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DESIGN AND DEVELOPMENT OF LOW-COST FRICTION STIR WELDING
AHMAD SYAZNI BIN ZAKARIA
A thesis submitted in fulfilment of the
requirements for the award of the degree of
Master of Engineering (Mechanical - Advanced Manufacturing Technology)
Faculty of Mechanical Engineering
Universiti Teknologi Malaysia
JULY 2015
iii
To my beloved father Dr. Zakaria Bin Haji Kassim
To my beloved mother Sharifah Binti Haji Idris
To my beloved sisters Datin Shazelina Binti Zakaria and Haslinda Binti Zakaria
iv
ACKNOWLEDGEMENT
In the name of Allah, the most Gracious and most Compassionate
First and foremost, I would like to thank Allah S.W.T for blessing and giving
me strength to accomplish this thesis.
A special thanks to my supervisor, Assoc. Prof. Zainal Abidin Ahmad, who
guided and helped me in every way I need to go through this final project. Special
credit to presentation panels and the program coordinator who lent their help too.
I like to give my appreciation to my classmates in Kolej Kemahiran Tinggi
Mara (KKTM) for their involvement in assisting me while I am in need. I like to give
my thanks to technicians in Universiti Teknologi Malaysia (UTM) who directly and
indirectly helping me in performing experiments, giving advice and tips while using
labs and tools in UTM.
Last but not least, I dedicated this thesis to my father, my mother and both of
my sisters. They gave their valuable support both in financially, morally, mentally
and spiritually.
v
ABSTRACT
The purpose of this study is to design and develop a friction stir welding
(FSW) based on current CNC machine. The development is based on CNC milling
machine using FSW tool that been machined. Aluminium Alloy 5083 was used as
workpiece sample while mild steel was selected as the material for the tool. The
experiments are based on selected welding conditions such as feed speed, tool
rotation speed, plunge depth and tool design. Some of the parameter was set to a
certain value, thus leaving 3 parameters with different value. For analyzation, feed
speed and tool rotation was concentrated to study which parameter is the best based
on analysis, either the combination of 10, 15 and 20 mm/min feed speed and tool
rotation of 1000, 1500 and 2000 rpm. Post analysis involving hardness test, impact
test and microstructure analysis. The experimental results were statistically analyzed
to study the influence of both parameters on weld area cross section. Based on
hardness test and impact test, the weld area are strong enough after combining two
aluminum. The microstructural imaging shows that at certain number of feed speed
or rotation speed, the weld area starting to crack. The outcome of this study shows
that feed speed and tool rotation speed have significance effects on the strength and
cosmetic of weld area and the best condition is at 10 mm/min feed speed and 1000
rpm of tool rotation speed. The results also shows that the setting of the experiment
can have bigger effect on the welding result.
vi
ABSTRAK
Tujuan kertas penyelidikan ini dijalankan adalah untuk merekabentuk dan
membangunkan kimpalan geseran kacau (FSW) berdasarkan pada mesin CNC yang
terkini. Pembangunan ini adalah berdasarkan pada mesin “milling” CNC
menggunakan alat FSW yang telah dimesin. Aluminium Alloy 5083 telah digunakan
sebagai sampel bahan kerja manakala “mild steel” telah dipilih sebagai bahan untuk
alat. Eksperimen berdasarkan keadaan kimpalan terpilih seperti kelajuan halaan, alat
kelajuan putaran, kedalaman tolakan bawah dan reka bentuk alat. Ada di antara
parameter yang telah ditetapkan kepada nilai tertentu, sekali gus meninggalkan 3
parameter dengan nilai yang berbeza. Untuk analisis, kelajuan halaan dan putaran
alat adalah tertumpu untuk mengkaji parameter yang terbaik berdasarkan analisis,
sama ada gabungan 10, 15 dan 20 mm / min kelajuan halaan dan putaran alat 1000,
1500 dan 2000 rpm. Analisis selepas eksperimen melibatkan ujian kekerasan, ujian
hentaman dan analisis mikrostruktur. Keputusan eksperimen telah dianalisis secara
statistik untuk mengkaji pengaruh kedua-dua parameter pada keratan rentas kawasan
kimpalan. Berdasarkan ujian kekerasan dan ujian kesan, kawasan kimpalan cukup
kuat selepas menggabungkan dua aluminium. Pengimejan mikrostruktur
menunjukkan bahawa pada sebilangan kelajuan suapan atau kelajuan putaran,
kawasan kimpalan mula retak. Hasil kajian ini menunjukkan bahawa kelajuan halaan
dan alat kelajuan putaran mempunyai kesan signifikan kepada kekuatan dan
kosmetik kawasan kimpalan dan keadaan yang terbaik adalah pada 10 mm / min
kelajuan halaan dan 1000 rpm kelajuan putaran alat. Keputusan juga menunjukkan
bahawa penetapan eksperimen boleh mempunyai kesan yang lebih besar ke atas hasil
kimpalan.
