 3DP machine [25]

Figure 2.4 shows the schematic diagram of Z310 3DP machine. The process

of model fabrication started with the addition of powder into the powder feed box.

Water based binder/resin is then poured into the resin reservoir to complete the

machine preparation for the model production run. Through the computer connected

to the machine, the CAD file is opened using the ZPRINT software. The software is

used to make final set-ups to the model before being printed by the machine. Using

the same software, the machine can be controlled and activated causing the printer to

build the model one layer at a time, gluing together the cross sections of the model

being built.

Figure 2.4: Schematic diagram of Z310 3DP machine [26]

Powder feed box

Print head

Powder overflow bin

Resin waste bottle

Resin Reservoir

Model tray

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Figure 2.5: The printing process [20]

Figure 2.5: The printing process [27]

Figure 2.5 explains the printing process of models. There are several

important characteristics of the 3DP system that help to print the best parts for

intended purpose which are [27]:

Step 1: As the gantry traverses left to right, the roller collects powder.

Step 2: The roller spreads a thin layer of powder over the build piston

Step 3: The roller discharges excess powder down the powder overflow chute

Step 4: As the gantry traverses right to left, the print head prints the part cross-section

Step 5: The feed piston moves up one layer, the build piston moves down one

layer, and the process is repeated

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(i). Part placement: The software automatically places the parts within the build

box to maximize build speed which is the most important criteria. The software

positions the parts with the smallest dimension in the Z (vertical) axis. In addition to

part placement, the following other characteristics should be considered.

(ii). Strength: The ultimate strength of the part will be somewhat affected by its

orientation within the print box. The part will be strongest along the Y-axis and the

X-axis and less strong along the Z-axis. This is because the cross sections are printed

in continuous strips along the Y or the “fast” axis (the print heads direction of

travel), bands across the X or the “slow” axis (the gantry direction of travel) and

laminated layers along the Z-axis as shown in Figure 2.6. This discussion only

applies to untreated parts, once parts are infiltrated; it is uniformly take on the

strength characteristics of the infiltrating material.

Figure 2.6: Comparing the strong and weak axis for print heads [27]

(iii). Accuracy: The accuracy of the system depends on the materials uses. Using

the anisotropic scaling feature in the software to adjust for expected shrinkage and

bring the parts into true scale.

�

2.3.2 3DP process

The quality of buildin

its process parameter

& core), anisotropic s

prototyping machine

part and the build tim

prototypes with poor

manufacturing proces

2.7

Location omade-up par

parameters

ng parts and building performance of 3DP are

s including layer thickness, binder setting satu

scaling value, and location of made-up parts o

[27]. Each process parameter may affect the

me. Unsuitable process parameters setting may

quality and may waste materials and building

ss parameters of Z310 3DP system can be illu

Figure 2.7: 3DP process parameters

3DP Process Parameters

Binder setting saturation value

Layer

Anisotropic scalling value

f rts

14�

e strongly related to

uration value (shell

of the rapid

quality of a RP

y make RP

g time. The

ustrated as Figure

r thickness

15��

(i) Layer thickness: The layer thickness means the height of the powder bed

that dropped down along Z-axis in processing. It can be set within the range

of 0.0035” – 0.008”. The quality of the RP parts in terms of dimensional

accuracy may decrease as the number of layers increase.

(ii) Binder setting saturation value (shell & core): The saturation values

(Figure 2.8) are referring to the determination of quantity of the binder placed

on the powder to print parts.

Figure 2.8: Binder setting saturation value description [27]

The building method of the Z310 3DP system uses a powder bound with

binder to shape RP parts. From 2D sectional layers that are sliced by slicing

algorithm system software, each 2D section is composed of shells and cores,

as shown in Figure 2.9. In general, the shell saturation is higher than the core

saturation. However, the saturation values are depended on the material used

in the 3DP process. For plaster material, the shell and core saturation values

are commonly consists of constant values, meaning that there is only one

value for all geometry types. While, the shell and core saturation values for

the starch material depends on the part geometry. A thick-walled part will

Binder setting saturation

value

16��

have lower shell saturation than a thin-walled part. Core saturation is affected

by the wall thickness of the part. The thinner the wall thickness the higher the

core saturation, and vice versa.

Figure 2.9: Definition of Shell and Core. The dark areas around the boundary of each layer of a 3DP built part are the shells. The inside area with light colour of each

layer of a 3DP built part is the core [27]

(iii) Anisotropic scaling value: Anisotropic scaling value scales the model to

accommodate shrinkage or expansion of the part either due to the

characteristics of the material system or the infiltrate system. A scaling value

of one (1) is equal to 100% of the part in a specific axis. If the part shrinks

1% in certain axis, the correct anisotropic scaling value would be 1.01 in that

axis. The scaling factors may differ according to wall thickness and geometry

of the part. A higher accuracy level may be obtained by measuring the part

and adjusting anisotropic scaling values as deemed necessary.

