Surface Integrity Of Aluminum Alloy LM6 When Machine With Coated High Speed Steel And Coated Carbide Cutting Tool.
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
SURFACE INTEGRITY OF ALUMINUM ALLOY LM6 WHEN
MACHINE WITH COATED IDGH SPEED STEEL AND
COATED CARBIDE CUTTING TOOL
This report submitted in accordance with requirement of the Universiti Teknikal
Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Process) (Hons.)
By
NUR NABILAH F ARHANA BINTI SULAIMAN
8050910127
900522105314
FACULTY OF MANUFACTURING ENGINEERING
2013
© Universiti Teknikal Malaysia Melaka
ABSTRAK
Dalam setiap operasi pemesinan, prestasi dan kualiti alat memotong dianggap
penting dalam usaha untuk meningkatkan produktiviti dan kecekapan apabila
memotong bahan. Sebagai permintaan meningkat produktiviti dalam industri
pemesinan, keperluan kelajuan pemotongan yang tinggi, kedalaman pemotongan dan
kadar suapan untuk pembuangan bahan adalah wajib. Dalam kajian ini, bahan yang
akan digunakan adalah aloi Aluminium LM6. Kebanyakan penyelidikan sebelumnya
pada aluminium LM6 memberi tumpuan kepada proses tuangan dan pelarik sahaja
yang bermaksud terdapat had ujian mengenai proses pengisaran. Oleh kerana proses
kisar adalah antara yang paling serba boleh dan berguna dan 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, kajian ini akan memberi tumpuan kepada di mesin
Aluminum Aloi LM6 dari segi pengoptimuman alat memotong, kehidupan alat, dan
memotong parameter dan mekanisme kehausan. Fokus utama kajian ini adalah untuk
menyiasat integriti permukaan aloi Aluminium LM6 menggunakan dua jenis
memotong alat, keluli bersalut kelajuan tinggi dan karbida bersalut. Parameter
pemotongan terbaik yang diperolehi dari eksperimen ini gelendong kelajuan 3000 rpm,
kadar suapan 60 mm / min dan kedalaman dalam pemotongan 0.07 mm menggunakan
bersalut kelajuan tinggi memotong alat keluli. Masa pemesinan adalah berkadar
songsang dengan kedalaman dalam pemotongan. Masa pemesinan yang lebih tinggi
telah diambil sebagai kedalaman jejarian penurunan dipotong. Ia menyimpulkan
bahawa bersalut keluli kelajuan tinggi dipilih sebagai alat terbaik untuk memotong
aluminium pemesinan LM6 kerana harga adalah lebih murah dan kemasan permukaan
adalah lebih baik berbanding dengan karbida bersalut.
i
ABSTRACT
In every machining operation, performance and quality of cutting tools are
considered essential in order to increase productivity and efficiency when cutting
materials. As the increasing demand of productivity in machining industry, the need of
high cutting speed, depth of cut and feed rate for material removal are compulsory. As
the use of high cutting temperature will eventually causes reduces in tool life as well as
impairs the product quality, developments of coated cutting tool are made to improve
the weakness of uncoated cutting tool. However, the material itself also contributed to
tool wear and wear mechanism of the cutting tool. 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, this study will focus on machinability of LM6 in terms of
optimization of cutting tool, tool life, and cutting parameter and surface integrity. The
main focus on this study is to investigate the surface integrity when machining
Aluminum alloy LM6 using two different types of cutting tool which are coated high
speed steel and coated carbide. The outcome is surface finish for coated high speed
steel is better compared to coated carbide. The best cutting parameters obtained from
the experiment are spindle speed 3000 rpm, feed rate 60 mm/min and radial depth of
cut 0.07 mm using coated high speed steel cutting tool. Machining time is inversely
proportional to radial depth of cut. Higher machining time was taken as the radial depth
of cut decrease. It is concluded that coated high-speed steel is selected as the best
cutting tool for machining aluminium LM6 because the price are less expensive and the
surface finish is better as compared to coated carbide.
ii
DEDICATION
To my beloved parents and siblings.
iii
ACKNOWLEDGEMENT
I would like to express my greatest gratitude to Allah SWT for giving me chances to
explore and gain new knowledge throughout the period of completing my Final Year
Project. I would also like to thank my family especially my beloved parents for their
never ending support and courage in terms of financial and emotion as well as their
prayers in order to provide me with better education for a better and brighter future.
Not to forget, millions of thanks I wish to my supervisor Dr. Hadzley bin Abu Bakar
for his continuous guidance and support throughout my learning process and
completing this study. I would also like to thanks each and everyone in Faculty of
Manufacturing Engineering; the lecturers, staffs and technicians for the cooperation in
sharing their experiences and knowledge as well as their time and energy.
I would also like to express my deepest appreciation to all my friends for their efforts
and willingness in sharing every knowledge and information without any difficulties.
Last but not least, I am also thankful to all those people who have directly or indirectly
helped me throughout this period.
