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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