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Thread: Flakes in Mold, gating?

  1. #1
    Join Date
    Dec 2016
    Posts
    130

    Smile Flakes in Mold, gating?

    Hello all,

    So I just sampled this new tool and everything looked great..... well.......until we starting noticing a lot of parts with flakes on them, attached at the parting line. (And looking inside the the mold there are plenty of flakes on the parting line face after running for 1 hour.)

    Pictures attached of a flake on the part, and the part, and the runners. Material is acetal. Mold is 4 cavity, hot to cold....with (3) tunnel gates each to the part .

    Our tooling guy is going to check the mold for sharp edges, but I think this is happening as the gates tear free from the parts as the mold opens at the tunnel gate. So, if I am correct, has anybody been able to successfully correct this issue by tooling or process?

    Thanks!
    Joel
    Attached Thumbnails Attached Thumbnails flake.jpg   runner.jpg   nut2.jpg  

  2. #2
    Join Date
    Aug 2011
    Location
    Upstate of South Carolina
    Posts
    659

    Re: Flakes in Mold, gating?

    When I see this, I feel that the gates are dull. The dull edges of the gate create the flakes at the runner is separated from the part. Part of your issue may be that the gate edges were dulled due to shear on the melt as the cavity is filled. The edge of the gate could be rolled over as well.
    Making them sharper will fix the flaking but you’ll have to watch the initial melt filling the cavity and ejection speed. An air blow off with really clean compressed air might be the easiest thing to do.
    Rick.

  3. #3
    Join Date
    Apr 2020
    Posts
    4

    Re: Flakes in Mold, gating?

    Looks like too large of a gate .You can try running a warmer mold to see if it will release better .It is literally tearing the gate off

  4. #4
    Join Date
    Dec 2016
    Posts
    130

    Re: Flakes in Mold, gating?

    Thanks JPlynn and Rick for the feedback... I do like the idea of sharpened, and Smaller Gates..... (the mold is brand new, Shees!)

    Thanks again,
    Joel

  5. #5

    Re: Flakes in Mold, gating?

    this issue due to the gate dull, saw you gate have do polish process, but the polish process not good and cause the gate knife dull, solution,1: remake the gate by mirror EDM, 2: add air gun to blow the gate area, mabey your material is POM, easy to appear static, use resist static air.

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