UNIVERSITI TEKNIKAL MALAYSIA MELAKA
Surface Integrity of Aluminium Lm6 Alloy When Machine with the
High Speed Steel and Uncoated Carbide Cutting Tool
This report submitted in accordance with requirement of the Universiti
Teknikal Malaysia Melaka (UTeM) for the Bachelor Degree of
Manufacturing Engineering (Manufacturing Process)
by
NORAINI BINTI SULAIMAN
B051010241
891122045074
Faculty of Manufacturing Engineering
2013
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA
TAJUK: Surface Integrity of Aluminium Lm6 Alloy When Machine with the High
Speed Steel and Uncoated Carbide Cutting Tool
SESI PENGAJIAN: 2013 SEMESTER 2
Saya NORAINI BINTI SULAIMAN
mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti
Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:
1. Laporan PSM adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis.
2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja dengan izin penulis.
3. Perpustakaan dibenarkan membuat salinan laporan PSM ini sebagai bahan
pertukaran antara institusi pengajian tinggi.
4. **Sila tandakan (√)
√
SULIT
(Mengandungi maklumat yang berdarjah keselamatan
atau kepentingan Malaysiasebagaimana yang termaktub
dalam AKTA RAHSIA RASMI 1972)
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(Mengandungi maklumat TERHAD yang telah ditentukan
oleh organisasi/badan di mana penyelidikan dijalankan)
TIDAK TERHAD
Disahkan oleh:
Alamat Tetap:
NO. 86 JALAN BERTAM JAYA 4
Cop Rasmi:
TAMAN BERTAM JAYA
76450 MELAKA
Tarikh: _________________________
Tarikh: _______________________
** Jika Laporan PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi
berkenaan dengan menyatakan sekali sebab dan tempoh laporan PSM ini perlu dikelaskan sebagai
SULIT atau TERHAD.
DECLARATION
I hereby, declare this thesis entitled “SURFACE INTEGRITY OF ALUMINIUM
LM6 ALLOY WHEN MACHINE WITH THE HIGH SPEED STEEL AND
UNCOATED CARBIDE CUTTING TOOL” is the results of my own research except
as cited in the reference.
Signature
:
Author Name
:
………………………………………….
NORAINI BINTI SULAIMAN
…………………………………………
Date
:
…………………………………………
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTeM
as a partial fulfillment of the requirements for the degree of Bachelor of
Manufacturing Engineering (Process) (Hons.). The member of the supervisory is
as follow:
………………………………
(Project Supervisor)
ABSTRAK
Pemesinan adalah satu proses untuk membentuk sebelum menghasilkan produk.
Penggunaan pemesinan berkelajuan tinggi secara automatik menjana banyak hasil
dan kualiti yang baik. Untuk menghasilkan keputusan yang baik perlu diambil kira
beberapa perkara termasuk kelajuan pemotongan, kedalaman potong dan kadar
suapan. Gunakan kelajuan pemotongan yang tinggi, kedalaman pemotongan dan
kadar suapan akan meninggalkan kesan pada permukaan bahan kerja.Pemotongan
pemilihan adalah juga penting untuk memastikan permukaan bahan kerja sentiasa
dalam keadaan baik. Dalam kajian ini, bahan yang akan digunakan adalah
Aluminium aloi LM6. Walau bagaimanapun, kebanyakan penyelidikan sebelumnya
pada aluminium LM6 hanya memberi tumpuan kepada proses melarik sahaja.
Penggunaan aluminium aloi LM6 adalah terhad sama sekali. Memandangkan mesin
pengisar adalah antara alat yang paling serba boleh dan berguna dan juga mampu
untuk menghasilkan profil dan pelbagai permukaan melengkung, kajian pengilangan
aluminium adalah penting untuk menentukan alat yang betul memotong, parameter
dan parameter pemotongan. Oleh itu, pemilihan mata pemotong yang betul juga
memainkan peranan bagi penghasilan permukaan. Kajian ini memberi tumpuan
lebih kepada integriti permukaan seperti kekasaran permukaan, kekerasan
permukaan, profil permukaan dan mikro suktur permukaan. Pemilihan mata
pemotong, masa pemotongan serta parameter yang sesuai juga memainkan peranan
bagi penghasilan permukaan yang baik.