(iv) Location of made-up parts: The working direction of the Z310 3DP

system’s spray-nozzle is from right to left on the powder bed. If the location

of RP parts is put on the right side, the path of the spray-nozzle may be

shortened, thus decreasing the part building time.

Shell Core

Building box

17��

2.3.3 3DP powder materials

Materials used in 3DP machine are powder-based. Current offerings include two

cellulose (starch) materials (ZP14 and ZP15E) and a plaster material (ZP102) [27].

Without further processing, these materials lack the desired mechanical properties

for advanced application [24]. The particle size of the powder is in range 0.089mm-

0.203mm which is not more than the layer thickness of the machine [11].

In addition, the particle size of the powder influences the surface smoothness

and feature definition of the 3DP part. Fine powders have the potential advantages of

lower surface roughness, smaller minimum features, and thinner layers. Larger

particles are easier to spread, have lower surface area per volume and the larger

pores facilitate fluid migration through the bed to aid in the production of more

homogeneous parts [24]

Moreover, if the particles size becomes too fine (less than 10μm for

example), the static charges on the surface of the particles cause the powder to

become ‘fluffy’, and spreading the powder with the roller mechanism becomes

increasingly difficult [24, 28].

2.3.4 3DP binder materials

There are a number of different ways of binding the powder, but the common

selection criterion is based on the binder location which is in-liquid or in-bed. A

liquid binder contains all of the binding components in the printed liquid, but liquid

binders tend to have the occurrence of print-head nozzle clogs. An in-bed component

of a binder system is mixed with the powder and binding occurs where it interacts

with the deposited liquid.

Fundamentally, 3DP by ZCorp. uses the in-liquid type. These liquid binders are

different for each powder material of starch and plaster material. The properties of

the liquid binder are as shown in Table 2.1.

18��

Table 2.1: The percentage weight chemical composition of ZCorp binders [29]

Liquid binder for plaster material: ZB56 binder Chemical composition Approximate % by weight

Glycerol 1-10%

Preservative (Sorbic acid salt) 1-5%

Surfactant <1%

Salt <1%

Pigment 1-10%

Water 75-95%

Liquid binder for starch material: ZB51 binder Alcohol <1%

Fatty Acid Compound 0-20%

Humectant 0-20%

Preservative 0-1%

Surfactant 0-1%

Dye 0-1%

Pigment 0-1%

Water 75-98%

In the development of new binder for 3DP system, there are several binder

selections including organic binder, inorganic binder and metal salts [24]. Organic

binders are compatible with almost any powder material and can thermally

decomposed to leave small residue [24]. Possible organic binders include butyral

resins, polwmeric resins, and various polyvinyls. Other types of organic binder are

maltodextrin and sucrose which are usually used as in-bed binder.

A common selection of inorganic binder is colloidal silica due its variety of

uses and ease of manipulation [24]. When a stabilized colloidal silica solution (pH 9-

9.5) is printed into a powder bed containing acid or is exposed to gaseous CO2, the

pH drops and the colloid gels and the powder will bind together. Other inorganic

binder is aluminium nitrate where the method involves depositing solid material into

the bed by printing precursors or solid dispersion; the aluminium nitrate decomposes

into alumina and can be dissolved in deionized water. Solids can be deposited

directly in dispersions with oxides such as alumina which can be surface-treated to

form stable aqueous suspensions that are printable. The deposited solids may not act

as a binder immediately after deposition, but the entire bed can be heated after

printing to convert, melt or sinter the deposited material to bind the part within the

19��

bed before depowdering [24]. These types of binder are not commonly used in 3DP

machine because it requires gaseous exposure and a heater element to act as a binder.

Metal salts are binders that are particularly useful for metal powders which may be

utilized as both in-liquid and in-bed binders [24].

2.4 Canon desktop printers

Canon is one of the manufacturers in business and consumer imaging products

which includes computer printers, scanner, compact digital cameras, film and digital

SLR cameras, and lenses. Canon printing technology includes the development of

the bubble jet technology [30]. An example of Canon’s bubble jet technology printer

is IP1880 as shown in Figure 2.10.

Figure 2.10: Canon IP1880 printer [30]

Bubble jet, also known as thermal inkjet, is a drop-on-demand technology

that uses electrical pulses applied to heating elements in contact with the fluid near

the ejection aperture nozzle in order to vaporize a small amount of liquid to produce

pressure impulses by the formation and collapse of gas bubbles [31]. Essentially,

this technology is similar to the concept used for 3DP machine of which the 3DP

20��

machine was developed from the very basic concept of a conventional desktop

printer. Basically, the two forms in common use are classified by their fabrication

technology as roof shooters and edge shooters (Figure 2.11). Roof shooters are

fabricated by bonding an ejection orifice plate structure over the top of a wafer on

which the fluid flow and heating elements are fabricated. Edge shooters, in contrast,

form their ejection apertures from channel etched longitudinally into the wafer [31].

