Vacuum Forming

By: Thomas Gibson-Gamache, Sunghyun Lee, Lisa Ngo-Nguyen, Rob Shudra, Davyn Wagner, Kevin Wong

Overview

Materials:

• Thermoplastics - HIPS, ABS, PC, HDPE, TPO, PVC, Acrylic​​​​

Basic Process:

• A sheet of plastic is heated until pliable.
• It is then lowered onto a 3D mold
• Air is vacummed out of the space between the mold and the sheet of plastic
• The sheet of plastic will take the shape, and the 2 pieces can be removed

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Machinery

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Male Mold

• Heated plastic is draped over a male mold

• Requires large draft angles and no undercuts

• Draw ratio should be <1:1

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Male Snap-Back Vacuum forming

• Mold is suspended on a pneumatic cylinder above a vacuum box

• • Vacuum is applied and stretches plastic

  • mold is brought down

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Billow Snap-Back Vacuum forming

• Better wall thickness distribution

• Box is pressurized and pre-stretched

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Straight Vacuum Forming - Female

• ​Vacuum is applied throughout mold - atmospheric pressure pushes sheet into mold

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Plug Assist Vacuum forming - Female

• Plug is used to force the sheet into the mold before vacuum is applied

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Plug Assist Pressure Forming - Female

• Similar to plug assist vacuum forming, pressure is applied from plug side

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Billow Plug Assist Vacuum Forming - Female

• Heated plastic is pre-stretched

  • when plug is at lowest position, vacuum is applied

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Benefits

• Least expensive tooling costs

• Tooling completion and implementation is faster than injection/pressure forming

• Tooling modifications can happen quickly/inexpensively

• Wide range of part production

• Allows for huge range of part sizes, shapes, colour

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Disadvantages

• Absorbed moisture can expand - forming bubbles within plastic’s inner layers

• Webbing

• Objects can stick to mold if draft angle is inefficient

• A lot of material waste

• Cannot easily form sharp edges

• Does not maintain consistent wall thickness

• Parts cannot easily have undercuts

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Examples

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Examples Cont.

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Vacuum Formed Stool

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