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Thread: Defects

  1. #1
    Join Date
    Jul 2017
    Posts
    6

    Defects

    Circle around the intake duct. Hot runner system. Material polypropyleneClick image for larger version. 

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  2. #2
    Join Date
    Aug 2011
    Location
    Upstate of South Carolina
    Posts
    651

    Re: Defects

    Adjust heat at tip of valve gate and see if slowing the injection rate helps.
    Rick

  3. #3

    Re: Defects

    In addition to Ricks comments, it appears that you may be trying to over pack the mould and "BALLOONING" is visible at the surface around the gate. The stress marks from the ejector pins would suggest this.

  4. #4

    Re: Defects

    What was the conclusion to this?

  5. #5
    Join Date
    Jun 2017
    Location
    Ningbo zhejiang Province China PR
    Posts
    9

    Re: Defects

    What is at bottom, and bigger ejector the same size as the circle? Actually, I am thinking of ejector rebounding after holding pressure removed.

  6. #6
    Join Date
    Nov 2012
    Posts
    101

    Re: Defects

    It looks, that the part is overpacked too much...… but this will not solve the sprue issue :-)

  7. #7

    Re: Defects

    This part is way too over packed to even worry about the blush at the gate. Is that defect on a short shot? Try reducing initial fill speed, adding extruder delay or reducing recovery (screw speed/BP). But first... get rid of the pin push.

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