vii
TABLE OF CONTENTS
CHAPTER
1
TITLE
PAGE
DECLARATION
ii
DEDICATION
iii
ACKNOLEDGEMENTS
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
xiv
LIST OF FIGURES
xvi
LIST OF SYMBOLS
xviii
LIST OF APPENDICES
xix
INTRODUCTION
1
1.1
Problem Statement
1
1.2
Objective of Study
3
1.3
Scope of Study
4
1.4
Methodology of Study
4
1.5
Significance of Findings
7
1.6
Report Structure
8
1.7
Summary
9
viii
2
LITERATURE REVIEW ON DESIGN FOR MANUAL
10
ASSEMBLY METHODOLOGY
2.1
Introduction
10
2.2
Design for “X”
11
2.3
Approaches for Implementing DFA
13
2.3.1 Hitachi Assemblability Evaluation Method
13
(AEM).
2.4
2.3.2 Boothroyd-Dewhurst (B-D) DFA
14
2.3.3 Lucas DFA
15
Assemblability Measures
2.4.1 Hitachi Assemblability Evaluation Method
17
17
(AEM)
2.5
2.4.2 Boothroyd Dewhurst DfA
18
2.4.3 Lucas DFA
20
Examples of DFA Methodologies
2.5.1
Redesign of a simple product using Hitachi
22
22
Assemblability Evaluation Method (AEM).
2.5.2
Redesign of a simple product using the
25
Boothroyd-Dewhurst DFA method
2.5.3 Redesign of a drain pump assembly using
29
Lucas DFA
2.6
3
Summary
DESIGN FOR AUTOMATIC ASSEMBLY (DFAA)
32
33
METHODOLOGY
3.1
Introduction
33
3.1.1
Fixed/ Hard automation
34
3.1.1
Robotic Assembly/ Soft automation
35
ix
3.2
Structure of DFAA
3.2.1
3.2.2
38
Product Level
38
3.2.1.1
Reduce Number of Parts
39
3.2.1.2
Unique Parts
40
3.2.1.3
Base object
41
3.2.1.4
Design base object
41
3.2.1.5
Assembly directions
42
3.2.1.6
Parallel operations
43
3.2.1.7
Chain of tolerances
44
3.2.1.8
Disassembly
44
3.2.1.9
Packaging
45
Part Level
45
3.2.2.1
Need to Assemble Part?
47
3.2.2.2
Level of Defects
48
3.2.2.3
Orientation
48
3.2.2.4
Non-Fragile parts
49
3.2.2.5
Hooking
50
3.2.2.6
Centre of Gravity
50
3.2.2.7
Shape
51
3.2.2.8
Weight
52
3.2.2.9
Length
52
3.2.2.10 Gripping
54
3.2.2.11 Assembly Motion
54
3.2.2.12 Reachability
55
3.2.2.13 Insertion
56
3.2.2.14 Tolerances
56
3.2.2.15 Holding Assembled Parts
57
3.2.2.16 Fastening Method
58
3.2.2.17 Joining
58
3.2.2.18 Check/Adjust
59
x
3.3
Applications of DFAA
3.3.1
Design and Evaluation During Early
59
59
Product Development
3.3.2
Redesign and Evaluation of an Existing
60
Product
4
3.4
Evaluation Philosophy and Criterions of DFAA
61
3.5
Summary
62
PRODUCT DETAIL FOR OLD DESIGN
63
4.1
Introduction
63
4.2
Product Specification
64
4.3
Product Structure
66
4.3
Product Assembly Operation Sequences
67
4.4
5
4.3.1
Base Part
67
4.3.2
Cover Part
69
Summary
72
EVALUATION OF THE ORIGINAL DESIGN
73
5.1
Introduction
