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عدد المساهمات : 18996 التقييم : 35494 تاريخ التسجيل : 01/07/2009 الدولة : مصر العمل : مدير منتدى هندسة الإنتاج والتصميم الميكانيكى
| موضوع: كتاب Robust Process Development and Scientific Molding الثلاثاء 10 سبتمبر 2019, 11:02 pm | |
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أخوانى فى الله أحضرت لكم كتاب Robust Process Development and Scientific Molding 2nd Edition Theory and Practice Suhas Kulkarni
و المحتوى كما يلي :
Contents Preface to the Second Edition . VII Preface to First Edition IX 1 Introduction to Scientific Processing 1 1.1 The Evolution and Progress of Injection Molding 1 1.2 The Molding Process 2 1.3 The Three Types of Consistencies Required in Injection Molding . 2 1.4 Scientific Processing 6 1.5 The Five Critical Factors of Molding . 7 1.5.1 Part Design . 8 1.5.2 Material Selection . 8 1.5.3 Mold Design and Construction . 9 1.5.4 Machine Selection 9 1.5.5 Molding Process . 9 1.6 Concurrent Engineering . 10 1.7 Variation 10 2 Properties of Polymers and Plastics That Influence Injection Molding . 13 2.1 Polymers 13 2.2 Molecular Weight and Molecular Weight Distribution 15 2.3 Polymer Morphology (Crystalline and Amorphous Polymers) 17 2.4 Role of Morphology in Injection Molding . 22 2.4.1 Differences in Shrinkage between Amorphous and Crystalline Materials . 22 2.4.2 Melt Processing Range 22 2.4.3 Mold Filling Speed . 23XIV Contents 2.4.4 Mold Temperatures 24 2.4.5 Barrel Heat Profile . 24 2.4.6 Screw Recovery Speeds . 25 2.4.7 Nozzle Temperature Control . 25 2.4.8 Cooling Times . 26 2.4.9 Mechanical Properties 26 2.4.10 Optical Clarity . 26 2.5 Exceptions of Morphology Rules to Polyolefins . 27 2.6 Thermal Transitions in Polymers 28 2.6.1 Relationship between the Glass Transition Temperature and Post Mold Shrinkage 32 2.7 Shrinkage of Polymers in Injection Molding . 36 2.8 The Plastic Pressure–Volume–Temperature (PVT) Relationship 39 2.8.1 Importance of Plastic Density in Injection Molding 40 2.8.2 Residence Time and Maximum Residence Time of a Plastic . 41 2.8.3 Plastic Datasheets 43 2.9 References 45 3 Polymer Rheology . 47 3.1 Viscosity 47 3.2 Newtonian and Non-Newtonian Materials . 49 3.3 Viscosity in Polymer Melts . 50 3.4 Effect of Temperature on Viscosity . 54 3.5 Velocity and Shear Rate Profiles . 55 3.6 Application to Injection Molding 56 3.6.1 Flow Imbalance in an 8-Cavity Mold 57 3.6.2 Racetrack Effect in a Part with Constant Thickness . 59 3.6.3 Stress Build-Up in Molded Parts . 59 3.6.4 Warpage Difference between Cavities . 60 3.7 Solving Flow Imbalances Using Melt Rotation Techniques 60 3.8 Fountain Flow 62 3.9 Effect of Fountain Flow on Crystallinity, Molecular Orientation, and Fiber Orientation 65 3.10 Characterization of Polymer Viscosity . 66 3.11 References . 67Contents XV 4 Plastic Drying . 69 4.1 Problems in Melt Processing Related to the Presence of Moisture 71 4.1.1 Degradation of Plastic 71 4.1.2 Presence of Surface Defects 71 4.2 Hygroscopic Polymers 75 4.3 Drying of Plastics . 77 4.3.1 Drying Temperatures and Times . 77 4.3.2 Relative Humidity and Dew Point 79 4.3.3 Air Flow Rate . 