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
1.1
Introduction
1
1.2
Problem Statement
2
1.3
Objective
3
1.4
Scope of Project
3
CHAPTER 2: LITERATURE REVIEW
4
2.1
Aluminum
5
2.1.1 Aluminum Alloy
6
2.1.2
6
2.2
LM6 (AISI 413) - Aluminum Alloy
6
2.2.1 Properties
7
2.2.2
2.3
Metal Matrix Composites
2.2.1.1 Chemical properties
7
2.2.1.2 Machinability
8
2.2.1.3 Corrosion Resistance
9
2.2.1.4
Physical Properties
9
2.2.1.5
Mechanical Properties
9
Applications
Machining
2.3.1
Elements of Machining
9
10
11
v
2.3.2
2.4
Classical Metal Machining Process
12
Milling machines
13
2.4.1
Peripheral Milling
14
2.4.2
Face milling
15
2.4.3
End milling
16
2.4.4
Cutting Parameter
17
2.4.4.1
Cutting Speed
17
2.4.4.2
Feed Rate
18
2.4.4.3
Depth of Cut
19
2.5
CNC Milling Machine
20
2.6
Cutting Tool
22
2.6.1 Coated High-Speed Steel cutting tool
23
2.6.2
24
2.7
Coated Carbide cutting tool
Surface Integrity
25
2.7.1
Surface Roughness
26
2.7.2
Material Side Flow
28
2.7.3
Build-Up Edge
29
2.7.4
Subsurface Microstructure Alteration
30
2.7.5
Changes in Microhardness
CHAPTER 3: METHODOLOGY
32
3.1
Project Planning
33
3.2
Experimental Equipment
34
3.3
Work Material
35
3.3.1
35
Aluminum LM6 Alloy
3.4
Cutting Tool
36
3.5
Cutting Condition
39
3.6
Machining
40
3.6.1
Bandsaw Machine
40
3.6.2
CNC Milling 3 Axis
41
3.7
Testing
3.7.1
3.8
42
Surface Roughness Measurement
Specimen Preparation
42
43
vi
3.8.1
Cutting Tool
43
3.8.2
Workpiece after Machining
44
3.8.3
Subsurface Microhardness Measurements
46
CHAPTER 4: RESULT & DISCUSSION
47
4.1
Introduction
47
4.2
Microstructure of Aluminum LM6 Alloy before machining
48
4.3
Parameter Selection
50
4.4
Surface Profile
54
4.5
Surface Roughness
58
4.6
Microstructure
61
4.7
Microhardness
63
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
65
5.1
Conclusion
65
5.2
Recommendations
67
REFERENCES
68
APPENDIX
71
vii
LIST OF TABLES
2.1
Chemical Properties of Aluminum LM6
7
2.2
Physical Properties of Aluminum LM6
8
2.3
Mechanical Properties of Aluminum LM6
9
3.1
Chemical composition of Al LM6 alloy
35
3.2
Mechanical properties of Al LM6 alloy produced by chill cast
36
3.3
Physical properties of Al LM6 alloy
37
3.4
Cutting parameters
39
4.1
Cutting parameter selection using uncoated high speed steel
51
4.2
Result for surface roughness (Ra)
58
4.3
Hardness data for surface machined by coated high speed steel
63
4.4
Hardness data for surface machined by coated carbide
65
viii
LIST OF FIGURES
2.1
Aluminum Alloy LM6 in ingot shape
6
2.2
Deformation of material in machining
11
2.3
(a) Orthogonal cutting
12
(b) Oblique cutting
12
(a) Peripheral milling
14
(b) Face milling.
14
(c) End milling.
14
(d) Ball-end mill
14
(e) Milling, using a five axis numerical control machine
14
(a) Schematic illustrations of conventional milling and climb
15
(b) Slab milling
15
(c) Schematic illustration of cutter travel distance
15
(d) Dimensions in face milling
15
(a) small corner radius
15
(b) Corner flat on inserts
15
(c) Wiper.
15
(d) Feed marks due to various insert shape
15
2.8
CNC milling machine
20
2.9
Coated High-Speed Steel (TiAlN) cutting tool
23
2.10
Coated Carbide cutting tool (TiAlN)
24
2.11
Schematic illustration to determine arithmetic average surface
27
2.4
2.5
2.7
roughness, Ra of surface texture
2.12
Example of material side flow
28
2.13
(a) Shearing of the workpiece materials during machining
30
2.13
(b) Microstructure alterations beneath the machined surface
30
2.14
The microhardness value measured beneath the machined surface
31
ix
3.1
Flow Chart
33
3.2
Aluminum LM6 Alloy
35
3.3
Coated High-Speed Steel (TiAlN) cutting tool
38
3.4
Coated Carbide cutting tool (TiAlN)
38
3.5
Bandsaw Machine
40
3.6
Haas’ 3 axis CNC vertical milling machine
41
3.7
Surface roughness tester Mitutoyo SJ-301
42
3.8
CARL ZEISS evo 50 scanning electron microscope (SEM)
43
3.9
Buehler Simplimet 3000 Automatic Mounting Press Machine
44
3.10
Buehlers Beta Twin Variable Grinder-Polisher
45
3.11
Sample preparation items for polishing
45
3.12
Mitutoyo Hardness Testing Machine MicroWizhard HR-500
46
4.1
Microstructure of aluminium LM6
48
4.2
Surface profile using coated high speed steel (a) Using 29X
magnification.
