Practical Guide to Rotational Moulding

Contents......Page 5
Preface......Page 9
1.1 Introduction......Page 13
1.2 The Rotational Moulding Process......Page 20
1.3 Overview of Rotational Moulding......Page 28
1.4 Special Nature of Rotational Moulding......Page 30
1.5 Advantages of Rotational Moulding......Page 32
1.6 Disadvantages of Rotational Moulding......Page 33
1.7.1 Material Handling Products......Page 34
1.7.3 Environmental Products......Page 35
1.7.5 Marine Products......Page 36
1.7.6 Road Signage......Page 37
2.1 Introduction......Page 41
2.3 Sheet Steel......Page 42
2.5 Electroformed Nickel......Page 43
2.6 Comparison Between Mould Materials......Page 44
2.7 Mould Design......Page 45
2.7.1 Mould Frame......Page 46
2.7.2 Moulded-in Inserts......Page 47
2.7.4 Temporary Inserts......Page 48
2.7.5 Movable Cores......Page 49
2.7.6 Threads......Page 50
2.7.7 Mould Venting......Page 51
2.7.8 Mould Surface Finish......Page 52
2.8.1 Mould Preparation for Release Agent......Page 53
2.8.2 Reactive Systems......Page 54
2.8.4 Permanent Systems......Page 55
2.9 Mould Cooling......Page 56
2.10 Mould Ancillaries......Page 59
2.11 Moulding Aids......Page 61
2.12 Kiss-Offs......Page 63
2.13 Calculation of Charge Weight......Page 64
3.2.1 Carousel Machines......Page 67
3.2.2 Shuttle Machines......Page 69
3.2.3 Clamshell Machines......Page 70
3.2.4 Rock and Roll Machines......Page 73
3.2.5 Other Types of Machines......Page 75
3.3 Mould Swing......Page 78
3.5 Speed Ratio......Page 80
3.6 Oven Air Flow Amplification......Page 81
3.8 Developments in Machine Control......Page 83
3.9 Internal Air Temperature Measurement in Rotational Moulding......Page 84
3.10 Preparation of Rotolog for Moulding Trials......Page 88
3.11 Monitoring Pressure Inside a Mould......Page 92
4.1 Introduction......Page 101
4.3 Materials Used in Rotational Moulding......Page 102
4.4 Polyethylene......Page 104
4.4.4 Linear Low Density Polyethylene (LLDPE)......Page 106
4.4.6 Ethylene-Vinyl Acetate (EVA)......Page 107
4.6.1 Nylon 6......Page 108
4.7.2 Fluoropolymers......Page 109
4.8 Other Plastics......Page 110
4.9.1 Fillers......Page 111
4.9.6 Ultraviolet Stabilisers......Page 112
4.9.9 Foaming Agents......Page 113
4.9.10 Pigments......Page 116
4.10.1 Introduction......Page 117
4.11 Particle Size Distribution......Page 123
4.12 Dry Flow......Page 124
4.13 Bulk Density......Page 126
4.14.1 Gap Size......Page 127
4.14.3 Grinding Temperature......Page 128
4.15 Micropelletising......Page 129
4.16 Colouring of Plastics for Rotational Moulding......Page 130
4.17 Types of Pigments......Page 133
5.2 Wall Thickness Distribution......Page 141
5.3.1 Shrinkage Guidelines......Page 145
5.3.2 Control of Shrinkage......Page 146
5.4 Warpage......Page 148
5.4.1 Control of Warpage......Page 149
5.5 Residual Stress......Page 152
5.5.1 Short-Term Effects of Residual Stresses......Page 154
5.5.2 Long-Term Effects of Residual Stresses......Page 155
5.6.1 Painting......Page 156
5.6.2 Hot Stamping......Page 157
5.6.4 In-Mould Decoration......Page 158
5.6.5 Post Moulding Decoration......Page 162
5.7 Foaming in Rotational Moulding......Page 163
5.7.1 Chemical Blowing Agent Technology......Page 165
5.7.2 Design of Foamed Sections......Page 166
5.7.4 Solid/Foam/Solid Cross-Sections......Page 168
6.1 Materials......Page 175
6.2 Moulds......Page 176
6.3 Moulding Equipment......Page 178
6.5 The Role that the Moulder Must Play......Page 180
6.6 The Role that the Suppliers Must Play......Page 181
Abbreviations and Acronyms......Page 183
Index......Page 185