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  • Shinohara 52 horizontal banding.

    Evening.
    We have a problem on our 4 colour shinohara 52 the machine is only a few months old and has had this problem since new. Plus our other 12 year old shino has the same problem.

    When we run a solid we get a heavy band running accross the sheet about 3/4 of the way down the sheet. now when the machine was first installed the band thickness was
    deck 1= 10mm
    deck 2= 20mm
    deck 3= 15mm
    deck 4= 5mm

    Also the solid coverage just doesn't look even from top to bottom of the sheet with light and heavy patches all over it but nothing as bad as the actual colour density change from the band.
    Now the technitions have tried adjusting all the rollers from light through to heavy with no change..
    I have now adjusted the water form to steel so it has a thicker bead line and now all the decks are down to a 5mm band.
    deck 1 and 3 have the band is in the same spot deck 2 and 4 are in the same spot but slightly different spot to 1/3 but this is to be expected as the water form circumfrence is different between 1/3 - 2/4

    The distance down the sheet were the band is is the exact circumfrence of the water forms and if you back off the pressure of the water form to plate the band nearly disapears but the machine can't be run like this.
    So if we are getting bruising on on the water form from the lead edge of the plate cylinder I assume this is (cylinder gap shock marking).
    Is there any way around it.

    On the old machine we just adjusted no. 4 form roller so it wasn't touching the plate and the banding improved vastly but this doesnt fix the problem on the new machine.

    Also durring test prints I ran a 80% screen over the whole sheet and turned the fount down till I was getting a slight amount of catch up on the sheet now where the band normally is on a solid print there was a heavy 5mm band of catch up but above that band there was a clear 5 mm band where there was no catchup at all (indicating fount was getting dumped in that one spot)
    (hard to explain but sort of like this from lead edge too tail of sheet.
    light amout of catchup -5 mm band no catch up - 5 MM band of near solid from catchup - light catchup the last 1/4 of the sheet.

    checked so fair
    fount solution /IPA levels ( I have changed founts and have dropped the IPA from 10% down to 5 % and solid prints seem cleaner but no improvment on the main problem.)
    Packing behind plates and blanket
    Blankets
    roller settings
    tried a different brand water form roller
    all the pressures were checked.

    Run a dry solid and we have no problems.

    Is it that shinohara 52 simply cannot print solids without bands??? or even a full sheet screen without the band showing up.
    We also get a lot of picture framing on the cylinders but is this to be expected when usin polyester plates?

    Sorry for such a long winded post but any help would be great

  • #2
    Re: Shinohara 52 horizontal banding.

    HI there,

    just a thought, check roller play in journals, left to right. there should only be about 0.10mm play i think. Can you alter your point in which the rollers oscillate (reciprication point), try to get the band to drop into the plate gap. I know this is not much help but its all ive got at the moment.

    Paul

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    • #3
      Re: Shinohara 52 horizontal banding.

      Describe the shinohara 52 dampener, gear reduction ? bridge roller to integrate ?, durometer that you have tried ? What type of bearings are you using on the water form ?

      Comment


      • #4
        Re: Shinohara 52 horizontal banding.

        Thank's for the reply's,

        I'm sure the roller play has been checked by the technition, but I will make sure.(I assume the journals are the mounts that the roller bearings sit in?
        Unfortunatly the timming of the ocillators can't be changed.
        I mentioned to the tech when we first got the problem if it could be caused by when the ocilator stops breifly and they were addiment that the occillators would not stop in the same spot every time, and even if they could adjust the timming it would do little to solve the problem But your not only person who thinks this is the cause of the band (remember the band is in the exactly the same spot every time.

