Vacuum Assisted Casting

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Vacuum Assisted Casting
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PU resin selection

• Polyurathene resin usually available as a
  two-part liquid set
• Cured resin can be
• As soft as rubber
• As hard as ABS
• As clear as Acrylic
• As heat-resistant as PC
• Filled with copper powder or glass fiber

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Colouring of PU resin

• Natural PU resins are usually black, white,
  ivory, or transparent
• White or transparent can be dyed by acrylic paint
  or model paint
• All hard PU can be primed and spray painted

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Vacuum PU casting machine
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Automatic and manual casting

• Automatic and manual machine work on the same
  principle
• Automatic machine can degas, mix, pour, and
  re-pressurise according to pre-programmed timing

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Casting setup
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PU Curing

• Curing temperature
• Heat can accelerate PU curing, ideally newly cast
  PU should be transfer to oven set to about 50
  deg. C
• some PU will not even cure in room temperature
• De-mould time
• Range from 5 min. to 30 min.
• Cure time
• Time to reach optimum strength
• Range from 30 min. to 12 hr.

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Post-processing issues

• Cut away the runner by saw or cutter
• Wash in warm water to remove trace of chemical on
  the surface
• Hard resin can be machined, filed, and sanded
• Primed and spray painted like ordinary plastic
  prototypes