80 4.4 Equipment for Drying Plastics 80 4.4.1 Oven Dryers 80 4.4.2 Hot Air Dryers 81 4.4.3 Desiccant Dryers 81 4.4.4 Classifications Based on the Location of the Dryer 81 4.5 Determination of the Amount of Moisture 82 4.5.1 The Glass Slide Technique (TVI Test) . 82 4.5.2 The Karl-Fischer Titration Method 83 4.5.3 Electronic Moisture Analyzer 83 4.5.4 Measurement of the Dew Point 84 4.6 ‘Overdrying’ or Overexposure to Drying Temperatures 85 4.7 Cautions 92 4.8 Prevention of Overexposure to Longer Drying Times . 92 4.9 Overdrying Controller . 93 4.10 References . 94 5 Common Plastic Materials and Additives . 95 5.1 Classification of Polymers 95 5.2 Commercially Important Plastics 97 5.2.1 Polyolefins 97 5.2.2 Polymers from Acrylonitrile, Butadiene, Styrene, and Acrylate 98 5.2.3 Polyamides (PA) . 99 5.2.4 Polystyrenes (PS) 100 5.2.5 Acrylics 101 5.2.6 Polycarbonates (PC) 101 5.2.7 Polyesters . 101 5.2.8 Polyvinyl Chloride (PVC) 101 5.2.9 Polyoxymethylene (POM or Acetal) 102 5.2.10 Fluoropolymers 103XVI Contents 5.3 Additives 103 5.3.1 Fillers 104 5.3.2 Plasticizers . 104 5.3.3 Flame Retardants 104 5.3.4 Anti-aging Additives, UV Stabilizers 105 5.3.5 Nucleating Agents . 105 5.3.6 Lubricants 106 5.3.7 Processing Aids 106 5.3.8 Colorants . 106 5.3.9 Blowing Agents 106 5.3.10 Other Polymers 107 5.4 Closing Remarks . 108 5.5 Reference . 108 6 Injection Molding and Molding Machines 109 6.1 The History of Injection Molding 109 6.2 Injection Molding Machines and Their Classifications 110 6.3 Machine Specifications 112 6.3.1 Clamp Force (Tonnage) . 113 6.3.2 Shot Size . 113 6.3.3 Screw Diameter and L/D Ratio . 113 6.3.4 Plasticating Capacity . 114 6.3.5 Maximum Plastic Pressure 114 6.4 The Injection Molding Screw . 114 6.5 Screw Designs . 117 6.6 The Check Ring Assembly 118 6.7 Intensification Ratio (IR) 119 6.8 Obtaining Intensification Ratios . 121 6.9 Selecting the Right Machine for the Mold . 122 6.9.1 Physical Size of the Mold . 122 6.9.2 Calculating the Required Machine Tonnage for a Mold . 124 6.10 The Rule of Thumb for Tonnage Is Only an Estimate 126 6.10.1 Percentage Shot Size Used and Number of Shots in the Barrel 127 6.10.2 Residence Time of the Material in the Barrel . 130 6.10.3 Practical Methods to Find Percentage Shot Size, Shots in a Barrel, and Residence Time 130 6.10.4 Residence Time Distribution . 131Contents XVII 7 Scientific Processing, Scientific Molding, and Molding Parameters . 133 7.1 Introduction . 133 7.1.1 Process Robustness 135 7.1.2 Process Consistency . 135 7.2 The 11 + 2 Plastic Injection Molding Machine Parameters 138 7.3 Process Outputs 141 7.4 What Scientific Molding and Scientific Processing Are Not 142 7.5 The Injection Molding Cycle 143 7.5.1 Injection, Pack, and Hold 143 7.5.2 Speed and Pressure 145 7.5.3 Pressure Limited Process . 146 7.5.4 Decoupled MoldingSM . 146 7.5.5 Intensification Ratio (IR) 147 7.5.6 Screw Speed 148 7.5.7 Back Pressure . 150 7.5.8 Cycle Time 151 7.6 References . 152 8 Process Development Part 1: the 6-Step Study – Exploring the Cosmetic Process . 153 8.1 Introduction . 153 8.2 Introduction to Process Development 153 8.3 Premolding Setup 156 8.4 Storage and Drying of Resin 156 8.4.1 Plastic Drying . 