Troubleshooting the Extrusion Process: A Systematic Approach to Solving Plastic Extrusion Problems

✍ Scribed by Noriega M.P.E., Rauwendaal C.

• Publisher: Hanser Publishers
• Year: 2019
• Tongue: English
• Leaves: 364
• Edition: 3
• Category: Library

✦ Synopsis

Troubleshooting extrusion problems is one of the most challenging tasks in extrusion operations, requiring a good understanding of the extrusion process and the material properties, good instrumentation, good analysis tools, and a systematic and logical approach. This book addresses all issues crucial in extrusion troubleshooting. Additionally, it includes industrial case studies, richly illustrated with photographs and photomicrographs, used to provide exemplary approaches to efficient problem analysis and problem solving. The interconnectivity between the different relevant knowledge areas such as materials engineering, processing technology, and product development is emphasized.
This revised third edition comprises a very significant update, with a great deal of new content, especially focusing on additional case studies as well as new sections on collection and interpretation of extrusion process data, rotational rheometry, the smartphone, how screw design can affect extruder performance, melt temperature variation, recent research on automatic optimization of extruder barrel temperatures, process signal analysis using Fast Fourier Transform, among other topics

✦ Table of Contents

Cover
Half Title
Troubleshooting the Extrusion Process: A Systematic Approach to Solving Plastic Extrusion Problems
Copyright
Acknowledgments
Preface
List of Acronyms
Contents
1. Requirements f or Efficient Troubleshooting
1.1 Instrumentation
1.2 U nderstanding the Extrusion Process
1.3 Collection and Analysis of Historical Data (Time Line)
1.4 Team Building
1.5 Condition of the Equipment
1.6 Information about the Feed Stock
1.7 Problem-Solving Techniques
1.8 Collection and Interpretation of Extrusion Process Data
1.8.1 Introduction
1.8.2 Vital Signs of the Extrusion Process
1.8.2.1 Melt Pressure
1.8.2.2 Melt Temperature
1.8.2.3 Training
1.8.3 Conclusions
2. Tools for Troubleshooting
2.1 T emperature Measurement Devices
2.2 Data Acquisition Systems
2.2.1 Portable Data Collectors/Machine Analyzers
2.2.2 Fixed-Station Data Acquisition Systems
2.3 Light Microscopy
2.4 Thermochromic Materials
2.5 Thermal Analysis , IR Spectroscopy, and Rheometry
2.5.1 Differential Thermal Analysis and Differential Scanning Calorimetry
2.5.2 Thermogravimetric Analysis
2.5.3 Fourier Transform Infrared Spectroscopy
2.5.4 Thermomechanical Analysis
2.5.5 Torque Rheometry
2.5.6 High Pressure Capillary Rheometry
2.5.7 Rotational Rheometry
2.5.8 Other Thermal Characterization Techniques
2.6 Miscellaneous Tools
2.6.1 Infrared Thermography
2.6.2 The Smartphone
2.6.3 Power Measurements
3. Systematic Troubleshooting
3.1 Upsets versus Development Problems
3.2 Machine-Related Problems
3.2.1 The Drive System
3.2.2 The Feed System
3.2.3 The Heating and Cooling System
3.2.4 How Screw Design Can Affect Extruder Performance
3.2.5 W ear Problems
3.2.5.1 Wear Mechanisms
3.2.5.2 T est Methods for Wear
3.2.5.3 Causes of Wear
3.2.5.4 Solutions to Wear Problems
3.2.5.5 Rebuilding Worn Screws and Barrels
3.3 P olymer Degradation
3.3.1 T ypes of Degradation
3.3.1.1 Thermal Degradation
3.3.1.2 Mechanical Degradation
3.3.1.3 Chemical Degradation
3.3.2 Degradation in Extrusion
3.3.2.1 Residence Time Distribution
3.3.2.2 Temperature Distribution Simple Calculations
3.3.2.3 Temperature Distribution Numerical Calculations
3.3.2.4 Reducing Degradation
3.4 Extrusion Instabilities
3.4.1 F r equency of Instability
3.4.1.1 High-Frequency Instabilities
3.4.1.2 Screw Frequency Instabilities
3.4.1.3 Low-Frequency Instabilities
3.4.1.4 Very Slow Fluctuations
3.4.1.5 Random Fluctuations
3.4.2 F unctional Instabilities
3.4.2.1 Solids-Conveying Instabilities
3.4.2.2 Plasticating Instabilities
3.4.2.3 Melt-Conveying Instabilities
3.4.2.4 Devolatilization Instabilities
3.4.2.5 Mixing Related Instabilities
3.4.2.6 Distributive Mixing Sections
3.4.2.7 Dispersive Mixing Sections
3.4.2.8 Solving Mixing Problems
3.4.2.9 Melt Temperature Variation
3.4.3 Solving Extrusion Instabilities
3.5 Air Entrapment
3.6 Gel Problems
3.6.1 Measuring Gels
3.6.2 Gels Created in the Extrusion Process
3.6.3 Removing Gels Produced in Polymerization
3.7 Die-Flow Problems
3.7.1 Melt Fracture
3.7.2 Die-Lip Buildup (“Die Drool”)
3.7.3 V - or W-Patterns
3.7.4 Specks and Discoloration
3.7.5 Lines in Extruded Product
3.7.5.1 Weld Lines
3.7.6 Optical and Appearance Properties
3.2.6 Screw Binding
3.2.6.1 Extrusion of Fluoropolymers
