Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
Leseprobe
zu
„Understanding Extrusion“
von Chris Rauwendaal
ISBN (Buch): 978-1-56990-698-9
ISBN (E-Book): 978-1-56990-699-6
Weitere Informationen und Bestellungen unter
https://www.hanser-
fachbuch.de/buch/Understanding+Extrusion/9783446416864
sowie im Buchhandel
© Carl Hanser Verlag, München
https://www.hanser-fachbuch.de/buch/Understanding+Extrusion/9783446416864https://www.hanser-fachbuch.de/buch/Understanding+Extrusion/9783446416864
The first edition of Understanding Extrusion was published in 2000 and the second edition in 2010. Since the second edition was issued several important develop-ments have taken place. As a result, it makes sense to have a third edition of Under-standing Extrusion.Most of the new material is incorporated in Chapter 2. Topics included in this chapter are interpretation of extrusion process data, dimensional variation by melt temperature fluctuations, efficient extrusion, and more. Chapters 7 and 8 have also been extended and now cover topics such as analysis of shrink void formation and grooved barrel extruder technology.I would like to thank Dr. Mark Smith for his encouragement to work on this third edition. I also want to thank my wife Sietske for her continued support and for put-ting up with me despite these time-consuming projects.
Chris RauwendaalSeptember 2018
Preface to the Third Edition
Preface to the Third Edition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V
1 Extrusion Machinery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 What is an Extruder? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Different Types of Extruders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.1 Single Screw Extruders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.2.2 Twin Screw Extruders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.2.1 Co-Rotating Twin Screw Extruders . . . . . . . . . . . . . . . . . 21.2.2.2 Counter-Rotating Twin Screw Extruders . . . . . . . . . . . . 3
1.2.3 Ram Extruders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.3 Components of an Extruder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3.1 The Extruder Screw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.3.2 The Extruder Barrel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.3.3 The Feed Throat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.3.4 The Feed Hopper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.3.5 Barrel Heating and Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.3.6 Screw Heating and Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.3.7 The Breaker Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.3.8 The Screen Pack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.3.8.1 Screen Changers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111.3.9 The Extrusion Die . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.3.9.1 Coextrusion Dies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141.3.10 The Extruder Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.3.10.1 Coupling between Motor and Gearbox . . . . . . . . . . . . . . 151.3.11 The Speed Reducer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.3.11.1 Thrust Bearing Assembly . . . . . . . . . . . . . . . . . . . . . . . . 161.3.12 The Gear Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2 Instrumentation and Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192.1 Instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192.2 Most Important Process Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.2.1 Melt Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202.2.2 Pressure Transducers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Contents
VIII Contents
2.2.3 Temperature Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222.2.4 Melt Temperature Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . 232.2.5 Barrel Temperature Measurement . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.3 Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262.3.1 On-Off Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262.3.2 Proportional Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262.3.3 Fuzzy Logic Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.4 Collection and Interpretation of Extrusion Process Data . . . . . . . . . . . . . 292.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292.4.2 Vital Signs of the Extrusion Process . . . . . . . . . . . . . . . . . . . . . . . 29
2.4.2.1 Melt Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.4.2.2 Melt Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352.4.2.3 Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.4.3 Examples of Extrusion Problems Solved by Using a Data Acquisition System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442.4.3.1 Variation in Stock Temperature . . . . . . . . . . . . . . . . . . . 442.4.3.2 Variation in Feed Housing Temperature . . . . . . . . . . . . 462.4.3.3 Variation in Melt Pressure . . . . . . . . . . . . . . . . . . . . . . . . 48
2.4.4 Process Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 502.4.5 Temperature-Induced Dimensional Changes of Extrudate . . . . . 50
3 Complete Extrusion Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 533.1 Tubing and Pipe Extrusion Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 533.2 Film and Sheet Lines Using the Roll Stack Process . . . . . . . . . . . . . . . . . 543.3 Film Lines Using Chill Roll Casting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553.4 Combination of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.4.1 Coextrusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 563.4.2 Extrusion Coating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 573.4.3 Extrusion Lamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
3.5 Blown Film Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 593.6 Extrusion Compounding Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 593.7 Profile Extrusion Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4 Plastics and Their Properties Important in Extrusion . . . . . . . . . . . . . 634.1 Thermoplastics and Thermosets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 634.2 Amorphous and Semi-Crystalline Plastics . . . . . . . . . . . . . . . . . . . . . . . . . 644.3 Liquid Crystalline Plastics (LCPs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 664.4 Elastomers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 664.5 Flow Behavior of Plastic Melts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 674.6 Melt Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 684.7 The Effect of Shearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 694.8 Shear Thinning or Pseudoplastic Behavior . . . . . . . . . . . . . . . . . . . . . . . . 69
Contents IX
4.9 Effect of Temperature on Viscosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 704.10 Viscous Heat Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 714.11 Thermal Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.11.1 Thermal Conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 724.11.2 Specific Heat and Enthalpy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 724.11.3 Thermal Stability and Induction Time . . . . . . . . . . . . . . . . . . . . . . 734.11.4 Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 744.11.5 Melting Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 764.11.6 Glass Transition Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
5 How an Extruder Works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 775.1 Solids Conveying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.1.1 Gravity Induced Conveying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 785.1.2 Drag Induced Conveying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 815.1.3 Starve Feeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 825.1.4 Grooved Feed Extruders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
5.2 Melting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 855.2.1 Contiguous Solids Melting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 855.2.2 Dispersed Solids Melting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
5.3 Melt Conveying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 895.3.1 Melt Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
5.4 Mixing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 935.4.1 Distributive Mixing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 935.4.2 Mixing Sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
5.4.2.1 Distributive Mixing Sections . . . . . . . . . . . . . . . . . . . . . . 985.4.2.2 Dispersive Mixing Sections . . . . . . . . . . . . . . . . . . . . . . . 102
5.5 Degassing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1085.6 Die Forming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
5.6.1 Size and Shape Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1115.6.2 Tubing and Pipe Dies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1145.6.3 Flat Film and Sheet Dies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1175.6.4 Profile Dies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
6 How to Run an Extruder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1236.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1236.2 Before Start-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1236.3 Getting Ready for a Run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1246.4 Starting the Extruder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1266.5 Actual Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1286.6 Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
6.6.1 Purging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1296.7 Safety Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
6.7.1 Heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
X Contents
6.7.2 Moving Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1316.7.3 Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1326.7.4 Weights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1326.7.5 Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
6.8 Inspection and Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
7 How to Troubleshoot Extrusion Problems . . . . . . . . . . . . . . . . . . . . . . . 1377.1 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1377.2 Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
7.2.1 Good Instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1377.2.2 Good Understanding of the Process . . . . . . . . . . . . . . . . . . . . . . . . 1387.2.3 Collect and Analyze Historical Data . . . . . . . . . . . . . . . . . . . . . . . 1387.2.4 Teamwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
7.3 Main Types of Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1397.3.1 Output Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
7.3.1.1 Low Extruder Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1397.3.1.2 Variation in Extruder Output . . . . . . . . . . . . . . . . . . . . . 141
7.3.2 Appearance Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1447.3.2.1 Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1457.3.2.2 Die Drool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1457.3.2.3 Discoloration and Degradation . . . . . . . . . . . . . . . . . . . . 1457.3.2.4 Voids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1477.3.2.5 Vent Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1567.3.2.6 Air Entrapment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1567.3.2.7 Gels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1577.3.2.8 Poor Mixing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