157 8.5 Machine Selection 159 8.6 Importance of Adding Charge Delay Time 160 8.7 Filling in Injection: Weight or Volume? . 161 8.8 Setting of the Melt Temperatures 162 8.9 Setting Mold Temperatures . 165 8.10 Process Optimization – the 6-Step Study . 165 8.10.1 Step 1: Optimization of the Injection Phase–Rheology Study . 165 8.10.2 Procedure to Determine the Viscosity Curve at the Molding Machine 169 8.10.3 How to Use this Information . 171 8.10.4 Cautions and Exceptions 173 8.10.5 Profiling of Injection Speeds . 173XVIII Contents 8.10.6 When a Short Shot Sticks . 174 8.10.7 Selecting Melt Temperature for Viscosity Graphs 176 8.10.8 Step 2: Determining the Cavity Balance – Cavity Balance Study . 177 8.11 Reasons for Cavity Imbalance . 180 8.11.1 Determining the Cause of Cavity Imbalances . 184 8.11.2 Calculating Cavity Imbalance 184 8.11.3 Acceptable Level of Cavity Imbalance . 185 8.11.4 Step 3: Determining the Pressure Drop – Pressure Drop Studies 187 8.12 Effect of Pressure Drop on the Pack and Hold Phase 194 8.12.1 Step 4: Determining the Cosmetic Process Window – Process Window Study 195 8.13 Relationship between Cavity Balance and Process Windows . 202 8.14 The Pack and Hold Pressure Rule Not to Be Used 202 8.14.1 Step 5: Determining the Gate Seal Time – Gate Seal Study 203 8.15 Differentiating between the Pack and the Hold Phase 206 8.16 Hot Runner and Valve Gated Molds 210 8.16.1 Step 6: Determining the Cooling Time – Cooling Time Study 210 8.16.2 Optimization of Screw Rotation Speed . 213 8.16.3 Why to Not Use the Rule of Thumb 214 8.17 Optimization of Back Pressures . 215 8.18 The Cosmetic Scientific Process . 216 8.18.1 Post Mold Shrinkage Studies . 216 8.18.2 Procedure to Measure Shrinkage . 219 8.19 Recommended Mold Function Qualification Procedure 220 8.20 Recommended Adjustments to Maintain Process Consistency and Robustness 221 8.21 Process Documentation . 222 8.22 References . 223 9 Process Development Part 2: Exploring the Dimensional Process via the DOE 225 9.1 Parameters in Injection Molding 226 9.1.1 Design of Experiments: Definition 228 9.2 Terminology . 230 9.2.1 Factor . 230 9.2.2 Response . 231Contents XIX 9.2.3 Level . 231 9.2.4 Designed Experiment . 231 9.3 Relationships between the Number of Factors, Levels, and Experiments . 232 9.4 Balanced Arrays 234 9.5 Interactions . 235 9.6 Confounding or Aliasing . 238 9.7 Randomization . 240 9.8 Factorial Experiments . 241 9.9 Data Analysis 241 9.9.1 Tornado Charts 243 9.9.2 Contour Plots 244 9.9.3 Prediction Equation 245 9.9.4 Process Sensitivity Charts . 246 9.10 Using the Results from DOE 247 9.10.1 Process Selection 247 9.10.2 Cavity Steel Adjustment . 248 9.10.3 Process Adjustment Tool 249 9.10.4 Setting Process Change Tolerances 249 9.10.5 Reducing Inspection 249 9.11 The Dimensional Process Window (DPW) . 250 9.12 Selections of Factors for DOEs 252 9.13 Analysis of Variance (ANOVA) 257 9.14 Collecting Shots for a Quality Check . 258 9.15 Choosing the Highs and Lows for DOEs from the Process Window 259 9.16 DOE Application to Optimize Pack and Hold Times . 260 9.17 Setting Acceptable Machine Tolerances and Alarms during Production 265 9.18 Summary 266 10 Mold Qualification Flowchart, Production Release, and Troubleshooting 269 10.1 Mold Qualification Flowchart . 