Vacuum Molding

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Vacuum Molding Plastisol dip

• Lili Esfahani, Kevin Griffin, Wes Lambert,
• Michelle McChesney, Andy Peterman, Nevin Smith,
  and Frank Yang
• for MatE 186 Polymers Lab
• Dr. Richard Chung

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Introduction

• Vacuum molding and Plastisol dipping
• Primary commercial use
• Overall method of process
• Process Variables
• Polymers used
• Results
• Conclusion

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Vacuum Molding Process

• Primary Commercial Uses
• blister pack, dashboard,..etc.
• Method of Process

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Vacuum Molding Schematic
Figure from Industrial Plastics by Richardson and
Lokensgard
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Forming Window
From Throne 1999, p. 83
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Vacuum Variables

• Material Characteristics
• Temperature Control
• Pressure Control
• Mold Characteristics

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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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Thermoforming Data
Draw Characteristics of Some Thermoformable
Polymers (adapted from Throne 1996, p. 97-100)
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Film Behavior in Mold
From Throne 1999, p. 27
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Vacuum Process Data
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Vacuum Results

• Successes
• ABS PE conformed at expected values
• PS conformed 10oC below expected
• Failure
• PS failed
• PE failed at 110oC

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Plastisol

• What is it?
• Polyvinyl chloride in plasticizer solution

• Method of liquid to homogenous solid
  transformation
• The key is heat!

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Plastisol
Figure from Polyvinyl Chloride (Sarvetnick,
Harold A., Polyvinyl Chloride, (1969) Reinhold
Book New York, 178.)
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Plastisol Process

• Primary Comericial Uses
• Electrical insulation on tools
• Handles for ergonomic comfort
• Flexible products (coin purses)
• Method of Process
• Preheat
• Dip
• Cure

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Plastisol Variables

• Material
• Heat Capacity
• Size
• Shape
• Dip Time
• Satisfactory for thermal mass
• Curing Time
• Surface properties highly dependant

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Plastisol Process Data
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Plastisol Process Trends
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Plastisol Process Data
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Plastisol Results
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Conclusion

• Vacuum Molding
• Advantages
• Simple procedure
• Inexpensive
• Disadvantages
• Formed pieces needs trim
• Scrap

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Conclusion

• Plastisol
• Advantages
• Easy
• Low cost
• Disadvantages
• Not Clean
• Limited Thickness