PM 74-2 powder problem

Discussion in 'Heidelberg Printing Presses' started by m_alatorre, Nov 26, 2011.

  1. m_alatorre

    m_alatorre Senior Member

    Joined:
    Mar 2008
    Messages:
    66
    Location:
    Monterrey, Mexico
    Hi everyone,

    We recently installed a used 2007 PM 74-2-p and everything have been working but i've been having trouble with the anti-setoff powder. It leaves a line of powder across the sheet aprox 1" from the sheet edge.(see pic) Then when running the pile again blanket picks it up forcing blanquet washes every 500 - 1000 sheets. It's a nightmare. It does it even with minimum powder in the powdering device.

    I tried to solve it moving the powdering starting point 10 degrees( from default 278 to 288) but i got the result shown in pic.

    I then reduced the degree from 278 to 270 to see if that solves it but i have to wait until monday to make a new test with this configuration.

    Has anyone experienced something similar? Solution???


    Tanks
    Moe
     

    Attached Files:

  2. FSA

    FSA Senior Member

    Joined:
    Jan 2011
    Messages:
    312
    Location:
    Winnipeg, Manitoba
    what type of spray unit is it?
     
  3. spike

    spike Senior Member

    Joined:
    Apr 2011
    Messages:
    139
    Location:
    new york
    check that you do not have an ink build or old powder buildup on your superblue
     
  4. m_alatorre

    m_alatorre Senior Member

    Joined:
    Mar 2008
    Messages:
    66
    Location:
    Monterrey, Mexico
    Hi,

    Device is a WEKO AP110.

    I checked the superblue net and it was dirty but no ink buildup in problem area. Very dusty. I vaccum cleaned it. I ran a pile today after this and also moved the starting spray point at 270 degrees and... SAME PROBLEM!

    I'm gonna move the spray starting to something like 4-5 inches away from sheet edge hoping to determine if problem comes from powder device.

    Ideas???
     
  5. FSA

    FSA Senior Member

    Joined:
    Jan 2011
    Messages:
    312
    Location:
    Winnipeg, Manitoba
    it not the degree of the spray unit start point, I would suggest to check out the transfer drum right after the head stops, clean and silcone the bar. Next question is what tpe of spray are you using, 230, 350, "C" or "R" ?
     
  6. m_alatorre

    m_alatorre Senior Member

    Joined:
    Mar 2008
    Messages:
    66
    Location:
    Monterrey, Mexico
    Ill check it today. How do i "silcone" the bar? Grease it? The powder is the same that came with the press. Since it looked the same we got here, i decided to just use it... could it be bad powder?
     
  7. FSA

    FSA Senior Member

    Joined:
    Jan 2011
    Messages:
    312
    Location:
    Winnipeg, Manitoba
    Silicone comes as a spray can or a liquid pump, it will help repel the spay powder, do not grease the bar. Now yes spay powder can go bad, it is NOT good to keep it in a moist enviroment, keep the bag or canister sealed. I like the C-350 because less is needed to do the job and it is better for printing card stock. So when you use less the back-up you can go further between blanket wipes.
     
  8. Grant B

    Grant B Senior Member

    Joined:
    Mar 2009
    Messages:
    77
    Location:
    Toronto
    We only use coated spray on one sided board jobs with heavy coverage. C-350 is a large granule spray. For most sheet work jobs I would recommend an uncoated spray like R-35.
    Here is a line from Prisco regarding spray:Use uncoated powder for multi-pass printing and coated for single-pass.
    Here is a link to Varn Chemical:http://www.lithcoproducts.com/prods/varn.htm#Anti Set-Off Sprays
     
  9. turbotom1052

    turbotom1052 Senior Member

    Joined:
    Oct 2008
    Messages:
    1,044
    Location:
    Vermont
    looking at the posted picture im thinking that its not the powdering timing but something disturbing the powder thats allready on the sheet when you back up. My first thought would be to look on the register plate and see if you find any kind of buildup at that very place just behind the gripper. The pulling side guide could be causing something on the underside of the sheet when your backing up to have a wiping effect thus leaving that hard powder line. I also suspect that for it to show up so quickly your probably running too much powder and as someone mentioned perhaps the wrong size powder. My preference for an all purpose powder for your run of the mill variety of commercial printing would be for a grain size in the 25 micron range.
     
