Energy Reduction in the Pultrusion and the Rotational Moulding Processes A thesis submitted to University of Manchester for the degree of PhD in the Faculty of Engineering and Physical Sciences 2010 Wajid Ali Khan School of Mechanical Aerospace and Civil Engineering List of Contents List of Contents 2 List of Tables 7 List of Figures 8 List of Abbreviation 15 Abstract 16 Declaration 17 Copyright Statement 17 Acknowledgement 18 Chapter 1 19 1.1 Introduction 20 1.2 Objectives 22 1.3 Thesis Organization 24 Chapter 2 27 2 .1 Objectives 28 2.2 Introduction: Pultrusion Process 28 2.3 Machine Design 30 2.2.1 Pultrusion Die 32 2.2.2 Heating Mechanisms 33 2.4 Pultrusion Materials 34 2.3.1 Epoxy Resin 35 2.3.2 Polyester Resin 35 2.3.3 Vinyl ester Resin 36 2.3.4 Carbon Fibres 36 2.3.5 Glass Fibres 37 2.5 Pultrusion Applications 38 2.6 Literature Review 39 2.5.1 Heating and Curing 40 2 2.5.2 Materials 41 2.5.3 Pultrusion Modelling 42 2.7 Summary 43 Chapter 3 45 3 .1 Introduction 46 3.1.1 Heat Transfer and Chemical Cross-Linking 47 3.1.2 Curing Kinetics 49 3.2 Finite Difference Methods 50 3.2.1 The Nodal Network 51 3.3 Finite Difference Form of the Equations 52 3.3.1 Finite-Difference Solution of Differential Heat Equations 54 3.3.2 The Explicit Method 55 3.3.3 Heat Transfer on the Boundary 57 3.4 The Implicit Method 59 3.4.1 Heat Transfer across the Die and the Control Algorithm 60 3.5 The MATLAB Language 61 3.5.1 Programme for Calculation of Kamal’s Rate Equation 61 3.5.2 Programme for 4th Order Runge-Kutta Integration 63 3.5.3 Final Programme for Explicit Method 63 3.5.4 Final Programme for Implicit Method 67 3.5.5 Die Temperature Calculation 69 Chapter 4 70 4.1 Pultrusion Simulations 71 4.2 Temperature 79 4.3 Degree of Cure/Conversion 82 4.4 The Die Temperature 83 4.5 Simulations 87 4.5. The Boundary Conditions 88 1 4.5. Die Length and Line Speed 89 2 3 4.5. Charge Temperature and Die Length 90 3 4.6 Parametric study of the profile properties 91 4.7 Experimental Verification of Duty Cycle 95 4.8 Curing Calculations by DSC 100 4.9 Calculations of Specific Energy Consumption 97 4.10 Conclusion 106 Chapter 5 109 5 .1 Objectives 110 5.2 Project Plan 111 5.3 Heat Transfer Analysis 112 5.4 Knowledge Share 113 5.5 Rotomoulding: The Process 114 5.6 Process Fundamentals 115 5.6.1 Materials 118 5.6.1.1 Polyethylene 119 5.6.1.2 Polypropylene 122 5.6.2 Rotational Moulding Machines 123 5.6.2.1 Rock and Roll Machine 123 5.6.2.2 Clamshell Machine 123 5.6.2.3 Vertical Machine 124 5.6.2.4 Shuttle Machine 124 5.6.2.5 Fixed Arm Carousel Machine 124 5.6.2.6 Independent Arm Carousel Machine 125 5.6.2.7 Oil Jacketed Machine 125 5.6.2.8 Electrically Heated Machine 125 5.7 Literature Review 125 5.7.1 Cycle Time and Product Quality 126 5.7.2 Simulation of Rotomoulding Process and Materials 131 4 5.7.3 Modelling of the Process 134 5.8 Summary of Literature Review 136 Chapter 6 138 6 .1 Background and Objective 139 6.2 Mould Design 139 6.3 Aluminium Plate Heating Simulations 140 6.3.1 Meshing 142 6.3.2 Interaction Properties 143 6.3.3 Boundary Conditions 145 6.3.4 Thermal Loads 145 6.4 Aluminium Plate Model 147 6.4.1 Results of Aluminium Plate Analysis 152 6.4.1.1 Simulations with Moving Jet of Hot Air 174 6.4.1.2 Comparison of Moving Source and