Extrusion in Ceramics

Contents

List of Contributors

Acknowledgements

Introduction

1.1 What to Expect

1.2 History of an Obsession

1.3 About the Various Contributions

1.4 Famous LastWords

References

Shaping in Ceramic Technology – An Overview

2.1 Dry Pressing

2.2 Extruding

2.3 Slip Casting

References

Current Classification of Ceramic Materials

3.1 Classification by Application or Chemical-Mineralogical Structure

References

Types of Extrusion Units

4.1 Classification by the Range of Application

4.2 Classification by the Product to be Extruded

4.3 Classification by the Arrangement of the Auger Shaft and Direction of Column Exit

4.4 Classification by the Diameter of the Extruder Barrel

4.5 Classification by the Number of Auger Shafts

4.6 Classification by the Consistency of the Body to be Processed

4.7 Classification by the Design of the Extruder Barrel

4.8 Classification by the Design and Mounting of the Augers

4.9 Classification by Specific Extrusion Method

4.10 Classification by the Type of De-Airing Device Employed

4.11 Classification by the Extruder Design Features

4.12 Classification by the Design of the De-Airing Mixer

4.13 Classification by the Design Version of the Combined De- Airing Extrusion Unit

References

A Short History of the Extruder in Ceramics

5.1 The Development of the Extruder and Column Shaping

5.2 The Development of Individual Extruder Components

5.3 The Development of the Vacuum Extruder and Combined De- Airing Extrusion Unit

5.4 The Extruder in the Different Fields of Ceramics

5.5 Chronology of Extrusion in Ceramics

References

The Principle of the Auger Extruder

6.1 Introduction

6.2 Liquid Phase and Additives

6.3 Physics of Process Steps

6.4 Engineering Implementation

6.5 Other Types of Product

6.6 Range of Product Size and Shape

6.7 Other Technologies

6.8 Final View

References

Rheology of Ceramic Bodies

7.1 Introduction

7.2 The Material Law

7.3 Dynamic Consideration of Cylindrical-Tube Pressure Flow of Bingham Media with Wall Slippage

7.4 True Flow Curve

7.5 The Rheological Simulation Model

7.6 Summary and Prospects

References

Rheology and Extrudability of Ceramic Compounds

8.1 Introduction

8.2 Rheological Test Methods for Describing Extrudability

8.3 Summary

References

Scenarios of Extrusion

9.1 Introduction

9.2 Functioning of Screw Extruders

9.3 Measures

9.4 Conclusion

References

Laminations in Extrusion

10.1 Definition

10.2 Causes of the Development of Laminations and Different Types of Laminations

10.3 De-Airing Laminations

10.4 Laminations as a Result of Inhomogeneous Body

10.5 Methods for Detection and Evaluation of Laminations

10.6 Opportunities for Minimising Detrimental Effects Caused by Laminations

10.7 Conclusion

References

Additives for Extrusion

11.1 Introduction

11.2 Additive Types

11.3 The Chemical Structure and Mechanism of Action of Plasticizing Additives

11.4 Summary

References

Dies, Pressure Heads, Strainer Plates and More

12.1 Outline/Introduction

12.2 Specific Characteristics of Ceramic Extrusion Body with Regard to Shaping

12.3 Factors of Influence to be Considered for the Design of Extrusion Tools

12.4 Combination Pressure Head and Die Assemblies for Technical Ceramics

12.5 Combination Pressure Head and Die Assemblies in Heavy Clay Ceramics

Conclusions

12.6 Brief Overview of Tribomaterials Customarily Employed in Ceramic Extrusion Tools

12.7 Closing Remarks

References

Twin-Screw Extruders in Ceramic Extrusion

13.1 Introduction

13.2 History of Batch and Continuous Kneading

13.3 Working Principle of Co-Rotating Twin-Screw Extruders

13.4 High-Torque Versus High-Volume Extruders

13.5 Compounding Applications with High Solid Contents

13.6 Ceramic Extrusion Plants

13.7 Summary

References

Piston Extruders

14.1 Piston Extruders in Ceramics

14.2 Types of Piston Extruder

14.3 The Components of Piston Extruders

14.4 The Pros and Cons of Piston Extruders

14.5 Auxiliary Equipment

14.6 Development

14.7 Literature

Evacuation in Ceramic Extrusion – Dependences and Local Situations

15.1 Vacuum Measurement

15.2 Percent Vacuum as a Function of Site Elevation, Parameter: Temperature of Extrusion Compound

15.3 Percent Vacuum as a Function of Weather-Induced Differences in Air Pressure Parameter: Temperature of Extrusion Compound

15.4 Physical Interdependences

References

Evacuation Technology for Ceramic Extrusion

16.1 Introduction

16.2 Liquid-Ring Vacuum Systems

16.3 Vacuum Systems with Rotary Vane Vacuum Pumps

16.4 Vacuum Systems with Dry-Running Vacuum Pumps

16.5 Vacuum Pump Combinations

16.6 Components of the Vacuum System

16.7 Control and Regulation

16.8 Summary

References

Thermoplastic Extrusion for Ceramic Bodies

17.1 Introduction

17.2 Thermoplastic Extrusion Processing

17.3 Thermoplastic Extrusion Processing

17.4 Conclusion

References

Tribological Principles

18.1 Tribological System

18.2 ElementaryWear Processes

References

Measures for Protection Against Abrasion on Screws Used in Extruding Ceramic Compounds

19.1 Protection Against Abrasion by Using the Appropriate Material

19.2 Layer-Based Abrasion Protection

References

Perspectives forWear Reduction with Ceramic Extruder Components

20.1 Introduction

20.2 Properties of Ceramics

20.3 Design and Field Testing of Ceramic Augers

20.4 Application of a Ceramic Auger in the Production Process for Al2O3 Filtration Tubes

20.5 Conclusions and Outlook

References

Test Methods for Plasticity and Extrusion Behaviour

21.1 Actuating Variables

21.2 Test Methods to Determine Plasticity

References

Simulation in Ceramic Extrusion

22.1 The Fundamentals

22.2 Solution of the Governing Equations

22.3 Computational Fluid Dynamics for Ceramic Extrusion

References

Selected Literature

The Authors of the Book

Index