Handbook of troubleshooting plastics processes : a practical guide
Contents
1. Parting Line 16 4 5 Bubbles on Part Surface or in the Cross section 16 4 6 Coining Pockmarks 16 4 7 Color Part Burned Discolored 16 4 8 Color Static Swirl 16 4 9 Color Unevenness 16 4 10 Flash at the Parting Line 16 4 11 Foaming Coarse or Uneven Foam 16 4 12 Foaming Gaps in Wall Cross section 16 4 13 Foaming Part Deformation 16 4 14 Incomplete Material Fusion 16 4 15 Incomplete Mold Fill Bridging 16 4 16 Low Impact Strength 16 4 17 Low Part Stiffness 16 4 18 Long Oven Cycle 16 4 19 Long term Part Failure 16 4 20 Mold Distortion Explosion 319 319 319 319 320 324 325 327 328 328 330 330 331 16 4 21 Plate Out 16 4 22 Sticking in Mold 16 4 23 Wall Thickness Uneven 16 4 24 Warpage 16 4 25 Whitish Part Appearance 17 Plastics Calendering Chellappa Chandrasekaran 18 17 1 17 2 17 3 17 4 17 5 17 6 17 7 17 8 17 9 Introduction Blending and Fluxing Mills and Strainers Calender General Description of a Calendering Machine 17 5 1 Rolls 17 5 2 Sheet Finishes 17 5 3 Roll Contours 17 5 4 Frame 17 5 5 Roll Adjustment 17 5 6 Bed Plate 17 5 7 Lubrication 17 5 8 Temperature Control 17 5 9 Safety and Safety Regulations The Calendering Process 17 6 1 Heating and Delivery to the Calender 17 6 2 Roll Banks 17 6 3 Sheet Takeoff and Post processing 17 6 4 Embossing and Laminating Input Materials and Products 17 7 1 The Formulas Why Calendering is Preferred to Extrus2. 157 157 158 159 159 160 162 164 164 CONTENTS 10 Troubleshooting the Thermoforming Process 11 James L Throne 10 1 General Concepts in Thermoforming 10 2 Categorization of the Process 10 2 1 Thick Gauge Process 10 2 2 Thin Gauge Process 10 3 Specific Aspects of the Thermoforming Process 10 3 1 Critical Material Issues 10 3 2 Molds and Mold Design 10 3 3 Incoming Sheet Quality Issues 10 3 4 Materials Handling Ingress 10 3 5 Heating 10 3 6 Pre stretching Plug Assist 10 3 7 Pre stretching Vacuum Air Pressure Formation 10 3 8 Contacting the Mold 10 3 9 Cooling and Rigidifying the Formed Part 10 3 10 Removing the Formed Part from the Mold 10 3 11 Materials Handling Egress 10 3 12 Trimming 10 3 13 Post trimming Issues 10 3 14 Regrind 10 4 Problem Solving Methodology 10 4 1 Trimming 10 5 General Preventative Maintenance Concepts 10 5 1 Crisis Maintenance 10 5 2 Routine Maintenance 10 6 General Predictive Maintenance Concepts 10 7 Safety during Troubleshooting 10 7 1 Make up of a Troubleshooting Team Appendix 1 Thermoforming References with Troubleshooting Sections Appendix 2 Plastic Materials References Appendix 3 Troubleshooting Guidelines for Thick Gauge Thermoforming Appendix 4 Troubleshooting Guidelines for Thin Gauge Thermoforming Appendix 5 Time dependent Ranking of Typical Courses of Action Appendix 6 Troubleshooting Guidelines for Trimming Parts Thin Gauge Thick Gauge Proper Equipment Processing
3. Wound Roll Appearance 8 3 14 Edge Tear Unstable Edges 8 3 15 Pin Holes 8 3 16 Extruder Surging 8 3 17 Draw Resonance 8 3 18 Film Discoloration 8 3 19 Poor Heat Seal Strength 8 3 20 Odor Flavor Scalping 8 3 21 Poor Strength 8 3 22 Film Blocking 8 3 23 Poor Printability 8 3 24 Camber or Curl 8 3 25 Scratches References Oriented Films Troubleshooting and Characterization Eldridge M Mount II 9 1 9 2 9 3 9 4 9 5 9 6 Introduction Process Overview Biaxial Orientation Oriented Film Markets 9 3 1 Oriented Polypropylene OPP or BOPP 9 3 2 Oriented Polyester OPET 9 3 3 Oriented Polystyrene OPS 9 3 4 Oriented Polyamide Nylon