7.3.3 Functional Product Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1607.3.4 High Melt Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1607.3.5 High Motor Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1617.3.6 Wear Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
7.4 Systematic Problem Solving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1637.5 Machine Troubleshooting and Maintenance . . . . . . . . . . . . . . . . . . . . . . . 164
7.5.1 Check the Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1657.5.2 Unusual Noises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1657.5.3 Drive Motors and Belts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1677.5.4 Spare Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1677.5.5 Screw and Barrel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1677.5.6 Extruder Maintenance Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . 168
7.6 Troubleshooting Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
8 New Developments in Extrusion and Methods to Increase Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
8.1 General Trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1758.2 High-Speed Extrusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Contents XI
8.2.1 Melt Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1758.2.2 Extruders without Gear Reducer . . . . . . . . . . . . . . . . . . . . . . . . . . 1768.2.3 Energy Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1778.2.4 Change-over Resin Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . 1778.2.5 Change-over Time and Residence Time . . . . . . . . . . . . . . . . . . . . . 177
8.3 Multi-Strand Extrusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1788.4 Reducing Material Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
8.4.1 Low Cost Filler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1808.4.2 Recycled Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1828.4.3 Foamed Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1828.4.4 Pre-compounded Material vs. In-house Compounding . . . . . . . . 1838.4.5 Start-up, Change-over, and Shutdown . . . . . . . . . . . . . . . . . . . . . . 1838.4.6 Polymer Processing Aids (PPA) . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
8.5 Increased Automation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1868.6 Efficient Extrusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
8.6.1 Instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1878.6.2 Data Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1878.6.3 Feed Stock Variability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1888.6.4 Flood Feeding versus Starve Feeding . . . . . . . . . . . . . . . . . . . . . . 1888.6.5 Purging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
8.6.5.1 Melt Displacement Behavior . . . . . . . . . . . . . . . . . . . . . . 1908.6.5.2 Effect of Viscosity Differences . . . . . . . . . . . . . . . . . . . . . 1938.6.5.3 Effect of Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1948.6.5.4 Dynamic versus Static Purging Methods . . . . . . . . . . . . 1958.6.5.5 Purging Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1988.6.5.6 Practical Rules to Reduce Purge Times . . . . . . . . . . . . . 198
8.6.6 Methods to Reduce Energy Consumption . . . . . . . . . . . . . . . . . . . 2008.6.6.1 Energy Requirement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2008.6.6.2 Energy Cost per Kilogram . . . . . . . . . . . . . . . . . . . . . . . . 2008.6.6.3 Energy Cost per Year . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2008.6.6.4 Barrel Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2008.6.6.5 Heat Loss at the Extrusion Die . . . . . . . . . . . . . . . . . . . . 2018.6.6.6 Melt Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2018.6.6.7 Pre-Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2028.6.6.8 Use of Filled Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2028.6.6.9 Tips to Reduce Energy Use in Extrusion . . . . . . . . . . . . 202
8.6.7 Flexible Manufacturing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2038.7 Statistical Process Control (SPC) and Design of Experiments (DOE) . . . 2068.8 Causes of Process Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
8.8.1 Melt Temperature Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2088.8.2 Melting Related Instabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
8.9 Grooved Feed and Grooved Barrel Extruders . . . . . . . . . . . . . . . . . . . . . . . 2098.9.1 Adjustable Grooved Feed Extruder . . . . . . . . . . . . . . . . . . . . . . . . 2108.9.2 Grooved Barrel Extruders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
8.10 The Rotary Channel Pump (RCP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
XII Contents
8.11 New Developments in Mixing and Screw Design . . . . . . . . . . . . . . . . . . . 2138.11.1 Elongational Mixing Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2138.11.2 Barrier Screws with Elongational Mixing Action . . . . . . . . . . . . . 2148.11.3 Floating Sleeve Intermeshing Pin Mixer . . . . . . . . . . . . . . . . . . . . 2158.11.4 High Heat Transfer (HHT) Screw Design Technology . . . . . . . . . 2168.11.5 The Single Screw Compounding Extruder (SSCE) . . . . . . . . . . . . 217
8.12 Fiber Reinforced Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2188.12.1 Conventional Methods to Make Fiber Reinforced Plastics . . . . . . 2188.12.2 Nexxus Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
8.13 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
9 Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2239.1 Appendix 1: Recommended list for further reading . . . . . . . . . . . . . . . . . 2239.2 Appendix 2: Extrusion Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
9.2.1 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2309.2.2 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
1.3 Components of an Extruder 5
1.3Components of an Extruder
In this section we will discuss: the extruder screw the screen pack the extruder barrel the extrusion die the feed throat the extruder drive the feed hopper the reducer barrel heating and cooling gear pumps the breaker plate instrumentation and control
1.3.1The Extruder Screw
The heart of the extruder is the extruder screw. This is a long cylinder with a heli-cal flight wrapped around it, see Figure 1.6. The screw is very important because conveying, heating, melting, and mixing of the plastic are mostly determined by the screw. The stability of the process and the quality of the extruded product are very much dependent on the design of the screw. The screw rotates in a cylinder that fi ts closely around it.
Figure 1.6 A single flighted extruder screw
1.3.2The Extruder Barrel
The cylinder is called the extruder barrel. The barrel is a straight cylinder usually equipped with a bimetallic liner; this liner is a hard, integral layer with high wear resistance. In most cases, the wear resistance of the barrel should be better than that of the screw. The reason is that the screw is much easier to rebuild and replace than the barrel. Bimetallic barrels usually cannot be rebuilt.The barrel may have a vent opening through which volatiles can be removed from the plastic, see Figure 1.7, a process called devolatilization. An example is the re-moval of moisture from a hygroscopic plastic. An extruder with a vent port should use a special screw geometry to keep the plastic melt from coming out of the vent port; such a screw is called a “two-stage screw,” see Figure 1.7.
Functions
6 1 Extrusion Machinery
Figure 1.7 A vented extruder barrel with a two-stage screw
1.3.3The Feed Throat
The feed throat is connected to the barrel; it contains the feed opening through which the plastic material is introduced to the extruder. The feed throat usually has water-cooling capability because we have to be able to keep the feed throat tempera-ture low enough to keep the plastic particles from sticking to the wall. To improve the intake capability of the feed throat, the feed opening can be offset as shown in Figure 1.8 and have an elongated shape. The length of the feed opening should be about 1.5 times the diameter of the barrel and the width about 0.7 times the dia-meter.Some extruders do not have a separate feed throat, but the feed opening is ma-chined right into the extruder barrel. There are both advantages and disadvantages to such a setup. The advantages are lower cost, fewer parts, and no problems with alignment of the barrel to the feed throat. Disadvantages are that it is more difficult to create a thermal barrier between the hot barrel and the cold feed throat region and good cooling of the feed throat region is more difficult.
Tangentialdesign
1.5D
0.7D AA
D
Top view Section A-A
Figure 1.8 Preferred geometry for feed opening in the feed throat
Material intake
1.3 Components of an Extruder 7
1.3.4The Feed Hopper
The feed throat is connected to the feed hopper and the extruder barrel. The feed hopper holds the plastic pellets or powder and discharges the material into the feed throat. The hopper should be designed to allow a steady flow of material. Steady flow is best achieved with a circular hopper with a gradual transition in the conical section of the hopper, see Figure 1.9.
Figure 1.9 Good hopper design (left) and bad hopper design (right)
For difficult bulk materials, special devices can be used to promote steady flow through the hopper; such as vibrating pads, stirrers, wipers, and even crammer screws to force the material to the discharge, see Figure 1.10.
Figure 1.10 Example of crammer feeder
1.3.5Barrel Heating and Cooling
The extruder barrel has both heating and cooling capability. Heating is usually done with electrical band heaters located along the length of the extruder. The heaters can be mica insulated heaters, ceramic heaters, or cast-in heaters. In cast-in heaters, the heating elements are cast in a semi-circular block of aluminum or bronze; these heaters provide good heat transfer. Aluminum cast heaters can heat up to 400 °C, while bronze cast heaters have a maximum operating temperature of about 550 °C. Other types of heating can be used, such as induction heating,
Conveying material
Various heating methods
38 2 Instrumentation and Control
The threaded probe with the sapphire window can be used in combination with a simple IR thermometer. This allows IR melt temperature measurement in the ex-truder barrel or in the die.IR temperature measurement provides two important benefits. One, the response time is fast, about 10 milliseconds. Two, the measurement does not disturb the flow as is the case with an immersion probe. Because of the fast response, the IR mea-surement can detect rapid changes in melt temperature that cannot be detected by an immersion melt temperature probe. Melt temperature variation will be discussed next.
Melt Temperature Variation in ExtrusionThe melt temperatures in extrusion result from viscous dissipation and heat trans-fer. In drag flow, the shear rates and viscous dissipation are relatively uniform. However, the heat transfer to the screw and barrel results in large temperature dif-ferences within the polymer melt. The largest temperature gradients tend to occur at the barrel surface.The melt temperature distribution can be determined by performing a non-isother-mal analysis of the flow in the screw channel. In the case of a non-Newtonian poly-mer melt this is typically done using finite element analysis (FEA). Figure 2.24 shows a color contour plot of melt temperatures in the screw channel of a 63 mm single screw extruder running a 0.2 melt index high density polyethylene (HDPE) at 100 rpm. The vertical axis has been stretched about eight times to make it easier to examine the temperature distribution.
