DuPont Crastin PBT and Rynite PET thermoplastic polyester resins Moulding manual - TRP 30 Registered trademarks of E.I. du Pont de Nemours and Company The miracles of science is a trademark of E.I. du Pont de Nemours and Company Moulding manual for CRASTIN PBT and RYNITE PET Table of contents 1 General information . 3 1.1 Foreword . 3 1.2 Description . 3 1.3 Safety precautions . 3 1.4 Handling and preparation of materials . 4 1.4.1 Packaging . 4 1.4.2 Storage. 4 1.5 Environment and disposal of waste. 4 2 Drying principles. 5 2.1 Effects of moisture . 5 2.2 Moisture absorption. 5 2.3 Drying conditions. 6 2.4 Drying equipment. 6 3 Moulding. 7 3.1 Process. 7 3.1.1 Injection unit . 7 3.1.1.1 Screw. 7 3.1.1.2 Back flow valve. 7 3.1.1.3 Corrosion/abrasion . 7 3.1.1.4 Nozzles. 7 3.1.1.5 Accumulator for thin wall applications . 8 3.1.2 Start-up and shutdown procedures . 8 3.1.2.1 Purging . 8 3.1.2.2 Start-up. 8 3.1.2.3 Shutdown. 9 3.1.2.4 Interruptions . 9 3.2 Parameters . 9 3.2.1 Melt and cylinder temperature. 9 3.2.2 Cavity temperature . 10 3.2.3 Injection phase. 10 3.2.4 Hold pressure phase. 11 3.2.5 Screw retraction phase. 11 3.2.6 Processing recommendation table . 11 4 Mould. 13 4.1 Mould temperature control . 13 4.2 Mechanical structure . 14 4.3 Runner system and gate layout. 14 4.4 Hot runner. 15 4.5 Venting. 16 4.6 Draft angles . 16 4.7 Sharp corners. 16 5 Material behaviour. 19 5.1 Chemical structure. 19 5.2 Flow length. 19 5.3 Shrinkage. 21 5.4 Post-shrinkage . 22 6 Auxiliary operations. 23 6.1 Regrind. 23 6.2 Colouring. 23 We recommend that you refer to the injection moulding recommendations for CRASTIN and RYNITE on pages 34 and 35. 1 1 1.1 General information Foreword CRASTIN and RYNITE glass reinforced thermoplastic polyester resins are unique among polyester systems. These products contain uniformly dispersed glass fibres and/or other fillers, specially formulated for rapid crys- tallisation during the injection moulding process. This makes possible the production of high performance parts by conventional injection moulding techniques. In this brochure, general handling and processing tech- niques are discussed. 1.2 Description RYNITE thermoplastic polyester resins contain uniformly dispersed glass fibres or mineral/glass combinations in polyethylene terephthalate (PET) resin which has been specially formulated for rapid crystalllisation during the moulding process. RYNITE thermoplastic polyester resins have an outstanding combination of properties - high strength, stiffness, excellent dimensional stability, outstanding chemical and heat resistance and good electrical properties. RYNITE resins are noted for their excellent melt flow characteristics, close moulding tolerances and high productivity from multicavity moulding. The properties, processing characteristics and competitive price of RYNITE