2nd Edition
Thermoforming A Plastics Processing Guide, Second Edition
FROM THE FOREWORD
Dr. Gruenwald has indicated the desirable properties of polymerics for differing applications; thus, his text is especially useful for polymer chemists who must "tailor" plastic materials for specific groups of applications. Engineers in extruding and calendering film and sheet will benefit from the intimate relationships elucidated between processing parameters imposed upon stocks employed in thermoforming and the products thereof. Mold designers are provided with a complete guide that will enable them to avoid the less obvious pitfalls and wasted effort so often experienced in the evolution of molds for (especially) complex parts.. Quite likely, Dr. Gruenwald's suggestions willl lead to considerable benefits to those who read and practice by this remarkable exposition of thermoforming technology.
Robert K. Jordan
Director-Metalliding Institute, Director-Engineering Research Institute, Scientist in Residence, Gannon University
Preface
Introduction
Heating of the Plastic
Means of conveying heat to the plastic Physics of radiation properties Thermal properties of plastics Heating equipment for plastic sheets Judging the correct temperature of the heated sheet Heater controls Clamping of sheets
Thermoforming Molds
Reduction in wall thickness, male and female molds Computer-aided engineering for thermoforming Part shrinkage and dimensional tolerances Warpage Draft in the mold Surface appearance Mold materials Mold-cooling provisions Air passage holes Increasing stiffness Mold plugs
Vacuum, Air pressure and Mechanical Forces
Measuring vacuum and pressure forces Vacuum sources Vacuum accumulators or surge tanks Application of vacuum forces Pressure forming Mechanical forming
Cooling of Thermoformed Parts
Means of cooling the formed part Non-conventional cooling methods
Trimming of Thermoforming Equipment
Tools for trimming
Thermoforming Equipment
Single-station thermoformer Shuttle thermoformer Rotary thermoforming equipment Continuous in-line thermoformers In-line thermoformer Linear thermoformers Pneumatic thermoformers Hydraulically operated thermoformers Mechanically operated thermoformers Skin packaging equipment Blister packaging equipment Snap packaging Vacuum packaging Packaging machinery Control mechanisms
Thermoforming-Related Material Properties
Glass transition temperature Heat deflection temperature Softening range and hot strength Specific heat Thermal conductivity Thermal expansion Heat of fusion Thermal diffusivity Thermal stability Water absorption Orientation and crystallization Manufacture of starting materials Coextrusions and laminates Mechanical properties Material economics Regrind utilization
Thermoforming Materials' Chemical Descriptions
Acrylics Cellulosics Polyolefins Styrene polymers Vinyl resins Engineering plastics Copolymers, blends, and alloys Fiber-reinforced thermoplastics Transparent materials Barrier materials Electrical properties Plastics recycling Flammability of plastics Toxicity of plastics
Thermoforming Processes
Billow, bubble, or free forming Cavity forming Drape forming Plug-assist forming Billow drape forming Snap-back forming Air slip forming Reverse draw with plug-assist forming Twin-sheet forming Pressure forming Mechanical thermoforming Other thermoforming processes Adjusting process parameters Thermoforming troubleshooting guide
Design Considerations Assembly and bonding Rigidized thermoformed parts Finishing and decorating thermoformed parts
Related and Competing Forming Processes
Forming processes performed at lower temperatures Packaging container forming Limitations for thermoforming
Appendices
Exemplary properties of thermoforming materials Exemplary properties of film materials Trade names and materials manufacturers Conversion factors
Index
Biography
Gruenwald, Geza