73
5.2
Product Level Evaluation of The Old Design
74
5.2.1
Reduce Number of Parts
74
5.2.2
Unique Parts
75
5.2.3
Base Object
75
5.2.4
Design Base Objects
75
5.2.5
Assembly Directions
76
5.2.6
Parallel Operations
76
5.2.7
Chain of Tolerances
78
5.3
Part Level Evaluation of The Old Design
78
8.2.1
79
Base Socket
xi
5.2
6
8.2.2
Switch On/Off
80
8.2.3
Spring
80
8.2.4
Panel 3 Pin
80
8.2.5
Cover Socket
80
8.2.6
Life Plate
81
8.2.7
Life Clamp
81
8.2.8
Life Screw φ6 X 11
81
8.2.9
Life U Plate
81
8.2.10 Connector Panel 3 Pin
82
8.2.11 Plate Switch On/Off
82
8.2.12 Earth U Plate
82
8.2.13 Earth Plate
82
8.2.14 Earth Clamp
83
8.2.15 Earth Screw φ6 X 11
83
8.2.16 Neutral U Plate
83
8.2.17 Neutral Clamp
83
8.2.18 Neutral Screw φ6 X 11
84
8.2.19 Screw φ5 X 12
84
8.2.20 Screw φ6.5 X 23
84
Summary
PROPOSED IMPROVEMENTS ON THE ORIGINAL
84
86
DESIGN
6.1
Introduction
86
6.2
Improvement of The Original Design
86
6.2.1
Eliminating Screws φ5 X 12 and Changing
87
to Snap Fits
6.2.2
Joining Life Plate, Life U Plate, Panel 3 Pin
88
and Connector 3 Pin
6.2.3
Joining Earth Plate, and U Plate
89
xii
6.2.4
6.3
7
Summary
PRODUCT DETAIL FOR PROPOSED DESIGN
90
91
92
7.1
Introduction
92
7.2
Product Specification
92
7.3
Product Structure
94
7.4
Product Assembly Operation Sequences
94
7.5
8
Joining Clamp and Screw φ6 X 11
7.4.1
Base Part
95
7.4.2
Cover Part
95
7.4.3
All Parts
96
Summary
EVALUATION OF THE NEW DESIGN
97
98
8.1
Introduction
98
8.2
Product Level Evaluation of The New Design
98
8.3
8.2.1
Reduce Number of Parts
99
8.2.2
Unique Parts
99
8.2.3
Base Object
100
8.2.4
Design Base Objects
100
8.2.5
Assembly Directions
100
8.2.6
Parallel Operations
100
8.2.7
Chain of Tolerances
101
Product Level Evaluation of The New Design
102
8.3.1
Base Socket
103
8.3.2
Switch on/off
103
8.3.3
Spring
103
8.3.4
Panel 3 Pin
103
8.3.5
Cover Socket 3 Pin
104
xiii
8.4
9
8.3.6
Life Plate
104
8.3.7
Life Clip
104
8.3.8
Earth Plate
104
8.3.9
Earth Clip
105
8.3.10 Neutral Plate
105
8.3.11 Neutral Clip
105
8.3.12 Screw φ6.5 X 23
105
Summary
106
DISCUSSION
107
9.1
Introduction
107
9.2
Comparison Between The Original Design and
108
Proposed Design
10
9.2.1
Number of Components
110
9.2.2
Number of Unique Components
111
9.2.3
Assembly Index for Product Level
112
9.2.4
Assembly Index for Part Level
112
CONCLUSIONS AND FUTURE
113
RECOMMENDATIONS
10.1 Introduction
113
10.2 Conclusions
113
10.3 Future Recommendations
115
REFERENCES
116
APPENDICES
118
xiv
LIST OF TABLES
TABLE NO.
