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Thread: M.F.R. Question

  1. #1
    Join Date
    Oct 2017
    Posts
    19

    M.F.R. Question

    Just curious as to what kind of variation I can expect in the MFR of a certain resin. The MFR is supposed to be 70. I do my own tests and I am seeing the MFR go from 50 to over 100 is this normal variation? Thanks in advance.

  2. #2
    Join Date
    Nov 2012
    Posts
    152

    Re: M.F.R. Question

    Hi, Range of your values is too big. Please check the conditions of your MFR test procedure, if is it acc standard EN ISO 1133. Normal range of MFI is +/-5 (max)

  3. #3
    Join Date
    Apr 2020
    Location
    Traverse City, MI
    Posts
    26

    Re: M.F.R. Question

    Name of plastic resin Melt flow rate
    Polypropylene 5 to 60
    Polystyrene 5 to 25
    AS resin 10 to 40
    ABS resin 5 to 60
    Acrylic resin 1 to 35
    Polyamide 6 10 to 80
    Polyamide 66 10 to 80
    Polyacetal 3 to 70
    Polycarbonate 2 to 30
    PBT 20 to 100
    PPO 7 to 30
    PSU 7 to 18
    PES 17 to 30
    Cyclo olefin polymer 7 to 60
    TPX 21 to 80
    PEEK 1 to 20

  4. #4
    Join Date
    Apr 2020
    Location
    Traverse City, MI
    Posts
    26

    Re: M.F.R. Question

    With those MFR's shown. I have personally seen a 20% MFR change within 1 gaylord before. The number placed on your incoming paperwork is simply an average for the lot of material that filled your purchased container. Having a viscosity shift that is large is referred to as "wide spec". Decoupled molding with cavity pressure sensors is an excellent way to combat the molding issues that I assume you are having.

  5. #5
    Join Date
    Aug 2011
    Posts
    623

    Re: M.F.R. Question

    Good Q!

    > MFR testing is very subjective. Each person is going to get a different result since there are a lot of variables. Even the way you pack the pellets will make a difference.

    > Agree with Cory above on using a pressure sensor if you have a very critical job and have a resin with viscosity variation.

  6. #6
    Join Date
    Aug 2011
    Location
    Upstate of South Carolina
    Posts
    689

    Re: M.F.R. Question

    I remember a resin supplier at one time would pull samples and watch the MFR of the resin. Typically you get low at the start- of a production run and high at the end. So they would go back and post blend the resin to get a better average of the MFR.
    Rick

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