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Thread: Enhancing flow properties of resin

  1. #1

    Enhancing flow properties of resin

    Hi, I am new in injection molding. I recently got a cable tie mold (cold runner) made from a domestic mold-maker. (32 cavities, 4*300 mm)
    But I am having several problems with the mold:
    1. When I try to fill the cavity with nylon 6 at high speed low pressure, the cavities doesn’t fills till the end.
    2. When I increase the pressure, there is flash at the gate.
    I think the clamping force is not a problem as It is being run on a 350 ton machine.
    Is there any way to enhance the flowability of the resin so that it fills till the end without flashing as the melt freezes before it reaches the end of cavity?
    Any other suggestion would be great?

    Thanks and Regards
    Abhishek

  2. #2
    Join Date
    Feb 2016
    Location
    San Francisco Bay Area, CA
    Posts
    199

    Re: Enhancing flow properties of resin

    Some ideas:
    increasing mold temp will improve flow
    Increase plastic melt temp will improve flow
    fast injection speed is your friend
    Open up gates


    If you're pressure limited, Read up on a "pressure loss study" to determine exactly where your pressure restrictions are, starting from the nozzle, cold-sprue, various sections of cold runner, the gates, then throughout your part geometry
    From this data you can look into opening up sprue, nozzle, runner or gates to assist

  3. #3
    Join Date
    Sep 2018
    Location
    Portland, OR
    Posts
    46

    Re: Enhancing flow properties of resin

    Is a pressure loss study even necessary on newer machines (last 20 years) that can graph the injection pressure vs screw position?

  4. #4

    Re: Enhancing flow properties of resin

    Thanks for the reply chris. I’ll try raising mold temperature and opening gates as I have tried other ideas. I’ll read more about “pressure loss study”. Thanks for the help.

  5. #5
    Join Date
    Dec 2012
    Location
    Serbia
    Posts
    107

    Re: Enhancing flow properties of resin

    Is tool venting OK? Making some additional scratches may hellp you (0,05mm).

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