SM102 8P Colour problem

Discussion in 'Heidelberg Printing Presses' started by speedie, Apr 27, 2010.

  1. speedie

    speedie New Member

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    Hi, we are currently experiencing colour issues mainly on coated papers, always on 5th unit which we are using for magenta. Intermittently maybe within 20-30 sheets the middle/left back edge of the sheet will flush with magenta then go back to normal within 1-2 sheets. This problem seems to come and go during runs i.e seems to be ok for 10000 impressions but then comes and goes. Sometimes the problem may be there at start of job. Really pulling our hair out on this one, my MD thinks it's gripper related, but can't see any doubling or slurring so my feeling is ink/water - any ideas guys?:confused:
     
  2. The Heidelberg Guy

    The Heidelberg Guy Senior Member

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    I would check to make sure all the roller settings are correct, then check the linkage on the forms, ink and dampening first.
     
  3. exheidmech

    exheidmech Senior Member

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    Its unlikely that grippers are causing your issue. I agree with Heidelberg Guy on roller settings, make sure your hangers are ok. Try desensitizing your matte chrome roller. If youve already done these things try swapping rollers with another unit. This will cause 2 things. Force you to check condition of rolles, bearings, and hangers when swapping and also isolate the issue to either unit or rollers.
     
  4. mrheidelberg

    mrheidelberg Senior Member

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    You might also want to shampoo / decontaminate the rollers. If it too bad you may have to take the rollers out and clean them by hand.
     
  5. turbotom1052

    turbotom1052 Senior Member

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    heavy ink

    have you ever gotten a rag caught in the rollers of the questionable unit?
    the reason i ask is because ive experienced something like that as a result of a really big low spot in one of the rollers. it went like this.... press would be running fine...then there would be a quick flood of ink in a few zones. what was happening was that the ink would be transfering down the roller train until the low spot was filled with ink. then once ink made the low spot high enuff for a full transfer then youd get that rush of ink in that area. what tipped me off to what was happening was that i noticed a trend where the amount of diodes of ink on the console was significantly higher in that area than on similar coverage areas of the sheet. as a test try to print a full dry solid on some waste sheets. if it requires 12 diodes of ink to get the desired color it should be 12 diodes across the entire sheet. if you find yourself needing more ink in that problem area then you need to look at either a low spot or a bent journal, or anything else that might affect transfer down the entire ink train. after finally resolving the problem i asked the feeder operator if he got a rag caught in the press. of course he denied it at first but eventually came clean and admitted that he in fact did. i would have expected nothing less from him!!!!! good luck in finding a solution and keep us posted.
     
    Last edited: Apr 30, 2010
  6. Tomatron

    Tomatron Member

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    Stripping?
     
  7. rolandman

    rolandman Senior Member

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    Who is? :)
     
  8. NZ Printer

    NZ Printer Member

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    Calcium build up ?. Maybe you need to de calcify the rollers - We find Magenta is always the first to go. If not that then take the rollers out and inspect.
     
  9. wiseguy

    wiseguy Member

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    Check that you donĀ“t have a formroller oscillating, especially form 3 or 4. I experienced that problem with a form roller oscillating.
     
  10. Data

    Data Senior Member

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    On the terminology, 'flush' with magenta. Are you saying that you get intermittent scumming?

    Sorry but reading your MD's idea 'grippers' confuses me against the other postings
     
  11. speedie

    speedie New Member

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    On the terminology, 'flush' with magenta. Are you saying that you get intermittent scumming?

    Sorry but reading your MD's idea 'grippers' confuses me against the other postings


    No scumming just a lot more magenta on print. Thanks for all replies guys - could have been a number of things in the end but it's sorted now.

    We decalcified, changed fount, checked all settings etc. Finally put a new deck of rollers in and Hey Presto good as new. Looks like we probably had a low spot in one or more of rollers (as somebody suggested earlier). As for my MD's idea - he's a nice guy BUT!!! ;)
     

  12. print101

    print101 Senior Member

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    Please check the vibrator roller. Check the roller diameter and bearings for play. We had something similar and it turned out to be an undersized vibrator, it didnt transfer the ink at a consistent rate resulting in variation on the sheet.

    Ok - ignore the above, I see you solved it - I didnt read page 2....oops
     
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