52
4.2
(b) Using 150 X magnifications
52
4.3
Surface profile using coated carbide (a) Using 17X magnification
54
4.3
(b)Using 150X magnification
54
4.4
Average Value of surface roughness VS radial depth of cut
57
4.5
Graph for time VS radial depth of cut
59
4.6
(a) Subsurface microstructure when machining aluminium LM6 using
60
coated high speed steel
4.6
(b) Subsurface microstructure when machining aluminium LM6 using
60
coated carbide
4.7
Hardness value when using coated high speed steel
62
4.8
Hardness value when using coated carbide
64
x
LIST OF ABBREVIATIONS, SYMBOLS AND
NOMENCLATURE
Al
-
CNC
-
Aluminium
Computer Numerical Control
Cu
-
Copper
d
-
Diameter
f
-
Feed rate
ft
-
Feed per Tooth
HSS
-
High-Speed Steel
Mg
-
Magnesium
Mm
-
millimeter
MMC
-
Metal matrix composites
Mn
-
Manganese
n
-
Cutter speed in revolution per minute
Ø
-
Angle of shear
Rpm
-
revolution per minute
RSM
-
Response Surface Methodology
SEM
-
Scanning Electron Microscopic
Si
-
Silicon
TiN
-
Titanium Nitride
TiAlN
-
Titanium Aluminium Nitride
V
-
Cutting speed
WC
-
tungsten carbide
-
Feed per Revolution
-
Feed per Unit of Time
)
xi
CHAPTER 1
INTRODUCTION
1.0 Introduction
Nowadays, machining of material are getting more advance as there are many
developments of new alloys and engineered material which eventually causes these
materials to have high strength and toughness as well as other material properties. In
manufacturing operations, it is important to view machining operations as a system,
consist of workpiece, cutting tool, machine tool and also production personnel.
Machining cannot be carried out efficiently or economically and also meet stringent
part specifications without a thorough knowledge of the interactions among these
four elements [Kapalkjian and Schmid (2006)].
One of the materials that are used in industry is aluminium alloy. The important
factors in selecting aluminum (AL) and its alloy are their high strength to weight
ratio, resistance to corrosion by many chemicals, high thermal and electrical
conductivity, nontoxicity, reflectivity, appearance, and ease of formability and of
machinability: they are also nonmagnetic [Kapalkjian and Schmid (2006)]. One of
the examples of aluminum alloy in industry is aluminum LM6. LM6 is a high purity
alloy, which is used in castings where thinner more intricate sections are required
particularly in a complex casting with large surface areas. This alloy has of medium
strength with excellent ductility but suffers a rapid loss of properties at elevated
service temperatures. Application of LM6 in industry includes electrical, marine,
intricate shaped castings, and buildings cladding panels.
1
In milling process, their efficiency depends on characteristics such as surface finish,
dimensional tolerances, production rate, and cost considerations. Many types of
milling machines are used, ranging from relatively simple and versatile machines
that are used for general purpose machining in job shops and tool and die work to
highly specialized machines for mass production. Some important factor in milling
are selection of cutting tools, cutting parameters such as cutting speed, feed rate and
depth of cut. These factors influence the efficiency of the machine in terms of time
usage, cost and operation technique. Machining of Aluminum LM6 is also influenced
by these processing items.
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 and surface integrity. Therefore, this study will focus on machinability of
LM6 in terms of surface integrity such as surface roughness, surface microhardness,
subsurface micro structure, and surface profile using two different types of cutting
tool which are coated high speed steel and coated carbide. Machining will be held in
CNC milling and the data will be based on its surface integrity and tabulated. The
expected outcome is to have database, guidance, fine property to machine Aluminum
LM6 efficiently and also good machinability cost.
2
1.1
Problem Statement
In present, machining of Aluminum Alloy LM6 in industry are widely used only in
casting and turning. There is lacking of research on milling Aluminum Alloy LM6
thus this project will initiate the machining trials of Aluminum LM6 in milling
process. The evaluation will be based on the surface roughness, surface
microhardness, subsurface micro structure, and surface profile. By undergoing this
project, it will benefited and contribute to the industry in terms of the optimization of
cutting tool, cutting parameter and surface integrity in milling of Aluminum Alloy
LM6.
1.2
Objectives
There are three main objectives by doing this project:
a) To identify the suitable cutting tool for milling machine.
b) To identify the appropriate cutting parameters for producing good surface.
c) To investigate whether the type of cutting tool and cutting parameters
affecting surface integrity of Aluminum LM6.
1.3
Scope of Project
This project will be focus on investigating the surface integrity of Aluminum LM6
using two different cutting tools which are coated carbide and coated high speed
steel. When all the data have been obtained and recorded, it will then is tabulated and
analyze. In analyzing the data, graph for results will be shown in results and
discussion section.
