Practical Guide to Rotational Moulding

Front cover
Half title
Title
Copyright
Contents
Preface
Chapter1 Introduction to the rotational moulding process
1.1 Introduction
1.2 The rotational moulding process
1.3 Overview of rotational moulding
1.4 Special nature of rotational moulding
1.5 Advantages of rotational moulding
1.6 Disadvantages of rotational moulding
1.7 Common applications for rotomoulded products
1.7.1 Material handling products
1.7.2 Industrial products
1.7.3 Environmental products
1.7.4 Leisure products
1.7.5 Marine products
1.7.6 Road signage
Chapter2 Rotational moulding moulds and tooling
2.1 Introduction
2.2 Mould materials
2.3 Sheet steel
2.4 Aluminium
2.4.1 The aluminium casting process
2.5 Electroformed nickel
2.6 Comparison between mould materials
2.7 Mould design
2.7.1 Mould frame
2.7.2 Moulded-in inserts
2.8 Moulded-in structural components
2.9 Temporary inserts
2.10 Threads
2.11 Mould clamps
2.12 Mould guides and hinges
2.13 Automatic mould movement
2.14 Mould venting
2.15 Automatic venting
2.16 Mould surface finish
2.17 Mould outer surface-heat transfer enhancement
2.18 Mould shielding (internal)
2.19 Mould shielding (external)
2.20 Mould release
2.20.1 Mould preparation for release agent
2.20.2 Reactive systems
2.20.3 Conventional systems
2.20.4 Permanent systems
2.20.5 Hybrid release systems
2.21 Moulding aids
2.22 Airflow amplification
2.23 Electrically heated moulds for rotational moulding
2.24 The use of internal mould cooling in rotational moulding
2.24.1 Material effects of differential cooling in rotational moulding
2.24.2 Rotocooler water spray system
2.24.3 The benefits of internal water spray cooling
2.25 Simulation of the rotational moulding process - Rotosim
Chapter3 Rotational moulding machinery
3.1 Introduction
3.2 Types of rotational moulding machines
3.2.1 Carousel machines
3.2.2 Shuttle machines
3.2.3 Clamshell machines
3.2.4 Rock and roll machines
3.2.5 Other types of machines
3.2.5 Hot oil rotational moulding machines
3.3 Mould swing
3.4 Mould speed
3.5 Speed ratio
3.6 Oven air flow amplification
3.7 Cooling
3.8 Material feed systems
3.9 Developments in machine control
3.10 Internal air temperature measurement in rotational moulding
3.11 Monitoring pressure inside a mould
Chapter4 Materials for rotational moulding
4.1 Introduction
4.2 Typical characteristics of rotationally moulded plastics
4.3 Materials used in rotational moulding
4.4 Polyethylene
4.4.1 Low-density polyethylene(LDPE)
4.4.2 High-density polyethylene(HDPE)
4.4.3 Medium-density polyethylene(MDPE)
4.4.4 Linear low-density polyethylene(LLDPE)
4.4.5 Metallocene polyethylene
4.4.6 Ethylene-vinyl acetate(EVA)
4.4.7 Ethylene-butyl acrylate(EBA)
4.5 Polypropylene(PP)
4.6 Polyamides(PA)
4.6.1 Polyamide 6(PA6)
4.6.2 Polyamide 11(PA11) and Polyamide 12 (PA12)
4.6.3 Reaction injection moulding polyamide
4.7 Amorphous materials
4.7.1 Polyvinyl chloride(PVC)
4.7.2 Fluoropolymers
4.8 Other plastics
4.9 Additives used in rotational moulding materials
4.9.1 Fillers
4.9.2 Plasticisers
4.9.3 Lubricants
4.9.4 Stabilisers
4.9.5 Antioxidants
4.9.6 Ultraviolet stabilisers
4.9.7 Flame retardants
4.9.8 Crosslinking agents
4.9.9 Foaming or blowing agents
4.9.10 Chemical blowing agent technology
4.10 Powders for rotational moulding - grinding/pulverising
4.10.1 Introduction
4.11 Particle size distribution
4.12 Dry flow
4.13 Bulk density
4.14 Factors affecting powder quality
4.14.1 Gap size
4.14.2 Number of mill teeth
4.14.3 Grinding temperature
4.15 Micropelletising
4.16 Colouring of plastics for rotational moulding
4.17 Types of pigments
4.17.1 Pigment selection criteria
Chapter5 Rotational moulding design for functionality
5.1 Introduction
5.2 Preliminary design considerations
5.3 Material
5.4 Number of parts
5.5 Size of moulds
5.6 Part complexity
5.7 Wall thickness distribution
5.8 Tolerances and shrinkage
5.8.1 Shrinkage guidelines
5.8.2 Control of shrinkage
5.8.3 Effect of release point on shrinkage
5.8.4 Other factors affecting shrinkage
5.9 Warpage
5.9.1 Control of warpage
5.10 Residual stress
5.10.1 Short-term effects of residual stresses
5.10.2 Long-term effects of residual stresses
5.10.3 Cures for residual stress problems
5.11 Stiffening of parts
5.12 Double walled parts
5.13 Corner radii
5.14 Draft angles
5.15 Surface quality
5.16 Surface texture
5.17 Graphics and surface decoration
5.17.1 Painting
5.17.2 Hot stamping
5.17.3 Adhesives
5.17.4 In-mould decoration
5.17.5 Post moulding decoration
5.18 Design of foamed sections
Chapter6 Rotational moulding industry – the future
6.1 Introduction
6.2 Rotomoulding Industry 4.0
6.2.1 Big data
6.2.2 Industrial robots
6.2.3 Process simulation and digital twins
6.2.4 Virtual reality and factory simulation
6.2.5 Smart Factories/lights out manufacturing
6.2.6 Internet of things and cyber security
6.2.7 The cloud
6.3 Material development
6.4 Rotational moulding mould and tooling development
6.5 Rotomoulding machine development
Index
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