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Thread: High Hot runner temps.

  1. #1
    Join Date
    Sep 2019
    Posts
    5

    High Hot runner temps.

    Hello all, just looking to see if i'm not the only one having these issues.
    PROBLEM:
    Glass filled nylons 13 to 33 % in hot runner systems.
    I don't think I've ever been able to run these jobs without cranking hot runner zones up to 650 - 700° range.
    Unfilled nylons not so bad, but I'm always being questioned from tooling and qc asking Why are zones so high?
    It gets frustrating because It's hard for them to understand that the only way i can get plastic through this mold without freezing off is to do this. the nozzles are pretty small on these, as some have diverter tips on them. side note: running mold temp at 185°
    Also we have UR robot taking about 10 seconds to load inserts in mold, i know this does not help. Any good ideas or insights?

  2. #2
    Join Date
    Jun 2014
    Location
    EU
    Posts
    68

    Re: High Hot runner temps.

    Hi,

    exchange the hot runners for hydraulic or air operated walve gate!!!
    Any kind of torpedos or free flow tips (or blocks inside of this tips) at the end of hot runner is not definitelly recomended for PA with GF!

    IŽm afraid its bad design and without change youŽll not do anything reasonable.
    J

  3. #3
    Join Date
    Aug 2011
    Location
    Upstate of South Carolina
    Posts
    639

    Re: High Hot runner temps.

    With that much glass filler a standard hot runner will wear out very quickly due to abrasiveness of the fibers. I’d make sure the screw reaches shot size and then stops decompression about 2-3 seconds before mold opens. If the mold stands still with fast recovery time, the open drops tend to drool while the mold is open. I’m also thinking that air or hydraulic valve gates would make this a better running tool!
    Rick.

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