Understanding Thermoforming

Name: Understanding Thermoforming
Brand: Hanser
Price: 79.99 EUR
Availability: OnlineOnly

James L. Throne(Author)

Hanser (Publisher)

1st Edition

Published on 12. November 2012

282 pages

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978-3-446-41855-4 (ISBN)

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Content

Intro
Foreword to the Second Edition
Contents
1 Introduction to Thermoforming
1.1 Brief History
1.2 General Markets
1.3 Terminology
1.4 General Characteristics of Thermoformed Products
2 General Forming Concepts
2.1 Heating and Bending
2.2 Simple Heating and Stretching
2.3 One-Step Forming
2.3.1 Drape Forming
2.3.2 Vacuum Forming
2.3.3 Free Forming
2.3.4 Non-Uniform Heating
2.3.5 Matched Mold Forming
2.4 Other One-Step Forming Processes
2.4.1 Autoclave Forming
2.4.2 Diaphragm Forming
2.5 Two-Step Forming
2.5.1 Pneumatic Preforming
2.5.2 Plug Assisted or Mechanical Preforming
2.5.3 Pressure Forming
2.5.4 Coining
2.6 Three-Step Forming
2.7 Twin-Sheet Forming
2.7.1 Heavy-Gauge Twin-Sheet Forming
2.7.2 Light-Gauge Twin-Sheet Forming
2.8 Contact Forming
2.9 Thermoforming as a Portion of the Overall Manufacturing Process
3 Part Design
3.1 Part Design Philosophy
3.1.1 Design Protocol
3.1.2 Project Protocol
3.2 Should This Part Be Thermoformed?
3.3 General Parameters Affecting Part Design
3.3.1 Shrinkage
3.4 General Product Design
3.4.1 Corner versus Chamfer
3.4.2 Draft Angles
3.4.3 Thermal Expansion
3.4.4 Dimensional Tolerance
3.4.5 Improving Dimensional Tolerance
3.5 Part Surface Quality
3.6 Trim Line Location
3.7 In-Mold Decorating and Labeling
3.8 Seal Designs on Twin-Sheet Thermoformed Parts
3.9 Some Guidelines to Successful Part Design
4 Machinery for the Thick-Gauge Forming Process
4.1 Shuttle Press
4.1.1 Two-Oven Shuttle Press
4.2 Cabinet Press
4.3 Rotary Thermoforming Press
4.4 The Elements of Heavy-Gauge Machinery
4.4.1 Sheet Handling
4.4.2 Sheet Clamping
4.4.3 Sheet Shuttle or Rotation
4.4.4 Oven(s)
4.4.5 The Forming Press
4.4.6 Pneumatic Prestretching
4.4.7 Plug Assist Prestretching
4.4.8 Load/Unload Elements
4.4.9 Vacuum Box and Vacuum System
4.4.10 Pressure Box and Pressurization System
4.4.11 Condition Monitors and Process Control
4.4.12 Safety Elements
5 Machinery for the Light-Gauge Forming Process
5.1 Standard Roll-Fed Machine
5.2 Contact Heater Machines
5.3 Form-Fill-Seal Operation
5.4 Elements of Light-Gauge Machinery
5.4.1 Sheet Take-off or Unwind Station
5.4.2 Pin-Chain and Pin-Chain Rail
5.4.3 Oven(s)
5.4.4 The Forming Press
5.4.5 Plug Assist Prestretching Devices
5.4.6 Trim Means
5.4.7 In-Machine Stacking Means
5.4.8 Vacuum Box and Vacuum System
5.4.9 Pressure Box and Pressurization System
5.4.10 Trim or Web Take-up Station
5.4.11 Condition Monitors and Process Control
5.4.12 Safety Features
6 Machines for Other Applications
6.1 Extrusion-Forming Lines
