Injection Moulding Materials

In order to make the subject manageable the term 'injection moulding' has been restricted in its use so that only those processes which rely on thermal softening of the polymeric materials have been described and discussed in this book. It is intended to discuss the subject of reaction injection moulding in a separate book. However, even with this omission, the subject is still a very large one as nowadays many sorts or types of polymers are injection moulded. For example, it is estimated that one-third of all plastics materials are injection moulded-the range of products produced is enormous and increases daily. Because most moulding materials are based on plastics, in particular thermoplastics, the materials guides which form a large part of this book concentrate on the moulding of thermoplastics materials. Such guides should only be treated as general guidelines as each of the materials is normally available in a wide range of grades. These may differ in polymer molecular weight, molecular weight distribution, the additives used and their concentration, the physical form of the moulding compound, etc. A wide range of processing behaviours and end-use properties is therefore possible from any of the materials listed. This versatility is typified by the rubbery polymers which are compounded into an incredibly wide range of compounds. Because of this versatility only a very general guideline has been given for such materials.

Contenu

1 Moulding Materials and Materials Handling.- 1. Introduction.- 2. Delivery of plastics.- 3. In-plant materials handling.- 4. Material reclamation.- 5. Drying.- 6. Mixing and blending.- 7. Colouring systems.- 2 Moulding Machines and Processes.- 1. Types of machine.- 2. Ram machines.- 3. Two-stage preplasticising systems.- 4. In-line preplasticising systems.- 5. Other machine types.- 6. Injection mould types.- 7. Alternative moulding techniques.- 8. Reaction injection moulding.- 3 Machine Specifications.- 1. Facts included.- 2. The injection unit.- 3. The clamping unit.- 4. The hydraulic system.- 5. Control and setting.- 6. Optional extras.- 7. Safety.- 8. Machine purchase.- 4 Component Finishing and Decoration.- 1. Flash removal and buffing.- 2. Machining of plastics.- 3. Metallisation.- 4. Printing on mouldings.- 5. Painting.- 6. Welding.- 7. Mechanical joining.- 8. Adhesive bonding.- 5 Effect of Processing on Properties.- 1. Introduction.- 2. General effect of orientation and crystallinity on properties.- 3. Mould filling, packing and stress relieving.- 4. Detection of orientation and crystallinity.- 5. Effect of moulding conditions on properties.- 6. Effect of changing gate size and position.- 7. Experiment design in injection moulding.- 8. Moulding quality and unknown changes.- 6 Testing and Quality Control.- 1. The object of testing.- 2. Standardisation.- 3. Common short-term tests.- 4. Long-term testing.- 5. Injection moulding of plastics test specimens.- 6. Quality control and testing.- 7 Material Recommendations for Injection Moulding.- 1. Polystyrene.- 2. Styrene acrylonitrile.- 3. Toughened polystyrene.- 4. Acrylonitrile-butadiene styrene.- 5. Acrylic.- 6. Unplasticised polyvinyl chloride.- 7. Plasticised polyvinyl chloride.- 8. Cellulosics.- 9. Polycarbonate.- 10. Polyethersulphone.- 11. Polyphenylene oxide (modified).- 12. Low density polyethylene.- 13. High density polyethylene.- 14. Polypropylene.- 15. Polybutylene terephthalate.- 16. Nylon.- 17. Acetals.- 18. Polyvinylidene fluoride.- 19. Polyphenylene sulphide.- 20. Rubber reinforced polypropylene.- 21. Thermoplastic polyurethane.- 22. SBS block copolymers.- 23. Thermoplastic polyetherester.- 24. Fibre reinforced thermoplastics.- 25. Structural foam.- 26. Aminoplastics.- 27. Phenolics.- 28. Dough moulding compound.- 29. Elastomers.- Appendix I Euromap documents.- Appendix II Troubleshooting.