Problems with print on reverse of sheet

Discussion in 'Heidelberg Printing Presses' started by richck, Jun 16, 2010.

  1. richck

    richck Member

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    We have recently been printing a job on an SM52-5 that when backing it up we have been having problems with the image doubling/slurring, the job has run perfectly on the first side. The stock is a good quality 170gsm gloss and is set up work and turn it has quite alot of coverage. Every other job we have done has been fine, on all other stocks. So i'm inclined to think that it is somthing to do with the paper, but don't understand why the first side would run fine. We had an engineer in the other day and he agreed it could be to do with the paper. He adjusted some of the grippers but we still had the same problem. The only thing i can think of that might of affected the paper (4 pallets SRA1) is that before it got to the press it wasn't brought into the pressroom to acclimatise, and was left in a storage area for 4 days that gets cold and very damp,and we had none stop rain for 4 days then it was put straight onto the press. Would this of had that much affect on the paper??
    Thanks.
     
  2. exheidmech

    exheidmech Senior Member

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    I think that letting the paper climatize would definitly help. Usually papaer is kept in a temp and humidity controlled environment for a few days before putting it on press. Also how many impressions does the press have? The SM52 comes with urithane grippers and at around 100 million impressions this urithane starts to show signs of wear which can also show problems, especially on lighter weight stock with alot of coverage.
     
  3. richck

    richck Member

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    It has around 89 million on the clock, i had thought about something like that but do you think it would affect one side of the sheet so much?
     
  4. Data

    Data Senior Member

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    If it was the paper why did it run OK on the first pass? Is the paper curled? Is the doubling/slurring front to back or one side? Try with one unit on impression then keep adding units, this should pin point if you have a gripper problem. Also you could try a different batch of the same stock if you think its the paper
     
  5. richck

    richck Member

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    If it was the press why would it run ok first side and not the second? The doubling/slurring is front to back. Tried different batches of the stock and its all the same.
     
  6. mrheidelberg

    mrheidelberg Senior Member

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    Have you tried a different stock altogether, but using the same set of plates ?
     
  7. print101

    print101 Senior Member

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    Make a 100% sure that the sheet is arriving into the lay all squared up. Meaning - no wavy bulges or sqewing. Sometimes the paper can react differently on the second pass having been put through the press already.

    Maybe also try putting the sheet through the macine under impression but no printing (say 500 sheets) then return those to the feeder and try print, you never know maybe it might solve it, wierd things can happen?
     

  8. richck

    richck Member

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    Print101,I had thought about doing what you suggest with putting the sheets through under impression, if we get the problem again i will try that. We have now finished that run and have had a second run to do today of the same job on the same brand paper, but which has had time to acclimatise and guess what..... it ran fine! I always knew in my own mind it was somthing to do with the paper but convincing the Managing Director was a different matter. Thanks for all the advice guys.
    Rich
     
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