The Art of Ceramic Extrusion

Foreword
Preface to the Extended Second Edition
Email Contacts to the Authors
Contents
1 How to Use This Booklet
	1.1 For Whom This Booklet Is Written
	1.2 Some Suggestions for the Use
	1.3 Conclusions
	Bibliography
2 What Do We Understand by Extrusion in Ceramics?
	2.1 Shaping Methods in the Ceramic Industry
	2.2 What Is Extrusion?
	2.3 Criteria for Extrusion
	2.4 Feeding Systems
	2.5 Auger and Barrel
		2.5.1 Auger
		2.5.2 Barrel
	2.6 De-airing
	2.7 Extruded Ceramic Products
	2.8 Conclusions
	Bibliography
3 Ceramic Materials—The Malice of the Object
	3.1 Definition of Ceramics
	3.2 Classification of Ceramic Materials
	3.3 Classification of Ceramics According to Applications
	3.4 The Main Properties of Ceramic Bodies for Extrusion
		3.4.1 Plasticity
		3.4.2 Yield Point, Viscosity and What Mr. Bingham Has to Say
		3.4.3 Homogeneity
		3.4.4 Grain Size Distribution
		3.4.5 Wall Friction
	3.5 Conclusions
	Bibliography
4 A Little Bit of Theory
	4.1 What This Chapter Is About
	4.2 Basic Terminology
	4.3 Scenarios of Pressure Build-up in the Extruder
		4.3.1 Scenario 1: The Notorious “Backflow”
		4.3.2 Scenarios 2 and 3—“Backflow” Again, But for Other Reasons
	4.4 The Benbow–Bridgwater Equation
	4.5 How to Calculate the Output of an Extruder
	4.6 Conclusions
	Bibliography
5 How to Determine an Extruder and Which Data Do We Need?
	5.1 The Decision Procedure and the Database
	5.2 The Decision Model
	5.3 About the Sense and Nonsense of Questionnaires
	5.4 Conclusions
	Bibliography
6 Plasticity or the Great Unknown
	6.1 What Does Plasticity Mean in Ceramics?
	6.2 The Two Plasticities
	6.3 How Do We Measure the Two Plasticities?
	6.4 Factors Determining Plasticity of a Ceramic Body
	6.5 Two Methods to Measure the Development of Plasticity
		6.5.1 Good-Natured and Nasty Ceramic Bodies—the Consistency Curve
		6.5.2 Kneading Curve
	6.6 Plasticity or Consistency or Extrudability?
	6.7 Conclusions
	Bibliography
7 Mixing and Kneading
	7.1 Short Introduction
	7.2 Mixing
	7.3 Kneading
	7.4 Macro-mixing and Micro-mixing
	7.5 Buffer Systems or Dosing Strainers?
	7.6 The Ceramic Body as Dispersed Material System
	7.7 Conclusions
	Bibliography
8 Extrusion as a System
	8.1 What Do We Understand by a System?
	8.2 Components of a System
	8.3 Consequences
	8.4 Conclusions
	Bibliography
9 Laminations and Chaos
	9.1 What Do We Understand by Laminations?
	9.2 Formation of Laminations
		9.2.1 The Pioneering Studies by BCRA
		9.2.2 Where Are Laminations Generated in Extrusion?
	9.3 Types of Laminations
		9.3.1 Flow Laminations
		9.3.2 Cutting Laminations
		9.3.3 Rotational Laminations
		9.3.4 Hub Laminations
		9.3.5 Laminations Caused by Insufficient De-airing
		9.3.6 Combined Laminations
	9.4 What Can Be Done?
	9.5 Conclusions
	Bibliography
10 About the Brave New World of Sensors and Control
	10.1 Introduction
	10.2 The Mechatronic Model
	10.3 Why There Is a Compelling Necessity for Better Measuring Systems for Ceramic Extrusion?
	10.4 What Are the Most Important Operating Data for Extrusion?
	10.5 Aggregated Measured Values/Operating Data
	10.6 Conclusions
	Bibliography
11 Ancillary Equipment and Accessories
	11.1 The Most Important Accessories for the Extrusion Unit
	11.2 Foundation, Base Frame and Supporting Structure
	11.3 Control
	11.4 Cooling/Chilling of Augers and Barrels
		11.4.1 Why and When Must an Extruder Be Cooled?
		11.4.2 Selection of the Cooling Unit
		11.4.3 The Major Operating Data for the Cooling System
		11.4.4 Also to Be Noted
	11.5 Vacuum Pump and Vacuum Monitoring
		11.5.1 Definition of the Vacuum Pump
		11.5.2 How to Measure the Level of Vacuum Correctly
		11.5.3 Types of Vacuum Pumps
		11.5.4 Regulation and Measurement of the Vacuum
		11.5.5 Checking and Testing the Vacuum
	11.6 Hydraulic and Pneumatic Equipment