i
ABSTRACT
Machining is a process to form before producing a product. Use of high-speed
machining automatically generates a lot of revenue and quality. To produce good
results should be taken into account a number of things including cutting speed, depth
of cut and feed rate. Use of high cutting speed, depth of cut and feed rate will leave
an impression on the surface of workpiece. Selection cutting is also important in
order to keep the surface of the workpiece. In this study, material that will be use is
Aluminum LM6 alloy. However, most of the previous researches on aluminium LM6
are focusing on turning and casting only which means there are limitation trials
regarding milling process. Since millings are among the most versatile and useful
tools and also capable to produce various profiles and curved surfaces, the study of
aluminum milling is important to determine the right cutting tool, parameter and
cutting parameter. Therefore, selecting the right cutting tools also play a role in the
production of the surface. This research focuses more on the integrity of the surface
such as surface roughness, surface hardness, surface profile and surface
microstructure. Selection of cutting tools, cutting time and the appropriate parameters
also play a role in producing a good surface.
ii
DEDICATION
First and foremost, , I would like to express my greatest appreciation to Universiti
Teknikal Malaysia Melaka for giving me the opportunity to undergo my final year
“Projek Sarjana Muda” under the supervision of Dr. Mohd Hadzley Bin Abu Bakar.
A special thank you also goes to my supervisor Dr. Mohd Hadzley Bin Abu Bakar for
his dedication and guidance during the period of undergoing my project and also to
master student Cik Siti Sarah Nadia Binti Ahmad for her guidance. Last but not least,
I want to thank my mom and dad for their support as well as to all my friends Cik Nur
Azza Syazwany Binti Azizol and Nur Nabilah Farhana Binti Sulaiman who never give
up encouraging me to complete this report.
Thank You!
iii
ACKNOWLEDGEMENTS
First of all, I would like to thank Universiti Teknikal Malaysia Melaka for
giving me the opportunity to undergo my “Projek Sarjana Muda 2” at the year 4 for
semester 2 of my studies.
My hearties appreciation especially to:
•
Dr. Mohd. Hadzley Bin Abu Bakar, my supervisor for Projek Sarjana Muda 2, for
his guide and support to complete my final year project.
•
All the technicians involved in my final year project.
It was their kind efforts that given me opportunity and guidance to successfully
undergo my “Projek Sarjana Muda 2” in the final year.
Last but not least, I would like to thanks all my friends that given me full support and
encouragement in completing my final year project.
Your help and support will always be cherished.
Thank You.
iv
TABLE OF CONTENT
Abstrak
i
Abstract
ii
Dedication
iii
Acknowledgement
iv
Table of Content
v
List of Tables
viii
List of Figures
ix
List Abbreviations, Symbols and Nomenclatures
xi
CHAPTER 1: INTRODUCTION
1.1
Background
1
1.2
Objective
3
1.3
Scope of Project
3
CHAPTER 2: LITERATURE REVIEW
2.1
Aluminium
4
2.2
Aluminium Alloy
5
2.3
Metal Matrix Composites
6
2.3.1
Stir Casting Method of Fabrication of MMCs
7
2.3.1.1 Stir Casting
7
2.3.2
Strengthening Mechanism of Composites
8
2.3.3
Strengthening Mechanism of Fiber Reinforced Composite
8
2.3.4
Dispersion Strengthening Mechanism of Strengthened
9
Composite
2.3.5
2.4
Strengthening Mechanism of Particulate Composite
9
Machining
10
2.4.1
10
Elements of Machining
v
2.4.2
2.5
2.6
2.7
Classical Metal Machining Process
11
2.4.2.1 Orthogonal Cutting System
11
2.4.2.2 Oblique Cutting System
12
Milling
13
2.5.1
Peripheral Milling
14
2.5.2
Face Milling
16
2.5.3
End Milling
17
