THERMOFORMING

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THERMOFORMING
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PRODUCTS
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Thermoforming

• This process consists of heating thermoplastic
  sheet to a formable plastic state and then
  applying air and/or mechanical assists to shape
  it to the contours of a mold.

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Outline

• Overview
• Application
• Basic processing steps
• Types of processing
• Process variables
• Materials
• Molds
• Trouble shooting
• Modeling
• Observing the process
• Hand-on experience

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PROCESS
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Vacuum Thermoforming
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Vacuum Thermoforming
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Continuous Thermoforming
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Vacuum Forming
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Vacuum Forming

• The alternative is to use positive mold. It will
  replicate the pattern onto the interior surface.
• Positive mold thermoforming has a less uniform
  thinning than the negative mold. This may be
  overcome by pre-stretching of the plastic sheet.

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Pressure Thermoforming

• The process uses air pressure to facilitate the
  forming process.

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Mechanical Thermoforming

• Air pressure is used as an external energy source.

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Mechanical Thermoforming
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Free Air Blow Forming Process
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Material

• Type
• Commonly used ABS, PMMA, polyolefins, HIPS, PVC
• Not usually used nylon, acetals
• Properties
• Morphology

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Thermoforming Data
Characteristic Temperatures of Some
Thermoformable Polymers (adapted from Throne
1996, p. 69)
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Thermoforming Data
Thermal Properties of Some Thermoformable
Polymers and Mold Material (adapted from Throne
1996, p. 85-86)
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Process Variables

• Heating
• Heating method (s)
• Temperature distribution
• Forming
• Depends on specific type
• Speed of vacuum
• Mold temperature
• Size of the bubble
• Plug size

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Forming Window
From Throne 1999, p. 83
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Thermoforming Machines
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Molds
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PROCESS MODELING