vii
TABLE OF CONTENTS
CHAPTER
1
TITLE
PAGE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
xi
LIST OF FIGURES
xii
LIST OF ABBREVIATION/SYMBOL
xv
LIST OF APPENDICES
xvi
INTRODUCTION
1.1 Introduction
1
1.2 Background of Study
1
1.3 Statement of the Problem
4
1.4 Objectives of the Study
5
1.5 Scopes of Study
5
1.6 Significant of Study
6
viii
2 LITERATURE REVIEW
2.1
Introduction
7
2.2 Overview of Machining and Grinding Process
7
2.3
8
Ductile Mode Machining of Hard and Brittle Materials
2.4 Models for Ductile Mode Machining of Brittle Materials
10
2.5 Diamond Tools
13
2.6 Diamond Grinding wheel
15
2.6.1 Bonded Diamond Grinding Wheel
2.7
15
2.6.1.1 Bond Materials
15
2.6.1.2 Abrasive Types
16
2.6.1.3 Grit Size
18
2.6.1.4 Grade
18
2.6.1.5 Structure
18
2.6.1.6 Concentration
19
2.6.2 Bondless Diamond Grinding Wheel
19
Grinding Wheel Wear
20
2.7.1 Wheel Wear Mechanism
21
2.7.1.1 Abrasive Wheel Wear
21
2.7.1.2 Adhesive Wheel Wear
22
2.7.1.3 Tribochemical Wheel Wear
22
2.7.1.4 Surfaces Disruptions
22
2.7.1.5 Diffusion
23
2.8
Speed Rating of Grinding Wheel
23
2.9
Grinding Dynamics
23
2.9.1 Forced and Regenerative Vibrations
24
2.9.1.1 Forced Vibration
24
2.9.1.2 Regenerative Vibrations
24
2.9.1.2.1 Work-Regenerative Chatter
25
2.9.1.2.2 Wheel-Regenerative Chatter
25
2.10
Grinding Fluid
26
2.11
Dressing and Truing of Grinding Wheels
27
2.12
Polishing
28
2.13
Lapping
29
2.14
Influence of Grinding Parameters Grinding Wheel Performance
29
ix
2.15
2.16
2.17
2.14.1 The Influence of Wheel Speed
30
2.14.2 The Influence of Work Speed
30
2.14.3 The Influence of Feedrate
30
2.14.4 The Influence of Infeed (Depth of Cut)
30
2.14.5 The Influence of the Grinding Fluids
31
2.14.6 The Influence of Severity of Dressing
31
Spherical and Aspherical Surface
32
2.15.1 Spherical Glass Lenses
34
2.15.2 Moulding of Spherical Glass Lenses
34
2.15.3 Aspherical Glass Lenses
35
Surface Technology and Assessment of Surface Texture and
Integrity
36
2.16.1 Surface Finish Units
42
2.16.2 Measurement of Surface Finish
43
2.16.3 Surface Finish Measurement Machines
44
Previous Research Studies on Spherical Grinding under
Different Parameters
46
3 RESEARCH METHODOLOGY
3.1
Introduction
48
3.2 Overall Methodology Flow Chart
49
3.3
Experimental Equipments
50
3.3.1
Ultra-Precision Lathe (Nanotech 220UPL)
50
3.3.2
Diamond Grinding Wheel
50
3.3.3
Dressing Tool
52
3.3.4
Workpiece Material
52
3.4
Machine Variables
53
3.5
Measurement Equipments
55
3.5.1
Surface Texture and Contour measuring Instrument
55
3.5.2
High Power Optical Microscope
56
4 RESULTS AND DISCUSSIONS
4.1
Introduction
57
4.2
Forming Results and Surface Texture
57
x
4.3
Finishing Grinding Results and Surface Texture
4.4
Surface Roughness, Form Accuracy and Radius of Curvature
4.5
61
Analysis
62
4.4.1 Surface Roughness Results
62
4.4.2 Form Accuracy Results
65
4.4.3 Radius of Curvature Results
67
Surface Texture Analysis
70
4 CONCLUSION AND RECOMMENDATIONS
5.1
Introduction
73
5.2
Conclusion
73
5.3
Recommendations for Future Study
74
REFERENCES
APPENDICES A-F
75
82-97
xi
LIST OF TABLES
TABLE NO.
TITLE
PAGE
2.1:
Different conic constant and it equivalent types of conics
33
3.1
Forming parameters
53
3.2
Machining variables use in finishing grinding
54
3.3
Experimental trials plan
54
4.1
Radius of curvature for forming surface
57
4.2
Grinding run sequence for resin bonded wheel
61
4.3
Grinding run sequence for bondless wheel
61
4.4
Ra results for resin bonded wheel
62
4.5
Ra results for bondless wheel
62
4.6
Rt results for resin bonded wheel
65
4.7
Rt results for bondless wheel
65
4.8
R results for resin bonded wheel
67
4.9
R results for bondless wheel
68
xii
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
1.1
Development of achievable machining accuracy
2
2.1
Schematic of ductile-regime machining (Liu et al., 2004)
9
2.2
Critical stress field is a function of uncut chip thickness; (a)
small depth of cut avoids the cleavage to initiate at the defects
and thus chip removal process by plastic deformation, (b) large
depth of cut results cleavage to initiate at the defects and
produce brittle fracture surface, (c) schematic diagram of cut
surface (Nakasuji et al., 1990)
11
2.3
An original Konig’s model (Konig and Sinhoff, 1992)
12
2.4
Konig’s model modified by Zhong and Venkatesh (Zhong, Z.
and Venkatesh, V.C, 1995)
2.5
13
A bondless diamond grinding wheel shown (a) without and
(b) with a shank (Venkatesh, V.C. and S. Izman, 2008)
20
2.6
Types of grinding wheel wear
21
2.7
An aspheric surface as a departure from a best-fit sphere.