        CKL, what do you mean by the shinohara 52 dampener, gear reduction ? ( possible the diamater and amount of teeth on the gears??)
        Its running a continuos dampening with the bridging roller down NOT intergrated, we have tried to run with it intergrated but the band size didn't change.
        You would not believe the tecnitions do not have a durometer tester, so I can only guess that the shore hardness of the rollers when new was correct, but we have tried aother roller companies water form roller with no change in band size.(I will get the shore hardness thats in the book at work and post it tonight.
        As for the bearings used there the same that is used on all the rollers on the machine exept for the metering roller bearings, but as to what type they are I do not know.
        One thing to note when you run a job then take the plate of straight away just as the fount is drying off the plate where the band line is there is a perfect wet band line on the plate itself

        I read on the shino website that there 66 and up run a 7o'clock cylinder arrangment to stop cyclinder gap shock marking and to give a more even ink coverage.. is this cylinder gap shock marking what we are getting on the 52?

        Thanks Luke.

        Comment


        • #5
          Re: Shinohara 52 horizontal banding.

          I was asking about the gears(if any) on the water form. You can pull those gears off and reinstall the roller and test print. Without gears you will see if your streaks are from those gears. Are the gears cut diagonal or straight. Feather the blanket packing to help the cylinder shock. Day 3610 is a very good blanket for streaks, the compressible layer is thicker. Get 2 blankets and test multiple screen solid combinations. 100 & 75, 75 & 75 50 & 50, 100 & 100. This will show worse case scenario but will save press time down the road. We get streaks when we run Carolina so we run Tango instead with no streaks. Small things make a difference

          Comment


          • #6
            Re: Shinohara 52 horizontal banding.

            I will take a photo of a sheet tomorow and post it, Its not your normal gear streak marks but just one 5mm band, in the same spot.
            To me it would seem that it is a press design fault, as it happens on both machines.( the water form needs to be larger in diameter)
            The water form to plate should be set at a bead line of 4mm, if you bring it back so there's a 2mm bead, so in thery when the form hits the lead edge of the plate cyclinder from the cut out it doen't hit as hard the band during a soild print nealy completly dissapears, but there's no way you can print a variety of jobs like this.
            I will see if I can get hold of that day 3610 blanket. at the moment I had just been using kinyo and then a brand that the shinohara reps recomended.
            Is there anyone here that runs a shinohara 52 ??
            Thanks luke

            Comment


            • #7
              Re: Shinohara 52 horizontal banding.

              Your ink is drying up semipolymerizing before it transfers. Picture framing is the clue. I have seen banding of this type on many presses. Ask your ink supplier to lower the dryer load by 15 to 20% you should see a big improvement.

              Comment


              • #8
                Re: Shinohara 52 horizontal banding.

                Hi,

                The banding (streaking) that you are experiencing on the Shinohara can come from a variety of causes. Roller to oscillator or roller to plate nip pressures, fountain solution, ink issues and gear shock from overpacking the plate and blanket cylinders as well as the inker and dampener design/layout.

                The Shinohara 52 series has a dampening system with a metering roller, pan roller, form roller and bridge roller. The only roller that oscillates is the bridge roller and it does not smooth out the water film before the water reaches the plate due to it's position.

                You are right in checking the roller circumference in regards to where the banding occurs. Ideally press manufacturers size their dampening form roller and ink form rollers so that they cancel each other out (no light or dark banding) when one revolution of the dampening and ink forms occur.

                Roller diameter, rubber hardness, a good ink with lots of pigment will help to cover up the banding.

                Call Sam Mezo at SM Graphics in the Melbourne area who can probably point you in the right direction if the Currie's guys can't find the solution. If that does not help, contact the factory in Japan and ask for a factory tech to come visit you.

                Comment


                • #9
                  Re: Shinohara 52 horizontal banding.

                  curries have been great trying to solve the problem there's no dout about that. and I would not be suprised if the japs do pay us a visit.

                  Ink has been ruled out - we have used ink from 3 different suppliers with no change - yes some colours like purples and dark greens exagerate the band.
                  fount has been rulled out 3 different founts have been used 2 with a glycol base and the other had a different base chemical
                  The dampening system used is a poor design, on there 66's they have a mini occilator under the water form to help get rid of any raining that you get all they need on the 52's is to have the pan steel roller occilate that would help that problem out considerbaly. the only thing you can do to help stop that is continualy tighten the nip of the metering roller to steel as it ages and change the roller more frequently.