3
CHAPTER 2
LITERATURE REVIEW
2.1 Aluminum
Pure aluminium is a weak, very ductile material. Its physical properties are shiny,
silvery white colored metal that is light in weight and strong. The density of
aluminum is 2.7 g/mL, which means the metal will sink in water, but is still
relatively light. 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. As for its chemical properties, the surface of aluminum metal is covered
with a thin layer of oxide that helps protect the metal from attack by air. So,
normally, aluminum metal does not react with air. If the oxide layer is damaged, the
aluminum metal is exposed to attack. As it 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 [W.Bolton (2000)].
4
2.1.1
Aluminium Alloy
Aluminium alloy can be divided into two groups which are, 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 resistance. The
corrosion resistance properties of sheet alloy are improved by cladding it with layers
of unalloyed aluminium. [W.Bolton (2000)]. Aluminum LM6 are categorised in cast
alloys and it contains composition of Silicon (Si), Copper (Cu), Manganese (Mn) and
Magnesium (Mg).
2.1.2
Metal Matrix Composites
Metal matrix composites are engineered materials combining two or more materials,
one of which is a metal, where the properties can be attained by systematic
combination of different constituent. 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. As for Aluminum LM6 that are used in this study, it often use
as matrix in producing alloy matrix composites to enhance their properties. In
previous research conducted by [ Hamouda et al (2007)] , Aluminum LM6 alloy act
as matrix while different percentages of silicon dioxide based on the variation in
5
volume fraction act as particulates to produces reinforced LM6 alloy matrix
composites.
2.2
LM6 (AISI 413)- Aluminum Alloy
LM6 is a high purity alloy, which is normally used in castings where thinner more
complex sections are required particularly in a complex casting with large surface
areas. The alloy is of medium strength with excellent ductility but suffers a rapid loss
of properties at elevated service temperatures. However, it is also depending on its
particulates in which contributes and varies in terms of its mechanical properties
such as tensile strength, elongation, fatigue strength, machinability and also shear
strength.
LM 6 is a high Silicon Aluminium alloy which can be rather difficult to machine.
Alloys of this type tend to drag when machined, causing rapid tool wear and
therefore carbide tools with large rake angles should be employed with adequate
cutting fluids.
Figure 2.1: Aluminum Alloy LM6 in ingot shape.
6
2.2.1
Properties
2.2.1.1 Chemical Properties
Table 2.1: Chemical Properties [http://www.nortal.co.uk/LM6/]
Percentage (%)
EN 1706 AC-44100
Copper
0.1 max
0.15(0.10)
Magnesium
0.10 max
0.10
Silicon
1-.0-13.0
10.5-13.5
Iron
0.6 max
0.65(0.55)
Manganese
0.5 max
0.55
Nickel
0.1 max
0.20
Zinc
0.1 max
0.25
Lead
0.1 max
0.20
Tin
0.05 max
-
Titanium
0.2 max
0.20(0.15)
Aluminium
remainder
-
7
2.2.1.2 Machinability
An enduring problem with this material is that they are rather difficult to machine.
This is due to the high hardness of the reinforcement materials which in many cases
are significantly harder than the commonly used high speed steel tools and carbide
tools. [Joardar et al. (2011)]. As for those issues, many previous and present
researches are conducted to find and focused on optimizing some machining
parameters so that roughness of the machined surfaces and tool wear can be
minimized.
2.2.1.3 Corrosion Resistance
LM6 exhibits excellent resistance to corrosion under both ordinary atmospheric and
marine conditions. For the severest conditions, this property can be further enhanced
by anodic treatment. [Hadleighcastings (2012)]
2.2.1.4 Physical Properties
Table 2.2: Chemical Properties [http://www.nortal.co.uk/LM6/]
Coefficient of Thermal Expansion (per°C at 20-100°C)
0.000020
Thermal Conductivity (cal/cm 2 /cm/°C at 25°C)
0.34
Electrical Conductivity (% copper standard at 20°C)
37
Density (g/cm 3 )
2.65
Freezing Range (°C) approx
575-565
8
2.3.1.5 Mechanical Properties
Table 2.3: Mechanical Properties [http://www.nortal.co.uk/LM6/]
SAND CAST
0.2%
Proof
Stress 60-70
CHILL CAST
70-80
(N/mm2)*
Tensile Stress (N/mm2)*
160-190
190-230
Elongation (%)*
5-10
7-15
Impact Resistance. Izod 6.0
9.0
(Nm)
Brinell Hardness Number
50-55
Endurance Limit (5 X 107 51
55-60
68
cycles; + N/mm2)
Modulus Of Elasticity (X 71
71
103 N/mm2)
Shear Strength (N/mm2)
2.2.2
120
Applications
LM6 has a high resistance to corrosion and excellent cast ability. It is often uses in
numerous places due to these properties such as marine, manifolds, motor casings,
cast doors, pumping applications. It is also especially suitable where castings need to
be welded together. The ductility of LM6 castings means they can be easily rectified
and modified into shape. It also has excellent resistance to corrosion in marine
environments, possesses excellent ductility, but is of medium strength and is not heat
treated. Its strength falls off rapidly at high temperatures. Its elastic limit is low and it
is fairly difficult to machine. [Hadleighcastings (2012)]
9
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
SURFACE INTEGRITY OF ALUMINUM ALLOY LM6 WHEN
MACHINE WITH COATED IDGH SPEED STEEL AND
COATED CARBIDE CUTTING TOOL
This report submitted in accordance with requirement of the Universiti Teknikal
Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Process) (Hons.)