2.5.4
Fundamentals of Milling Processes
19
2.5.5
Cutting Parameter
20
Choosing the Process
22
2.6.1
25
CNC advantages and disadvantages
Surface Integrity
26
2.7.1
Surface and Subsurface Metallurgy
27
2.7.1.1 Surface Roughness
27
2.7.1.2 Natural Surface Roughness
29
2.7.1.3 Material Side Flow
30
2.7.1.4 Built-Up Edge
31
2.7.1.5 Subsurface Microstructure Alteration
32
2.8
Cutting tool
35
2.9
Sumarry
36
CHAPTER 3: METHODOLOGY
3.1
Flow Chart
38
3.2
Workpiece
39
3.2.1
39
LM6 - Aluminium Casting Alloy
3.3
Cutting tool
41
3.4
Cutting Condition
42
3.5
Experimental Equipment
43
3.5.1
3 Axis CNC Vertical Milling Machine
43
3.5.2
Surface Roughness Measurement
44
3.5.3
Surface microhardness measurement
45
vi
3.5.5
Subsurface Microstructure
46
3.5.4
Polishing
47
3.5.4
Etching
48
CHAPTER 4: RESULT AND ANALYSIS
4.1
Introduction
50
4.2
Microstructure Aluminium LM6 before Machining
51
4.3
Parameter Selection
52
4.4
Surface Profile
55
4.5
Surface Roughness
58
4.6
Microstructure
61
4.7
Microhardness
63
CHAPTER 5: CONCLUSION AND RECOMENDATION
5.0
Conclusion
64
5.1
Recommendations
65
vii
LIST OF TABLE
2.1 CNC advantages and disadvantages
25
3.1 Chemical composition
39
3.2 Physical properties
40
3.3 Mechanical Properties
40
3.4 Initial cutting parameters
42
4.1 Cutting parameter selection using uncoated high speed steel
52
4.2 Result for surface roughness (Ra)
58
viii
LIST OF FIGURE
2.1 Electron configuration
4
2.2 Deformation of material in machining
10
2.3 Orthogonal cutting system
12
2.4 Oblique cutting system
13
2.5 Milling process on job part
14
2.6 Different Types of Peripheral Milling
15
2.7 Conventional Face Milling
16
2.8 Partial Face Milling
17
2.9 End Milling
17
2.10 Profile Milling
18
2.11 Pocket Milling
18
2.12 Surface Contouring
18
2.13 CNC Milling Machine
23
2.14 Coordinate System used in CN for Flat and Rotational Work
24
2.15 Definition of roughness average
29
2.16 Surface damage when a worn tool is used under dry-cut conditions
31
2.17 Plastic deformation at the cutting tool edge (The white dashed line is
32
the original tool profile)
2.18 The microhardness value measured beneath the machined surface
33
2.19 Effects of elevated temperature on strain hardened materials when
34
machining
3.1 Research methodology
38
3.2 Aluminium LM6 in ingot shape
41
3.3 High speed steel cutting tool
41
3.4 Uncoated carbide cutting tool
42
3.5 Haas’ 3 axis CNC vertical milling machine
43
ix
3.6 Surface roughness tester Mitutoyo SJ-301
44
3.7 Mitutoyo microhardness testing machine
45
3.8 Scanning electron microscope (SEM)
46
3.9 Surface grinding and polishing machine
47
3.10 Grinding paper
47
3.11 Etching solution for aluminium alloy
48
4.1 Microstructure of aluminium LM6
51
4.2 Cutting parameter experiment design
53
4.3 Surface profile using high speed steel
55
4.4 Surface profile using uncoated carbide
56
4.5 Graph for surface roughness versus radial depth of cut
59
4.6 Graph for time versus radial depth of cut
59
4.7 Microstructure when aluminium LM6 machine
61
4.8 Microstructure when aluminium LM6 machine with uncoated carbide
62
4.9 Hardness value after machining aluminium LM6
63
x
LIST OF ABBREVIATIONS, SYMBOLS AND
NOMENCLATURE
Al
-
Aluminium
CNC
-
Computer Numerical Control
MMC
-
Metal matrix composites
CM
-
Centimetre
MM
-
Milimeter
>
-
More than
σ
-
Stress
τ
-
Torque
d
-
Diameter of milling cutter in mm
V
-
Cutting speed (linear) in meter per minute
N
-
Cutter speed in revolution per minute
Ra
-
Roughness average
Rv
-
Maximum depth
Rp
-
Maximum height
Rt
-
Total height
BUE
-
Built-up edge
SEM
-
Scanning Electron Microscope
xi
Min
-
Minutes
Kg
-
Kilogram
xii
CHAPTER 1
INTRODUCTION
1.1
Background
Machining is a chip removal process to form a shape by using a specific machine.
