Fundamentals of Plastics Thermoforming

Cover
Synthesis Lectures on Materials and Optics Series
Fundamentals of Plastics Thermoforming
Copyright
Dedication
Acknowledgements
Contents
About the Author
List of Figures
1. Introduction
	1.1 Introduction to Thermoforming
		1.1.1 Common Thermoformed Products
	1.2 Why Use Thermoforming?
		1.2.1 Advantages of Thermoforming
		1.2.2 Limitations/Disadvantages of Thermoforming
	1.3 Plastic Memory
	1.4 Processes Comparison
		1.4.1 Injection Molding
		1.4.2 Blow Molding
		1.4.3 Rotational Molding
2. Plastics Materials
	2.1 Introduction
	2.2 Molecular Structure
	2.3 Morphology
	2.4 Van Der Waals’ Forces
		2.4.1 Discovering Van Der Waals’ Forces
	2.5 Most Used Materials
		2.5.1 Polystyrene (PS)
		2.5.2 Acrylonitrile Butadiene Styrene (ABS)
		2.5.3 Polyvinyl Chloride (PVC)
		2.5.4 Polymethyl Methacrylate (PMMA or Acrylic)
		2.5.5 High Density Polyethylene (HDPE)
		2.5.6 Low Density Polyethylene (LDPE)
		2.5.7 Polypropylene (PP)
		2.5.8 Cellulosics
		2.5.9 Polyethylene Terephthalate (PET)
		2.5.10 Green Plastics
	2.6 Important Terminology
		2.6.1 Heat Deflection Temperature (HDT)
		2.6.2 Glass Transition Temperature (Tg)
		2.6.3 Melt Temperature (Tm)
		2.6.4 Polymer Set Temperature
		2.6.5 Homopolymer
		2.6.6 Thermoforming Window
3. Thermoforming Process Overview
	3.1 The Thermoforming Process
	3.2 Sheet Preparation
		3.2.1 Drying
	3.3 Loading
	3.4 Heating
	3.5 Forming
	3.6 Cooling
	3.7 Unloading
	3.8 Trimming
4. The Forming Process
	4.1 Forming Introduction
	4.2 Mechanical Forming
	4.3 Vacuum Forming
	4.4 Pressure Forming
	4.5 Combination Forming Processes
		4.5.1 Drape Forming
		4.5.2 Pneumatic Preforming
		4.5.3 Mechanical Preforming
	4.6 Twin Sheet Thermoforming
	4.7 Laminating Thermoforming
5. Part Design
	5.1 Design Questions
	5.2 Wall Thickness Variation
		5.2.1 Plug Versus Cavity
	5.3 Draw Ratios
		5.3.1 Aerial Draw Ratio (ADR)
		5.3.2 Linear Draw Ratio (LDR)
		5.3.3 Height—to—Dimension Ratio
	5.4 Material Selection
	5.5 Part Geometry
		5.5.1 Corners and Radii
		5.5.2 Draft Angles
		5.5.3 Depth of Draw
		5.5.4 Webbing
		5.5.5 Undercuts or Negative Draft
	5.6 Part Application Issues
		5.6.1 Useful Temperature Range
		5.6.2 Strength Requirements
		5.6.3 Stiffness
	5.7 Quality Requirements
		5.7.1 Cosmetics
		5.7.2 Optics
		5.7.3 Dimensional Tolerances
	5.8 Textured Surface Finishes
6. Mold/Tool Design
	6.1 Purpose of the Mold or Tool
	6.2 Mold Materials
		6.2.1 Low Volume Mold Making
	6.3 Mold Geometry/Shrinkage
	6.4 Venting
	6.5 Temperature Control
	6.6 Multi Cavity Molds
7. Quality Control Issues
	7.1 Introduction
	7.2 Material Source
		7.2.1 Regrind
		7.2.2 Sheet Orientation
		7.2.3 Orientation Test
		7.2.4 Moisture
		7.2.5 Cosmetics
	7.3 Process Quality
		7.3.1 Machine Set-Up
		7.3.2 Variation
		7.3.3 Tool Quality
		7.3.4 Facility Quality
	7.4 Quality Inspection
		7.4.1 Quality Tools
8. Environmental Issues
	8.1 Introduction
	8.2 Source Reduction
	8.3 Recycling
	8.4 Material Selection
	8.5 Green Plastics
References