269 10.1.1 Mold Function Qualification Procedure 271 10.1.2 Mold and Part Quality Qualification Procedure 271 10.2 Mold Qualification Checklist 271XX Contents 10.3 Process Documentation 272 10.3.1 Process Sheet . 272 10.3.2 Waterline Diagrams 273 10.3.3 Mold Temperature Maps 274 10.3.4 Setup Instructions . 275 10.3.5 Operator Instructions . 275 10.4 Documentation Books . 276 10.5 Qualification Production Runs 277 10.6 Mold Specific Troubleshooting Guide 277 10.7 Molding Startup and Shutdown . 278 10.7.1 Purging 278 10.7.2 Startup of a Molding Machine 279 10.7.3 Shutdown of a Molding Machine . 280 10.8 Troubleshooting 280 10.9 Important Equipment and Tools for Qualifications and Troubleshooting 283 10.10 Common Defects, Their Causes, and Prevention . 284 10.10.1 Splay: What is it? How to get rid of it? . 285 10.10.2 Defects in Molding . 287 11 Role of Mold Cooling, Venting, and Regrind in Process Development . 293 11.1 Mold Cooling . 293 11.1.1 Number of Cooling Channels 294 11.1.2 Reynolds Number of the Coolant Flow 294 11.1.3 Type of Coolant . 295 11.1.4 Series and Parallel Cooling 296 11.2 Venting . 297 11.2.1 Dimensions of the Vent . 298 11.2.2 Primary Vent Depths . 299 11.2.3 Location of Vents 302 11.2.4 Forced Venting or Vacuum Venting . 304 11.3 Regrind . 305 11.3.1 Effect of the Molding Process on the Part Properties 305 11.3.2 Using Regrind 307 11.3.3 Batch and Continuous Processes of Incorporating Regrind 307 11.3.4 Estimating the Amount of Regrind from Different Generations 308Contents XXI 11.3.5 Effect of Regrind on Processing . 311 11.3.6 Closing Remarks . 311 12 Related Technologies and Topics 313 12.1 Cavity Pressure Sensing Technology . 313 12.1.1 Sensors and Output graphs 314 12.1.2 Types and Classification of Pressure Sensors . 315 12.1.3 Use of Information from the Pressure Graphs . 317 12.1.4 Controlling the Process with Cavity Pressure Sensors 319 12.1.5 Sensor Locations 321 12.2 Building a Knowledge Base 322 12.3 Concurrent Engineering in Injection Molding . 324 12.3.1 The Product Designer . 326 12.3.2 The Tooling Engineer . 326 12.3.3 The Mold Designer and Mold Maker 327 12.3.4 The Material Supplier 327 12.3.5 The Process Engineer . 328 12.3.6 The Quality Engineer . 329 12.3.7 The Sales Team at the Molder 329 12.3.8 Mandatory for All Departments 330 12.3.9 Implementing Concurrent Engineering 330 13 Quality Concepts 333 13.1 Basic Concepts . 333 13.2 Histogram . 334 13.3 Normal Distribution . 335 13.4 Standard Deviation 336 13.5 Specification Limits and Standard Deviation 337 13.6 Capability Index 339 13.7 Process Capability 340 13.8 Statistical Quality Control (SQC) and Statistical Process Control (SPC) 342 13.9 References . 342 Appendix A Materials Data Sheet 343 Appendix B Conversion Tables for Commonly Used Process Parameters . 349XXII Contents Appendix C Water Flow Tables . 351 Appendix D Part Design Checklist 353 Appendix E Mold Design Checklist . 355 Appendix F Mold Qualification Checklist 357 Appendix G Regrind Tables – Percentage of Regrind in Total Shot . 359 Index
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