Machining is used because it has a high accuracy. By using this machine will also
save time and production will rise higher. Machining refers to several processes
such as sawing, drilling, boring, Shaping, reaming and others. There are various
types of machining in manufacturing which lathe machine, milling machine, drill
machine Presses and so on. Nowdays, a used machine is in automatic form. It is
controlled by a computer program called numerical control (CNC). CNC is a
command-based coordinate to get a form for you automatically (Kalpakjian 2006).
Physically, chemically and mechanically aluminium is a metal like steel, brass,
copper, zinc, lead or titanium. It can be melted, cast, formed and machined much
like these metals and it conducts electric current. In fact often the same equipment
and fabrication methods are used as for steel (Boyer 2006). Pure aluminium is a
weak, very ductile, material. The mechanical properties depend not only on the
purity of the aluminium but also upon the amount of work to which it has been
subject. A range of tempers is thus produced by different amounts of work
hardening. It has an electrical conductivity about two-thirds that of copper but
weight for weight is a better conductor. One of the most common end users of
aluminium is packaging, including drinks cans, foil wrappings, bottle tops and
foils containers (Forbes 2001). Each of these relies on aluminium to provide a
way of containing the food cleanly, and to protect it from changes in the local
environment outside the packaging. Aluminium natural resistance to corrosion
aids it in its role in packaging. Aluminium unbeatable strength to weight ratio
1
gives it many uses in the transport industry. Aluminium is so lightweight this
means that less energy needs to be used to move a vehicle made with aluminium
than one made from a heavier metal. Aluminium is also vital in power lines, the
building and construction industry and commonplace household objects. The key
features that lend aluminium to these uses are corrosion resistance, low density,
ductility, electrical conductivity and strength in alloys (Davyson 2002).
Aluminium not only offers many advantages due to its material properties.
Aluminium is also extensively adaptable to fabrication and machining processes.
Aluminiun be used because aluminum is a very light metal. Aluminium also
naturally generates a protective oxide coating and is highly corrosion resistant.
Aluminium is an excellent heat and electricity conductor and in relation to its
weight is almost twice as good a conductor as copper. This has made aluminium
the most commonly used material in major power transmission lines. Aluminium
is a good reflector of visible light as well as heat, and that together with its low
weight, makes it an ideal material for reflectors in and aluminium also ductile and
has a low melting point and density (Davyson 2002).
One of the common aluminium alloys is aluminium LM6. Aluminium LM6 is a
high purity alloy, which is used in castings where thinner more intricate sections
are required. Aluminium LM6 contains of copper, magnesium, silicon, iron,
manganese, nickel, zinc, lead, tin, titanium and aluminium. This alloy has medium
strength with excellent ductility but suffers a rapid loss of properties at elevated
service temperatures (Sayuti 2008).
There is established study of machinery aluminium LM6 particularly in
machining process. Many researcher have report that the characteristic of
machinery of this material in turning process. However, there is limitation
knowledge about machining aluminium LM6 especially in milling operation and
by using the commercial cutting tool such as high speed steel and uncoated
carbide. Milling process is important to produce a flat shape such as flat bar, vise
and many more (Joardar 2011). Therefore the study of milling aluminium LM6
tends to investigate the machinability of aluminium LM6 in term of the cutting
tool, the cutting parameters and the surface integrity. This report will focus more
2
into surface integrity such as surface roughness, surface microhardness,
subsurface micro structure and surface profile when machining aluminium LM6
using high speed steel and uncoated carbide cutting tools.
The research will create knowledge of machining characteristic of aluminium
LM6. It will be beneficial in terms surface to the machinist whenever they want
performing milling. The research also will provide useful information about
suitable parameters to machinery aluminium LM6.
