i effect of machining parameters and bismuth...
TRANSCRIPT
i
EFFECT OF MACHINING PARAMETERS AND BISMUTH ADDITION ON AL-
20%MG2SI MACHINABILITY DURING DRY TURNING
ABBAS RAZAVYKIA
A project report submitted in partial fulfilment of the
requirements for the award from the degree of
Master of Engineering (Mechanical-Advanced Manufacturing Technology)
Faculty of Mechanical Engineering
Universiti Teknologi Malaysia
JUNE 2014
iii
To my beloved family and specially my dear father, mother, brother and sisters
iv
ACKNOWLEDGEMENT
First and foremost, I would like to thank Allah Almighty for his guidance,
help and giving me the strength to complete this report. A special thank to my great
supervisor Prof. Dr. Noordin Mohd Yusof for his advice, encouragement and
continuous assistance whenever required.
I would like also to express my sincere thanks to all technical staffs at the
Production and Material Science Laboratories.
I am also forever indebted to my parents Eslamali Razavykia and Kobra
Marjani who gave me real love, pray, moral support, and all their doa.
v
ABSTRACT
The metal matrix composite has become an important material in aerospace
and automotive industry due to their mechanical properties such as light weight, wear
resistance and high strength. although metal matrix composite, are produced in net
shape, there is some need for secondary operation such as machining. The main
problem in MMC machining is high tool wear which result in extra cost. This
observation has resulted in an investigation to evaluate the effect of machining
parameters and Bismuth as modifier on machinability of Al-20%Mg2Si. The
classical experimental design was also applied to develop empirical model,
(regression model), to represent the relationship between machining parameters and
cutting forces, surface roughness and the Bi modifier.
vi
ABSTRAK
Komposit logam matrik merupakan bahan yang penting terutamanya dalam
industri aero-angkasa dan automotif. Ini kerana bahan tersebut mempunyai sifat-sifat
mekanikal seperti ringan, rintangan terhadap kehausan dan mempunyai kekuatan
yang tinggi. Walaupun komposit logam matrik dihasilkan dalam bentuk yang tepat
dan jelas, ianya masih memerlukan operasi sekunder seperti pemesinan. Namun,
masalah utama dengan komposit logam matrik ini adalah kehausan pada mata alat
yang tinggi dan secara tidak langsungnya, kos yang tinggi juga diperlukan.
Pemerhatian ini telah menderong satu pengiastan untuk menilai kesan parameter
pemesinan dan penambahan Bismuth sebagai pengubahsuai lupada kebolehmesihan
Al-20%Mg2Si. Rekabentuk ujikaji klasik juga digunakan untuk menghasilkan model
emprikal (model regresi) untuk menjelaskan hubungan antara parameter pemesinan
dengan daya pemotongan, kekasaran permukaan dan juga pengubahsuai Bi.