OPA Troubleshooting the Film Orientation Process as Applied to OPP Films 9 4 1 Control Variables 9 4 1 1 Resin Drying 9 4 1 2 Extrusion 9 4 1 3 Casting and Pinning 9 4 1 4 Machine Direction Orientation 9 4 1 5 Transverse Direction Orientation 9 4 1 6 Web Handling and Surface Treatment 9 4 1 7 Winding 9 4 2 Noise Variables 9 4 3 Dependent Variables Special Tools for Troubleshooting Case Studies 9 6 1 Casting Capacity Limitation in PET Film Production 9 6 2 Floating Gauge Extrusion Instability and MDO Heat Transfer Limitations 9 6 3 Output Limitation from CoextrusionInstability References Bibliography 124 125 125 126 126 127 127 128 128 129 129 129 129 130 130 131 131 131 133 133 134 141 141 143 144 145 146 146 146 147 149 153 153 156 156
4. 10 14 3 13 Poor Wound Roll Appearance 311 14 3 14 Edge Tear Unstable Edges 311 14 3 15 Pin Holes 312 14 3 16 Extruder Surging 312 14 3 17 Draw Resonance 312 14 3 18 Poor Heatseal 313 14 3 19 Odor Flavor Scalping 313 14 3 20 Poor Printability 313 14 3 21 Camber or Curl 314 14 3 22 Scratches 314 References 314 Part 3 Non extrusion Processes 315 15 Adhesive and Thermal Lamination 317 Tom Dunn 15 1 Introduction 317 15 1 1 Process Overview 317 15 1 2 Markets Served 318 15 1 3 Historical and Future Growth Projections Technology Challenges and Threats 318 xii 16 CONTENTS 15 2 Process Description 15 2 1 Major Process Components 15 2 2 Equipment Production Ranges 15 2 3 Manufacturers 15 3 Control Variables 15 4 Random Cause Variables 15 5 Dependent Variables 15 6 Special Tools for Troubleshooting 15 6 1 Product 15 7 Case Studies 15 7 1 Easy peel or Rip off 15 7 2 Spotty Results Bibliography Troubleshooting for Rotomolding Paul Nugent 16 1 The Basic Process 16 2 Key Quality Control Steps in Rotomolding 16 2 1 Materials In bound and Powder Preparation 16 2 2 Colorants and Additives 16 2 3 Material Mixing 16 2 4 Molds and Fixtures 16 2 5 Machinery 16 2 6 Calibration 16 2 7 Production Process and Records 16 3 Typical Rotomolding Problems 16 4 Typical Solutions 16 4 1 Adhesion Difficulty in Painting or Applying Labels 16 4 2 Blowholes Around Inserts 16 4 3 Blowholes Other Areas 16 4 4 Blowholes
5. 3 Future Trends 19 9 4 Fundamentals References Pultrusion Process Troubleshooting Joseph E Sumerak 20 1 20 2 Introduction 20 1 1 Pultruded Products are Governed by a Performance Specification Materials Review 20 2 1 Resin 20 2 2 Resin Reactivity 20 2 3 Resin Reactivity Measurement 20 2 4 Resin Viscosity 20 2 5 Reinforcements Process Parameters 20 3 1 Composition and Process Specification 397 397 398 399 400 400 401 401 402 402 402 403 404 404 405 405 405 407 407 409 410 410 411 412 414 415 416 417 21 CONTENTS 20 4 Manufacturing Defects 20 4 1 Defects 20 5 Material Related Defects 20 5 1 Resin 20 5 2 Reinforcements 20 6 Process Parameter Related Defects 20 7 Methods Related Defects 20 8 The Troubleshooting Process 20 8 1 Subjective versus Objective 20 8 2 Visual Tools 20 8 3 On Line Quantitative Analysis Tools 20 8 4 Off Line Quality Assessment Tools 20 9 Troubleshooting Examples 20 10 Summary Acknowledgement References Troubleshooting Static Problems in Plastics Processes Kelly Robinson 21 1 21 2 21 3 Introduction 21 1 1 Nature and Character of Static 21 1 2 Cost of Static Problems Root Causes of Static 21 2 1 Tribocharging Contact Charging 21 2 1 1 Triboelectric Series 21 2 2 Application of the Triboelectric Series 21 2 3 Charge Induction 21 2 4 Ionizer Imbalance Active Charging Static Measurement Tools 21 3 1 Electrostatic Fieldmeters FMs and Non Con
