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Pressure in injection molding

  1. Mar 16, 2017 #1
    Im currently trying to calculate the pressure inside an injection mold. Does anyone have experience with similar problems? I need to use coeficient of Thermal expansion and volume. please help .
  2. jcsd
  3. Mar 16, 2017 #2
    What is your understanding of how the injection molding process works?
  4. Mar 16, 2017 #3


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    In 20 years of injection moulding I have never needed to use the coefficient of thermal expansion in consideration of cavity pressure. Please state your problem with more detail so that we can give a meaningful answer.
  5. Jun 6, 2017 #4
    Depends on if you are using an electric machine or a hydraulic machine and what stage you are in. If you are in the 1st stage then the cavity pressure should be zero as the polymer hasn't reached the end of the cavity yet. If you are in 2nd stage then I need to know if it is an electric machine or a hydraulic machine. If it is electric then the cavity pressure will typically be whatever you set your pack stage too. If it is a hydraulic machine then you need to take your set pack pressure and multiply it by your screws intensification ratio (get this information from the machine manual or ask your maintenance guy).

    Not sure where you are going with the coefficient of thermal expansion. This information will not give you cavity pressure as you are packing the cavity out with plastic in a confined space. The coefficient of thermal expansion is great for designing the mold, but not for calculating cavity pressure.
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