Static Heaters 179 6.4.1.3 Radiation Factor 179 6.4.2 Simulations with Polymer Powder Added 181 Chapter 7 188 7 .1 Objectives 189 7.2 Measurement of Baseline Energy Consumption 189 7.3 Fuel Consumption Measurements 192 7.4 Pins Installation 197 7.5 Process Modifications 202 7.6 Temperature Measurements for Aluminium Plate Model 204 7.7 Importance of Uniform Heat Distribution 212 7.8 Specific Energy Consumption with Direct Heating 214 Chapter 8 219 8 .1 Project Summary 220 8.2 Conclusion about Pultrusion 220 8.3 Recommendations and Future Work on the Pultrusion 223 5 8.4 Conclusion Rotational Moulding Part 224 8.5 Future Work: The Rotational Moulding 226 8.6 Publications 227 Appendices 228 A1 Chemical Reaction and Kamal’s Equation 229 A2 MATLAB Programme for Calculation of Kamal Rate Equation 235 A3 MATLAB Programme for 4th Order Runge-Kutta Integration 235 A4 Final Programme for Explicit Method 235 A5 Final Programme for Implicit Method 237 B1 Finite Element Modelling and ABAQUS 240 B2 User Subroutine DFLUX 249 B3 An Example Input File for Abaqus Finite Element Analysis 251 References 253 Total Words 54382 6 List of Tables Table 3.1 Coefficients of Kamal’s and Arrhenius Equations 62 Table 3.2 Different Parameter Values used in Main Programme 64 Table 4.1 Die Lengths, Line Speed and Charge Temperatures for 90 90% Curing Table 4.2 SEC Comparison for different line speeds and pre- 105 heaters Table 5.1 Uses of Rotational Moulding Products 117 Table 5.2 Melt Temperatures of some common thermoplastics 122 Table 7.1 Base Line Energy Consumption 196 Table 7.2 Properties of the Materials used in moulding 216 7 List of Figures Figure 2.1 A Schematic Pultrusion Line 30 Figure 2.2 Fibres pulled from creels and passing through resin bath 31 Figure 2.3 (a) Pre-former (b) Die Entrance 32 Figure 2.4 Pultrusion Die 32 Figure 3.1 A Schematic Nodal Network 51 Figure 3.2 The Finite Difference Approximation 53 Figure 3.3 Surface Nodes with Convection and Transient 58 Conduction Figure 3.4 Programme Algorithm for MATLAB Programme of 66 explicit solution Figure 3.5 Programme Algorithm of MATLAB Programme of 68 Implicit solution Figure 4.1 (a)Temperature at Boundary Slice(b) Temperature at 73 Centre Slice Figure 4.2 (a)Conversion at the Boundary Slice(b) Conversion at 74 Centre Slice Figure 4.3 (a)Temperature at Boundary(b) Temperature at Centre 75 Figure 4.4 (a) Conversion at Boundary (b) Conversion at Centre 76 Figure 4.5 (a)Conversion at Boundary(b) Conversion at Centre 77 Figure 4.6 (a)Conversion at Boundary(b) Conversion at Centre 78 Figure 4.7 Die Temperature variations with time at different line 84 speeds Figure 4.8 Die Temperature variations with time at line speed 1/min 84 for multiple cycles Figure 4.9 Duty Cycle of Power Heaters at 0.2m/min 85 Figure 4.10 Duty Cycle for one Heater at 1m/min 85 Figure 4.11 Die Temperature variation for Figure 4.10 Duty cycle 86 Figure 4.12 Die Length vs Temp for Different Line Speeds 91 Figure 4.13 Temperature variations at 0.2m/min with variations in 93 Specific Heat Capacity 8 Figure 4.14 Exothermic reaction variations with density variations at 94 0.2m/min Figure 4.15 Exothermic reaction variations with thermal conductivity 95 variations at 0.2 m/min Figure 4.16 The Fluke Pr 20 Multimetre 