Figure 2.11: Thermal inkjet schematic diagram [31]

2.5 Palm oil-based fly ash (POFA)

In this study, POFA which is one of the biomass fly ash was chosen as a material to

make comparison with existing material for reducing the cost of material. Ashes can

be classified into two types which is bottom ash and fly ash. But, in this study it is

focusing on fly ash from palm oil. The term for “Biomass” is a material that derived

from living or recently living biological organisms, but in the energy context, it is

often used to refer to plant material, however by product and waste from livestock

forming, food processing and preparation and domestic organic waste that can be

formed as a source of biomass [32]. While for the term “Ash” is refer to the non-

combustible mineral content of biomass [32]. During combustion, bottom ash is the

ash that is left behind in or under the grate or combustion region, or at the bottom of

21��

a gasifier. “Fly Ash” consists of very small particles of ash that are carried out of

the system along with the flue gases. Various types of biomass produces ash that has

similar pozzolonic activity as coal fly ash, which include palm, rice husk, wheat

straw, sugar cane straw and wood [32].

With the growing general concern about the pollution by fly ash (FA), there

has been global interest in its utilization. Biomass Fly Ash is prohibits of ASTM

C618, precludes the use of any material not derived from coal combustion.

Typically, fly ash from neat biomass combustion has more alkali (Na and K) and less

alumina (Al2O3) than coal fly ash [33]. As a class, biomass fuels exhibit more

variation in both composition and amount of inorganic material than is typical of

coal. A purified fly ash (FA) containing 90% globular particle with a reasonable size

distribution is low in density, good shape with good dispersity and fluidity is suitable

as a polymer filling material [34].

POFA is heterogeneous fine powder consisting mostly of rounded or

spherical particles variable silica, alumina, and iron content. The major chemical

constituents of POFA are SiO2, Al2O3, Fe2O3 and CaO [35].

2.6 Previous study on the development of new material for 3DP

This section is to present previous studies done by other researchers on the

development new material of 3DP processing. Aimed to help making this research

successful, these studies were well considered throughout the development of the

project. There are numbers of studies reported in the literature related to

development of new material for 3DP.

Lam et al. [36], studied scaffold development using 3DP with a blended

starch-based polymer. These scaffold development are referring to an artificial

structure capable of supporting three-dimensional tissue formation. The aim of the

research is to explore the feasibility of using 3D printing in combination with natural

polymers and water-based binders. From the result presented as in Figure 2.12, there

was a significant increase in the compressive stiffness and yield strength after

infiltration. This reinforced the theory that infiltration improved the mechanical

properties of the scaffolds.

22��

(a)

(b)

Figure 2.12: Scaffolds (a) compressive stiffness and (b) initial yield strength [36]

Patirupanusara [6], investigated fabrication of polymethyl methacrylate

(PMMA) structure by 3DP for medical application. The studied involved

formulating the suitable PMMA blended with binder-based powder which is

maltodextrin and polyvinyl alcohol (PVA) for using in 3DP machines. In addition, it

focused on the influence of adhesive binder-based powder content on the physical

and mechanical properties of the fabricated parts from PMMA. The studied used

water as a binding liquid in all formulations. From the results obtained as shown in

23��

Table 2.2, the errors of fabricated samples for all formulations do not exceed 6% in

all directions and increasing binder content increased both the modulus and strength

values. Considering the results of dimensional accuracy and mechanical properties,

formulations with binder content of 30–40% were found to give the optimized

properties for three dimensional printing of PMMA. The printing have been set to

100% saturation and 0.175 mm layer thickness in this research. This appears to be a

safe value that avoids the problem of the layer slippage.

Table 2.2: Influence of binder content on dimensional error, strength and modulus [6]

Binder content

(%)

Dimensional error (%) Strength (MPa) Modulus (GPa)

Width Length Thickness Flexural Compressive Flexural Compressive

60 -5.70 0.71 1.40 1.16 4.35 0.36 0.38

50 -4.78 0.99 3.43 0.87 3.76 0.20 0.27

40 -4.72 0.57 1.43 0.44 1.88 0.13 0.16

30 0.21 1.88 3.80 0.32 0.42 0.08 0.03

20 0.97 2.37 5.16 0.20 0.20 0.04 0.01

10 0.37 3.14 2.42 N/A N/A N/A N/A

Chumnanklang et al. [37], study 3DP processing of pre-coating of

hydroxyapatite by sprays drying technique. The aimed of the study is to investigate

the effect of binder concentration in pre-coated particle on part strength. The

concentration of binder was found to influence properties of both green and sintered

parts. It was observed that sintered strength of hydoxyapetite increased with

increasing green strength which in turn increased with increasing the binder

concentration and pre-coated particle size as shown in Figure 2.13. These results are

not practical since the increase in the concentration of maltodextrin (binder) forms

high viscosity slurry which is not suitable for the spray dryer. This is also against the

common thought that increasing binder content will result in decrease in strength

since the burn out of binder during sintering should leave pores in the sintered

specimens.

24��

(b)

(c)

Figure 2.13: Influence of (a) ratio of maltodextrin to water on green strength

(b) green strength on sintered strength and (c) precoated particle size on green

strength [37]

(a)

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