  10. Dougiefresh

    Dougiefresh Member

    Joined:
    Nov 2011
    Messages:
    6
    Location:
    Chicago
    I'm leaning towards where turbotom1052 is going. I would also check the filters on your compressors. I have experienced sucker marks in powder on the sheets and blankets before even though the compression timing on the feeder head was proper because the filters and lines were filthy. If a filter is unable to scrub that air blast of it's powder, then it is just sucking and blowing it right back onto your sheet. You could test this by blanking 1,000 printed sheets either side up and seeing where the powder builds up WITH the powder unit off on the blanking pass. If you do that and the powder is still building up in one spot rather than evenly across the blankets(assuming your powder timing is correct) then you can rule out the powder unit. Just don't forget to turn your powder back on before you run again.
     
    Last edited: Dec 1, 2011
  11. m_alatorre

    m_alatorre Senior Member

    Joined:
    Mar 2008
    Messages:
    66
    Location:
    Monterrey, Mexico
    Hi everyone and thanks for the ideas.

    Finally found it. The sheet separator roll was set too tight. While it did not affected register, it was creating some sort of disturbance by scrubbing powder and accumulating it on that line.

    One thing that happend is that i switched to the powder we're using in our 2col GTO and found myself needing to wash blankets every 2500-3000 sheets. The powdering device is set to the lowest poslible amount of powder and we're using a 300/25C powder... Is that normal? I remember in our old SORMZ being able to run 5000 sheets piles.

    One question that might sound stupid... Does somebody know how to call the print count on the CP Tronic? I don't seem able to find that in the OM. By the way... We are missing the maintenance manual... Does somebody have that??? Either PDF or printed copy(i'll pay for whatever shipping and printing expenses) will work.

    Thanks again!

    Moe
     
  12. Grant B

    Grant B Senior Member

    Joined:
    Mar 2009
    Messages:
    77
    Location:
    Toronto
    Spray codes with a 'C' mean that the spray is coated and is best used for one sided jobs. Try using an uncoated spray-as was mentioned on a previous post a spray of 25 microns (R-27) should work well for most 2 sided jobs on text and most card stocks.
     
  13. peterh

    peterh Senior Member

    Joined:
    Dec 2010
    Messages:
    48
    Location:
    south wales
    hi stupid question perhaps but as we got a cd74 with no coater we also get a similar build on our press,heidelberg have told us to use the first unit as a scavanger(bloody expensive scavengar) but thats not an option as we seal on unit 5,but this sheet roll separator you mention,can you put a pic or let me know where that is(maybe its only on a pm74) so we can see if its causing our problem,we are using ksl 22 mic spray.
    peter
     
  14. m_alatorre

    m_alatorre Senior Member

    Joined:
    Mar 2008
    Messages:
    66
    Location:
    Monterrey, Mexico
    Peterh,

    What i call sheet separator roll(only because that's what OM calls it) is shown in pic 3. In pic 2 you can see the "barrels" that guide the sheet. You can rise or lower the hole bar with adjustment control shown in pic 1 or individually with the nut above each "barrel".

    OM recomends to set it to 6 - 10 thickness of material being printed. When done, we got the powder problem that started this tread. I raised it to highest position and problem went away without affecting register, so i'm just curious what problem might that cause in the future.

    Hope that helps you! I can't imagine having to stop a 15000 sph 5 color machine every 2000 sheets for blanket washes.

    Moe
    P.D. No wonder why many operators go bald! (not my case tough)
     

    Attached Files:

    • 2.jpg
      2.jpg
      File size:
      1,014 KB
      Views:
      752
    • 1.jpg
      1.jpg
      File size:
      889.2 KB
      Views:
      697
    • 3.jpg
      3.jpg
      File size:
      981.9 KB
      Views:
      709

  15. peterh

    peterh Senior Member

    Joined:
    Dec 2010
    Messages:
    48
    Location:
    south wales
    hi,

    thanks for that,on our cd im sure i`ve seen very similar things,and im sure the press lads have said that when we raise ours it makes it better,crazy though if this is a cause for concern as the whole idea of these is to guide the sheet flater into the front lay i would presume.
    anybody else find they have to raise theirs to get rid of the spray issue.?
     
Loading...