Designing Plastic Parts for Assembly 8E

Designing Plastic Parts for Assembly 8E

by Paul A. Tres

Hardcover(Updated)

$153.36 $159.99 Save 4% Current price is $153.36, Original price is $159.99. You Save 4%. View All Available Formats & Editions
Choose Expedited Shipping at checkout for guaranteed delivery by Thursday, March 28

Product Details

ISBN-13: 9781569906682
Publisher: Hanser Publications
Publication date: 04/10/2017
Edition description: Updated
Pages: 415
Sales rank: 1,088,440
Product dimensions: 6.50(w) x 1.50(h) x 9.50(d)

Table of Contents

Introduction xvii

1 Understanding Plastic Materials 1

1.1 Basic Resins 1

1.1.1 Thermoplastics 1

1.1.2 Thermosets 2

1.2 Basic Structures 2

1.2.1 Crystalline 2

1.2.2 Amorphous 3

1.2.3 Liquid Crystal Polymer 3

1.2.4 New Polymer Technologies 4

1.2.4.1 Inherently Conductive Polymers (ICP) 4

1.2.4.2 Electro-Optic Polymers (EOP) 5

1.2.4.3 Biopolymers 6

1.3 Homopolymer vs. Copolymer 6

1.4 Reinforcements 7

1.5 Fillers 7

1.5.1 Glass Sphere 8

1.5.1.1 Microphere Properties 8

1.5.1.2 Compounding 9

1.5.1.3 Injection Molding 10

1.5.1.4 Mechanical Properties in Injection Molded Thermoplastic Applications 10

1.6 Additives 11

1.7 Physical Properties 12

1.7.1 Density and Specific Gravity 12

1.7.2 Elasticity 13

1.7.3 Plasticity 14

1.7.4 Ductility 14

1.7.5 Toughness 14

1.7.6 Brittleness 15

1.7.7 Notch Sensitivity 15

1.7.8 Isotropy 20

1.7.9 Anisotropy 20

1.7.10 Water Absorption 20

1.7.11 Mold Shrinkage 21

1.8 Mechanical Properties 23

1.8.1 Normal Stress 23

1.8.2 Normal Strain 23

1.8.3 Stress-Strain Curve 24

1.9 Creep 26

1.9.1 Introduction 26

1.9.2 Creep Experiments 26

1.9.3 Creep Curves 27

1.9.4 Stress-Relaxation 29

1.10 Impact Properties 29

1.11 Thermal Properties 31

1.11.1 Melting Point 31

1.11.2 Glass Transition Temperature 31

1.11.3 Heat Deflection Temperature 31

1.11.4 Coefficient of Thermal Expansion 31

1.11.5 Thermal Conductivity 33

1.11.6 Thermal Influence on Mechanical Properties 33

1.11.7 Case History: Planetary Gear Life Durability 34

2 Understanding Safety Factors 40

2.1 What Is a Safety Factor 40

2.2 Using the Safety Factors 40

2.2.1 Design Safety Factors 40

2.2.1.1 Design StaticSafety Factor 41

2.2.1.2 Design Dynamic Safety Factor 41

2.2.1.3 Design Time-related Safety Factor 41

2.2.2 Material Properties Safety Factor 42

2.2.3 Processing Safety Factors 43

2.2.4 Operating Condition Safety Factor 43

3 Strength of Material for Plastics 44

3.1 Tensile Strength 44

3.1.1 Proportional Limit 45

3.1.2 Elastic Stress Limit 45

3.1.3 Yield Stress 45

3.1.4 Ultimate Stress 46

3.2 Compressive Stress 46

3.3 Shear Stress 47

3.4 Torsion Stress 48

3.5 Elongations 49

3.5.1 Tensile Strain 49

3.5.2 Compressive Strain 51

3.5.3 Shear Strain 51

3.6 True Stress and Strain vs. Engineering Stress and Strain 51

3.7 Poisson's Ratio 52

3.8 Modulus of Elasticity 54

3.8.1 Young's Modulus 54

3.8.2 Tangent Modulus 55

3.8.3 Secant Modulus 56

3.8.4 Creep (Apparent) Modulus 56

3.8.5 Shear Modulus 57

3.8.6 Flexural Modulus 57

3.8.7 The Use of Various Moduli 58

3.9 Stress Relations 58