Figure 2.24 Melt temperature distribution in 63 mm extruder running at 100 rpm
The top surface is the barrel, the bottom surface is the root of the screw, the left vertical boundary is the pushing flank of the flight, and the right vertical boundary
IR temperature measurement provides two important benefits:
1) fast response, 2) no disturbance of flow
Melt temperature distribution can be
determined by perform-ing a non-isothermal
analysis of the flow in the screw channel
Melt temperatures in the screw channel are
highly non-uniform
2.4 Collection and Interpretation of Extrusion Process Data 39
is the trailing flank of the flight. It is clear that the melt temperatures are highly non-uniform. The temperatures close to the barrel are relatively low because of the heat transfer to the barrel – the barrel cools down the melt that is in close proxim-ity to the barrel. The temperatures at the pushing flight flank are low because the cool melt close to the barrel moves down along the flight when it reaches the push-ing flight flank.At the root of the screw, the cool melt from the pushing flight flank moves toward the trailing side of the flight. If there is no heat transfer with the screw, the melt temperatures will gradually increase as the melt moves from the pushing flank to the trailing flank. The melt reaching the trailing flight flank moves up along the flight until it gets close to the barrel. At that point the cycle starts again. The outer region of the screw channel stays relatively cool because of the heat transfer from the melt to the barrel. The situation is quite different for the inner region of the screw channel.The melt in the inner region remains in this region as it travels down the length of the screw channel – it will not come into close proximity of the barrel. The inner region is thermally insulated from the barrel by a relatively thick layer of polymer melt. As a result, the temperatures in this region increase higher than in any other part of the channel – it is a natural hot spot. In Figure 2.24 the temperatures in the hot spot are more than 100 °C above the barrel temperature.When the screw discharges the melt, this melt will be non-uniform in temperature. A number of studies have analyzed the variation of melt temperatures in extruders. One such study was made by E. Brown and A. Kelly at Bradford University in Eng-land. In this work, a fast response thermocouple (TC) mesh was used to measure melt temperature variation using three different extruder screws. The TC mesh was located in the breaker plate recess of the extruder barrel, see Figure 2.25.
Figure 2.25 Experimental setup for melt temperature study
Melt temperature was measured at multiple locations, see Figure 2.26. It is clear from this figure that the melt temperatures across the channel are quite non-uni-form with a low temperature of 190 °C and a high temperature over 215 °C.
Hot spots tend to form in the center region of the screw channel
40 2 Instrumentation and Control
Figure 2.26 Melt temperatures versus radial distance from the center
The melt temperatures vary not only across the melt stream but also over time – this is shown in Figure 2.27.
Figure 2.27 Melt temperature versus time
The melt at TC4 (radial location –10 mm in Figure 2.26) drops from 215 °C to 180 °C within four seconds and then increases again to almost 215 °C within two seconds. This is rapid and substantial melt temperature variation! Interestingly, this melt temperature variation cannot be detected with an immersion melt tem-perature probe because of the slow response time.In this study, the melt temperatures were also measured with an infrared thermo-meter. The results are shown in Figure 2.28.
5.3 Melt Conveying 89
Figure 5.14 Cross section of a barrier screw
One variable that affects the melting in an extruder is the temperature at which the plastic is introduced to the extruder. By preheating the plastic in the feed hopper or before, the amount of heat that has to be added to melt the plastic in the extruder is reduced and, as a result, melting occurs earlier in the extruder. When it is sus-pected that an extrusion problem is related to melting, preheating is a method of diagnosing the problem.The barrier screw has the following advantages:
The barrier screw achieves more stable extrusion than a simple conveying screw.
With a barrier screw, there is virtually no chance of unmelted material beyond the barrier section.
There is a certain amount of dispersive mixing that occurs as the plastic melt flows over the barrier flight into the melt channel.
Next to these advantages, there are the following disadvantages: Barrier screws are no better in performance than non-barrier screws designed
with effective mixing sections. Barrier screws tend to be more expensive than non-barrier screws, particularly
when purchased from an original equipment manufacturer (OEM). Because the solid material is restricted to the solids channel, the barrier screw
is inherently more susceptible to plugging. This occurs when melting cannot keep up with the reduction in the size of the channel in the compression section of the screw, resulting in the solid material getting stuck in the screw channel. This creates a momentary obstruction to flow and leads to surging. Surging is a variation in extruder output.
5.3Melt Conveying
Melt conveying starts when the melting is completed in the extruder. Strictly speak-ing, melt conveying starts when melting starts, because the melting zone is where we have both solids conveying and melt conveying with the amount of solid mate-rial gradually decreasing and, at the same time, the amount of melted material
Pre-heating material
Barrier screw advantages
Disadvantages
Mechanisms of conveying
90 5 How an Extruder Works
gradually increasing. However, we define the melt-conveying zone as the region where all the plastic is completely melted.The mechanism of melt conveying is viscous drag. In other words, the viscous forces acting on the plastic melt are responsible for the forward conveying of the melt. As we saw in the solids conveying zone, the viscous force at the barrel is re-sponsible for forward conveying, while the viscous force at the screw is a retarding force. As a result, melt conveying is improved by reducing the barrel temperature and increasing the screw temperature. Interestingly, screw heating in the melt con-veying zone makes more sense than barrel heating.The optimum screw geometry for melt conveying can be determined from extrusion theory. The optimum helix angle is dependent only on the degree of non-Newtonian behavior of the plastic melt; it can be determined from the following expression:
optimum helix angle degrees (power law index = +13 5 16 5. . )) (5.1)
The optimum helix angle for melt conveying decreases as the power law index de-creases or the plastic is more shear thinning. A similar expression can be derived for the optimum depth of the channel in the melt-conveying zone. The optimum depth depends on the viscosity, the pressure gradient, and the power law index. When the plastic becomes more shear thinning, the channel depth should be re-duced to maintain good melt conveying.
5.3.1Melt Temperatures
Because of the low thermal conductivity of the plastic melts, the temperatures in the melt-conveying zone can vary substantially. Local temperatures are difficult to measure because it is hard to put a probe in the screw channel while the screw is rotating. Melt temperatures can be predicted from extrusion theory using numeri-cal techniques. A popular technique for this purpose is finite element analysis (FEA). With this technique the flow patterns and temperature distribution can be predicted.Figure 5.15 depicts the temperature distribution in the screw channel by looking at a cross section of the screw channel. The temperatures are shown in colors; differ-ent colors represent different temperatures, just like the weather map on the back page of USA Today. The lower surface of the picture is the root of the screw; the upper surface is the extruder barrel. The barrel is maintained at 175 °C and the screw surface is considered insulated (adiabatic). It can be seen in the figure that the highest melt temperatures occur in the mid-region of the channel, while the outside region of the channel remains at a lower temperature.
Optimum screw geometry
Optimum helix angle
Predicting melt temperature by FEA
Distribution of melt temperature
5.3 Melt Conveying 91
Figure 5.15 Predicted melt temperatures in the screw channel
The reason for this temperature distribution is the way the plastic melt flows along the screw channel. We can illustrate this flow by unrolling the screw channel and by looking at it as a straight trough (see Figure 5.16) and the barrel as a flat plate.
Figure 5.16 Flow along the unrolled screw channel
If we look at the flow relative to the screw, then the barrel moves in tangential direction, vb, making an angle φ with the channel. Angle φ is the helix angle of the screw flight. A fluid element close to the barrel surface flows in the direction of the barrel until it gets to the pushing side of the flight. At this point, the element moves downward and then crosses the screw channel. When the element gets to the trailing side of the flight, the element moves up again close to the barrel surface and the element starts moving in the direction of the barrel again. This pattern re-peats itself numerous times as long as the regular flight geometry is maintained.If we look at the flow in the cross section of the screw channel (see Figure 5.17), we see the material moves to the pushing side of the flight at the top of the channel. This flow results from drag flow. At the bottom of the channel, the material moves toward the trailing side of the flight. This is a pressure flow resulting from the fact that the pressure at the pushing side of the flight is higher than at the trailing side
Movement of fluid ele-ment through the barrel
Different types of flow through channel
92 5 How an Extruder Works
of the flight. If the leakage flow through the flight clearance is negligible, the amount of material flowing to the pushing flight flank is the same as the amount of material flowing to the trailing flight flank. Thus, we get a recirculating flow1 as shown in Figure 5.17.