By
NUR NABILAH F ARHANA BINTI SULAIMAN
8050910127
900522105314
FACULTY OF MANUFACTURING ENGINEERING
2013
© Universiti Teknikal Malaysia Melaka
ABSTRAK
Dalam setiap operasi pemesinan, prestasi dan kualiti alat memotong dianggap
penting dalam usaha untuk meningkatkan produktiviti dan kecekapan apabila
memotong bahan. Sebagai permintaan meningkat produktiviti dalam industri
pemesinan, keperluan kelajuan pemotongan yang tinggi, kedalaman pemotongan dan
kadar suapan untuk pembuangan bahan adalah wajib. Dalam kajian ini, bahan yang
akan digunakan adalah aloi Aluminium LM6. Kebanyakan penyelidikan sebelumnya
pada aluminium LM6 memberi tumpuan kepada proses tuangan dan pelarik sahaja
yang bermaksud terdapat had ujian mengenai proses pengisaran. Oleh kerana proses
kisar adalah antara yang paling serba boleh dan berguna dan 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, kajian ini akan memberi tumpuan kepada di mesin
Aluminum Aloi LM6 dari segi pengoptimuman alat memotong, kehidupan alat, dan
memotong parameter dan mekanisme kehausan. Fokus utama kajian ini adalah untuk
menyiasat integriti permukaan aloi Aluminium LM6 menggunakan dua jenis
memotong alat, keluli bersalut kelajuan tinggi dan karbida bersalut. Parameter
pemotongan terbaik yang diperolehi dari eksperimen ini gelendong kelajuan 3000 rpm,
kadar suapan 60 mm / min dan kedalaman dalam pemotongan 0.07 mm menggunakan
bersalut kelajuan tinggi memotong alat keluli. Masa pemesinan adalah berkadar
songsang dengan kedalaman dalam pemotongan. Masa pemesinan yang lebih tinggi
telah diambil sebagai kedalaman jejarian penurunan dipotong. Ia menyimpulkan
bahawa bersalut keluli kelajuan tinggi dipilih sebagai alat terbaik untuk memotong
aluminium pemesinan LM6 kerana harga adalah lebih murah dan kemasan permukaan
adalah lebih baik berbanding dengan karbida bersalut.
i
ABSTRACT
In every machining operation, performance and quality of cutting tools are
considered essential in order to increase productivity and efficiency when cutting
materials. As the increasing demand of productivity in machining industry, the need of
high cutting speed, depth of cut and feed rate for material removal are compulsory. As
the use of high cutting temperature will eventually causes reduces in tool life as well as
impairs the product quality, developments of coated cutting tool are made to improve
the weakness of uncoated cutting tool. However, the material itself also contributed to
tool wear and wear mechanism of the cutting tool. 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, this study will focus on machinability of LM6 in terms of
optimization of cutting tool, tool life, and cutting parameter and surface integrity. The
main focus on this study is to investigate the surface integrity when machining
Aluminum alloy LM6 using two different types of cutting tool which are coated high
speed steel and coated carbide. The outcome is surface finish for coated high speed
steel is better compared to coated carbide. The best cutting parameters obtained from
the experiment are spindle speed 3000 rpm, feed rate 60 mm/min and radial depth of
cut 0.07 mm using coated high speed steel cutting tool. Machining time is inversely
proportional to radial depth of cut. Higher machining time was taken as the radial depth
of cut decrease. It is concluded that coated high-speed steel is selected as the best
cutting tool for machining aluminium LM6 because the price are less expensive and the
surface finish is better as compared to coated carbide.
ii
DEDICATION
To my beloved parents and siblings.
iii
ACKNOWLEDGEMENT
I would like to express my greatest gratitude to Allah SWT for giving me chances to
explore and gain new knowledge throughout the period of completing my Final Year
Project. I would also like to thank my family especially my beloved parents for their
never ending support and courage in terms of financial and emotion as well as their
prayers in order to provide me with better education for a better and brighter future.
Not to forget, millions of thanks I wish to my supervisor Dr. Hadzley bin Abu Bakar
for his continuous guidance and support throughout my learning process and
completing this study. I would also like to thanks each and everyone in Faculty of
Manufacturing Engineering; the lecturers, staffs and technicians for the cooperation in
sharing their experiences and knowledge as well as their time and energy.
I would also like to express my deepest appreciation to all my friends for their efforts
and willingness in sharing every knowledge and information without any difficulties.
Last but not least, I am also thankful to all those people who have directly or indirectly
helped me throughout this period.