vii
TABLE OF CONTENT
CHAPTER TITLE PAGE
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENTS iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES xi
LIST OF FIGURES xii
1 INTRODUCTION 1
1.1 Background 1
1.2 Problem Statement 2
1.3 Objective 2
1.4 Scope 3
1.5 Thesis Organization 3
2 LITERATURE REVIEW 5
2.1 The Aluminium Industry Today 5
2.1.1Recycled or Secondary Aluminium 6
2.1.2Important Physical Properties 7
2.1.3Crystal Structure 7
2.1.4Density 8
2.2 Metal Matrix Composites
2.3 Magnesium
9
11
2.4 Bismuth and Its Properties 13
viii
2.5 Silicon 13
2.6 Al-Mg2Si 14
2.6.1The Effect of Adding Bismuth on
Al-20%Mg2Si
15
2.7 Machining 17
2.7.1 Mechanics of Cutting 20
2.7.2 Types of Chips Produced in Metal Cutting 23
2.7.2.1 Continuous Chips 23
2.7.2.2 Built-up Edge Chips 23
2.7.2.3 Serrated Chips 24
2.7.2.4 Discontinuous Chips 24
2.8 The Forces During Turning 25
2.8.1 Cutting Force 26
2.8.2 Thrust Force 26
2.9 Temperatures in Cutting 27
2.10 Surface Finish and Integrity 28
2.11 Machinability 28
2.11.1 Machinability of Nonferrous Metals 29
2.11.2 Machinability of Miscellaneous Materials 30
2.12 Cutting Tool 31
2.12.1 High-Speed Steels 33
2.12.2 Cast-Cobalt Alloys 33
2.12.3 Carbides 34
2.12.3.1 Tungsten Carbide 34
2.12.3.2 Titanium Carbide 35
2.12.3.3 Inserts 35
2.12.4 Coated Tools 36
2.12.5 Alumina-Based Ceramics 37
2.12.6 Cubic Boron Nitride 38
2.12.7 Silicon Nitride Based Ceramics 39
2.12.8 Diamond 39
2.12.9 Whisker Reinforced Materials and Nano-
materials
40
ix
2.14 Surface Integrity 41
2.15 Surface Roughness 42
2.15.1 Arithmetic Parameters 42
2.16 Previous Research 44
3 RESEARCH METHODOLOGY 49
3.1 Introduction 49
3.2 Research Design Variables 50
3.2.1 Response Parameters 50
3.3 Cutting Condition 50
3.4 Work-piece Material 51
3.5 Preliminary Machining 51
3.6 Tool Material 51
3.7Cutting Forces Measurements 52
3.8 Surface Roughness Measurement 52
3.9 Machines and Equipment 53
3.10 Experimental Set Up 54
4 EXPERIMENTAL RESULTS AND DISCUSSION 56
4.1 Introduction 56
4.2 Effect of Cutting Condition on Cutting Force 57
4.2.1 Effect of Feed Rate on Cutting Force 58
4.2.2 Effect of Cutting Speed on Cutting Force 60
4.2.3 Effect of Modifier on Cutting Force 60
4.3 Effect of Cutting Condition on Surface Roughness 64
4.3.1 Effect of Cutting Speed on Surface Roughness 65
4.3.2 Effect of Feed Rate on Surface Roughness 67
4.3.3 Effect of Modifier on Surface Roughness 68
4.4 Classical DOE Method Data Analysis 70
4.4.1 Experiment Design 71
4.4.2 Data Analysis for Cutting Force 72
4.4.2.1 Box-Cox Plot 76
4.4.2.2 Contour Plot 77
x
4.4.2.3 3D Surface 78
4.4.3 Data Analysis for Surface Roughness 80
4.4.3.1 Box-Cox Plot 83
4.4.3.2 Contour Plot 84
4.4.3.3 3D Surface 85
4.5 Confirmation Test 86
5 CONCLUSION AND RECOMMENDATION FOR
FURTHER STUDIES
87
5.1 Conclusion 87
5.2 Recommendation 88
REFERENCES 90-92
xi
LIST OF TABLES
TABLE NO. TITLE PAGE
2.1 Factors influencing machining operation 21
3.1 Cutting conditions 51
4.1 Experimental results of cutting force (Al-20%Mg2Si) 57
4.2 Experimental results of cutting force (Al-20%Mg2Si-
0.6wt.%Bi)
58
4.3 Experimental results for surface roughness (Al-20%Mg2Si) 64
4.4 Experimental results for surface roughness (Al-20%Mg2Si-
0.6wt.%Bi)
65
4.5 Average of surface roughness for non-modified work-piece
V= 210 m/min, f= 0.2 mm/rev and D=0.5 mm
67
4.6 Average of surface roughness for modified work-piece V=
210 m/min, f= 0.2 mm/rev and D=0.5 mm
68
4.7 Design summary 73
4.8 Analysis of variance table [Partial sum of squares - Type III 74
4.9 Post ANOVA table 75
4.10 Analysis of variance table [Partial sum of squares - Type
III]
81
4.11 Post ANOVA table 82
4.12 Confirmation experiments 86
xii
LIST OF FIGURES
FIGURE NO. TITLE PAGE
2.1 Atomic structure of aluminium 8
2.2 Volume per unit weight 9
2.3 Classification of composite materials with metal matrixes 10
2.4 Schematic presentation of three shapes of metal matrix
composite materials
11
2.5 Cooling curves of Al–Mg2Si respective with the
morphology changes at different concentrations of Bi
refiner; 0.2, 0.4, 0.6, 0.8 and 1.0 wt.%.