Figure 5.17 Recirculating flow in the cross section of the screw channel
The fluid is sheared as it flows along the screw channel and, as a result, there is viscous heat generation in the plastic melt. The actual temperatures that occur at different points in the screw channel are determined not only by viscous heating, but also by how efficiently this heat can be removed. If the barrel is cooled, the melt flowing close to the barrel surface can exchange heat and cool down efficiently. When this outer layer moves along the screw surface, it remains relatively cool even if the screw is insulated.However, the situation is quite different for the inner layer. Because this layer is trapped in the inner recirculating region, it never gets close to the barrel. As a re-sult, this layer has very limited opportunity for removal of its heat; the outer layer of plastic melt essentially insulates the inner layer. This explains why the tempera-ture in the inner region of the screw channel tends to be higher than in the outer region. In Figure 5.15, the temperature in the center region is about 60 °C higher than the barrel temperature. Thus, it is clear that considerable melt temperature differences can occur in the screw channel.If these temperature differences are carried to the end of the screw, the melt dis-charged into the die is not thermally homogeneous. This leads to flow problems in the die and distortion of the extruded product. It is important, therefore, to try to keep these non-uniform melt temperatures from reaching the end of the screw.The most efficient method to do this is by incorporating mixing elements into the design of the screw. Mixing sections are not only important when we mix different plastics, but also when we extrude a single plastic in order to achieve a thermally homogeneous melt at the end of the screw.
1 There are also small velocity components in the normal direction close to the flight flanks. At the pushing flight flank, the normal flow is downward toward the root of the screw; at the trailing flight flank, the normal flow is upward, toward the barrel. The normal flow also results from pressure differences. For instance, the pressure at the top of the pushing flight flank is higher than at the bottom of the flight flank, which is why the flow is downward in this region.
Melt temperature close to surface
Melt temperature of inner layer
Importance of homoge-neous melt temperature
5.4 Mixing 93
5.4Mixing
Mixing takes place both in the melting zone as well as in the melt-conveying zone of the extruder. The solid plastic typically moves in plug flow, which means that there is no relative motion between the solid plastic particles. As a result, there is little or no mixing in solids conveying. This means that complete mixing does not start until all the plastic has melted. For this reason, we will look at mixing only in the melt conveying zone of the extruder.
5.4.1Distributive Mixing
The extent of distributive mixing can be determined from the total shear deforma-tion of the plastic melt in the melt conveying zone. The total shear deformation is also called the total shear strain; it is determined by the product of the shear rate and the length of time that the fluid is exposed to the shear rate. For instance, if the plastic melt is exposed to a shear rate of 100 s–1 for 15 seconds, the resulting shear strain is 100 × 15 = 1500. The shear strain is dimensionless. The shear rate is de-termined by the velocity profiles in the extruder.Mixing in single screw extruders is determined mostly by the two main velocity components in the screw channel. These are the velocity in the direction of the channel (z-direction) and the velocity in the cross-channel direction (x-direction), see Figure 5.18.
Figure 5.18 The two main flow components in a single screw extruder
There is also a velocity component in the third direction (y-direction) parallel to the flight flank. This velocity component is usually very small and therefore can usu-ally be neglected. The velocities in the down-channel direction depend on the pres-sure gradient; this can be positive, zero, or negative. When the pressure gradient is positive, pressure is increasing along the melt conveying zone; when the pressure gradient is negative, pressure is decreasing along the melt conveying zone. Down-channel velocity profiles for different values of the pressure gradient are shown in Figure 5.19.
Mixing in the melt stage
Definition
Pressure gradient
94 5 How an Extruder Works
Figure 5.19 Down-channel velocity profiles for three pressure conditions
The cross-channel flow is shown in Figure 5.17. At the top of the channel, the mate-rial flows to the left by drag flow and at the bottom of the channel, the material flows to the right by pressure flow. Figure 5.20 shows the cross-channel velocities.
vbx
Figure 5.20 Cross-channel velocity profile
The shear rate can be determined from the velocity profile; the shear rate is equal to the slope of the velocity profile. This slope of the velocity profile is also called the velocity gradient. From the down-channel velocities, we can determine the down-channel shear rates; these are shown in Figure 5.21.
Figure 5.21 Down-channel shear rates for three pressure conditions
When the pressure gradient is positive, the shear rates increase toward the barrel surface; when the pressure gradient is zero, the shear rate is constant, and when the pressure gradient is negative, the shear rates decrease toward the barrel sur-face. The same approach can be used to determine the cross-channel shear rate from the cross-channel velocities. The cross-channel shear rate profile is shown in Figure 5.22.
Types of flow
Shear rate
6.8 Inspection and Training 133
6.8Inspection and Training
It is the responsibility of the employer to establish and follow a program of periodic inspections of the extruder to ensure that all safeguards are in proper operating condition. The employer must also train operators in safe extruder operation before actually working on one. An effective training program should include the follow-ing four steps:
Tell workers how to do it safely Show them the safe way to do it Encourage them to ask questions Have them show you that they know how to do it safely
Three important rules regarding safety training: Never assume that employees know how to carry out a new task Frequent reminders should be given concerning safety procedures Never assume that safety rules are remembered
It is good practice to have regular safety inspections, at least once a quarter. The objective is to identify as many safety and health hazards as possible before they can cause an accident. The following checklist can be used for a successful safety inspection.
Housekeeping□ Is the work place clean and orderly?□ Are floors free from protruding nails, holes, and loose boards?□ Are the aisles and passageways kept clear of obstructions?□ Are permanent aisles and passageways clearly marked?□ Are covers or guardrails in place around open pits, tanks, and ditches?
Floor and wall openings □ Are ladder ways and door openings guarded by a railing?□ Do skylights have screens or fixed railings?□ Do temporary floor openings have standard railings or guards?□ Are wall openings with a drop of more than 1.2 meter (4 feet) guarded by a railing?□ Do all stairways with four or more risers have a handrail?□ Are stairways strong enough, adequately illuminated, and slip resistant?
Escape routes□ Are there enough exits to allow prompt escape?□ Do employees have easy access to exits?□ Are exits unlocked to allow people to leave?□ Are exits and exit routes equipped with emergency lighting?
Proper training
Checklists
Housekeeping
Floor and wall openings
Escape routes
134 6 How to Run an Extruder
Personal protective equipment□ Is the required equipment provided, maintained, and used?□ Does the equipment meet requirements and is it reliable?
Employee facilities□ Are facilities kept clean and sanitary?□ Are toilets kept clean and in good repair?□ Are cafeteria facilities a sufficient distance from toxic materials?
Medical and first aid□ Is there a hospital, clinic, or infirmary nearby?□ Are employees trained in first aid on each shift?□ Are physician-approved first aid supplies available?□ Are first aid supplies replenished as they are used?
Fire protection□ Are fire extinguishers available for the types of fire most likely to occur?□ Are there enough fire extinguishers available to do the job?□ Are fire extinguisher locations clearly marked?□ Are fire extinguishers properly mounted and easily accessible?□ Are all fire extinguishers fully charged and operable?□ Are special purpose extinguishers clearly marked?
Material handling and storage□ Is adequate clearance allowed in aisles?□ Are stacked materials interlocked, locked, and limited in height to maintain
stability?□ Are storage areas kept free of tripping, fire, explosion, and pest hazards?□ Is proper drainage provided?□ Are signs warning of clearance limits posted?□ Are powered industrial truck operators adequately trained?
Machine guarding and signs □ Are point-of-operation guards in place and working on all equipment?□ Are all belts and pulleys less than 2.1 meters (7 feet) from the floor guarded?□ Are spinning parts guarded?□ Are warning signs properly located? Show warning signs on the extruder, see
Figure 6.10.