6. Handbook of Troubleshooting Plastics Processes A Practical Guide Edited by John R Wagner Jr Scrivener G WILEY Contents Preface xvii List of Contributors xix Part 1 Troubleshooting Basics 1 1 The Economics of Troubleshooting Polymer Processing Systems 3 Mark D Wetzel 1 1 Introduction 3 1 2 Economic Incentives and Necessities 4 1 3 Troubleshooting Resources and Their Cost 6 1 4 Managing Resources and Costs 1 1 5 Troubleshooting Techniques and Their Relative Costs 12 1 6 Case Histories 14 1 6 1 Single Screw Extrusion Instability 14 1 6 2 Compounding Extruder Catastrophic Failure 14 1 6 3 Polymer Degradation During Melt Processing 16 1 7 Conclusions 2 References 20 2 Troubleshooting Philosophy 21 John R Wagner Jr 2 1 Introduction 21 2 2 Troubleshooting Methodology 23 Bibliography 25 3 Statistical Tools for Trouble Shooting a Process 27 Vincent Vezza 3 1 Introduction 27 3 2 Basic Statistical Concepts 28 3 2 1 Histogram 28 3 2 2 Scatter Diagram 28 3 3 Sample Mean and Standard Deviation 29 3 4 Design of Experiments DOE 31 3 4 1 Factorial Design 3 3 4 2 Fractional Factorial Design 34 3 5 Process Capability 37 3 6 Control Charts 38 3 7 1 Central Limit Theorem 39 3 7 2 Variable Data Control Charts 4 3 7 3 Control Charts for Attribute Data 43 vi CONTENTS References Bibliography Statistics Design of Experiments Statistical Process Control Part 2 Extrusion Processes 4 Single Screw Extrusio
7. for Industrial Technical Blow Molding Robert A Slawska 11 1 Introduction of Blow Molding 11 1 1 How Parts are Blow Molded 11 1 2 Positive Benefits of the Process 11 1 3 Negative Factors of Accumulator Head Blow Molding 11 2 Select the Proper Equipment 11 3 Extruder 11 4 Accumulator Head 11 5 Importance of Cleaning ix 167 167 169 169 170 172 172 173 174 174 175 176 176 176 177 178 178 178 179 180 180 182 183 184 184 187 188 192 193 193 194 199 209 210 210 213 217 218 218 219 219 220 222 225 226 xX 12 13 CONTENTS 11 6 Press 11 7 Hydraulics 11 8 Microprocessor 11 9 Pneumatic Systems 11 10 Part Take Out System 11 11 Selection of Equipment PET Stretch Blow Molding Dan Weissmann 12 1 Introduction 12 2 The PET Universe 12 3 Technology History 12 4 PET Chemistry 12 5 PET Morphology 12 6 Bottle Universe 12 7 Bottle Manufacturing 12 8 Commercial Manufacturing Processes 12 9 Process Elements 12 9 1 Injection Molding 12 9 1 1 IV Drop 12 9 1 2 Acetaldehyde 12 9 1 3 Molding Stresses 12 9 2 Hot Runner System 12 9 2 1 Gate Crystallinity and Separation 12 9 2 2 Gate Pin Holes 12 9 3 Mold Cooling 12 9 3 1 Preform Problem Analysis 12 9 4 Blow Molding 12 9 4 1 General Principles Reheating and Preform Temperature 12 9 5 Preform Temperature Profiling 12 9 6 Blowing 12 9 6 1 Quality Attributes and Performance Issues 12 9 6 2 Blow Molding Process Monitoring 12 9 6 3 On Line Ins
8. ion Calendering Process Variables 17 9 1 Barring and Noise Due to Roll Vibration 17 9 2 Machine Dependent Variable 17 9 3 Product Variation 17 9 4 Overcoming and Correcting Process Variation 17 10 Conclusion References Bibliography Compression Molding Muralisrinivasan Natamai Subramanian 18 1 18 2 Introduction Materials 18 2 1 Thermoplastics and Compression Molding 18 2 2 Thermosets and Compression Molding 18 2 3 Premix or Prepreg Preparation 18 2 4 Fiber Alignment CONTENTS xiii 358 359 360 360 361 363 363 364 365 365 367 307 368 369 370 370 370 371 371 372 372 373 373 374 374 375 375 377 377 377 378 379 381 381 382 382 383 383 384 384 