Capillary Forces in Microassembly (eBook)

Foreword 7
Preface 9
0.1 Context 9
0.2 Contributions of this Book 12
0.3 What this Book Does Not Tell 15
0.4 Reading Suggestion 16
Contents 17
Part I Microassembly Specificities 23
1 From Conventional Assembly to Microassembly 24
1.1 Introduction 24
1.2 Design of Monolithic Products for Microassembly 25
1.3 Combined Part Manufacturing and Assembly 27
1.4 Product External Assembly Functions 27
1.5 Product Internal Assembly Functions 27
1.6 Stochastic or Self-Assembly 28
1.7 Parallel Assembly 29
1.8 Conclusions 29
2 Classification of Forces Acting in the Microworld 30
2.1 Introduction 30
2.2 Classification Schemes of the Forces 31
2.3 Conclusions 33
3 Handling Principles for Microassembly 34
3.1 Introduction 34
3.2 Presentation of Gripping Principles 34
3.3 Classification of Gripping Principles 46
3.4 Comparison between Gripping Principles 49
3.5 Conclusions 50
4 Conclusions 55
Part II Modeling and Simulation of Capillary Forces 56
5 Introduction 57
6 First Set of Parameters 58
6.1 Introduction 58
6.2 Surface Tension 58
6.3 Young–Dupr ´ e Equation and Static Contact Angle 59
6.4 Laplace Equation 60
6.5 Effects of a Liquid Bridge on the Adhesion Between Two Solids 62
6.6 A Priori Justification of a Capillary Gripper 64
6.7 Conclusions 66
7 State of the Art on the Capillary Force Models at Equilibrium 67
7.1 Introduction 67
7.2 Energetic Approach: Interaction Between Two Parallel Plates 67
7.3 Energetic Approach: Other Configurations 71
7.4 Geometrical Approach: Circle Approximation 73
7.5 Geometrical Approach: Parabolic Approximation 77
7.6 Comparisons and Summary 77
8 Static Simulation at Constant Volume of Liquid 80
8.1 Introduction 80
8.2 Description of the Problem 80
8.3 Assumptions 81
8.4 Equations and Numerical Simulation 82
8.5 Discussion and Conclusions 86
9 Comparisons Between the Capillary Force Models 88
9.1 Introduction 88
9.2 Qualitative Arguments 88
9.3 Analytical Arguments 90
9.4 Conclusions 96
10 Example 1: Application to the Modeling of a Microgripper for Watch Bearings 97
10.1 Introduction 97
10.2 Presentation of the Case Study 97
10.3 Analytical Model Based on the Circle Approximation 100
10.4 Numerical Model Based on the Laplace Equation 103
10.5 Benchmark 107
10.6 Pressure Difference Saturation 108
10.7 Conclusions 110
11 Second Set of Parameters 111
11.1 Introduction 111
11.2 Surface Heterogeneities and Surface Impurities 111
11.3 Surface Roughness 112
11.4 Static Contact Angle Hysteresis 113
11.5 Dynamic Spreading 114
11.6 Conclusions 115
12 Limits of the Static Simulation 116
12.1 Introduction 116
12.2 Performances of the Assembly Machines 116
12.3 Nondimensional Numbers and Buckingham p Theorem 116
12.4 Another Approach: Use of a 1D Analytical Model 119
12.5 Limitations of the Static Model 121
12.6 Conclusions 123
13 Approaching Contact Distance, Rupture Criteria, and Volume Repartition After Separation 124
13.1 Introduction 124
13.2 Approaching Contact Distance 124
13.3 Rupture Distance and Residual Volume of Liquid 126
13.4 Mathematical and Notation Preliminaries 127
13.5 Volume Repartition 128
13.6 Rupture Condition and Rupture Gap 130
13.7 Analytical Benchmarks 132
13.8 Summary of the Methods 133
13.9 Comparison between the Methods 135
13.10 Conclusions 137
14 Example 2: Numerical Implementation of the Proposed Models 139
14.1 Introduction 139
14.2 Liquid Bridge Simulation for the Analysis of a Meniscus 139
14.3 Evaluation of the Double Iterative Scheme 143
14.4 Pseudodynamic Simulation 145
14.5 Conclusions 147
15 Conclusions of the Theoretical Study of Capillary Forces 148
Part III Experimental Aspects 150
16 Introduction 151
17 Test Bed and Characterization 153
17.1 Introduction 153
17.2 Requirements 153
17.3 Test Bed Principles 155
17.4 CAD Model and Drawings 158
17.5 Characteristics of the Force Measurement Set Up 161
17.6 Characteristics of the Contact Angles Measurements 164
17.7 Surface Tension Measurement 165
17.8 Modus Operandi 165
17.9 Characterization 168
17.10 Conclusions 172
18 Results 173
18.1 Introduction 173
18.2 Preliminary Results: Validation of the Simulation Code 173
18.3 Advancing vs Receding Contact Angle 178
18.4 Influence of the Gap 180
18.5 Influence of the Gripper Geometry 181
18.6 Influence of the Surface Tension 182
18.7 Influence of the Contact Angle .1 184
18.8 Influence of the Relative Orientation 184
18.9 Auxiliary PTFE Tip 186
18.10 Dynamical Release 187
18.11 Approaching Contact and Rupture Distances 195
18.12 Shear Force 196
18.13 Conclusions 197
19 Example 3: Application to the Watch Bearing Case Study: Characterization 198
19.1 Introduction 198
19.2 Available Grippers 198
19.3 Available Components 200
19.4 Liquid Properties 200
19.5 Liquid Dispensing 201
19.6 Contact Angles 204
20 Example 4: Application to the Watch Bearing Case Study: Results 207
20.1 Introduction 207
20.2 Picking 207
20.3 Placing 212
20.4 Compliance Effect 213
20.5 Force Measurement 214
20.6 Conclusions 217
21 Conclusions 219
21.1 Introduction 219
21.2 Picking Operations 219
21.3 Releasing Strategies 221
21.4 Design Aspects 223
Part IV General Conclusions and Perspectives 227
22 Conclusions and Perspectives 228
22.1 Conclusions 228
22.2 Perspectives 230
Part V Appendices 231
A Modeling Complements 232
A.1 Analytical Approximations of the Capillary Forces 232
A.2 Volume Repartition by the Energetic Approach 238
B Geometry Complements 242
B.1 Area and Volume of a Spherical Cap 242
B.2 Differential Geometry of Surfaces 243
B.3 Catenary Curve 245
C Comparison Between Both Approaches 247
D Symbols 251
References 254
Index 264