vii
TABLE OF CONTENTS
CHAPTER TITLE PAGE
TABLE OF CONTENTS vii
LIST OF TABLES xi
LIST OF FIGURES xii
LIST OF ABBREVIATATIONS xvi
1 INTRODUCTION 1
1.1 Background 1
1.2 Problem Statement 5
1.3 Objective 6
1.4 Scope 7
1.5 Significant of Study 7
viii
2 LITERATURE REVIEW 8
2.1 Overview 8
2.2 Theory and Concept
- Friction Stir Welding (FSW) 8
2.3 Milling Machine 12
2.4 Workpiece - Aluminum 13
2.5 Machining Tool 16
2.6 Analysis Tool 19
2.7 Previous Researches 22
3 METHODOLOGY 38
3.1 Research Planning 38
3.1.1 Gantt chart 38
3.1.2 Flow chart 39
3.2 Experimental Design 42
3.3 Experimental Setup and Steps 45
3.3.1 Workpiece Preparation 45
3.3.2 Tool Preparation 48
3.3.3 Machine Preparation 52
3.4 Studies and Measurements after
Experimentation 56
ix
3.4.1 Tensile Strength 57
3.4.2 Hardness Test 49
3.4.3 Charpy impact test 63
3.4.4 Cross Section Observation 68
3.5 Expectation of Study 72
4 RESULTS AND DISCUSSION 73
4.1 Starting and End of Experiment 73
4.2 Experimental Observation and Result 77
4.3 Discussion 97
5 CONCLUSION AND RECOMMENDATION 99
5.1 Conclusion 99
5.2 Recommendations 100
REFERENCES 101
APPENDICES 105-118
x
LIST OF TABLES
TABLE NO. TITLE PAGE
2.1 Summary of tool materials 18
3.1 Experimental design with welding
parameters 43
3.2 Experimental design with welding
parameters with dummy 44
3.3 Experimental design with for conical
pin tool 45
3.4 Description of (a) physical and
(b) mechanical properties of
Aluminium 5083 47
4.1 Comparison of percentage between
thickness at weld area and base metal 79
4.2 Hardness comparison of thickness at
weld area 83
xi
4.3 Impact test measurement 90
4.4 Cross section at weld area for all
9 samples 93
4.5 Microstructural at bottom of weld area 95
xii
LIST OF FIGURES
FIGURE NO. TITLE PAGE
1.1 Chart tree of joining process category 2
2.1 How friction stir welding works 10
2.2 A typical vertical milling machine 13
2.3 Aluminum alloy 14
2.4 Friction stir welding tool 17
2.5 Vernier caliper with digital meter 19
2.6 Tensile testing machine 20
2.7 Vickers hardness testing machine 21
2.8 Charpy impact tester 22
2.9 Experiment setup for research in Akita,
Japan by Riichi Suzuki, Susumu Hioki,
Naoki Yamamoto, Yuuta Kaneko and
Takehiko Takahashi 24
2.10 Experiment setup for research in Poland
xiii
by Marek Stanislaw Weglowski 25
2.11 Experiment setup for research in India
by Govindaraju M, Prasad Rao K, Uday
Chakkingal and K Balasubramanian 27
2.12 Relationships between rotational or attack
angle versus tensile strength or elongation 30
2.13 Surface and root appearance of friction
stir processed the aluminium alloy sheet
produced at 2500 rpm and 50 mm/min 33
DMG CTX 310 Glidimiester
2.14 Surface appearance of friction stir weld
of aluminium and copper sheet produced
at 950 rpm and 150 mm/min 33
2.15 Stress/Strain curves of FSP of the
aluminium alloy sheet produced at 2500
rpm and 50 mm/min 34
2.16 Tool used in the research for
optimization 35
2.17 Graph summarized the findings of
the research 35
3.1 Gantt Chart for project 39
3.2 Flow Chart for project 41
xiv
3.3 Mild steel sheet metal as workpiece 46
3.4 Various design of FSW tooling 48
3.5 Initial design of the tooling 49
3.6 Turning machine for tool machining 50
3.7 Final design of the tooling 51
3.8 CNC Milling Machine to use in experiment 53
3.9 Wirecut machine 54
3.10 Band saw machine 55
3.11 Disc saw machine 56
3.12 Tensile strength equipment 58
3.13 Vickers scale tester 63
3.14 Machining a sample with (a) cutting using
band saw and (b) making a notch 65
3.15 Sample with a notch 66
3.16 Impact test machine 67
3.17 Example of cross section imaging 68
3.18 Smaller sample that been cut with sawing
Machine 69
3.19 Polishing machine 70
3.20 Sample that been polished 70
xv
3.21 Optical microscope used to observe
microstructure of the sample 71
4.1 Tooling setup 73
4.2 Workpiece setup 74
4.3 Preparation before experiment 75
4.4 Experiment in process 76
4.5 Resultant Workpiece after Experiment 78
4.6 Bar graph on comparison for percentage
thickness versus the rotation tooling speed 81
4.7 Location approximately for hardness test
done on sample denoted with red and
blue circle 8.2
4.8 Bar graph on comparison for hardness
versus the rotation tooling speed 85
