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cip3/4 pre inking systems

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  • cip3/4 pre inking systems

    Now I'm new to all this cip3/4 . automation systems applied to the machines these days, and have a few queries.the old 2 colour I used to run used the twist style duct keys,
    The shinohara I now run uses spis (shinohara pre inking system) and so far it has been setup great for CMYK with the right colour being achieved within 20-30 sheets, which to me is amazing.even going from coated to uncoated it sets it properly.(with only the odd occasion were I have to manualy adjust the colour, can't have a machine do it all I spose)
    But currently I am trying to set the ink zones to try and use it to set ink keys for PMS colours and I have it near spot on for any jobs that have a resonable coverage but for any jobs with a small amount of ink coverage its not opening the keys enough to match PMS colours colours maybee I have to adjust the % gain for the lower end of the scale. etc..
    Am I wrong in thinking you can use this system on PMS colours is it only for CMYK?

    Also does anyone bother with the auto speed compensation for the ink and fount % or do the amount of variables throughout the day make this not worthwhile ? I havent used it yet, still trying to get my head around how to set it..
    The only downside to all this automation is that after a while the skill of manualy adjusting ink keys will be lost.

  • #2
    Re: cip3/4 pre inking systems

    There are several fundamental problems with ink key presetting that can cause quite large errors if the algorithm used is too simple. But your specific question related to low coverage error is related to the press design itself.

    As one goes to the lower end of the scale, the issue of "zero set point" and consistency of ink feed start to affect predictability in a big way.

    The zero set point in principle is that datum or base line where one sets the zero ink feed value for the ink key. So at the zero set point, no net amount of ink goes to the press roller train. The zero set point does not mean that the ink key is shut completely. If you shut the ink key completely, ink would be transported by the ductor roller from the roller train back to the ink fountain.

    The ink transfer from the ink fountain roller to the roller train via the ductor roller is in general, not very consistent. The amount of ink transferred can change due to changes in water, temperature, press speed, etc.

    So there are two basic problem that cause presetting error at the low end, not only for PMS inks but for any ink. One is the fact that on a traditional press with a ductor roller, it is impossible to obtain an accurate zero set point. It can not be set directly but can only be guessed at. Then on top of that is the inconsistent ink feed due to the ductor. This results in a situation where predictability at low coverage is not possible with the existing 150 year old ink feed concept that exists on modern offset presses.

    As an example, let's say the error in setting the zero set point is 2%. It is probably higher but for this example we will use 2%. If you wanted to set the ink key for 5% but the actual setting is 3% due to the 2% error in the zero set point, then the result is 3% which is an error of:
    3/5 x 100% = 60% of the target and an error of 100% -60% = 40%.

    If the 2% error in setting the zero set point is on the plus side, the aiming at 5% results in a 7% actual output. The 7/5 x 100% = 140% of the ink that you wanted. Again an error in the range of 40% too much ink.

    Hopefully you followed the explanation. This is very similar to an explanation I had in a TAGA paper I presented in 1997. The problem can be corrected at a lower cost in technology than what exists on presses now but there is no interest in the industry to correct these kinds of problems.

    So don't get frustrated about the lack of low coverage predictability and consistency. The press is not now capable of doing much better.

    Edited by: Erik Nikkanen on May 18, 2008 1:39 PM


    • #3
      Re: cip3/4 pre inking systems

      I think I undersand what your saying and it seems to make sense.
      Today I fidled with the pre-set numbers a little. basically I lowered the first imput number and raised the percentage to still get the same final number were as beforeI had a higher first number and a lower % number and this has now opened the duck keys far enough for jobs with little ink coverage
      I didn't realise the fist numbers you put in were so importnt I thought it was just the final numbers you ended with


      • #4
        Re: cip3/4 pre inking systems

        We have CIP 3 on our six color Shinohara and it is great, not perfect.
        Four color ink films tend to be thinner and more predictable than PMS colors. Reflex, for example always needs an ink key setting higher than yellow. You can use the compensation on the console to dial in your color profiles to be closer on the first pull. It will still be a craft because you are learning your particular inks and how to adjust for them electronically instead of manually.
        Heidelberg has the new Anicolor press which uses and Anilox roller in the ink train without ink keys. It only can be used for process colors at this time because of differences in ink film thickness with PMS colors.
        As for the speed compensation, we don't mess with it much. When we run over 15,000 per hour we do need to increase our water speeds but this is to be expected and I would rather have the pressman do it on an as needed basis only, to avoid any excess emulsification. We haven't noticed huge color shifts at higher speeds because we make ready at the speed we will be printing the job. This is essential! A lot of guys will make ready at a slower speed and then speed up the press after the ok. This will cause color shifts and fit movement when you change the speed up or down. In addition when you make ready at slower speeds, you do not see the issues associated with running the press faster, scum, marking, banding, registration movement etc..


        • #5
          Re: cip3/4 pre inking systems

          Thought I'd ask this question even though it may be a long shot..
          shino cip3
          Can anyone explain in leymans terms what effect the middle number the % has on the opening of the ink ducts.

          Say I have set the profiles too
          10 20 30 40 50
          x x x x x
          110 110 90 95 110 %
          = = = = =
          11 22 28 38 55

          But If I use the second profile

          3 20 30 40 50
          x x x x x
          370 110 90 95 110 %
          = = = = =
          11 22 28 38 55

          Even thought the last number is still 11 the duct keys open up further, in the lower ink coverage areas Does it mean that the duct keys of the lower ranges of the second profile will open up 260% more then what they would have from the first profile. So the first row of numbers and the % have an imoact on the key openings just as much as the last row of numbers

          Now I can easily alter the numbers to get what I want, but I just want to know what the numbers are ment to be doing, if I read the book and try and do the graph thing it makes zero sence if anyone knows how the graph works that would be great.

          hope someones got some clues, otherwise I'll just check with the tech nect time he's in.
          Thanks Luke.


          • #6
            I run a Heidelberg CD-102 and I have found that you need to turn your pre-setting values up as much as 40%. This is all according to the brand of ink you use. However most PMS inks are not as highly pigmented as Process inks. They this before adjusting at individual areas of the zone.



            • #7
              Explanation of numbers for opening of Ink Ducts


              I saw your post about your numbers some time ago and have just seen it again and realised that there is a simple explanation. I do not fully understand what your numbers represent - Is it ink coverage and density multiplier to get to the Ink Key settings?

              Anyway I assume that these 5 points represent a way of entering a curve/algorithm with the system/software interpolating values in between.

              So if you graph them (assuming the 0,0 point should be included) you get:


              So using your first numbers/graph you get for instance:
              5 x 55 % = 2.75
              15 x 110 % = 16.5

              But using your second numbers/graph you get:
              5 x 340 % = 17
              15 x 190 % = 28.5

              Does this explain what you have observed for low coverage? Please let me know.

              Thanks and Regards

              Henry Kafeman
              HDK Solutions Ltd.


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