Personal protective equipment
Employee facilities
Medical and first aid
Fire protection
Material handling and storage
Machine guarding and signs
Symbols
3D finite element analysis 19934CrAlNi7 185
A
abnormal sounds 165abrasive 162abrasive compounds 167abrasive fillers 18abrasive fillers downstream 173abrasive wear 162, 173ABS 105, 130accelerometer 166acceptable variation 206accidents 132accumulation in the hopper 188acetal (POM) 65, 130, 132AC motors 14, 167acrylic (PMMA) 64, 105acrylonitrile butadiene styrene
(ABS) 64active flight flank 85actual operation 123, 128actual temperatures 92adhesion 56adhesive 58adjustable calibrating basket
204adjustable calibration sleeve
204adjustable depth 24adjustable die gap 203adjustable die restriction 156
adjustable flow restriction 179adjustable grooved depth 210adjustable grooved feed extruder
(AGFE) 210adjustable melt temperature
probe 36adjustment nuts 57adjustment of the concentricity
115Advantage 204AGFE 210agglomeration 60, 189agricultural research 207air cooling 8air currents 20, 144, 189air entrapment 147, 156air filters 167air flow 168air hose 129air knife 55air velocity 25aisles 133allowed moisture content
108aluminum alloys 185aluminum cast heaters 7ambient air 201ambient temperature 20, 144,
187amorphous 64, 160amorphous plastics 64, 70, 72,
76, 112, 124, 172, 200amount of cooling 187
amount of resident polymer at the discharge 192
amperage of barrel heaters 168amplitude of the oscillations 27analysis of process problems 71annular channel 219annular dies 12, 114anti-oxidant 185anti-seize compound 167appearance 201appearance problems 73, 139,
144, 174arc-over 167armature cooling blower intake
169aromatic 185artificial intelligence-based
technology 28attrition of the fiber 218automatic die adjustment 116automatic feed to hopper 171automatic hopper feeder 144automatic screen changers 11,
203automatic shutoff 21, 132automation 175, 186auto-tuning controller 28axial adjustment 115axial length of the feed opening
143axial loads 16axial melting length 87, 227Axon mixing section 100
Index
234 Index
B
B-10 life 17backlash 143backlash of the gearbox 16back relieving 112ball mill 104barium chromate 194barrel 5, 87, 124, 167, 169barrel and die temperatures 187barrel cooling 200, 201barrel friction 84barrel liner 167barrel or die temperature
variations 171barrel pins 215barrel pressure 140barrel temperature 19, 87, 128,
140, 156, 171barrel temperature
measurement 24barrel temperature sensors 167barrier flight 88, 105, 214barrier screw 88, 144, 214batch internal mixers 59Battenfeld 175beard formation 85bearing covers 165bearing problems 165bearing temperature 166Beddus 203belt 134, 167, 169belt guards 168belt tension 167beneficiated calcium carbonate
182bimetallic liner 5biological degradation 146black box process 137black specks 145bleed trim 203bleed valve 11blenders 157blending 171blister ring 102, 160blockage 161
blockage along the screw 140, 172
blocking 140blower motors 170blowers 8blow molding 142, 209blown film 114, 209blown film dies 12blown film extrusion 142, 181blown film line 59blow up ratio 59bore-scope 167boron nitride 85, 198brass 130breaker plate 9, 31, 129, 140breaker plate recess 130, 170bridge with multiple probes 24bridging 79, 140, 171, 189broader process control 189bronze metal particles 165brush holder 169brushless DC drives 15brushless DC motors 167brush sparking 167BSP feeders 213bubbles 156, 174bucket brigade 18buildup of colorant 195buildup of material inside the die
145buildup of metal particles 161bulk density 78, 138, 140, 213bulk handling equipment 157bulk handling hardware 157bulk materials 78bulk solids pump (BSP) 213burning 73bushing 167, 169butt end of the screw 167Byk-Gardner 195
C
cable jacketing 115CaCO3 180cafeteria facilities 134
calcium carbonate (CaCO3) 47, 180, 182
calcium deposits 187calcium scale 47calibrating 61, 138calibrating device 53calibration 204calibration of all temperature
controllers 170calibrator 53, 145, 204cancer causing 183candles 130capability of measuring
instruments 138capillary 21capillary strain gage 22capillary strain gage transducers
132carbon black 194Cartesian coordinate system
225cartridge heater 85cast acrylic 130cast film extrusion 142cast-in heaters 7cast iron powder 165catalytic properties 185catalytic surface conversion 85catastrophic failure 165causes of process variation 52,
208cavity mixers 98cavity transfer mixer (CTM) 98center region 97centrifugal action 60centrifugal dryer 60ceramic heaters 7chance of degradation 97, 104,
126, 216change-over 177, 183, 195, 203change-over time 177, 190, 194,
203changes in ambient conditions
144chart recorder 128chemical degradation 146
Index 235
chemical purging compounds 130
chemical reactions 86chilled air 202chill roll casting 55chill roll unit 55chillWARE 149chips 169chloride ion concentration 170chlorinated polyethylene 105chlorophyll 194choker bar 57, 156chromium pigments 194circular dies 12circular feed hopper 79circular hopper 7, 79circumferential grooves 98circumferential orientation 117clamp area 169clam shelling 118, 119clean filter screen 170cleaning tools 130clean screw 172clean the die 129clean the extruder 123clearance 134, 161clear plastics 194clinic 134closed-loop control of extruded
tubing 128closed-loop control systems 54CO2 216coated wires 115coat hanger 119coat hanger manifold 119coating 56, 85coefficient of friction 140coextruders 202coextrusion 56coextrusion die 14coextrusion flow 193coiler 61cold air 206cold drawing of man-made fibers
113cold start-up 125
collapsing frame 59color 138, 194colorants 194color contour plot 38colored plastics 194colored resin particles 194colored resins 198colorimeter 194color measurement 195color veil 195commodity polymers 191commutator 169compacted clump 79comparative facts 163compatibilizer 145, 174competitive disadvantage 180competitive world market 219complete extrusion line 200composition of the metal
surface 185compounding extruder 183compounding lines 59compounding procedure 145,
174compressibility 78, 79compression ratio 157, 162, 173compression ratio of the screw
144concave side 113concentricity 116concentricity adjustment 116concentric twin screw extruder
211condition of seal 169conductive melting 227conductor 115cone-and-plate rheometer 74conical nozzle 206conical screws 3consistency index 70consistency of the feed material
188contact pressure 204contaminants 9contamination 123, 145, 147, 157,
165, 167, 173
contamination of the plastic 160
contiguous solids melting (CSM) 34, 85, 227
continuity 170continuous band of screen
material 12continuous improvement 186continuous internal mixers 59continuous screen changers 11control 19, 20control charts 207conventional barrier 214conventional extruders 176conventional SPC 207conventional (vulcanizable)
elastomers 66conveying ability of the pump
section 109conveying capability 87conveying capacity 156conveying characteristics 141,
210conveying rate of the second
stage 110conveying system 173cooling 7, 9, 13, 61, 72, 111, 112,
156, 185cooling capacity 216cooling channels 187cooling device 53cooling rate 20, 128cooling section 55cooling system 160, 172cooling to the feed throat 124cooling water temperature 20copper mesh cloth 130copper phthalocyanine 194coring the screw 85corona discharge treatment 56corona treaters 132co-rotating twin screw extruder
2corrosion pencil anodes 169corrosion-resistant materials
162, 173
236 Index
corrosive attack 123corrosive substance 173corrosive wear 162, 173cost effective extrusion 198counter-pressure of the haul-off
tracks 204counter-rotating twin screw
extruder 3coupling 15cracked bearing or broken gear
165cracking 160, 167cracks 169crammer feeder 7, 78, 79, 171crammer screws 7CRD 217CRD barrier section 214CRD mixer 105, 213critical diehead pressure for vent
flow 110critical draw ratio 142critical level in the hopper 144critical process variables 187critical skin thickness 148critical solid skin thickness 149critical value 142cross-channel flow 94cross-channel shear rate 94cross-channel shear strain 96cross-channel velocities 94crosshead 115crosshead die 115crosslinked material 157crosslinking 64crosslinking reaction 64cross section of the screw