3.9.1 Introduction 58

3.9.2 Experiment 59

3.9.3 Equivalent Stress 59

3.9.4 Maximum Normal Stress 59

3.9.5 Maximum Normal Strain 60

3.9.6 Maximum Shear Stress 60

3.9.7 Maximum Deformation Energy 61

3.10 Conclusions 62

4 Nonlinear Considerations 63

4.1 Material Considerations 63

4.1.1 Linear Material 63

4.1.2 Nonlinear Material 63

4.2 Geometry 64

4.2.1 Linear Geometry 64

4.2.2 Nonlinear Geometry 64

4.3 Finite Element Analysis (FEA) 65

4.3.1 FEA Method Application 65

4.3.2 Using FEA Method 65

4.3.3 Most Common FEA Codes 66

4.4 Conclusions 66

5 Assembly Techniques for Plastics 67

5.1 Ultrasonic Welding 67

5.1.1 Ultrasonic Equipment 67

5.1.2 Horn Design 70

5.1.3 Ultrasonic Welding Techniques 72

5.1.4 Control Methods 75

5.1.5 Common Issues with Welding 78

5.1.6 Joint Design 81

5.1.6.1 Butt Joint Design 82

5.1.6.2 Shear Joint Design 83

5.2 Ultrasonic (Heat) Staking 86

5.2.1 Standard Stake Design 86

5.2.2 Flush Stake Design 87

5.2.3 Spherical Stake Design 88

5.2.4 Hollow (Boss) Stake Design 89

5.2.5 Knurled Stake Design 90

5.3 Ultrasonic Spot Welding 91

5.4 Ultrasonic Swaging 92

5.5 Ultrasonic Stud Welding 92

5.6 Spin Welding 93

5.6.1 Process 93

5.6.2 Equipment 96

5.6.3 Welding Parameters 96

5.6.4 Joint Design 97

5.7 Hot Plate Welding 100

5.7.1 Process 103

5.7.2 Joint Design 104

5.8 Vibration Welding 106

5.8.1 Process 108

5.8.2 Equipment 110

5.8.3 Joint Design 111

5.8.4 Common Issues with Vibration Welding 113

5.9 Electromagnetic Welding 114

5.9.1 Equipment 115

5.9.2 Process 115

5.9.3 Joint Design 116

5.10 Solvent and Adhesive Bonding 118

5.10.1 Types of Adhesives 119

5.10.2 Advantages and Limitations of Adhesives 120

5.10.3 Stress Cracking in Bonded Joints 120

5.10.4 Joint Design 121

5.11 Radio Frequency (RF) Welding 123

5.11.1 Equipment 123

5.11.2 Process 124

5.12 Laser Welding 125

5.12.1 Equipment 125

5.12.2 Process 127

5.12.2.1 Surface Heating 128

5.12.2.2 Through Transmission 128

5.12.2.3 Staking 129

5.12.3 Techniques for Laser Welding 130

5.12.4 Polymers 132

5.12.5 Applications 134

5.13 Conclusion 137

6 Press Fitting 138

6.1 Introduction 138

6.2 Definitions and Notations 138

6.3 Geometric Definitions 139

6.4 Safety Factors 139

6.5 Creep 140

6.6 Loads 140

6.7 Press Fit Theory 141

6.8 Design Algorithm 143

6.9 Case History: Plastic Shaft - Plastic Hub 144

6.9.1 Shaft and Hub Made of Different Polymers 144

6.9.2 Safety Factor Selection 144

6.9.3 Material Properties 145

6.9.3.1 Shaft - Material Properties at 23 °<$$$>[Page No. xiv]C 145

6.9.3.2 Shaft - Material Properties at 93 °C 149

6.9.3.3 Creep Curves at 23 °C 150

6.9.3.4 Creep at 93 °C 151

6.9.3.5 Pulley at 23 °C 152

6.9.3.6 Pulley at 93 °C 155

6.9.3.7 Creep, Pulley at 23 °C 156

6.9.3.8 Creep, Pulley at 93 °C 157

6.10 Solutions: Plastic Shaft - Plastic Hub 158

6.10.1 Case A 158

6.10.2 Case B 159

6.10.3 Case C 160

6.10.4 Case D 161

6.11 Case History: Metal Ball Bearing - Plastic Hub 163

6.11.1 Fusible Core Injection Molding 163

6.11.2 Upper Intake Manifold Background 164

6.11.3 Design Algorithm 167

6.11.4 Material Properties 168

