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Thread: Troubleshooting surface

  1. #1
    Join Date
    Nov 2017
    Posts
    1

    Troubleshooting surface

    Hello,

    We have a problem with the surface of a black product.
    I think that the plastic is solidifies to fast.
    Is it a sort of blushing or delamination?
    See attachments.

    Regards
    Ruben
    Attached Thumbnails Attached Thumbnails 20171120_112010.jpg   20171120_112007.jpg  

  2. #2
    Join Date
    Aug 2014
    Location
    Saint Paul, MN
    Posts
    181

    Re: Troubleshooting surface

    If the part is cooling too fast – raise the mold temperature. The appearance issue could conceivably be gas trapping (seems like an odd location for it though) so check your venting. It could also be blooming of an additive on to the surface of the mold. Clean the cavity surface thoroughly and see if it goes away temporarily. I’m assuming that the material is dried properly.
    More information would help.
    What’s the material?
    How big is the part?
    What’s the mold temperature?
    Is the problem consistent throughout the run?

  3. #3
    Join Date
    Aug 2014
    Location
    Michigan
    Posts
    71

    Re: Troubleshooting surface

    That tiger striping could be from flow hesitation for sure. The surrounding area seems to have some kind of texture to it, does the area with the tiger striping have texture to it as well? If so, then yes you could be getting delamination or "ghosting" from the mold surface texture. I would start with the flow hesitation, either raise mold temp, melt temp, fill speed or a combination of those things. If you cant process it out, I would start looking at the surface texture.

    Husky

  4. #4
    Join Date
    Aug 2011
    Location
    Upstate of South Carolina
    Posts
    701

    Re: Troubleshooting surface

    It looks like back fill to me caused by the melt fronts race tracking around the perimeter wall and trapping air in the part. The different flow directions create the defect. Higher melt and mold temp plus faster fill rate will help. You may even have to put flow helpers in the mold to eliminate the defect.
    Rick

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