6.1.1 Advantages of Extrusion-Forming Lines for Heavy-Gauge Forming
6.1.2 Advantages of Extrusion-Forming Lines for Light-Gauge Forming
6.1.3 Disadvantages of Extrusion-Forming Lines for Heavy-Gauge Forming
6.1.4 Disadvantages of Extrusion-Forming Lines for Light-Gauge Forming
6.1.5 Important Extruder Characteristics in In-Line Forming
6.2 Matched Mold Forming Machines
6.2.1 Foamed Polymer Machines
6.2.2 Composite and Composite Laminate Machines
6.3 Wheel Machines
6.4 Custom Machines
6.5 Twin-Sheet Forming Machines
7 Molds and Mold Design
7.1 Production Mold Materials
7.1.1 Cast Aluminum
7.1.2 Machined Aluminum
7.1.3 Other Production Mold Materials
7.2 Prototype Mold Materials
7.2.1 Hardwoods
7.2.2 Plaster
7.2.3 Medium-Density Fiberboard
7.2.4 Syntactic Foam
7.2.5 Thermoset Plastics
7.2.6 Sprayed Metal
7.3 Mold Design Elements
7.3.1 Cooling
7.3.2 Venting
7.3.3 Undercuts
7.3.4 Mold Surface Texture
7.3.5 Textured Mold or Textured Sheet?
7.4 Plug Assist Materials and Designs
7.5 Other Mold Features
7.5.1 Cavity Isolators or Grids and Perimeter Clamps
7.5.2 Pressure Box
7.5.3 Draw Box
7.5.4 Coining
7.5.5 Web Breakers and Chasers
7.5.6 Rapid Tool Change
7.6 Molds for Matched Mold Forming
7.7 Molds for Twin-Sheet Forming
8 Methods of Heating Sheet
8.1 General Heating Concepts
8.1.1 Conduction
8.1.2 Convection
8.1.3 Radiation
8.2 Common Thermoforming Heaters
8.2.1 Convection or Hot Fluid Heating
8.2.2 Electric Heaters
8.2.3 Combustion Heating
8.2.4 Contact Heating
8.3 Selecting the Proper Heater
8.4 A Comparison of Widely Used Heaters
8.5 Heating Cycle Time
8.5.1 Forming Temperature Range
8.5.2 Energy Uptake
8.5.3 Polymer Characteristics
8.5.4 Geometric Factors
8.5.5 The Issue of Sheet Sag
8.5.6 Heating Composites, Laminates, and Other Plastics
8.5.7 Pattern or Zonal Heating
8.5.8 One-Sided versus Two-Sided Heating
8.5.9 Heating Cycle Time Prediction
8.5.10 Equilibration
9 Sheet Stretching and Cooling
9.1 Modulus and Stiffness
9.2 The Concept of Viscoelasticity
9.2.1 Elasticity
9.2.2 Viscosity
9.2.3 Viscoelasticity
9.2.4 Measuring Viscoelastic Properties of Polymers
9.3 The Concepts of Stress and Strain
9.3.1 The Forming Window
9.3.2 Forming Area Diagram
9.4 Prestretching
9.5 Pressure Forming
9.6 The Effect of Sheet Cooling
9.6.1 Forming Area Diagrams for Laminates and Composites
9.6.2 Differential Stretching against a Mold Surface
9.7 Draw Ratios
9.7.1 The Usefulness of Draw Ratios
9.7.2 Wall Thickness Reduction in Laminates
9.8 Part Wall Thickness Prediction
9.8.1 Finite Element Analysis
9.8.2 FEA Data Input
9.8.3 Model Verification
9.9 Sheet Sag and Sag Rate
9.10 Cooling Against a Mold Surface
9.10.1 Light-Gauge Cooling Criteria
9.10.2 Heavy-Gauge Cooling Criteria
9.10.3 Cooling and Residual Stress
9.10.4 Coolant Characteristics
9.10.5 Coolant Flow Rate and Temperature Control
9.11 Cooling Against the Plug
9.12 Heat Removal by Mold and Coolant
9.13 Forming Times
10 Trimming
