Mechanical Ghosting on Heidelberg KORA? Need help.

Discussion in 'Heidelberg Printing Presses' started by geraldko, Jan 5, 2016.

  1. geraldko

    geraldko Member

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    I've been brought in as a manager at a print shop. My background is in QA but I'm new to print. Our Heidelberg KORA is having problems with solid reverse prints and from what I've read it seems to be an issue of mechanical ghosting? This problem has existed for a while with that machine and no one in the shop knows how to avoid it. A photo of one of the prints is attached.

    Thanks for helping!
     

    Attached Files:

  2. junker1984

    junker1984 Senior Member

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    Suggest you start with the basics. Roller settings and replacement if needed.
     
  3. geraldko

    geraldko Member

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    Thanks for the reply! I don't mind learning all the basics, but I'm not sure where! We don't have print schools here in the Philippines, and lots of sketchy info on the net.
     
  4. junker1984

    junker1984 Senior Member

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    Start with the instructions in the operation manual. If you don't have one, you really must get one. How long has it been since roller diameters, durometers and settings have been gone through?
     
  5. alibryan

    alibryan Senior Member

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    As mentioned roller condition and settings are critical, but this press should be able to handle the image posted. I believe there's also a couple of rollers below in the ink train that engage/disengage with lever(s) to change the direction of ink traveling through the ink train. I can't remember if the KORA had these or not for sure, but I know the KORD did.

    As long as this doesn't get die cut, another option to possibly help with the image quality is to change the imposition. By flipping one of the rows, it might eliminate some of the ghosting.
     
  6. geraldko

    geraldko Member

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    After scouring the internet I managed to find an operator's manual for the KORD but not for the KORA. I hope it's sufficiently close.

    Also thinking about it more, the ghosting problem only appears because the ink runs out in the first place. The entire black area is supposed to be solid, right?
     

    Attached Files:

  7. geraldko

    geraldko Member

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    I just finished reading the manual and there's nothing on it about the form rollers on the inking and dampening units.. so I'm back to square one.
     
  8. turbotom1052

    turbotom1052 Senior Member

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    as mentioned the best bet would be to change the imposition. That is to stagger the images so that the white skull reverse image does not line up with the one behind it. You could also image a ghostbuster if you have enough room on the tail of the sheet.
     
  9. alibryan

    alibryan Senior Member

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    Isn't there a lever or two on the OP side of the press under the ink train for changing ink distribution? Should be a white or blue colored handle and it engages/disengages distributor rollers. That might not completely solve your problem but if the press has them, try using them and see if it helps.
     
  10. mcsongor

    mcsongor Member

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    as i see rather is a dampening problem than bad ink roller settings...i suggest to make sure the ink-water balance is ok...also check ph and conductivity...increasing little more the ink feed and less water you shoul solve the problem (increasing IPA also might help )
     
  11. aqazi81

    aqazi81 Senior Member

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    As far as I know, KORA does not have an Alcolor dampening system. So no need for IPA.
     

  12. geraldko

    geraldko Member

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    Problem solved

    Thanks for all help guys. Back to basics was the right answer. We had a mechanic take a look and the form rollers were not aligned properly. That led to what I believe is a loss of ink thickness, which is why the ghosting happened.
     
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