channel 91crystal 64crystalline regions 64crystalline wax 130crystallites 64crystal polystyrene 65CSM 34, 228cubic 60curing 66
cut off flow from the hopper 129
cutter 53, 61cutter knives 60cycle time 141cyclical noise 165cyclic variation 49, 141
D
damaged belts 167dark colors 123, 194, 198Darnell and Mol 225DA software 187data acquisition (DA) 187data acquisition system (DAS)
21, 29, 50, 128, 143data collection rate 29, 44DC brush motor 14, 167DC motor 14dead spots 23, 98, 119, 157decomposition 125deep flighted screw 160defect 163defective bearings or gear teeth
165degassing 73, 77, 86, 108degradation 18, 73, 145, 147,
201, 214 – problems 138 – promoting substances 147
degradation of the plastic 109degree of fill in the grooved
barrel section 210degrees of shear thinning 191demixing action 96densify feed stock 171density 71, 74, 180, 182depolymerization 130depth filtration medium 157Derenzinski 225derivative action 28descaler 47design of experiments (DOE)
206, 207devolatilization 5, 77, 108
dial indicator 166diameter of the calibration
basket 204diameter recognition system
204diamondback hopper 80diaphragm 21, 31, 132dicer 60die 1, 13, 140, 156, 167die design 13, 111, 145, 172die drool 85, 145, 174die face pelletizers 60die forming 110die gap 156diehead pressure 16, 20, 110diehead pressure fluctuation
128die heaters 167die inlet pressure 30die land 174die lines 174die lip buildup 183die opening 174die plate freeze-off 60die restriction 161die swell 111die temperature 19, 124, 156, 174die temperature sensors 170die tooling 124different functional zones 225digital DC brush drives 15dimensional changes 50dimensional control 208, 214dimensional variation 208dimensionless layer thickness
190dimensionless time 190dimensions of the extrudate
128dimensions of the extruded
product 20, 127direct drive 15direct extrusion 183, 217dirty oil 165discharge channel 219discharge end of the screw 140
Index 237
discharge melt temperature 201discharge pressure 49discoloration 125, 145discolored armature 167Disco purge 195diskpack 213dislodge the bridging 171dispersed solids melting (DSM)
86, 227disperse mixing ability 214dispersive 214dispersive mixing 107, 213, 214dispersive mixing capability 158dispersive mixing elements 157dispersive mixing sections 102displacement behavior 193displacing polymer 193distortion of the extruded
product 92distributive 213distributive mixing 93, 214distributive mixing devices 208distributive mixing element 158distributive mixing sections 98ditches 133diverging discharge channel 219door interlock 170door openings 133double flighted screw 88, 173double wave screw 101down-channel shear rates 94down-channel shear strain 96down-channel velocity profiles
93downstack mode 55downstream cooling conditions
128downstream equipment 124downstream feed port 60downtime 165, 183, 190downtime needs 186drag flow 94, 229drag flow rate 140drag induced conveying 78, 80drag induced melt removal 87,
227
drainage 134drawdown 13, 111draw ratio 142, 174draw resonance 141, 142, 174drive 169 – potentiometer 170
drive belts 165, 167drive fuses 167drive motors 167drum or disk extruder 2dry die face pelletizers 60dryer 200drying capacity 123drying plastics 108drying system 53DSM 228DSM melting mechanism 227DSM model 227dual heads 203dual strand extrusion 178Dulmage 100Duranickel 162dust 167Dutch twill 10dyes 194Dynamar from Dyneon 183dynamic choke 109dynamic purging methods 195,
197dynamic response 22
E
Easychange 203eccentrically 167edge trim 203effective length 82effective length of the screw
188effective mixing action 100effectiveness of purging 198effect of air currents 25efficiency 175efficient cooling 181efficient distributive mixing 215efficient extrusion 186, 187
efficient extrusion operations 201
efficient melting 87efficient operation 187efficient troubleshooting 187Egan mixer 104Egan mixing section 103E-gels 157Egeplast Werner Strumann
GmbH 203elastic effects 179elastic nature 111elastomers 66electrical band heaters 7electrical codes 132electrical enclosures 132electrical properties 160electric drill 130electricity 131electric motor 14elongated feed opening 80elongational 214elongational flow 106, 213elongational mixing 214elongational mixing action 214elongational mixing devices 213elongational stresses 102emergency lighting 133emergency stop 132, 135emergency stop switch 169employee facilities 134energy consumption 100, 177,
181, 200, 202energy cost 200energy cost per kilogram 200energy cost per year 200energy efficiency 15, 16, 29energy loss 15energy reduction 183energy requirement in extrusion
200energy savings 201energy use 203energy use of the extruder
202engineering 138
238 Index
engineering calculations 13entanglements of the molecules
70enthalpy 29, 72enthalpy difference 72entrapped air 11, 156environment 189epoxy 64, 105equilibrium moisture content
108equipment 187equipment design 187Esde 175ethyleneacrylic acid (EAA) 74excessive die restriction 172excessively high pressures 125excessive noise 167excessive pressure 132excessive screen pack
restriction 172excess wear 169exit routes 133exits 133exit velocity 110extension cords 135external coefficient of friction
78, 79external cooling 206extinguishers 134extraction section 110extraction section of the screw
109extrudate swell 111extruded product 85extruder 1extruder barrel 5extruder barrel temperatures
128extruder drive 14extruder feed hopper 206extruder motor load 184extruder output 169extruder output rate 204extruder performance 84, 187extruder screw 5, 124, 156
extruders without gear reducer 176
extrusion blow molding 181extrusion blow molding ma-
chines 53extrusion coating 57, 181extrusion compounding 59extrusion compounding lines
53extrusion die 12, 110, 201extrusion equipment 186extrusion lamination 58extrusion line 53extrusion pressure 184extrusion technology 219extrusion theory 225
F
fabric 57Farrel 213fast cooling 147Fast Fourier Transform 44fast variation 141faulty bearings 166Fe2O3 194feed block system 14, 56feeders 157feed hopper 7, 78feed hopper design 171feed housing 187 – temperature 46
feed housing water flow rate 187
feeding characteristics 83feeding device 188feeding problems 126, 143, 171feed opening 6, 125, 143feed problems 124, 129feed section 77, 157, 167feed section casting 169feed stock characteristics 209feed stock variability 188feed stock variation 171feed temperatures 171feed throat 6, 78, 140
feed throat housing 84feed throat temperature 156feed tubes 157FFT 44fiber 12fiber addition 218fiber addition port 218fiber breakage 218fiber feed rate 219fiber reinforced plastics (FRP)
218fiber spinning 142, 178fiber spinning lines 53fiber wetting 218fibrous strand bundles 219fibrous strands 219filled polyolefins 181filler 180film and sheet extrusion lines
53film extrusion 183film lines 55filter 169final extruded product 183fines 157finite element analysis (FEA)
90, 208first aid 134first aid supplies 134first stage 156first stage of the screw 109fishbone chart 147flame treatment 56flat film 12, 117flat film or sheet die 110flat plate 229flat plate approximation 229flat trough 229FLC 28flexible bands construction 204flexible manufacturing 203flexible membrane 57flex lip adjustment bolts 57flight clearance 87, 92flight flank radius 84flight helix angle 225
Index 239
floating sleeve intermeshing pin mixer 215
flood fed 126flood feeding 188, 210flood feeding rate 127flood feed rate 82floor openings 133flow along the unrolled screw
channel 91flow behavior of plastic melts
67flow-chart 163flow of the feed material 188flow of tower/municipal water
source 168flow properties 111, 138flow rate 111flow rate of cooling water 187flow rate ratio (FRR) 192flow simulation 199flow splitter 115flow splitting 101, 179fluid heating 8fluidized bed 129fluorinated polymers 183fluorinated PPA 183fluoro-elastomer 142, 145fluoropolymers 123flushing action 190flushing out the resin 189flush lines with scale removing
compound 169flush-mounted melt temperature
160flush-mounted probe 24, 172fluted mixing sections 102foamed plastics 182foam extrusion 182, 210, 216foaming action 130foil 57force balance 225forced conveying 18fork lift truck 132forming 77forward pumping capability 98,
