Update on Troubleshooting for Thermoforming

Preface......Page 8
1 Introduction......Page 10
References......Page 12
2 Plastic Sheet, Sheet Materials, Physical Properties and Plastics – an Overview......Page 14
2.1.1 Acrylonitrile-butadiene-styrene (ABS)......Page 17
2.1.2 Polyvinyl Chloride (PVC)......Page 19
2.1.3 Low-Density Polyethylene (LDPE)......Page 21
2.1.4 High-Density Polyethylene (HDPE)......Page 22
2.1.5 Polypropylene (PP)......Page 23
2.1.6 Polystyrene (PS)......Page 25
2.1.7 Expanded Polystyrene (EPS) (Foam)......Page 27
2.1.8 Polyethylene Terephthalate (PET)......Page 28
2.1.9 Polymethylmethacrylate (PMMA)/Acrylic......Page 29
2.1.10 Polyetheretherketone (PEEK)......Page 30
2.1.11 Polycarbonate (PC)......Page 31
2.1.13 Polyphenylene Oxide (PPO)......Page 32
2.1.15 Biodegradable Polymer......Page 33
2.1.16 Cyclic-olefi n Copolymer (COC)......Page 34
2.1.18 Composites......Page 35
References......Page 36
3 Machine Specifications – Effect of Parameters......Page 44
3.1.2 Vacuum (Thermo) Forming......Page 48
3.1.3 Pressure Forming......Page 50
3.1.5 Plug-assist Vacuum Forming......Page 51
3.1.8 Matched-die Forming......Page 55
3.1.9 Drape Forming......Page 57
3.1.10 Vacuum Snap-back Forming Process......Page 58
3.2.1 Raw Material (Plastic Sheets)......Page 60
3.2.2 Moulds......Page 62
3.2.4 Vacuum Holes......Page 65
3.2.6 Sheet Temperature......Page 66
3.2.7 Heaters......Page 67
3.2.8 Daylight......Page 68
3.2.9 Process Parameters......Page 69
References......Page 72
4 Problem Identification – Classification – Troubleshooting – Flow Chart......Page 76
4.1.1 Blisters or Bubbles......Page 80
4.1.2 Webbing or Bridging......Page 82
4.1.3 Excessive Sheet Sag......Page 83
4.1.4 Pinhole or Rupturing......Page 84
4.1.5 Excessive Post Shrinkage......Page 85
4.1.7 Part Sticks to Mould......Page 86
4.1.9 Nipples on Mould Side of Thermoformed Part......Page 87
4.1.10 Pock Marks......Page 88
4.1.11 Poor Wall Distribution......Page 89
4.1.12 Uneven Edges......Page 90
4.1.13 Tearing of Sheet When Forming......Page 91
4.1.14 Bad Definition at the Edges of the Forming Area......Page 92
4.1.15 Glossy Spots......Page 93
4.1.16 Part Warpage......Page 94
4.1.17 Cracking in Corners......Page 95
4.1.18 Raised Corners......Page 96
4.1.19 Surface Markings......Page 97
4.1.20 Parts in the Corners Too Thin......Page 98
4.1.22 Part Deforms During De-moulding......Page 99
4.2.1 Migration of Additives......Page 100
4.2.3 Blue Coloured Dots......Page 102
References......Page 103
5 Optimisation of the Production......Page 106
References......Page 110
6 Case Studies......Page 112
6.1 Case Study 1......Page 113
6.2 Case Study 2......Page 115
References......Page 116
7 Conclusion......Page 118
References......Page 120
Abbreviations......Page 122
Author Index......Page 124
Subject Index......Page 130