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
1.1
Introduction
1
1.2
Problem Statement
2
1.3
Objective
3
1.4
Scope of Project
3
CHAPTER 2: LITERATURE REVIEW
4
2.1
Aluminum
5
2.1.1 Aluminum Alloy
6
2.1.2
6
2.2
LM6 (AISI 413) - Aluminum Alloy
6
2.2.1 Properties
7
2.2.2
2.3
Metal Matrix Composites
2.2.1.1 Chemical properties
7
2.2.1.2 Machinability
8
2.2.1.3 Corrosion Resistance
9
2.2.1.4
Physical Properties
9
2.2.1.5
Mechanical Properties
9
Applications
Machining
2.3.1
Elements of Machining
9
10
11
v
2.3.2
2.4
Classical Metal Machining Process
12
Milling machines
13
2.4.1
Peripheral Milling
14
2.4.2
Face milling
15
2.4.3
End milling
16
2.4.4
Cutting Parameter
17
2.4.4.1
Cutting Speed
17
2.4.4.2
Feed Rate
18
2.4.4.3
Depth of Cut
19
2.5
CNC Milling Machine
20
2.6
Cutting Tool
22
2.6.1 Coated High-Speed Steel cutting tool
23
2.6.2
24
2.7
Coated Carbide cutting tool
Surface Integrity
25
2.7.1
Surface Roughness
26
2.7.2
Material Side Flow
28
2.7.3
Build-Up Edge
29
2.7.4
Subsurface Microstructure Alteration
30
2.7.5
Changes in Microhardness
CHAPTER 3: METHODOLOGY
32
3.1
Project Planning
33
3.2
Experimental Equipment
34
3.3
Work Material
35
3.3.1
35
Aluminum LM6 Alloy
3.4
Cutting Tool
36
3.5
Cutting Condition
39
3.6
Machining
40
3.6.1
Bandsaw Machine
40
3.6.2
CNC Milling 3 Axis
41
3.7
Testing
3.7.1
3.8
42
Surface Roughness Measurement
Specimen Preparation
42
43
vi
3.8.1
Cutting Tool
43
3.8.2
Workpiece after Machining
44
3.8.3
Subsurface Microhardness Measurements
46
CHAPTER 4: RESULT & DISCUSSION
47
4.1
Introduction
47
4.2
Microstructure of Aluminum LM6 Alloy before machining
48
4.3
Parameter Selection
50
4.4
Surface Profile
54
4.5
Surface Roughness
58
4.6
Microstructure
61
4.7
Microhardness
63
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
65
5.1
Conclusion
65
5.2
Recommendations
67
REFERENCES
68
APPENDIX
71
vii
LIST OF TABLES
2.1
Chemical Properties of Aluminum LM6
7
2.2
Physical Properties of Aluminum LM6
8
2.3
Mechanical Properties of Aluminum LM6
9
3.1
Chemical composition of Al LM6 alloy
35
3.2
Mechanical properties of Al LM6 alloy produced by chill cast
36
3.3
Physical properties of Al LM6 alloy
37
3.4
Cutting parameters
39
4.1
Cutting parameter selection using uncoated high speed steel
51
4.2
Result for surface roughness (Ra)
58
4.3
Hardness data for surface machined by coated high speed steel
63
4.4
Hardness data for surface machined by coated carbide
65
viii
LIST OF FIGURES
2.1
Aluminum Alloy LM6 in ingot shape
6
2.2
Deformation of material in machining
11
2.3
(a) Orthogonal cutting
12
(b) Oblique cutting
12
(a) Peripheral milling
14
(b) Face milling.
14
(c) End milling.
14
(d) Ball-end mill
14
(e) Milling, using a five axis numerical control machine
14
(a) Schematic illustrations of conventional milling and climb
15
(b) Slab milling
15
(c) Schematic illustration of cutter travel distance
15
(d) Dimensions in face milling
15
(a) small corner radius
15
(b) Corner flat on inserts
15
(c) Wiper.
15
(d) Feed marks due to various insert shape
15
2.8
CNC milling machine
20
2.9
Coated High-Speed Steel (TiAlN) cutting tool
23
2.10
Coated Carbide cutting tool (TiAlN)
24
2.11
Schematic illustration to determine arithmetic average surface
27
2.4
2.5
2.7
roughness, Ra of surface texture
2.12
Example of material side flow
28
2.13
(a) Shearing of the workpiece materials during machining
30
2.13
(b) Microstructure alterations beneath the machined surface
30
2.14
The microhardness value measured beneath the machined surface
31
ix
3.1
Flow Chart
33
3.2
Aluminum LM6 Alloy
35
3.3
Coated High-Speed Steel (TiAlN) cutting tool
38
3.4
Coated Carbide cutting tool (TiAlN)
38
3.5
Bandsaw Machine
40
3.6
Haas’ 3 axis CNC vertical milling machine
41
3.7
Surface roughness tester Mitutoyo SJ-301
42
3.8
CARL ZEISS evo 50 scanning electron microscope (SEM)
43
3.9
Buehler Simplimet 3000 Automatic Mounting Press Machine
44
3.10
Buehlers Beta Twin Variable Grinder-Polisher
45
3.11
Sample preparation items for polishing
45
3.12
Mitutoyo Hardness Testing Machine MicroWizhard HR-500
46
4.1
Microstructure of aluminium LM6
48
4.2
Surface profile using coated high speed steel (a) Using 29X
magnification.
