horizontal stripes KBA 105

Discussion in 'KBA Printing Presses' started by mark jones, Jun 6, 2013.

  1. mark jones

    mark jones New Member

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    Jun 2013
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    Location:
    England
    Hi all

    we currently have an issue with our KBA 105 6 col press

    we have an issue with horizontal stripes across the printed sheet. this is noticeable in both screen and solid work and on all units
    the first noticeable stripe appears about 200mm back on sheet and it appears that the press has run out of ink, the ink is a lot lighter for a further 200mm then it returns to strength (the light band extends to about 300mm long when the differential drive is on)
    all roller and damp stripes have been checked and are correct.
    the stripes are not as prominent when printed as a dry solid
    has anyone experienced this problem and could anyone give me advice on how to cure it?
    KBA are being little/no help

    thanks

    mark j
     
  2. Graphinnovator

    Graphinnovator New Member

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    Location:
    Melbourne Australia
    Hi Mark
    These lines or "streaks" have numerous causes . All manufacturers has a list of streak marks ,measurements, which would identify thing like ,impression off plate blanket or third form roller one rotation from front edge and so on . These marks can indicate the cause from back edge of cylinder or front edge of cylinder . In your case I think the things that should first be looked at would be the common ones . So its on every unit ....make sure your water is in good condition and that IPA isn't to high , check water hardness , soft water can be a common cause . After that I would check the inker oscillation dead point . It possibly is the cylinder gap your seeing ? Your oscillation dead point should roughly coincide with the centre of the plate cylinder in most cases .It may appear to be OK with a dry solid visually but maybe measure for density drop off at the point where you can see it on the "wet print "
    Double check you plate packing specs and more importantly check you blanket height to bearer with a blanket gauge . Have a look at these things and let me know .
    I ran Planeta's for many years and they were notorious for that type of streak but I would hope todays machines from KBA would suffer the same .I always say , your machine is like a baby , it cant tell you what's wrong so its a matter of looking for the symptoms and eliminating the causes until you hit the right one . In your case a hint is that ALL units are the same so its a common denominator causing it wouldn't you think . Fix one unit and then you will know how to fix the rest
    Let me know how you go and good luck ...don't you just love printing !!!!!!
    G
     
  3. mark jones

    mark jones New Member

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    Location:
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    Thanks G
    plenty to think about there
    we are in a soft water area but monitor our water and our supply is PH neutral at arrival to press we are currently running alcohol free fount so that at this moment rules those two possibilities out
    I have recently checked plate and blanket packings and all are to specification
    oscillation dead point sounds like a good starting point i'll look into it and keep you informed

    thanks for the info

    Mark J
     
  4. rapida guy

    rapida guy Member

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    Location:
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    Are you running the dampener integrated to the inker or separated?
     
  5. mark jones

    mark jones New Member

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    Location:
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    Hi rapida guy

    we've tried both with and without, why what are you thinking?

    Mark J
     

  6. rapida guy

    rapida guy Member

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    Location:
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    What year Ra 105? P40 or Universal style?
    And no, KBA Rapidas are NOT known for streaking or any other print defect.
    Good solid press and I would imagine the problem isn't all that severe.
    Has this problem been there since new / installed. If not, something has changed and I would go back and see what changed at or around the time this started. It is odd to have this issue start all of a sudden in all units. It is either a water issue, material issue or a main setting in the console that affects all units.
    I know you said that all the roller settings have been checked and are good. I'm not judging but if I had a nickel for every time I heard that, I wouldn't be wasting my time on a printing forum. LOL Roller settings might be a good place to start but it would be unusual to have every unit set wrong unless you had put new rollers in recently and set them all to a wrong spec. It sounds more like something isn't engaging or connecting properly and a vibrator roller is getting partially inked.