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Thread: help with problem

  1. #1

    help with problem

    Guys i am looking for some opinions on what this is and what is causing it. what do you need to know?
    4 cavity mold, but only running 2 due to shot size to small. 500 ton. 100% pp mfi of 75. this material is a clean, stead waste stream that is ground, washed and reextruded into pellets.
    Attached Thumbnails Attached Thumbnails Problem 1.jpg   problem 2.jpg   problem 3.jpg   problem 4.jpg  

  2. #2
    Join Date
    Aug 2011
    Posts
    625

    Re: help with problem

    Hi,
    How does the purge look?
    Can you check the melt temp out of the manifold?
    Suhas

  3. #3
    Join Date
    Aug 2011
    Location
    Upstate of South Carolina
    Posts
    701

    Re: help with problem

    Ok to me it looks like a couple things. Is this cloudy area truly part of the polymer or can you peel it out of the part wall? It may be PE mixed in. Hence the lamination. If not it could be extrusion or blow mold grade resin, try raising the melt temps. I also think it could be calcium or talc filler in the resin, again raising the heats should better disperse the filler.
    What about drying the resin to see if it's water from pelletizer? Maybe it's clarifying agent and the barrel heats or residence time is consuming part of it. Can you lower barrel settings?
    What are the actual machine settings?
    Rick.

  4. #4
    Join Date
    Mar 2014
    Location
    Minnesotan living in Wisconsin
    Posts
    28

    Re: help with problem

    Has the part run in the press running two cavities before without the problem? or is this something you are just trying to get started?

    Maybe the barrel is still too small for what you are doing, making the residence time too short for your process to have a good melt.

  5. #5
    Join Date
    Sep 2012
    Location
    Indianapolis, IN
    Posts
    114

    Re: help with problem

    Do you have the ability to try a different PP to see if it is material related vs. manifold or machine related? Change up variables to pin point root cause.

  6. #6
    Join Date
    Sep 2013
    Posts
    127

    Re: help with problem

    I suggest to try to inject slower

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