52
4.2
(b) Using 150 X magnifications
52
4.3
Surface profile using coated carbide (a) Using 17X magnification
54
4.3
(b)Using 150X magnification
54
4.4
Average Value of surface roughness VS radial depth of cut
57
4.5
Graph for time VS radial depth of cut
59
4.6
(a) Subsurface microstructure when machining aluminium LM6 using
60
coated high speed steel
4.6
(b) Subsurface microstructure when machining aluminium LM6 using
60
coated carbide
4.7
Hardness value when using coated high speed steel
62
4.8
Hardness value when using coated carbide
64
x
LIST OF ABBREVIATIONS, SYMBOLS AND
NOMENCLATURE
Al
-
CNC
-
Aluminium
Computer Numerical Control
Cu
-
Copper
d
-
Diameter
f
-
Feed rate
ft
-
Feed per Tooth
HSS
-
High-Speed Steel
Mg
-
Magnesium
Mm
-
millimeter
MMC
-
Metal matrix composites
Mn
-
Manganese
n
-
Cutter speed in revolution per minute
Ø
-
Angle of shear
Rpm
-
revolution per minute
RSM
-
Response Surface Methodology
SEM
-
Scanning Electron Microscopic
Si
-
Silicon
TiN
-
Titanium Nitride
TiAlN
-
Titanium Aluminium Nitride
V
-
Cutting speed
WC
-
tungsten carbide
-
Feed per Revolution
-
Feed per Unit of Time
)
xi
CHAPTER 1
INTRODUCTION
1.0 Introduction
Nowadays, machining of material are getting more advance as there are many
developments of new alloys and engineered material which eventually causes these
materials to have high strength and toughness as well as other material properties. In
manufacturing operations, it is important to view machining operations as a system,
consist of workpiece, cutting tool, machine tool and also production personnel.
Machining cannot be carried out efficiently or economically and also meet stringent
part specifications without a thorough knowledge of the interactions among these
four elements [Kapalkjian and Schmid (2006)].
One of the materials that are used in industry is aluminium alloy. The important
factors in selecting aluminum (AL) and its alloy are their high strength to weight
ratio, resistance to corrosion by many chemicals, high thermal and electrical
conductivity, nontoxicity, reflectivity, appearance, and ease of formability and of
machinability: they are also nonmagnetic [Kapalkjian and Schmid (2006)]. One of
the examples of aluminum alloy in industry is aluminum LM6. LM6 is a high purity
alloy, which is used in castings where thinner more intricate sections are required
particularly in a complex casting with large surface areas. This alloy has of medium
strength with excellent ductility but suffers a rapid loss of properties at elevated
service temperatures. Application of LM6 in industry includes electrical, marine,
intricate shaped castings, and buildings cladding panels.
1
In milling process, their efficiency depends on characteristics such as surface finish,
dimensional tolerances, production rate, and cost considerations. Many types of
milling machines are used, ranging from relatively simple and versatile machines
that are used for general purpose machining in job shops and tool and die work to
highly specialized machines for mass production. Some important factor in milling
are selection of cutting tools, cutting parameters such as cutting speed, feed rate and
depth of cut. These factors influence the efficiency of the machine in terms of time
usage, cost and operation technique. Machining of Aluminum LM6 is also influenced
by these processing items.
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 and surface integrity. Therefore, this study will focus on machinability of
LM6 in terms of surface integrity such as surface roughness, surface microhardness,
subsurface micro structure, and surface profile using two different types of cutting
tool which are coated high speed steel and coated carbide. Machining will be held in
CNC milling and the data will be based on its surface integrity and tabulated. The
expected outcome is to have database, guidance, fine property to machine Aluminum
LM6 efficiently and also good machinability cost.
2
1.1
Problem Statement
In present, machining of Aluminum Alloy LM6 in industry are widely used only in
casting and turning. There is lacking of research on milling Aluminum Alloy LM6
thus this project will initiate the machining trials of Aluminum LM6 in milling
process. The evaluation will be based on the surface roughness, surface
microhardness, subsurface micro structure, and surface profile. By undergoing this
project, it will benefited and contribute to the industry in terms of the optimization of
cutting tool, cutting parameter and surface integrity in milling of Aluminum Alloy
LM6.
1.2
Objectives
There are three main objectives by doing this project:
a) To identify the suitable cutting tool for milling machine.
b) To identify the appropriate cutting parameters for producing good surface.
c) To investigate whether the type of cutting tool and cutting parameters
affecting surface integrity of Aluminum LM6.
1.3
Scope of Project
This project will be focus on investigating the surface integrity of Aluminum LM6
using two different cutting tools which are coated carbide and coated high speed
steel. When all the data have been obtained and recorded, it will then is tabulated and
analyze. In analyzing the data, graph for results will be shown in results and
discussion section.