                  Maybee there is a packing that you can get to go under the blamket that is softer then the normal calibrated paper packing I will check that out.

                  Its definatly caused from the dampening system most likely the water form as dry solids show zero bands and if you print a solid and turn the water down till theres scumming the band nearly goes.
                  I will post a photo tonight of a printed sheet.

                  Comment


                  • #10
                    Re: Shinohara 52 horizontal banding.

                    How about trying some ink with no dryer. See if that has an effect.

                    Comment


                    • #11
                      Re: Shinohara 52 horizontal banding.

                      Here are some photo's I hope they will work.
                      Pat I will see if I can get some ink without dryers. and try (but if it was the ink wouldn't it still show up if when you run a dry solid or does this cover any problems up?)



                      Comment


                      • #12
                        Re: Shinohara 52 horizontal banding.

                        When running a dry solid there is no interaction between the ink, plate and water. Ink film thickness and transfer can change drastically when mixed with some fountain solutions.

                        Also this problem can occur when the durometer of the water form and meter roller are to high. Durometer of 20 to 25 usually works better. Anything harder and the proper water film has trouble getting through the nips.

                        Comment


                        • #13
                          Re: Shinohara 52 horizontal banding.

                          I saw a suggestion about changing the oscillation stroke timing by Paul. His idea is good and yes it is true that the oscillation stroke timing (the point where it stops and changes direction at the end of a stroke) is not an operator adjustment but I have seen the cam that drives the oscillation stroke mounted in the wrong position. Typically on that press there are either three or four bolts holding the oscillation stroke cam, if you mark the cam and the shaft it is mounted to in order to put it back where you found it, you can move the cam clockwise or counter-clockwise one bolt hole at a time and see what changes on the printed sheet. On the Shinohara, the oscillation stroke should change direction when the leading edge of the plate cylinder reaches the fourth form roller when running the press in the forward direction if my memory serves me correctly. Since this is not an operator adjustment and requires removing safety covers and exposing yourself to moving parts and high voltage wiring, extreme care needs to be exercised or severe injury or death can result. I have to say that so I won't get sued if you get hurt or die trying that procedure. No kidding.

                          Another idea to check is the point where the sheet transfers from the impression cylinder to transfer cylinder and does this correspond to the band that you see on the sheet. On that press the sheet is transferring between impression cylinder and transfer cylinder during printing and a band or streak can occur if the stars are all aligned just right.

                          Another item to check is the ink ductor timing cam. When is the ink ductor roller transferring ink to roller train. If the cam timing is off due to incorrect timing during assembly then your charge of ink is getting down to the plate at the wrong time and when printing a full solid like you photographed samples, you are running out of ink in the middle of the sheet and the sins of the dampener are showing themselves.

                          Just some ideas to check, good luck mate.

                          Comment


                          • #14
                            Re: Shinohara 52 horizontal banding.

                            Hi there,

                            i think the point above is worth further investigation. Looking at the pictures they look just like the roller marks i get from the oscillator return point. They will always be in the same place as one revoloution of the press is equal to a full movement of the oscillator form drive side to operators side, so the point at which the play is noticed will always be the same. The journals are the metal blocks which hold the rollers, on my speedmaster there like small cups. Check for movement in these as these can wear and cause movement when the roller goes between the plate gap and then comes back under preassure. If the mark is coming from the dampening unit then moving the return point and dropping the mark into the plate gap should be an easy fix, appart from losing fingers or facing electrocution.

                            Paul

                            Comment


                            • #15
                              Re: Shinohara 52 horizontal banding.

                              If you have any side play in any of your form rollers water and or ink sometime you will see the band when the form rollers skids across the plate. I have seen this happen with as little as .25mm of side play.

                              Comment

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