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Backing material for a one-shot mold?

  1. Oct 2, 2012 #1
    Hi,

    I currently have a fragile metallic cylindrical mold (wall thickness ~1 micron) into which I want to injection mold a thermoplastic polymer at about 150 MPa (3.14 Mlb/sq.ft). The mold and polymer together will form the final part. However, such injection pressure far outstrips the rupture stress of the mould; so I'm looking for some sort of backing which I could use to support the mold while injecting; but which I can then remove afterwards - ideally via some kind of solvent.

    Unfortunately, due to the nature of the mold material, I can not use anything which requires a temperature >150°C (>300°F) to remove it.

    Initially I considered some sort of epoxy, but it seems the only way to remove a crosslinked thermoset is via heat; and that really doesn't suit at all.


    Any suggestions?



    All the best,

    Phil
     
  2. jcsd
  3. Oct 9, 2012 #2
    How about a 2-part firm silicone? It's used in dentristry, is pretty inexpensive if you hunt around, and gives you a few minutes of very soft pliability (warm plasticine) before setting to the firmness of a shoe sole in under 10 mins. It'll provide 1-time support and slip off a treat when you're done.

    http://www.amazon.co.uk/Hiflex-Silicone-Putty-Rubber-Moulding/dp/B007DKSH9Q for instance
     
    Last edited by a moderator: May 6, 2017
  4. Oct 9, 2012 #3
    I don't know 150MPa is really high. As in you'd have to be careful even with cement.

    http://www.theconcreteportal.com/images/constrelation/stressstrain2.JPG

    21755 psi. That would break apart a cement mold. Is there a reason you have to use this mold? Sounds like recreating it out of stronger materials would be better.

    Normally large volume plastic molds are made from machined steel.
     
  5. Oct 11, 2012 #4
    Do u want to use a solvent to lower viscosity of melt ? what is the radius of the mold?
    which is the thermoplastic ?
     
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