4.9 Comparison of thickness for 9 conical
tool samples 86
4.10 Comparison between hardness for 9
samples of conical tool 88
4.11 Sample after performing impact test 88
4.12 Reading of impact test machine 89
4.13 Data trend on the impact test result 90
xvi
4.14 Data comparison between energy and
hardness for 9 samples 92
4.15 Depth and length comparison between
Samples 94
xvii
LIST OF FIGURES
NO. TITLE PAGE
A Project Planning 105
B Design Drawing 106
C Microstructural Imaging 111
xviii
LIST OF ABBREVIATATIONS
i Material Safety Data Sheet MSDS
ii Computer Numerical Control CNC
iii Revolution Per Minute RPM
iv Analysis of Variance ANOVA
v Machine Condition Monitoring MCM
vi Surface Roughness Ra
vii Design of Experiment DOE
viii Friction Stir Welding FSW
CHAPTER 1
INTRODUCTION
1.1 Background
Joining two or more materials become one of essential processes in machinery
industry. Since centuries and decades ago, these processes of joining materials become a
norm to produce a better and more flexible shape for easy usage. One material can be
join with similar or different and suitable material. Nail and hammer is the most basic
tool to combine the materials but have a lot of limitations such as material hardness,
accuracy, number of product to be produced and product durability.
Joining between two metals are generally categorize from metal fabrication.
Chart below detailing the joint process categorization, from permanent and
nonpermanent category to further level of subcategory. One of the process often used in
industry are from solid state category.
Figure 1.1: Chart tree of joining process category
Metal fabrication is a value added process that involves the construction of
machines and structures from various raw materials. A fab shop will bid on a job,
usually based on the engineering drawings, and if awarded the contract will build the
product. Large fab shops will employ a multitude of value added processes in one plant
or facility including welding, cutting, forming and machining. These large fab shops
offer additional value to their customers by limiting the need for purchasing personnel to
locate multiple vendors for different services. Metal fabrication jobs usually start with
shop drawings including precise measurements then move to the fabrication stage and
finally to the installation of the final project. Fabrication shops are employed by
contractors, OEMs and VARs. Typical projects include; loose parts, structural frames
for buildings and heavy equipment, and hand railings and stairs for buildings. Metal
fabrication are divided to cutting, bending and assembly. Metal joining are from
assembly category.
Assembling (joining of the pieces) is done by welding, binding with adhesives,
riveting, threaded fasteners, or even yet more bending in the form of a crimped seam.
Structural steel and sheet metal are the usual starting materials for fabrication, along
with the welding wire, flux, and fasteners that will join the cut pieces. As with other
manufacturing processes, both human labor and automation are commonly used. The
product resulting from fabrication may be called a fabrication. Shops that specialize in
this type of metal work are called fab shops. The end products of other common types of
metalworking, such as machining, metal stamping, forging, and casting, may be similar
in shape and function, but those processes are not classified as fabrication [26].
Welding is one of process of joining two or more material. Welding is a
fabrication or sculptural process that joins materials, usually metals or thermoplastics, by
causing coalescence. This is often done by melting the workpieces and adding a filler
material to form a pool of molten material (the weld pool) that cools to become a strong
joint, with pressure sometimes used in conjunction with heat, or by itself, to produce the
weld. This is in contrast with soldering and brazing, which involve melting a lower-
melting-point material between the workpieces to form a bond between them, without
melting the workpieces [1]. There are few process derived from the welding process
with different attribute. One of it is friction welding, which used the heat from friction
phenomena to melt the filler material.