33
2.8
Schematic illustration of a lens moulding process
34
2.9
Schematic showing spherical aberration in a spherical lens
35
2.10
Moore’s aspheric generator showing path trace for convex and
Concave aspheric surfaces (Tabor, 1986)
36
2.11
Surface roughness parameters
37
2.12
Surface roughness parameter Ra
38
2.13
Surface roughness parameter Rmax
38
2.14
Surface roughness parameter Rt
39
2.15
Surface waviness parameter Wa
39
xiii
2.16
Surface waviness parameter Wmax
40
2.17
The primary texture, secondary texture and form errors
41
2.18
Surface produced by cutting processes
42
2.19
Measurement of surface finish by comparative methods of two
Products
43
2.20
The stylus to measuring of surface finish
44
2.21
The stylus is (a) in 180° out of phase, (b) in phase
45
3.1
Summary of the overall methodology used in this study
49
3.2
Ultra precision diamond turning machine (Nanotech 220UPL)
50
3.3
Resin bonded forming wheel with grit size 40-60µm
51
3.4
Finishing grinding wheel (a) Bondless wheel (b) Resin bonded
wheel both with grit size 1-3µm
51
3.5
Dressing Tool with SS-66 REX sticky wax
52
3.6
Tungsten carbide fit with the fixture to hold the workpiece
material
3.7
53
(a) Surfcom 5000 stylus-and-arm system (b) Surfcom 5000
machine
55
3.8
Zeiss Axiotech optical microscope
56
4.1
The LVDT probe used for tool setup and measuring of the wheel
diameter
4.2
58
Schematic diagram shows the of-centre problem of the LVDT
Probe
59
4.3
Snake skin-like surface at outer portion of specimen 1
59
4.4
Snake skin-like surface at inner portion of specimen 2
60
4.5
Snake skin-like surface at inner portion of specimen 7
60
4.6
(a) Increment of the work speed from 350 rpm to 100 rpm reduce
the snake skin-like surface problem and only the inner portion still
have some snake skin-like surface, (b)Zoomed at inner portion of
the specimen to show the snake skin-like surface
4.7
Aritmetric average roughness Ra vs. feedrate for resin bonded
and bondless wheel at wheel speed of 26 m/s, 30 m/s
4.8
60
63
Aritmetric average roughness Ra vs. wheel speed for resin
bonded and bondless wheel at feedrate of 0.2 mm/min,
0.6 mm/min
63
xiv
4.9
Form accuracy Rt vs. feedrate for resin bonded and bondless
wheel at wheel speed of 26 m/s, 30 m/s
4.10
Form accuracy Rt vs. wheel speed for resin bonded and bondless
wheel at feedrate of 0.2 mm/min, 0.6 mm/min
4.11
66
Radius of curvature R vs. feedrate for resin bonded and bondless
wheel at wheel speed of 26 m/s, 30 m/s
4.12
66
68
Radius of curvature R vs. wheel speed for resin bonded and
bondless wheel at feedrate 0.2 mm/min and 0.6 mm/min
69
4.13
Surface texture zoomed location
70
4.14
Surface texture for resin bonded wheel with varying feedrate (F)
and wheel speed (Vc)
4.15
71
Surface texture for bondless wheel with varying feedrate (F) and
wheel speed (Vc)
72
xv
LIST OF ABBREVIATIONS/SYMBOL
Ø
Diameter
SEM
Scanning Electron Microscope
K
Kelvin
mm
millimeter
WC
Tungsten Carbide
°C
Degree Celsius
μ
micro
%
Percent
"
inch
<
Less than
&
And
Ge
Germanium
Si
Silicon
Al2O3
Aluminium oxide
Si3N4
Silicon Nitride
SiC
Silicon Carbide
NaSiO3
Sodium Silicate
CBN
Cubic Boron Nitride
UTM
University Technology Malaysia
FEPA
Federation of European Producers of Abrasives
US
United State
μm
Micrometer, micron
λ
Wave length
Al
Aluminium
HK
Knoop Hardness
°
Degree Celsius
xvi
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
A
Moore Nanotech 250 UPL Specification
82
B
Surfcom 5000DX/SD Specification
84
C
Workpiece Material Properties
86
D
Aluminium Fixture Detail Drawing
87
E
Forming Surface Texture
88
F
Finishing Surface Texture with Different Grinding
Parameter - Resin Bonded Wheel
G
Finishing Surface Texture with Different Grinding
Parameter - Bondless Wheel
H
94
Finishing Surface Roughness Analysis, V-Mag 100000
(Magnification 100,000) Resin Bonded Wheel
I
91
95
Finishing Surface Roughness Analysis, V-Mag 100000
(Magnification 100,000) Bondless Wheel
97