DESIGN, ANALYSIS AND SIMULATION IN INJECTION IN-MOLD LABELING WERKZEUGAUSLEGUNG, ANALYSE UND SIMULATION DES IN-MOLD LABELING SPRITZGIEßENS Von der Fakultät Energie-, Verfahrens-, und Biotechnik der Universität Stuttgart zur Erlangung der Würde eines Doktor-Ingenieurs (Dr.-Ing.) genehmigte Abhandlung Vorgelegt von M.Sc. Patcharee Larpsuriyakul aus Bangkok, Thailand Hauptberichter: Prof. Dr.-Ing. H.-G. Fritz Mitberichter: Prof. Dr.-Ing. C. Merten Tag der mündlichen Prüfung: 26. März 2009 Institut für Kunststofftechnik der Universität Stuttgart 2009 2 Acknowledgements This Ph.D. dissertation was performed during my work as scientific coworker in the department of process analysis and modeling at the Institute of Plastics Technology (IKT), University of Stuttgart. My very first sincere thanks are given to Prof. Dr.-Ing. H.-G. Fritz, director of the institute and my supervisor, who not only accepted and gave me chances to conduct scientific works self-reliantly but also was abundantly helpful and offered invaluable assistance, support and guidance. It was my honor to be one of the institute members to work in an international environment on interesting projects under his supervision. Deepest gratitude is also given to Prof. Dr.-Ing. C. Merten for his revision of the dissertation. Special thanks go to Ligia Mateica and Lin Leyu, my diploma students at the IKT, who made a contribution to my experiments, and all the colleagues and technicians at the IKT for their supports, cooperation and good advices. As a scholar, I am very grateful to The Royal Thai Government and Land of Baden- Württemberg for granting me the financial support to do the Ph.D. in the field of polymer engineering in Germany. Eventually, I personally would like to thank my parents and my family for their encouraging and assistance during my long stay in Germany. Stuttgart, March 2009 Patcharee Larpsuriyakul 4 I Content List of Figures ........................................................................................................................ IV List of Tables........................................................................................................................ VII List of Symbols and Abbreviations ................................................................................... VIII Abstract ................................................................................................................................ XII Kurzfassung ........................................................................................................................ XIII 1 Introduction and Objectives ......................................................................................... 1 2 Fundamentals ................................................................................................................ 4 2.1 Injection Mold Design ....................................................................................... 4 2.1.1 Runner System Design .......................................................................... 6 2.1.2 Gate Design ........................................................................................... 9 2.1.3 Cooling System Design ....................................................................... 12 2.1.4 Design of Ejection ............................................................................... 17 2.1.5 Design of Venting ............................................................................... 18 2.1.6 Selection of Mold Materials ................................................................ 20 2.1.7 Part Shrinkage ..................................................................................... 20 2.2 Injection In-Mold Labeling ............................................................................ 22 2.2.1 A Brief History of IML ....................................................................... 22 2.2.2 Injection IML Process ......................................................................... 22 2.2.3 Key Label Properties ........................................................................... 24 2.2.4 Automation in IML ............................................................................. 25 2.3 Injection Molding Simulation ........................................................................ 28 2.3.1 Concept of the Hele-Shaw Model (2.5D Analysis)............................. 29 2.3.2 Concept of Solid Modeling (3D Analysis) .......................................... 31 2.3.3 Viscosity Models for Thermoplastics ................................................. 33 2.3.4 Thermal Equation of State................................................................... 35 2.3.5 Numerical Discretization Methods...................................................... 36 3 Flow Analysis and Simulation in Injection Molding based on the Double-Plated Part with Non-Uniform Part Thickness .................................................................... 41 3.1 Design of Experiments .................................................................................... 41 3.1.1 Part Geometry ..................................................................................... 41 3.1.2 Material Properties .............................................................................. 42 3.1.3 Machine Setting................................................................................... 44 3.1.4 Melt Pressure and Melt Temperature Detection by means of a Combined Pressure and Temperature Transducer .............................. 45 3.2 Simulation on a Basis of Surface Mesh (2.5D Simulation) .......................... 46 3.2.1 Discretization of the Model ................................................................. 46 3.3 Simulation on the Basis of Volume Mesh (3D Simulation) ......................... 48 II 3.3.1 Discretization of the Model ................................................................. 48 3.4 Simulation Parameters ................................................................................... 50 3.5 Simulation Results and Its Comparison with the Real Injection Molding Process .............................................................................................................. 50 3.5.1 Filling Analysis (Short-Shot Study) .................................................... 51 3.5.2 Course of the pressure ......................................................................... 63 3.5.3 Time/temperature Profiles ................................................................... 69 4 Design of an Injection Mold for Injection In-Mold Labeling ................................. 75 4.1 IML Part Geometry ........................................................................................ 75 4.2 Type of Mold .................................................................................................... 75 4.3 Runner Design ................................................................................................. 76 4.4 Gating ............................................................................................................... 77 4.5 Mold Cooling ................................................................................................... 77 4.6 Part Release/Ejection ...................................................................................... 78 4.7 Mold Venting ................................................................................................... 79 4.8 Label Insertion................................................................................................. 79 5 Simulation and Experimental Study on the Injection In-Mold Labeling Process 80 5.1 Simulation on the Injection In-Mold Labeling ............................................. 80 5.1.1 Mesh Generation ................................................................................. 80 5.1.2 Viscosity Model .................................................................................. 80 5.2 Experimental Study on the Injection In-Mold Labeling ............................. 81 5.2.1 IML Part Geometry ............................................................................. 81 5.2.2 In-mold Label Properties ..................................................................... 81 5.2.3 Design of Experiments ........................................................................ 83 6 IML-Simulation and Experimental Results .............................................................. 85 6.1 Melt Front Advancement................................................................................ 85 6.2 Course of the Pressure .................................................................................... 86 6.3 Temperature Profiles and Distributions ....................................................... 88 6.4 Structure of an Injected IML Part ................................................................ 90 6.5 Warpage of an Injected IML Part ................................................................. 95 6.6 Modulus of Elasticity .................................................................................... 106 III 7 Summary .................................................................................................................... 110 References ............................................................................................................................ 113 Appendix 1 Standard Components of an Injection Mold ................................ 118 Appendix 2 Description of the Simulation