96 Figure 4.17 The Pultrusion Machine with Oscilloscope 97 Figure 4.18 Recording of the duty cycle 95 Figure 4.19 The Perkin Elmer Jade DSC Machine 100 Figure 4.20 DSC curve at 50°C/min for first heating 101 Figure 4.21 DSC curve at 50°C/min for second heating after the 101 cooling stage Figure 4.22 Profile Exit Temperature 102 Figure 5.1 Principle of Rotational Moulding 115 Figure 6.1 Specific heat, latent heat definitions 141 Figure 6.2 (a) Mould (b) Mould in wireframe 142 Figure 6.3 (a) Meshed Model (b) Meshed Model in wireframe 143 Figure 6.4 3-D Model of Aluminium Plate with dimensions 150 Figure 6.5 Meshed Aluminium Plate 151 Figure 6.6 Two heaters shown with heat flux as load 151 Figure 6.7 Aluminium Plate heated with one 220W heater in the 152 centre for 5 minutes Figure 6.8 Aluminium Plate with Paths 1 and 2 heated for 5 minutes 153 and cooled for 2 minutes after that with one heater. Figure 6.9 Temperature distributions along Path-1 (as shown in Fig 153 6.8) after 5 minutes of heating Figure 6.10 Temperature distributions along Path-2 (as shown in Fig 154 6.8) after 5 minutes of heating Figure 6.11 Temperature distributions along Path-1 (as shown in Fig 154 6.8) after 5 minutes of heating and 2 minutes of cooling Figure 6.12 Temperature distributions along Path-2 (as shown in Fig 155 6.8) after 5 minutes of heating and two minutes cooling 9 Figure 6.13 Temperature distributions along Path-1 (as shown in Fig 155 6.8) after 5 minutes of heating and two minutes cooling Figure 6.14 Temperature Distribution and Paths 1 and 2 with two 156 heaters after 5 minutes of heating Figure 6.15 Temperature distributions along Path-1 (as shown in Fig 157 6.14) after 5 minutes of heating Figure 6.16 Temperature distributions along Path-2 (as shown in Fig 157 6.14) after 5 minutes of heating Figure 6.17 Temperature Distribution and Paths 1 and 2 with two 158 heaters after 5 minutes of heating and 2 minutes cooling Figure 6.18 Temperature distributions along Path-1 (as shown in Fig 158 6.17) after 5 minutes of heating and 2 minutes cooling Figure 6.19 Temperature distributions along Path-2 (as shown in Fig 159 6.17) after 5 minutes of heating and 2 minutes cooling Figure 6.20 Temperature distributions along Path-2 (as shown in Fig 159 6.17) after 5 minutes of heating and 2 minutes cooling Figure 6.21 Temperature Distribution and Paths 1 and 2 with three 160 heaters after 5 minutes of heating Figure 6.22 Temperature distributions along Path-1 (as shown in Fig 160 6.21) after 5 minutes of heating Figure 6.23 Temperature distributions along Path-2 (as shown in Fig 161 6.21) after 5 minutes of heating Figure 6.24 Temperature Distribution with three heaters after 5 161 minutes of heating and two minutes of cooling Figure 6.25 Temperature distributions along Path-1 (as shown in Fig 162 6.24) after 5 minutes of heating and two minutes cooling Figure 6.26 Temperature distributions along Path-2 (as shown in Fig 162 6.24) after 5 minutes of heating and two minutes cooling Figure 6.27 Temperature distributions along Path-2 (as shown in Fig 163 6.24) after 5 minutes of heating and two minutes cooling(same scale as of Fig 6.23) Figure 6.28 Temperature Distribution and Paths 1 and 2 with four 163 heaters after 5 minutes of heating 10