385 386 386 xiv CONTENTS 19 20 18 2 5 Pre form 18 2 6 Prepreg 18 3 Sheet Molding Compound Production 18 3 1 Mold 18 4 Technology Compression Molding 18 4 1 Important Variables during Processing 18 5 Troubleshooting 18 6 Problems and Solution s 18 7 Summary 18 7 1 Fundamentals 18 7 2 Advantages 18 7 3 Disadvantages 18 7 4 Future Trends References Transfer Molding Muralisrinivasan Natamai Subramanian 19 1 Introduction 19 2 Curing 19 3 Processing 19 4 Mold 19 5 Process Optimization 19 6 Method 19 7 Pot Type Transfer Molding 19 7 1 Plunger Transfer Molding 19 7 2 Screw Type Transfer Molding 19 7 3 Screw Injection Type 19 8 Troubleshooting 19 9 Summary 19 9 1 Advantages 19 9 2 Disadvantages 19 9
9. n John R Wagner Jr 4 1 Introduction 4 2 Process Description References Troubleshooting the Co rotating Fully Intermeshing Twin screw Compounding System Paul Andersen Rich Kanarski and John R Wagner Jr 5 1 Introduction 5 2 Equipment Description 5 3 Troubleshooting 5 3 1 What is Troubleshooting 5 4 Tools of the Successful Troubleshooter 5 4 1 Experience 5 4 2 Vent Flow Problem 5 5 Product Process and Equipment Knowledge 5 5 1 High Discharge Pressure Problem 5 5 2 Barrel Temperatures Higher than Set Points Problem 5 5 3 Climbing Discharge Temperature Problem 5 5 4 Gels and Un melts in the Extrudate Problem 5 5 5 Holes or Bubbles in the Extrudate Problem 5 5 6 Process Surging Problem 5 6 Conclusion References Troubleshooting for Injection Molding James J Wenskus 6 1 Introduction 6 1 1 The Basic Approach 6 2 Understanding Temperature Control 6 3 Product Shift to a Different Machine 6 3 1 Calculate the New Pressure Settings 6 3 2 Procedure 6 4 Part Weight as an Analytical Tool 6 4 1 Example Part Weight for Process Variability Analysis 6 4 2 Long Term Variability Analysis 6 4 3 Short Term Variability Analysis 6 4 4 Variability Evaluation 6 4 5 Process Benchmarking for Quality 6 4 6 Benchmark Evaluation 6 4 7 Summary CONTENTS vii 6 5 Part Weight as Dimensional Aimpoint Control 79 6 5 1 Unconstrained Process 80 6 5 2 Partially Constrained Process 8I 6 5 3 Constrained Process 82 6 5 4 Warpage 82 6 5 5 Relationshi
10. p of Shot Weight and Hydraulic Pressure 84 6 6 Determining the Gate Freeze Off Time 85 6 6 1 Procedure to Determine the Freeze Off Point 86 6 6 2 Time Analysis 86 6 6 3 Pressure Procedure 86 References 88 Blown Film 89 Karen Xiao and Steve Gammell 7 1 Introduction 89 7 2 Process Description 92 7 2 1 Extruders 94 7 2 2 Dies 94 7 2 3 Process Cooling 97 7 2 4 The Bubble Collapsing Process and Systems 98 7 2 5 Haul Off Primary Nip 99 7 2 6 Film Winding 101 7 2 6 1 Center drive Winder 102 7 2 6 2 Surface Winders 102 7 3 Special Tools for Troubleshooting 105 7 3 1 Winding Systems 108 7 4 Case Studies 109 7 4 1 Case Study 1 Carbon Buildup 109 7 4 2 Case Study 2 Poor Gauge Uniformity 110 References 111 Cast Film Troubleshooting 113 Andrew W Christie and Beth M Foederer 8 1 Coextrusion Film Systems 113 8 2 Troubleshooting Method 114 8 2 1 The Problem Statement 115 8 2 2 The Hypothesis 115 8 2 3 Testing the Hypothesis 116 8 2 4 Evaluating the Results 117 8 3 Common Problems Hypotheses and Tests 117 8 3 1 Gels in Film 117 8 3 2 Film Clarity 120 8 3 3 Wrinkling 120 8 3 4 Inability to Reach Output 121 8 3 5 Poor Melt Mixing 122 8 3 6 Melt Temperature Too Low 123 8 3 7 Melt Temperature Too High 123 8 3 8 Extruder Power Insufficient 124 viii CONTENTS 8 3 9 Film Streaks or Lines 8 3 10 Melt Appearance Defects 8 3 11 Thickness Variation Cross Direction 8 3 12 Thickness Variation Machine Direction 8 3 13 Poor