100, 104, 214
four-motor CMG torque drive 175
fractional melt plastic 68fraying 167free extrusion process 53freeze-off 60frictional force 81, 225FRP compounds 218full factorials 207full intermeshing action 216fully beneficiated 182fully intermeshing 3fully streamlined die 119fumes 135functional product problems
160functional product properties
139functional zone 77fuzzy logic control 28fuzzy rules 28
G
gaskets 167gas-laden melt 216gearbox 15, 167, 169gearbox assembly 167gearbox problems 143gearcase 166gear or bearing problems 165gear pump 17, 48, 54, 60, 156,
161, 179gear reducer 16, 176gears 165gel 157, 173, 214, 215gel capture capability 173generation of a knowledge base
28geometrical sections 77GFE 209glass fiber 162glass transition temperature 71,
76, 138, 160glued 166gouges 157, 169
granulators 202, 203gravity induced 80gravity induced conveying 78Gregory 103grooved barrel extruders 210grooved barrel in feed section
171grooved feed extruders (GFE)
83, 84, 157, 209, 210grooved feed section 78, 83grooved feed throat 141grooved liner 84grooves 157Gross 194ground connections 170grounds 132guardrails 133guards 133, 169, 170
H
hairnets 131hand-squeeze test 79hanger die 118hang-up 104, 173hang up or build up 85Hansen 181“hard” water 47Hastelloy 162haul-off 61, 204HDPE 74, 75, 141, 181head 204head/die cords 170head pressure 126health hazards 133heat 131heat-activated chemical reaction
130heater clamping bolts 170heater contacts 132heater terminal connections
170heat exchange 165heating 7, 72heat insulating blanket 201heat insulating material 201
240 Index
heat loss 201heat resistant gloves 129, 131heat resistant layer of plastic
126heat-sensitive materials 105heat soak 124heat-soak cycle 130heat transfer 181, 187, 216heat transfer conditions 189heat transfer fluid 85Helibar extruder 211helical channels 116helical flight 5helical flow path 95helical orientation 103helical solid ribbon 35helix angle 84, 87, 91, 104helix angle of the barrier flight
104hemi-spherical cavities 98herringbone gear 16HHT 217HHT screw geometry 216high die restriction 172high discharge pressures 217higher barrel temperature 87high filler levels 217high frequency envelope (HFE)
166high frequency impact sounds
166high friction 209high heat transfer (HHT) screw
216highly compressible materials
79highly corrosion-resistant
162highly stabilized version of the
plastic 126, 157high melt index 123high melt index masterbatch
159high melt temperature 139, 157,
160, 172
high molecular weight droplets 157
high motor load 139, 161high oil temperatures 165high precision extruded product
15high-precision extrusion 18high precision operations 14high pressure 131high-pressure alarm 132, 135high pressure drop 104high restriction at screen pack
172high-restriction die 110high-speed extruder 3, 177high-speed extrusion 175high-speed Helibar extruder
211high-speed single screw extruder
(HS-SSE) 175, 183high-speed twin screw extruders
82high stock temperatures 147high stress region 102, 106high temperature 161, 167high temperature and pressure
alarms 165high temperature plastics 123high viscosity plastics 160, 176,
193high voltage devices 132historical data 137hoist 129, 132hoop strength 117hopper 140, 157hopper barrier guards 169hopper loaders 203hopper slide valve 126hopper with a square or rectan-
gular cross section 79horseshoe die 118horseshoe manifold 119hoses 167hospital 134hot air 206hot plastic 131
hot spot 39, 208housekeeping 133hydraulic ram 11hydraulic screen changers 11hydrolysis 109, 202hygroscopic materials 5, 108hyperactive screw 201
I
identify the problem 163identify the process 163ID waviness 43IKV (Institut für Kunststoff-
verarbeitung = Institute for Polymer Processing) 182
imbalance 166imbalance between the first and
second stages of the extruder 156
immersion melt temperature probe 35
immersion probe 24, 172immersion TC 23immersion temperature probe
160impending failure 165important process parameters
19improper use of the plastic
product 160impurities 182IMS 198inadequate exhaust air flow
167incoming material 157incompatible component 174Inconel 162in control 206incorrect screw design 110indigestion 210indigo 194indirect drive 16induction heating 7induction time 71, 73, 138inefficient venting 147
Index 241
infiltration 219infirmary 134infrared (IR) detectors 23infrared (IR) temperature
measurement 143infrared radiation 36infrared thermometers 36in-house compounding 183injection molding machines
227inlet channel 12, 117inline 115inline die 115inner layer 92inner recirculating region 92,
96inner region of the channel 96inner vortex 206Inoex 204inorganic 194inorganic pigments 194input 165inside diameter of barrel 169inspection 133Institut für Kunststofftechnik
(IKT) 211instrumentation 19, 137, 187instrument panel 189insufficient barrel friction 172insulate all hot oil lines 202insulated TC 25insulated wires 132insulate extruder 171insulation spark testers 132insulation tape in conduit box
169intake capability 6integrated sheet and thermo-
forming lines 53intelligent manufacturing
methods 175intensely cooled grooved feed
extruders 210interface 193, 226interface distortion 57interlocked 132
interlocking guards 135intermediate 165intermediate material 190intermediate pelletizing 183intermeshing action 48intermeshing region 216internal air pressure 54internal coefficient of friction
78, 79internal cooling 206internal die surfaces 174internal heat generation 8internal screw heating 85internal stresses 113intractable plastics 4iron oxide 194irregular feeding 144IR temperature measurement
38
J
J-Tex 85junction boxes 135
K
K&A Knoedler 175keyways 130Kramer 203Krause 197Krauss-Maffei 203K-tron 213Kuhne 175Kulikov 183Kynar from Atofina 183
L
labor intensive 204Labtech Engineering 217ladder ways 133laminating 56lamination 56land length 145
land region 12, 110land section 117large diameter extruders 132large diameter pipe extrusion
206large differences in melt
temperature 208large sidegroup 64large volume compounding 165laser gage 54layer thickness 192layflat film 59L/D 4, 209L/D of the extruder 161LDPE 73, 145, 184, 194lead chromate 194leading side of the screw flight
110leakage at seals 169leakage flow 92leaks in closed-loop systems
168legs 113length of the compression
section 144, 162length-to-diameter (L/D) ratio
4, 209LeRoy 103LeRoy mixer 104less restrictive die 171less restrictive screen pack 171,
172level of vacuum 124levels of crystallinity 65lifting techniques 132light colors 194, 198lightly colored plastics 123lights off 186light transmission 65linear plastics 141lines 145line speed 20, 115line tension 20, 128liquid crystalline plastics (LCPs)
66LLDPE film 183
242 Index
loading pattern 202log-log plot 139longer extruder barrel 156long loose hair 131long residence times 147, 157long shaft wire brush 130loose boards 133loose clothing 131looseness in rotating machinery
166loss of physical properties 145loss of volatiles 145low bulk density feed stock 171low cost fillers 180low-density polyethylene (LDPE)
65lower critical shear rate 142lower mesh screens 172lower portion of the channel 95lower viscosity resin 193lowest viscosity 198low frequency instabilities 144low friction coating 85, 145, 171,
173, 174low friction screw coating 171,
172low melt index masterbatch 159low melt index material 123, 158low melting point plastics 126low melt temperatures 185low oil levels 165low output 139low speed extruders 3low-temperature gas stream
206low temperature plastics 123low viscosity plastics 160lubricating effect 184lubricating oil 165lubrication 185
M
machine downtime 166machine geometry 77machine troubleshooting 164
Maddock 103Maddock mixer 104Maddock mixing section 157main drive 202main flight 105main power switch 124maintenance 138, 164, 166maintenance activities 164Maintenance Professional 164maintenance software 164maintenance tool 207mandrel 116manifold 12, 14, 117manifold system 178manual 203manual cleaning 195manual screen changers 11manual tuning 28manufacture 98manufacturing discipline 187marble 182Massachusetts Institute of