6.11.4.1 CAMPUS 169

6.11.5 Solution 170

6.11.5.1 Necessary IF at Ambient 174

6.11.5.2 IF Available at 118 °C 175

6.11.5.3 IF Verification at -40 °C 175

6.11.5.4 Stress Check at -40 °C, Time = 0 176

6.11.5.5 Stress Level at -40 °C, Time = 5,000 h 176

6.11.5.6 Stress Level at 23 °C, Time = 5,000 h 176

6.11.5.7 Stress Level at 118 °C, Time = 5,000 h 177

6.11.6 Conclusion 177

7 Living Hinges 178

7.1 Introduction 178

7.2 Basic Design for PP, PE 178

7.3 Common Living Hinge Design 180

7.4 Basic Design for Engineering Plastics 180

7.5 Living Hinge Design Analysis 181

7.5.1 Elastic Strain Due to Bending 181

7.5.1.1 Assumptions 181

7.5.1.2 Geometric Conditions 182

7.5.1.3 Strain Due to Bending 182

7.5.1.4 Stress Due to Bending 183

7.5.1.5 Closing Angle of the Hinge 184

7.5.1.6 Bending Radius of the Hinge 184

7.5.2 Plastic Strain Due to Pure Bending 184

7.5.2.1 Assumptions 184

7.5.2.2 Strain Due to Bending 184

7.5.3 Plastic Strain Due to a Mixture of Bending and Tension 186

7.5.3.1 Tension Strain 186

7.5.3.2 Bending Strain 189

7.5.3.3 Neutral Axis Position 190

7.5.3.4 Hinge Length 190

7.5.3.5 Elastic Portion of the Hinge Thickness 193

7.6 Computer Flow Chart 194

7.6.1 Computer Notations 194

7.7 Computer Flow Chart Equations 196

7.8 Example: Case History 198

7.8.1 World Class Connector 198

7.8.1.1 Calculations for the 'Right Way' Assembly 199

7.8.1.2 Calculations for the 'Wrong Way' Assembly 201

7.8.2 Comparison Material 203

7.8.2.1 'Right Way' Assembly 203

7.8.2.2 'Wrong Way' Assembly 204

7.8.3 Ignition Cable Bracket 205

7.8.3.1 Initial Design 206

7.8.3.2 Improved Design 206

7.9 Processing Errors for Living Hinges 208

7.10 Coined Hinges 209

7.11 Conclusion 212

7.12 Exercise 212

8 Snap Fitting 218

8.1 Introduction 218

8.2 Material Considerations 219

8.3 Design Considerations 221

8.3.1 Safety Factors 223

8.4 Snap Fit Theory 224

8.4.1 Notations 224

8.4.2 Geometric Conditions 225

8.4.3 Stress Strain Curve and Formulae 226

8.4.4 Instantaneous Moment of Inertia 229

8.4.5 Angle of Deflection 229

8.4.6 Integral Solution 229

8.4.7 Equation of Deflection 231

8.4.8 Integral Solution 232

8.4.9 Maximum Deflection 232

8.4.10 Self-locking Angle 235

8.5 Case History: One-way Continuous Beam with Rectangular Cross Section 235

8.5.1 Geometrical Model 237

8.6 Annular Snap Fits 240

8.6.1 Case History: Annular Snap Fit - Rigid Beam with Soft Mating Part 241

8.6.2 Notations 241

8.6.3 Geometric Definitions 242

8.6.4 Material Selections and Properties 242

8.6.5 Basic Formulas 243

8.6.6 Angle of Assembly 244

8.7 Torsional Snap Fits 245

8.7.1 Notations 245

8.7.2 Basic Formulae 247

8.7.3 Material Properties 248

8.7.4 Solution 248

8.8 Case History: Injection Blow Molded Bottle Assembly 250

8.9 Tooling 251

8.10 Assembly Procedures 252

8.11 Issues with Snap Fitting 254

8.12 Serviceability 255

8.13 Conclusions 255

Appendix A Enforced Displacement 257

Appendix B Point Force 266

References 276

World Wide Web References Related to Plastic Part Design 283

Index 287

Customer Reviews

Most Helpful Customer Reviews

See All Customer Reviews