11. pection 12 9 6 4 Testing and Test Procedures 12 9 6 5 Special Processes 12 10 Case Sample Thermal Stability Failure of CSD Bottles References Blow Molding Problems and Solutions Norman C Lee 13 1 Introduction 13 2 Troubleshooting 13 3 Variables Affecting the Blow Molding Process 13 3 1 PART 1 Defects in Article 13 3 1 1 PART I Defect in Finished Article 13 3 2 PART II Parison Defects 13 3 2 1 PART II Defects of the Parison 229 230 232 233 233 234 237 281 281 282 283 284 284 289 289 CONTENTS Xi 13 3 3 Noise 293 13 3 4 Ambient Conditions 293 13 4 Preventative Maintenance 293 13 4 1 Maintenance Recommendations 293 13 4 2 Machine Check Out 294 13 5 Injection and Stretch Blow Molding 294 13 6 Computer Integrated Manufacturing CIM in Extrusion Blow Molding 295 Acknowledgement 207 Bibliography 298 14 Extrusion Coating Troubleshooting 299 Beth M Foederer and Andrew W Christie 14 1 Coextrusion Extrusion Coating Laminating Systems 299 14 2 Troubleshooting Method 300 14 3 Common Problems Hypotheses and Tests 301 14 3 1 Gels in Film 301 14 3 2 Poor Adhesion 304 14 3 3 Wrinkling 305 14 3 4 Low Output 306 14 3 5 Poor Melt Mixing 307 14 3 6 Melt Temperature Too Low 308 14 3 7 Melt Temperature Too High 308 14 3 8 Extruder Power Insufficient 309 14 3 9 Die Lines 309 14 3 10 Melt Appearance Defects 309 14 3 11 Thickness Variation Cross Direction 310 14 3 12 Thickness Variation Machine Direction 3
12. stem Maintenance 21 5 2 1 21 5 2 2 21 5 2 3 21 5 2 4 21 5 2 5 21 5 2 6 21 5 2 7 21 5 2 8 21 5 2 9 21 5 2 10 21 5 2 11 21 5 2 12 21 5 2 13 21 5 2 14 Clean Static Bars Replace Ionizing String Verify Gaps Verify Performance Clean Rollers Belts and Guides Restore Surfaces of Tacky Cleaning Rollers Check the Electrical Resistivity of Static Dissipative Rollers Test the Bearing Drag on Low Wrap Rollers Align Roller Nip Pressure Lay on Rollers Web Tension Winding Tension Profile Humidifier Maintenance 21 5 3 Conductive Layers in Products References Recommended Reading for Further Study
13. tacting Electrostatic Voltmeters ESVMs 21 3 1 1 Electrostatic Fieldmeters Fieldmeters Respond to Net Charge 21 3 1 2 Non contacting Electrostatic Voltmeter Voltmeters Respond to Surface Charge 21 3 1 3 Spatial Resolution and Response Time 21 3 1 4 Typical Applications Monitor Static Performance with Fieldmeters and Voltmeters 21 3 2 Charge Meter Coulomb Meters are a Direct Measure of Charge 21 3 2 1 Principles of Operation 21 3 2 2 Typical Applications 21 3 3 Resistivity Meters 21 3 3 1 Volumetric Resistivity Meters 21 3 3 2 Surface Resistivity Meters 21 3 4 Charge Dissipation Time Measurements 21 3 4 1 Importance of Charge Dissipation Time 21 3 4 2 Principles of Operation Static Dissipation Time 21 3 4 3 Typical Application Static Dissipation Time XV 417 417 419 419 420 429 420 429 429 430 434 435 438 438 439 439 441 44 44 442 443 443 444 445 446 446 447 447 447 448 450 451 455 455 456 457 457 460 463 463 463 464 xvi CONTENTS 21 4 Static Problem Diagnosis 21 4 1 Understand the Problem 21 4 2 Baseline Data and Control Charts 21 4 3 Hot Rolls 21 4 4 Static Specifications 21 5 Solving Static Problems 21 5 1 Locate the Source of Charge Separation 21 5 1 1 21 5 1 2 21 5 1 3 21 5 1 4 21 5 1 5 21 5 1 6 Unwinding Roll Drive Roller Coater Backing Roller Dryer Conveyance Rollers Dryer Exit Nip Roller Winder Lay on Roller 21 5 2 Static Control Sy
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