Friction welding (FRW) is a solid-state welding process that generates heat
through mechanical friction between workpieces in relative motion to one another, with
the addition of a lateral force called "upset" to plastically displace and fuse the materials.
Technically, because no melt occurs, friction welding is not actually a welding process
in the traditional sense, but a forging technique. However, due to the similarities
between these techniques and traditional welding, the term has become common.
Friction welding is used with metals and thermoplastics in a wide variety of aviation and
automotive applications.
The combination of fast joining times (on the order of a few seconds), and direct
heat input at the weld interface, yields relatively small heat-affected zones. Friction
welding techniques are generally melt-free, which avoids grain growth in engineered
materials, such as high-strength heat-treated steels. Another advantage is that the motion
tends to "clean" the surface between the materials being welded, which means they can
be joined with less preparation. During the welding process, depending on the method
being used, small pieces of the plastic or metal will be forced out of the working mass
(flash). It is believed that the flash carries away debris and dirt.
Another advantage of friction welding is that it allows dissimilar materials to be
joined. This is particularly useful in aerospace, where it is used to join lightweight
aluminum stock to high-strength steels. Normally the wide difference in melting points
of the two materials would make it impossible to weld using traditional techniques, and
would require some sort of mechanical connection. Friction welding provides a "full
strength" bond with no additional weight. Other common uses for these sorts of bi-metal
joins is in the nuclear industry, where copper-steel joints are common in the reactor
cooling systems; and in the transport of cryogenic fluids, where friction welding has
been used to join aluminum alloys to stainless steels and high-nickel-alloy materials for
cryogenic-fluid piping and containment vessels.
Friction welding is also used with thermoplastics, which act in a fashion
analogous to metals under heat and pressure. The heat and pressure used on these
materials is much lower than metals, but the technique can be used to join metals to
plastics with the metal interface being machined. For instance, the technique can be used
to join eyeglass frames to the pins in their hinges. The lower energies and pressures used
allows for a wider variety of techniques to be used [27].
Friction-stir welding (FSW) is a solid-state joining process (the metal is not
melted) that uses a third body tool to join two faying surfaces. Heat is generated between
the tool and material which leads to a very soft region near the FSW tool. It then
mechanically intermixes the two pieces of metal at the place of the join, then the
softened metal (due to the elevated temperature) can be joined using mechanical
pressure (which is applied by the tool), much like joining clay, or dough. It is primarily
used on aluminum, and most often on extruded aluminum (non-heat treatable alloys),
and on structures which need superior weld strength without a post weld heat treatment
[2].
There are few factors of why not many using FSW in their factories. One of the
reason is high cost involving owning and setup the machine. However, FSW machine
can be designed and developed from other machining process for purpose of it capable
of welding materials. With different setup and parameters, achieving this is not
impossible.
1.2 Problem Statement
FSW is one of the most recommended and used choice of joining metals in
industry. Top companies used FSW in producing their own product. For example, tech
giant Apple used FSW to produce its line of computer product. Other example is the
production of fast train in Japan. However, one of the downside of using FSW is the cost
of owning, using and maintaining a dedicated FSW machine.
For factories that are small or having limited space, having a dedicated machine
to do the process are not recommended unless the machine are maximize its utilization.
This is because, it is less productive to keep an underutilize FSW machine in production
space. It is rather productive to place an additional production machine in line instead.
Owning a FSW machine does not only consume some space but also dishing out
an additional cost for obtaining the machine. Other than buying the machine, the
maintenance cost for the machine need to be in consideration. In Malaysia, the FSW
process are quite new to our engineers and technical personnel. Therefore, training
course to operate the FSW dedicated machine need to be provided to the technical
workers including operators. Thus, another cost to be considered to supply the course
needed.
Having a machine that may not always on use could be unwise. Instead of buying
the machine, FSW can be developed by redesign another machine by adjusting its
parameters and settings.
1.3 Objective
To design and fabricate or modify an existing CNC milling drilling machine to
perform as a friction welding machine suitable for experimental and basic research
activities.
1.4 Scope
1. To carry out in-depth study on the friction stir welding process – steps,
parameters, machines and applications.
2. To carry out in-depth study on the CNC milling machine structure and
modification related issues.
3. To carry out modification/fabrication of the machines.
4. To perform basic performance test of the machine.
1.5 Significant of Study
After fulfilling the project scope and methodology, fabricating a friction stir
welding machine by redesign a milling machine can be achieved. Achieving this feat not
only giving the alternative process for joining two or more materials, but also prevent
additional cost by having milling machine to do welding process apart of its usual
milling process.
This study can be expanded further with design and development of friction stir
welding using various machines like turning.
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