1.2
Objective
There are three main objectives by doing this project:
a) Identify the appropriate cutting parameter when machining aluminium LM6
using high speed steel and uncoated carbide cutting tools.
b) To investigate the characters of surface integrity when machining aluminium
LM6 using high speed steel and uncoated carbide cutting tools.
c) To compare the surface roughness, surface microhardness, subsurface
microstructure and surface profile.
1.3
Scope of Project
This project will be focus on identifying the surface integrity when machining
aluminium LM6. On this project milling machine will use to machine the
material. By using a different type of cutting tool such as high speed steel and
uncoated carbide with the different cutting parameter the surface integrity will get
the different result. The result will plot on a graph scratch after the testing has
been done. Refer to the result conclusion will be make to make sure the surface
integrity for LM6 are suitable in milling machinery.
3
CHAPTER 2
LITERATURE REVIEW
2.1
Aluminium
Aluminium is a chemical element in the boron group with symbol Al. It is silvery white, and
it is not soluble in water under normal circumstances. Aluminium is a recyclable metal that is
lightweight, strong, and conductive. It is inexpensive and will not rust, nor will this natural
resource ever run out because to some extent, the earth's crust is made of it. It can be molded
into casts, worked with machine tools, and made into sheet metal, making it useful for a wide
variety of products (Kalpakjian 2006).
Figure 2.1: Electron configuration (Davyson 2002)
The mechanical properties depend not only on the purity of the aluminium but also upon the
amount of work to which it has been subject. Instead, it is found combined in over 270
different minerals including clay, bauxite, mica, feldspar, alum, cryolite, and the several
forms of aluminium oxide such as emery, corundum, sapphire, and ruby. Aluminium is
remarkable for its ability to resist corrosion and it is light weight. The yield strength of pure
aluminium is 7-11 MPa. Aluminium has about one-third the density and stiffness of steel yet
it is ductile, and easily machined, cast, and importantly in this piece is easily extruded. The
4
chief source of aluminium is bauxite ore. Structural components made from aluminium and
its alloys are vital to the aerospace industry and as we will find out are very important in
other areas of transportation and building. A range of tempers is thus produced by different
amounts of work hardening. It has an electrical conductivity about two-thirds that of copper
but weight for weight is a better conductor. Aluminium has a great affinity for oxygen and
any fresh metal in air rapidly oxidizes to give a thin layer of the oxide on the metal surface.
This layer is not penetrated by oxygen and so protects the metal from further attack.
Aluminum is the most heavily consumed non-ferrous metal in the world, with current annual
consumption at 24 million tons. About 75% of this total volume, or18 million tons, is primary
aluminum (that is, aluminum extracted from ore, as opposed to secondary aluminum which is
derived from scrap metal processing).
The process of primary aluminum production can be divided into three independent stages
which are, as a rule, carried out at different plants. These are:
•
The actual mining of the necessary raw materials (bauxite and a variety of other
ores);
2.2
•
The processing of the ore and preparation of aluminum oxide (alumina);
•
Production of primary aluminum from alumina.
Aluminium Alloy
Aluminiun normally is not stable to machining on the properties is not adequate
enough to caters all process. Therefore, it’s normally been alloyed to get the best
chateristic of all alloying properties. Aluminium alloy can be divided into two groups,
wrought alloys and cast alloys. Each of these can be divided into two further groups:
those alloys which are not heat treatable and those which can be heat treated. The
non-heat treatable alloys have their properties controlled by the extent of the working
to which they are subject. A range of tempers is thus produced. The heat-treatable
alloys have their properties controlled by heat treatment. Like aluminium, the alloys
have a low density, good electrical and thermal conductivity and a high corrosion
5
resistance. The corrosion resistance properties of sheet alloy are improved by
cladding it with layers of unalloyed aluminium (Kalpakjian 2006).