TITLE
PAGE
1.1
Gantt chart for Master Project I
5
1.2
Gantt chart for Master Project II
7
2.1
DFX as lifecycle oriented or ability oriented (WDK, 1993)
12
2.2
DFA worksheet analysis
18
2.3
Evaluation score and the cost ratio of the original design
23
2.4
Evaluation score and the cost ratio of redesign 1
24
2.5
Evaluation score and the cost ratio of redesign 2
25
2.6
Manual assembly worksheet for the original design
26
2.7
Manual assembly worksheet for Redesign 1
27
2.8
Manual Assembly Worksheet for Redesign 2
28
3.1
The evaluation of the part reduced in the product
40
3.2
The evaluation of the unique parts in the product
40
3.3
The evaluation of the base object of the product
41
3.4
The evaluation of the design base object of the product
42
3.5
The evaluation of the assembly directions of the product
42
3.6
The evaluation of the parallel operations of the product
43
3.7
The evaluation of the chain of tolerances of the product
44
3.8
The evaluation need to assemble part of each part
45
3.9
The evaluation level of defects of each part
47
3.10
The evaluation for orientation of each part
48
3.11
The evaluation for non-fragile parts
48
3.12
The evaluation for hooking of each part
49
3.13
The evaluation for centre of gravity of each part
49
3.14
The evaluation for shape of each part
50
3.15
The evaluation for weight of each part
51
xv
3.16
The evaluation for length of each part
52
3.17
The evaluation for gripping of each part
52
3.18
The evaluation for assembly motion of each part
53
3.19
The evaluation for reachability of each part
54
3.20
The evaluation for insertion of each part
55
3.21
The evaluation for tolerances of each part
55
3.22
The evaluation for holding assembled parts
56
3.23
The evaluation for fastening method of each part
57
3.24
The evaluation for joining of each part
58
3.25
The evaluation for check/ adjusts of each part
59
3.26
Evaluation sheet for Product Level
61
3.27
Evaluation sheet for Part Level
62
4.1
Three (3) Pin Wall Socket Specification
64
5.1
Evaluation sheet of product level for the old design of 3 pin
74
wall socket
5.2
Evaluation sheet of part level for the old design of 3 pin wall
79
socket
7.1
Specification of Three (3) Pin Wall Socket New Design
92
8.1
Evaluation sheet of product level for the old design of 3 pin
99
wall socket
8.2
Evaluation sheet of part level for the new design of 3 pin
102
wall socket
9.1
Comparison in Percentage between the Original Design and
108
Proposed Design
9.2
Comparison between the Number of Components in Original
Design and New Design
111
xvi
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
1.1
Types of DFA
2
1.2
Flow Chart Master Project I
5
1.3
Flow Chart Master Project II
6
2.1
Assembly sequence flow chart
21
2.2
Original design
22
2.3
Redesign 1
23
2.4
Redesign 2
24
2.5
Original design
25
2.6
Redesign 1
27
2.7
Redesign 2
28
2.8
Original drain pump assembly design
30
2.9
Redesign using the Lucas DFA method
31
3.1
Classification of Automatic Assembly
33
3.2
DFAA Method
38
3.3
Suggested structure for Product level in the DFAA method
39
(Stephan Eskilander, 2001)
3.4
Suggested structure for Part level in the DFAA method
46
(Stephan Eskilander, 2001)
4.1
(a) Front view (b) Back view of 3 pin wall socket
63
4.2
Three (3) Pin Wall Socket Structure of the Old Design
66
4.3
Summary of the Assembly Process for Base Part
67
4.4
(a) Before assembled (b) After assembled for base part
68
4.5
Assembly Sequences for Cover Part
70
4.6
(a) Before assembled (b) After assembled for cover part
71
5.1
Parallel Operations
77
xvii
6.1
The location of screw φ5 X 12 on the 3 pin wall socket
86
6.2
The Proposed Design from Screws φ5 X 12 to Snap Fits
87
6.3
The Proposed Design from Separate Life Plates to a Life
88
Plate
6.4
The Proposed Design from Separate Earth Plates to an Earth
89
Plate
6.5
The Proposed Design from Separate Clamp and Screw
89
φ6 X 11 to a Clip
7.1
Three (3) Pin Wall Socket Structure of the New Design
93
7.2
Summary of the Assembly Process for Base Part
94
7.3
Assembly Sequences for Cover Part
95
7.4
Assembly Sequences for 3 Pin Wall Socket of the New
96
Design
8.1
Parallel Operations
101
9.1
Comparison Number of Components in Old and New
109
Designs
9.2
Comparison Number of Unique Components in Old and
109
New Designs
9.3
Comparison between Assembly Index in Old and New
Designs
110
xvi
LIST OF SYMBOLS
AEM - Assemblability Evaluation Method
E
- Assemblability Evaluation Score
DFA
- Design for Assembly
DFAA - Design for Automatic Assembly
DFM - Design for Manufacture
DFE
- Design for environment
DFC
- Design for cost
DFT
- Design for test
DFMA - Design for Manufacture and Assembly
DFX
- Design for “X”
TM
- Assembly time
CM
- Assembly cost
NM
- Theoretical minimum number of parts
ADE - Assembly Design Efficiency
K
- Estimated Assembly Cost Ratio
xix
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
A1
Manual Handling Time (seconds)
118
A2
Manual Insertion and Fastening Time (seconds)
119
B1
Design Samples of 3 Pin Wall Socket (Overall)
120