10.1 The Mechanics of Trimming
10.2 Light-Gauge Trimming
10.2.1 In-Mold Trimming
10.2.2 In-Machine Trimming
10.2.3 In-Line Trimming
10.2.4 Two-Step Trimming
10.3 Prototype Trimming
10.4 Heavy-Gauge Trimming
10.4.1 In-Plane Trimming
10.4.2 Hand Power Tool Trimming
10.4.3 Milling or 3-Axis Machines
10.4.4 Multi-Axis Routers
10.4.5 Robotic Trimmers
10.5 The Importance of the Trim Fixture
10.5.1 Cutter Design
10.6 Trim Tolerance
10.7 Other Trimming Concepts
10.7.1 Water Jet Cutting
10.7.2 Laser Cutting
10.7.3 Trimming Foam
11 Polymers and Plastics
11.1 Polymer Characterization
11.1.1 Plastic vs. Polymer
11.1.2 Thermoset and Thermoplastic Definitions
11.1.3 Crystalline and Amorphous Definitions
11.1.4 Homopolymers, Copolymers, Terpolymers, and Blends
11.1.5 Additives, Fillers and Reinforcements
11.2 The Thermoforming Window
11.3 Thermoformable Polymers
11.3.1 Polystyrene and Other Styrenics
11.3.2 Polyvinyl Chloride and Other Vinyls
11.3.3 Acrylics
11.3.4 Cellulosics
11.3.5 Polycarbonate
11.3.6 Polyesters
11.3.7 Polyethylene
11.3.8 Polypropylene
11.3.9 Other Polyolefins
11.3.10 Formable Biopolymers
11.3.11 Other Formable Polymers
11.4 Multilayer Polymers
11.5 Foamed Plastics
11.5.1 High-Density Foams
11.5.2 Low-Density Foams
11.6 Thermal Properties
11.6.1 Heat Capacity
11.6.2 Thermal Conductivity
11.6.3 Polymer Density
11.6.4 Thermal Diffusivity
11.6.5 Thermal Coefficient of Expansion
11.6.6 Thermal Properties of Multilayer Structures, and Filled and Reinforced Polymers
11.7 Infrared Energy Absorption for Specific Polymers
12 Issues of Quality Control
12.1 Incoming Sheet Quality
12.1.1 What the Thermoformer Needs to Know About the Extrusion Process
12.1.2 What the Thermoformer Needs to Know About Quality
12.1.3 What the Thermoformer Needs to Know About Regrind
12.2 The Role of the Purchase Order
12.2.1 Incoming Sheet Quality Evaluation
12.3 Production Monitoring
12.3.1 Monitoring Temperature
12.3.2 Sheet Formability
12.3.3 Cutting Surfaces - Microfracture Concerns
12.3.4 Finished Part Performance
13 Comparison with Other Technologies
13.1 Classification of Plastics Molding Technologies
13.2 Polymer Material Choices
13.3 Other Processing Concerns
14 Pragmatic Aspects of Thermoforming
14.1 Safety
14.2 Thermoforming Machine Set-Up
14.2.1 Set-Up for a New Machine
14.2.2 Set-Up for a Used Machine
14.3 Mold Set-Up
14.3.1 New Mold Set-Up
14.3.2 Existing Mold Set-Up
14.4 Trim Set-Up
14.4.1 Heavy-Gauge Trim Set-Up
14.4.2 Light-Gauge Trim Set-Up
14.5 Maintenance
14.5.1 Emergency Maintenance
14.5.2 Preventative Maintenance
14.6 Troubleshooting Tips
14.6.1 Non-Crisis Troubleshooting
14.6.2 The Crisis Situation
References
Recommendations for Further Reading
Books
Other Sources
Historical Reading
Appendix: Glossary of Thermoforming Terms
Subject Index

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Understanding Thermoforming

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