	11.7 Screen and Die Changers
	11.8 Infrastructure
	11.9 Conclusions
	Bibliography
12 Pressure Heads and Dies
	12.1 What Matters
	12.2 Typical Pressure Head/Die Combinations
		12.2.1 Example 1: Pressure Head/Die Combination to Produce Large Brick Blocks
		12.2.2 Example 2: Pressure Head/Die Combination to Produce Stiff-Extruded Face Bricks
		12.2.3 Example 3: Typical Pressure Head/Die Combination to Produce Honeycombs
	12.3 A Look Over the Fence
	12.4 Conclusions
	Bibliography
13 Extrusion Problems and How to Solve Them
	13.1 A Bit of Help for Self-Help
	13.2 Conclusions
	Bibliography
14 Pelletizing by Extrusion
	14.1 What Do We Understand by Pelletizing?
	14.2 Pelletizing by Extrusion
	14.3 Plasticity as a Prerequisite for Pelletizing
	14.4 Pellet Geometry
	14.5 Essential Features of a Pellet Extruder
	14.6 Dies and Matrix Plate
	14.7 Matrix Plate Changer
	14.8 Other Pelletizing Methods
	14.9 Conclusions
	Bibliography
15 Wear, Tear and No End
	15.1 Wear—A Real Challenge
	15.2 Types of Wear
	15.3 Summary of the Most Important Wear Solutions
	15.4 Roughness of Auger Surfaces
	15.5 “Where There Is No Friction There Is No Wear”
	15.6 Function of the Barrel in Extrusion of Ceramic Materials
	15.7 Conclusions
	Bibliography
16 The Ceramic Production Laboratory
	16.1 What Are the Reasons for Having a Production Laboratory?
	16.2 The Types of Production Laboratories
	16.3 Frequency of Sample Testing
		16.3.1 When and How Often?
		16.3.2 The Worst Case
	16.4 The Subject of Random Samples
	16.5 A Short Real-Life Story
	16.6 Methods and Instruments
	16.7 Conclusions
	Bibliography
17 Piston Extruders in Ceramics
	17.1 Types of Piston Extruders
	17.2 Working Principle of a Piston Extruder
	17.3 Advantages of Piston Extruders
	17.4 Components of the Piston Extruder
		17.4.1 Hydraulic System and Hydraulic Piston
		17.4.2 Base Frame and Press Frame of the Piston Extruder
		17.4.3 Material Container
		17.4.4 Die Holder
		17.4.5 Vacuum System
		17.4.6 PLC and Data Logging
	17.5 Auxiliary Equipment
		17.5.1 Handling and Cutting Device
		17.5.2 Automation of a Piston Extruder
	17.6 Further Developments
	17.7 Conclusions
	Bibliography
18 Does that Exist—The Optimal Extruder?
	18.1 A Sad Story
	18.2 Questions and Criteria
	18.3 Optimal Extruder = Optimal Extrusion?
	18.4 Conclusions
	Bibliography
19 Additives for Extrusion
	19.1 Objectives for the Use of Additives
	19.2 Types of Additives
		19.2.1 Plasticizers
		19.2.2 Lubricants
		19.2.3 Additives to Influence the pH Value
	19.3 Technological Aspects of the Use of Additives
	19.4 Conclusions
	Bibliography
20 Additive Manufacturing by Extrusion in Ceramics
	20.1 Introduction
	20.2 Theoretical Principles of Extrusion
	20.3 Configurations
	20.4 Hardening of the Green Extrudates
	20.5 AM by Extrusion—examples in Development and Practice
		20.5.1 Development by ECT-KEMA GmbH/TU Dresden
		20.5.2 3D Minerals Development
	20.6 Three Machines, Three Sizes
		20.6.1 AM by Thermoplastic Extrusion
	20.7 Prospects
	20.8 Conclusions
	Bibliography
21 Simulation in Ceramic Extrusion
	21.1 Introduction
	21.2 The Principle of CFD Simulations
	21.3 Determining Model Parameters and Boundary Conditions
	21.4 Error Estimation
		21.4.1 Programming Error
		21.4.2 Iteration Error
		21.4.3 Discretization Error
		21.4.4 Modelling Error
	21.5 Application of Simulation Methodology
		21.5.1 Ceramic Masses in Battery Systems
		21.5.2 Extrusion of Profile Geometries
		21.5.3 Calculation of Extrusion Screws
	21.6 Conclusion
	Bibliography
22 A Look-Ahead
	22.1 Predictions, Strategies and Wishes
	22.2 Gaps and Blind Spots
		22.2.1 The Know-How Gap
		22.2.2 The Wear Protection Gap
		22.2.3 The Sensor Gap
	22.3 The Contribution of Artificial Intelligence
	22.4 En Route to the “Smart Extrusion Concept” (SEC)
	Bibliography