2.3
Metal Matrix Composites
One of the techniques to alloy the aluminium is to combine the materials with
composite. This called metal matrix composites (MMC). Metal matrix composites are
engineered materials combining two or more materials, one of which is a metal,
where the tailored properties can be attained by systematic combination of different
constituents. A variety of methods available for producing these advanced materials
include the conventional casting process which is considered as the easiest processing
technique. Preparation of these composite materials by foundry technology has the
unique benefit of near-net shape fabrication in a simple and cost-effective manner.
Besides, casting processes lend themselves to manufacture large number of complex
shaped components of composites at a faster rate required by the automotive,
transportation, sports and other consumer oriented industries. Metal matrix
composites (MMC) are composed of an elemental or alloy matrix in which a second
phase is embedded and distributed to achieve some property improvement. Based on
the size, shape and amount of the second phase, the composite property varies.
Particulate reinforced composites are often called as discontinuously reinforced metal
matrix composites, constitute a large portion of these new advanced materials. The
microstructures of the processed composites influence and have a great effect on the
mechanical properties. Metal matrix composites (MMC) are considered as potential
material candidates for a wide variety of structural application in the transportation,
automobile and sport goods manufacturing industries due to the superior range of
mechanical properties they possess (Hasyim 2002). MMCs combine metallic
properties of matrix alloys (ductility and toughness) with ceramic properties of
reinforcements (high strength and high modulus), leads to greater strength in shear
and compression and higher service-temperature capabilities (Clegg 1997).
6
2.3.1 Stir Casting Method of Fabrication of MMCs
Therefore a lot of fabrication technique in producing MMC Liquid state fabrication of
Metal Matrix Composites involves incorporation of dispersed phase into a molten
matrix metal, followed by its Solidification. In order to provide high level of
mechanical properties of the composite, good interfacial bonding (wetting) between
the dispersed phase and the liquid matrix should be obtained.
Wetting improvement may be achieved by coating the dispersed phase particles
(fibers). Proper coating not only reduces interfacial energy, but also prevents
chemical interaction between the dispersed phase and the matrix. The simplest and
the most cost effective method of liquid state fabrication is Stir Casting (Kalpakjian
2006).
2.3.1.1Stir Casting
Stir Casting is a liquid state method of composite materials fabrication, in which a
dispersed phase (ceramic particles, short fibers) is mixed with a molten matrix metal
by means of mechanical stirring. The liquid composite material is then cast by
conventional casting methods and may also be processed by conventional Metal
forming technologies.
Stir Casting is characterized by the following features:
•
Content of dispersed phase is limited (usually not more than 30 vol. %).
•
Distribution of dispersed phase throughout the matrix is not perfectly
homogeneous:
o There are local clouds (clusters) of the dispersed particles (fibers);
o There may be gravity segregation of the dispersed phase due to a difference
in the densities of the dispersed and matrix phase.
7
•
The technology is relatively simple and low cost.
Distribution of dispersed phase may be improved if the matrix is in semi-solid
condition. The method using stirring metal composite materials in semi-solid state is
called Rheocasting. High viscosity of the semi-solid matrix material enables better
mixing of the dispersed phase.
2.3.2 Strengthening Mechanism of Composites
The strengthening mechanisms of the composites are different with different kind of
reinforcing agent morphology such as fibers, particulate or dispersed type of
reinforcing elements.
2.3.3 Strengthening Mechanism of Fiber Reinforced Composite
In such type of composite the reinforcing phase carries the bulk of the load and the
matrix transfers the load to the reinforcing phase by the mechanism of seam. The high
strength of the reinforcing phase restrict the free elongation of the matrix especially in
its vicinity, whereas later is free to elongate at some distance away from the former.
This type of non uniform deformation of the matrix leads to a shear stress at the
matrix reinforcement interface which results tensile stress at the reinforcing phase.
Thus the stress is transferred to the reinforcing phase. The fibers either may be
continuous or discontinuous in the matrix. In the former case the load is directly
applied to the reinforcing phase and stress is constant over its entire length. In case of
discontinuous fibers, the stress in the fiber increased from zero value at the end to a
maximum value in the centre and thus average tensile strength developed is always
less than those of continuous fibers. For the same when the fracture of the reinforcing
phase, therefore the strength of the discontinuous fiber reinforced composite increases
with increasing the length of the fiber and artifacts that of the continuous fiber
8