3.2.6.2 The Mechanics of Screw Binding
3.2.6.3 Changes in Clearance Due to Temperature Differences
3.2.6.4 Analysis of Temperature Distribution in Extruder Screws
3.2.6.5 Change in Clearance Due to Compressive Load
3.2.6.6 R esults from Analysis
4. Case Studies
4.1 Film Coextrusion — Degradation in the Middle Layer
4.1.1 Description of the Problem
4.1.2 Analysis of the Problem
4.1.3 Solution
4.2 F ilm Coextrusion with Interfacial Problems
4.2.1 Description of the Problem
4.2.2 Analysis of the Problem
4.2.3 Solution
4.3 Lines in the Extruded Film
4.3.1 Description of the Problem
4.3.2 Analysis of the Problem
4.3.3 Solution
4.4 Color Variation in Polypropylene Carpet Fiber
4.4.1 Description of the Problem
4.4.2 Analysis of the Problem
4.4.3 Solution
4.5 Plastic Film with Poor Transparency
4.5.1 Description of the Problem
4.5.2 Analysis of the Problem
4.5.3 Solution
4.6 Wear Problem in Film Extrusion
4.6.1 Description of the Problem
4.6.2 Solution
4.7 Multilayer Film — Several Appearance Problems
4.7.1 Description of the Problem
4.7.2 Analysis of the Problem
4.7.3 Solution
4.8 Dispersion Problem in a High-Density Polyethylene Bottle
4.8.1 Description of the Problem
4.8.2 Analysis of the Problem
4.8.3 Solution
4.9 P olymer Degradation
4.9.1 Description of the Problem
4.9.2 Analysis of the Problem
4.9.3 Solution
4.10 Heat-Sealing Problems in a Coextruded Film
4.10.1 Description of the Problem
4.10.2 Analysis of the Problem
4.10.3 Solution
4.11 Output Problem in a Blown Film Line
4.11.1 Description of the Problem
4.11.2 Analysis of the Problem
4.11.3 Solution
4.12 Masterbatch Selection
4.12.1 Description of the Problem
4.12.2 Analysis of the Problem
4.12.3 Solution
4.13 Pipe Extrusion Problem
4.13.1 Description of the Problem
4.13.2 Analysis of the Problem
4.13.3 Solution
4.14 Gel Formation in a Coextruded Film
4.14.1 Description of the Problem
4.14.2 Analysis of the Problem
4.14.3 Solution
4.15 Agglomerates and Grammage Variation in a PP Sheet
4.15.1 Description of the Problem
4.15.2 Analysis of the Problem
4.15.3 Solution
4.16 Insufficient Melting and Mixing in a Plasticating Unit
4.16.1 Description of the Problem
4.16.2 Analysis of the Problem
4.16.3 Solution
4.17 High Melt Temperature and Insufficient Output in Coextrusion
4.17.2 Analysis of the Problem
4.17.1 Description of the Problem
4.17.3 Solution
4.18 Deficient Solids Conveying and Dispersion
4.18.1 Description of the Problem
4.18.2 Analysis of the Problem
4.18.3 Solution
4.19 Instability of Formation at the Die
4.19.1 Description of the Problem
4.19.2 Analysis of the Problem
4.19.3 Solution
4.20 Intermittent Pumping in a Vented Extruder
4.20.1 Description of the Problem
4.20.2 Analysis of the Problem
4.20.3 Solution
4.21 Melt Fracture or Sharkskin in m-PE
4.21.1 Description of the Problem
4.21.2 Analysis of the Problem
4.21.3 Solution
4.22 Scale-up of LLDPE Single-Screw Extruder
4.22.1 Description of the Problem
4.22.2 Analysis of the Problem
4.22.3 Solution
4.23 Non-homogeneous Melt in Blow Molding
4.23.1 Description of the Problem
4.23.2 Analysis of the Problem
4.23.3 Solution
4.24 High Melt Temperature in Sheet Extrusion
4.25 Gear Pump Speed Variation in Sheet Extrusion
4.26 Melt Temperature Variation in Tubing Extrusion
4.27 Black Specks in Tubing Extrusion
4.28 Mechanical Degradation in TPE Extrusion
4.29 Degradation in a Long Adapter
4.30 Shrink Voids in Rod Extrusion
4.31 Improper Preheating of Extruders
Appendix 1: Systematic Problem Solving
Step 1: Problem definition
Step 2: Understand observed and comparative facts
Step 3: Identify relevant distinctions and generate likely causes
Step 4: Test and verify the likely causes
Step 5: Develop action plan/implement solution
Step 6: Monitor the solution’s effectiveness, and communicate the solution
Appendix 2: Machine Troubleshooting and Maintenance
A2.1 Check the Oil
A2.2 Unusual Noises
A2.3 Vibration Monitoring
A2.4 Drive Motors and Belts
A2.5 Spare Parts
A2.6 Screw and Barrel
A2.7 Extruder Maintenance Checklist
Appendix 3: Extruder Barrel Temperatures
A3.1 Setting Extruder Barrel Temperatures
A3.2.1 Introduction
A3.2.2 Facts about Barrel Temperature Profile (BTP)
A3.2 Extruder Barrel Temperature Profile Optimization
A3.2.3 Typical Process Temperatures for Different Plastics
A3.2.4 Guidelines and Considerations for Setting Barrel Temperatures
A3.2.5 BTP Optimization by Design of Experiments (DOE)
A3.2.6 BTP Optimization by One-at-a-Time Experiments (OTE)
A3.2.7 Dynamic BTP Optimization
A3.2.8 Other Studies on Optimization of Extruder Barrel T emperature Pr
A3.2.9 Conclusions
Appendix 4: Process Signal Analysis Using Fast Fourier Transform
References
Index