3
CHAPTER 2
LITERATURE REVIEW
2.1 Aluminum
Pure aluminium is a weak, very ductile material. Its physical properties are shiny,
silvery white colored metal that is light in weight and strong. The density of
aluminum is 2.7 g/mL, which means the metal will sink in water, but is still
relatively light. 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. As for its chemical properties, the surface of aluminum metal is covered
with a thin layer of oxide that helps protect the metal from attack by air. So,
normally, aluminum metal does not react with air. If the oxide layer is damaged, the
aluminum metal is exposed to attack. As it 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 [W.Bolton (2000)].
4
2.1.1
Aluminium Alloy
Aluminium alloy can be divided into two groups which are, 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 resistance. The
corrosion resistance properties of sheet alloy are improved by cladding it with layers
of unalloyed aluminium. [W.Bolton (2000)]. Aluminum LM6 are categorised in cast
alloys and it contains composition of Silicon (Si), Copper (Cu), Manganese (Mn) and
Magnesium (Mg).
2.1.2
Metal Matrix Composites
Metal matrix composites are engineered materials combining two or more materials,
one of which is a metal, where the properties can be attained by systematic
combination of different constituent. 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. As for Aluminum LM6 that are used in this study, it often use
as matrix in producing alloy matrix composites to enhance their properties. In
previous research conducted by [ Hamouda et al (2007)] , Aluminum LM6 alloy act
as matrix while different percentages of silicon dioxide based on the variation in
5
volume fraction act as particulates to produces reinforced LM6 alloy matrix
composites.
2.2
LM6 (AISI 413)- Aluminum Alloy
LM6 is a high purity alloy, which is normally used in castings where thinner more
complex sections are required particularly in a complex casting with large surface
areas. The alloy is of medium strength with excellent ductility but suffers a rapid loss
of properties at elevated service temperatures. However, it is also depending on its
particulates in which contributes and varies in terms of its mechanical properties
such as tensile strength, elongation, fatigue strength, machinability and also shear
strength.
LM 6 is a high Silicon Aluminium alloy which can be rather difficult to machine.
Alloys of this type tend to drag when machined, causing rapid tool wear and
therefore carbide tools with large rake angles should be employed with adequate
cutting fluids.
Figure 2.1: Aluminum Alloy LM6 in ingot shape.
6
2.2.1
Properties
2.2.1.1 Chemical Properties
Table 2.1: Chemical Properties [http://www.nortal.co.uk/LM6/]
Percentage (%)
EN 1706 AC-44100
Copper
0.1 max
0.15(0.10)
Magnesium
0.10 max
0.10
Silicon
1-.0-13.0
10.5-13.5
Iron
0.6 max
0.65(0.55)
Manganese
0.5 max
0.55
Nickel
0.1 max
0.20
Zinc
0.1 max
0.25
Lead
0.1 max
0.20
Tin
0.05 max
-
Titanium
0.2 max
0.20(0.15)
Aluminium
remainder
-
7
2.2.1.2 Machinability
An enduring problem with this material is that they are rather difficult to machine.
This is due to the high hardness of the reinforcement materials which in many cases
are significantly harder than the commonly used high speed steel tools and carbide
tools. [Joardar et al. (2011)]. As for those issues, many previous and present
researches are conducted to find and focused on optimizing some machining
parameters so that roughness of the machined surfaces and tool wear can be
minimized.
2.2.1.3 Corrosion Resistance
LM6 exhibits excellent resistance to corrosion under both ordinary atmospheric and
marine conditions. For the severest conditions, this property can be further enhanced
by anodic treatment. [Hadleighcastings (2012)]
2.2.1.4 Physical Properties
Table 2.2: Chemical Properties [http://www.nortal.co.uk/LM6/]
Coefficient of Thermal Expansion (per°C at 20-100°C)
0.000020
Thermal Conductivity (cal/cm 2 /cm/°C at 25°C)
0.34
Electrical Conductivity (% copper standard at 20°C)
37
Density (g/cm 3 )
2.65
Freezing Range (°C) approx
575-565
8
2.3.1.5 Mechanical Properties
Table 2.3: Mechanical Properties [http://www.nortal.co.uk/LM6/]
SAND CAST
0.2%
Proof
Stress 60-70
CHILL CAST
70-80
(N/mm2)*
Tensile Stress (N/mm2)*
160-190
190-230
Elongation (%)*
5-10
7-15
Impact Resistance. Izod 6.0
9.0
(Nm)
Brinell Hardness Number
50-55
Endurance Limit (5 X 107 51
55-60
68
cycles; + N/mm2)
Modulus Of Elasticity (X 71
71
103 N/mm2)
Shear Strength (N/mm2)
2.2.2
120
Applications
LM6 has a high resistance to corrosion and excellent cast ability. It is often uses in
numerous places due to these properties such as marine, manifolds, motor casings,
cast doors, pumping applications. It is also especially suitable where castings need to
be welded together. The ductility of LM6 castings means they can be easily rectified
and modified into shape. It also has excellent resistance to corrosion in marine
environments, possesses excellent ductility, but is of medium strength and is not heat
treated. Its strength falls off rapidly at high temperatures. Its elastic limit is low and it
is fairly difficult to machine. [Hadleighcastings (2012)]
9