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Thread: Blush or Graying at molded part edges

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  1. #1
    Join Date
    Sep 2019
    Posts
    3

    Blush or Graying at molded part edges

    Good day all.

    This is my first post to this forum so I'll try to be as specific and brief as possible.

    I have been working in injection molding in China for 16 years and this is the first time I have experienced this issue.

    We make a variety of part sizes (PC/ABS blend resin) and we are getting what might be called 'blush' on the textured appearance surface (MT-11020) and is quite undesirable.

    The blush appears as a graying of the dark blue color along the sides of the parts adjacent to the terminating walls of the part, being the transition between core and cavity creating wall thickness.

    There is no discoloration on the core half surfaces nor does the graying 'wrap' onto the edge of the part. Safe to say my issue seems to be strictly related to the texture and where the melt may be either cool enough and/or the injection pressure has decreased near the end of the shot.

    Fill looks good and geometry as close to perfect as I need. There is no warp in the part(s).

    Photos attached to save a bit of time.

    Any ideas would be greatly appreciated. I'm thinking possibly the tool needs additional venting and perhaps higher tool temperature.

    Thanks for any and all feedback.
    Attached Thumbnails Attached Thumbnails Blush 1.jpg   Blush 2.jpg  

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