Technology (MIT) 182material blockage 172material change 158material choice 160material consumed in the
change-over 177material cost 180materials QC 138material stuck 172Maxflexx 205measurement 61measurement error 22, 25measurement of melt
temperature 160measure screws and barrels
167mechanical degradation 146mechanical properties 160mechanical specific energy
consumption 177medical 132, 134medical tubing 14melamines 64
melt conveying 77, 86, 88, 89, 228
melt conveying problems 171melt conveying zone 90, 93melt displacement behavior 190melt-fed extruder 1melt film 85, 87, 226melt film thickness 87Melt Flipper 179melt flow index (MFI) 68melt fracture 141, 174, 183melt index (MI) 68, 138melt index tester 68melting 85, 226, 228melting capacity 88, 202, 209melting efficiency 87melting or plasticating 77melting point 71, 75, 138melting problem 140, 144, 171,
209melting rate per unit down-
channel distance 227melting related instabilities
202, 209melting theory 226melt pool 35, 85, 88, 226melt pressure 19, 29, 30, 48,
128, 187melt pressure measurement
135melt pump 179, 228melt strength 209melt temperature 19, 29, 35,
90, 104, 128, 160, 174, 175, 187, 189, 201, 214
melt temperature and pressure fluctuations 167
melt temperature differences 92
melt temperature distribution 38, 208
melt temperature fluctuation 214
melt temperature measurement 23
Index 243
melt temperature variation 38, 141, 143, 144, 208
melt viscosity 104, 138membership functions 28mercury 21, 31, 132, 135meshing gear teeth 165mesh number 10mesh value screens 156metal glass (Lunac) 198metallic particles 161metal particles 162, 173metal sheath 24metering section 109meter-weight of the pipe 204method of internal pipe cooling
205methods to increase efficiency
175mica insulated heaters 7Michaeli 120microcellular foam 182micron rating 10mid-region of the channel 90milieu 189minimum residence time 190,
191misalignment 166mixed alkyl-aryl phosphites 185mixing 10, 77, 86, 93, 158mixing capability 100mixing elements 92mixing screw 174mixing sections 10, 158mix quality 158mixture 158modular extruders 203moisture-induced degradation
109moisture level of feed stock 187molecular weight 68, 184, 209molybdenum disulfide 183Monastral blue 194morphology 65motor 15motor bearings 169motor brushes 167
motor efficiency 167motor load 19, 29, 84, 126–128,
140, 161, 166, 187, 189, 214motor problems 143motor vibration 168movable guards 131moving parts 131MTC 166multi-flighted discharge 144multi-flighted screw 88multi-layered product 14multi-layer pipes 204multi-lumen tube 113multi-manifold system 14, 56multiple flights 88multiple haul-offs 180multiple knife cutter 60multi-screw extruder 2multi-strand extrusion 178multivariate analysis (MVA) 207municipal water 169MVA system 207
N
narrower pellet size distribution 188
natural bridge 79NCF (Nexxus Channel-F) 219neck ties 131neutral screw 9new developments in extrusion
175Newtonian 70Newtonian fluid 104, 229Nexxus technology 219Niemeier 199nip roll 55, 59, 131nip roll section 54nitrided steel 185noise level 176noise level of bearings 168no material in the feed hopper
171nominal speed 14non-catalytic steels 185
non-coated part of the screw 198
non-colored plastics 194, 198non-contact temperature
measurement 23non-foam extrusion 182non-insulated TC 25non-intermeshing 3non-isothermal analysis 38non-linear fluid 69non-Newtonian 69non-Newtonian behavior 90non-Newtonian fluids 104, 229non-Newtonian plastics 38, 142non-return valve (NRV) 215non-uniform flow 72, 201, 208non-uniform melt temperatures
97, 179, 208non-uniform mixing 97non-uniform plastic tempera-
tures 72non-uniform temperatures
201non-vented single screw
extruder 160no-output condition 171Noriega 209normal flow 92Novachem 198Nucrel Disco purge 196number of screens in the screen
pack 156nylon (PA) 65, 130, 142
O
objective 163observed and comparative facts
163obstruction 133octahedral shape 60off-spec product 188oil 167oil cooling 8oil filter 169oil flow to all bearings 168
244 Index
oil heat exchanger 169oil leaks 168oil pump 165oil sump 169oil temperatures and pressures
168on-off control 26on-off temperature control
144onset of sharkskin 184on-the-fly adjustment of pipe
204open discharge 140opening of a door 189operating conditions 77operating cost 217operating procedures 172, 175operator friendly 98operator skill 217optical properties 160Optifoam© 182optimizing the process 187optimum depth of the channel
90optimum helix angle 90, 104optimum helix angle for melt
conveying 90optimum screw geometry 90organic acids 183organo-phosphates 185, 186organo-phosphite anti-oxidants
185orientation 113original equipment manufacturer
(OEM) 89orthogonal arrays 207outer layer 92outer region 96outer vortex 206output 161output fluctuations 128output problems 139output stability 214output variation 17, 139, 144outside diameter 54
outside region of the channel 90
oven 129overheating of the plastic 201overloads 170over-pressure safety device 21,
125, 170over-pressure shutdown 32oxygen 73, 147ozone layer 183ozone treatment 56
P
packaging products 132Paetzold 197paper 57paperboard 57parallel screws 3parison 204partially filled 82, 109partially intermeshing 3partially streamlined dies 120particle rotation 214particle shape 78particle shape distribution 78particle size 78, 138, 157, 174particle size distribution 78parts 131Pascal · second 67passageways 133P-control 27PD-control 28PE 200, 205pellet concentrate 130pelletized resins 189pelletizers 60pelletizing system 60pellet size distribution 188performance improvement 138P-gels 157phosphoric acid 185phthalocyanines 194physical characteristics 138physically clean the extruder
198
physical properties 181, 201, 218physical purging compounds
130PID-control 28piezo-electric transducer 21, 22pigments 194pin barrel extruder 100pinholes 145, 146pin mixers 98, 99pin mixing sections 99pipe 12, 114, 181pipe extrusion 203pipe or tubing die 110pits 133plain weave 10planetary barrel section 105planetary gear extruders 102planetary gear mixers 105planetary screws 105plant voltage variations 20, 144plasticating extruder 1, 77plastic film 57plastic melt 63plastic properties 77plastic residue 130plastics extruder 1plastic temperature 8, 132plate die 119platinum resistance element 23plug 170plug flow 93, 191plugged filter 165plugging 89, 209PMEW 164pneumatic pressure transducer
22point-of-operation guards 134Poise 67polishing rolls 54polyamide (nylon) 109polybutadiene 66polycarbonate (PC) 64, 109,
130, 198polyester 64, 105, 109, 142polyesters of oxiacids 184
Index 245
polyethylene 63, 64, 142, 147, 183, 185
polyethylene-based compounds 130
polyethylene glycol (PEG) 183polyethylene terephthalate (PET)
65polyisoprene 66polymer feed port 218polymer header system 178polymerization 157, 173polymerization reactor 157polymer melts 208polymer processing aids (PPA)
183polyolefins 180PolyOne 198polypropylene (PP) 64, 65, 177,
180, 181polystyrene (PS) 64, 76, 142, 177polyurethane 67, 105, 109polyvinylchloride (PVC) 64polyvinylidene fluoride 132Ponzielli 213poor melt temperature
measurement 172poor mixing ability 97poor screw design 201portable hand tools 135position of the interface 190,
193position of the pin 204position of the vacuum tank
204post consumer reclaim (PCR)
78post-reactor finishing 165post-treatment ovens 202powder 156powder coatings 105powder leaks 168power consumption 181, 187,
209, 214power draw 19power draw from the heaters
128
powered industrial truck operators 134
power law approximation 70power law expression 70, 139power law fluid 70power law index 70, 90, 191power transmission capability
16PP 200, 205PPA 184, 185pre-compounded material 183pre-control method 207pre-drying 174, 202 pre-dry the plastic 108preheating 58, 89, 202preheating the plastic 89, 162pre-heating zones 203preheat the plastic pellets 206pre-land section 117preparation of the machine 123pressure 127, 128, 132, 165 – feedback control 31, 32 – pulses 48
pressure and temperature regulators 168
pressure drop 98, 104pressure flow 91, 94, 229pressure fluctuation 144pressure generating capability
18, 217pressure gradient 93, 193pressure indicator 169pressure indicators/controllers
170pressure