16
2.6 (a) Depression in TN and TG corresponding to different
Bi addition and (b) characteristic particles of primary
Mg2Si as a function of Bi content
17
2.7 Some examples of common machining operations 18
2.8 Schematic illustration of the turning operation, showing
various features
19
2.9 Schematic illustration of a two-dimensional cutting
process, also called orthogonal cutting
20
2.10 Force components in three dimensional oblique cutting 27
2.11 The hardness of various cutting-tool materials depend on
the temperature
32
2.12 Methods of mounting inserts on tool holders 36
2.13 Relative time required to machine with various cutting-
tool materials, indicating the year the tool materials were
first introduced.
37
2.14 Mean line system and definition of Ra 43
2.15 Definition of the Rt, Rp and Rv amplitude parameters 44
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3.1 Summary of the methodology used in the study 50
3.2 Mitutoyo surface tester SJ-301 53
3.3 ALPHA 1350S 2-axis CNC Lathe 53
3.4 Scanning Electron Microscopy 54
4.1 Cutting force and feed rate relationship when turning non-
modified (Al-20%Mg2Si)
59
4.2 Cutting force and feed rate relationship when turning
modified specimen (Al-20%Mg2Si-0.6wt.%Bi)
59
4.3 SEM picture of microstructure of non-modified work-
piece with 500X magnification
61
4.4 SEM picture of microstructure of modified work-piece
with 500X magnification
61
4.5 SEM picture of machining surface of work-piece (left
non-modified, right modified) with 200X magnification
62
4.6 The relationship of cutting force and modifier when
turning work-piece at cutting speed 70 m/min
62
4.7 The relationship of cutting force and modifier when
turning work-piece at cutting speed 140 m/min
63
4.8 The relationship of cutting force and modifier when
turning work-piece at cutting speed 210 m/min
63
4.9 Surface roughness and feed rate relationship when turning
Al-20%Mg2Si
66
4.10 Surface roughness and feed rate relationship when turning
Al-20%Mg2Si-0.6wt.%Bi
66
4.11 Surface roughness graph and machining surface for non-
modified work-piece (with 50X magnification), V= 210
m/min, f= 0.2 mm/rev and D=0.5 mm
67
4.12 Surface roughness graph and machining surface for
modified work-piece (with 50X magnification), V= 210
m/min, f= 0.2 mm/rev and D=0.5 mm
68
4.13 Surface roughness and feed rate relationship when turning
with cutting speed 70 m/min
69
4.14 Surface roughness and feed rate relationship when turning
xiv
with cutting speed 140 m/min 69
4.15 Surface roughness and feed rate relationship when turning
with cutting speed 210 m/min
70
4.16 BUE formation in both specimens, left side non-modified
and right side modified work-piece at V= 210 m/min, f=
0.2 and D= 0.5
70
4.17 Multilevel categoric design 71
4.18 Design layout screen 72
4.19 Half-normal plot of effects for cutting force 73
4.20 Normal plot of residuals 76
4.21 Box-Cox plot 77
4.22 Contour plot for non-modified 78
4.23 Contour plot for modified 78
4.24 3D Surface plot for non-modified 79
4.25 3D Surface plot for modified 79
4.26 Half-Normal plot of effects for cutting force 80
4.27 Normal plot of residuals 83
4.28 Box-Cox plot 83
4.29 Contour plot for non-modified 84
4.30 Contour plot for modified 84
4.31 3D Surface plot for non-modified 85
4.32 3D Surface plot for modified 85
1
CHAPTER 1
INTRODUCTION
1.1 Background
MMCs are compounded of a moderately soft and ductile metal base material,
or ‘‘matrix’’ reinforced with a hard and brittle reinforcement material. The
reinforcement are divided to three groups, particles, whiskers, or fibers. The first
advantages provided by these materials are their enhanced mechanical properties,
especially in the aspects of wear, strength and stiffness. These matrix materials
contributes to the properties of high specific stiffness and strength. In the form of
particle is most typically shape for reinforcement. Fiber reinforcement is not so
common and is barred to situations where performance is the important factor rather
than cost. The amount of reinforcement in MMCs is often less than 40%.
The perfect properties are experienced with Mg2Si, and as result have high
potential as structural material. It attracts engineers attention in the automotive
industry to produce items such as cylinder blocks and cylinder heads. The low
density of Mg2Si brings about weight reduction and reduce cost as result of Al, Mg
and Si as starting materials, provide excellent advantages. Attributed to the
intermetallic compound Mg2Si offers some advantages such as high melting
temperature, low density, high hardness, low thermal expansion coefficient and high
elastic modulus.
2
The cast composites which are produced by conventional casting tends to
form undesirable coarse primary Mg2Si particulates, which have considerable effect
on the mechanical properties because of the large and brittle nature of Mg2Si
particles and enhancement in the mechanical properties may be obtained by fast
solidification during casting and mechanical alloying which result in the production
of composite with very fine matrix structure and in situ Mg2Si particles(Nordin,
Farahany et al. 2013).
Although the MMCs are produced to net shape by using appropriate
techniques, there is still the need for some operation such as secondary machining.
The high tool wear due to the abrasive action of reinforcement particles is the most
important consideration during MMCs machining(El-Gallab and Sklad 1998).
1.2 problem Statement
There are many factors including cutting speed and feed rate which
influenced the machining of AL-Mg2Si. However the following reasons provide the
motivation for performing this work.
• Unavailability of information of machining and machinability of Al-Mg2Si.
• To make available empirical models to predict the final surface roughness
and cutting force when turning Al-Mg2Si (Non-modified) and Bismuth modified Al-
Mg2Si in specific cutting speed and feed rate.
1.3 Objective
The objective of this study are as follow:
3
To evaluate the effect of machining parameters (Cutting speed and Feed rate)
on surface roughness and cutting forces when turning non-modified and
modified Al-20%Mg2Si.
To develop empirical model, to represent the relationship between machining
parameters and surface roughness and cutting forces.
1.4 Scope
The scope of this work are as follow:
Work-piece materials which will be used in this investigation are, Al-
20% Mg2Si (non-modified) and Al-20% Mg2SiBi modified (0.6wt.%Bi).
The experiments will be conducted on an ALPHA 1350S 2-Axis CNC Lathe
turning machine and PVD coated ceramic cutting tool will be used.
The surface roughness and cutting force (Fc) during the dry turning are the
machinability parameters that will be evaluated in terms of determine
machinability.
Statistical Design of Experiment will be implemented in this study.
The surface morphology and integrity will be analyzed by using Scanning
Electron Microscope (SEM).
1.5 Thesis Organization
Chapter one, covers an introduction and overview of metal matrix composites
and their properties. This chapter also discusses background of the study, statement
of problem, determining the objective and scope of the study.
4
Chapter two includes the review of literature consisting of basic definitions
regarding composites, machining and related concepts. And finally all information
about machinability, cutting tools, cutting forces and related equipment.
chapter three puts forward research framework and methodology, which
provides guidelines on how this research will be conducted in order to reach its
objective.
In chapter four, the appropriate model and experiment variables based on
objective and study condition are selected. And all data are compared to evaluate the
concerned material and its machinability.
In chapter five, the result of the study is provided and findings are discussed.
In order to investigate the effect of machining parameters on Al-20%Mg2Si
machinability and develop empirical model to represent the relationship between
cutting speed, feed rate, cutting force and surface roughness.
90
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