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Thread: Optimum Flexo Dot Size (plate)

  1. #1
    Junior Member ecrm is on a distinguished road
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    Optimum Flexo Dot Size (plate)

    Hello,

    Was wondering if anyone can give a complete list of the "optimum" dot size for rotary flexo plate (150lpi & 175lpi)?

    Thanks.

  2. #2
    Donor Apa_Cska is on a distinguished road
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    It depends

    especially on your plate technology. What kind of system do you have?

    Ap

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    Junior Member ecrm is on a distinguished road
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    Asahi DSF 1.14mm plate with Esko CDI

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    Donor Apa_Cska is on a distinguished road
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    By my experiences

    with a standard UV-tube technology about 20 pixel is ok at 2400 dpi (it equals 23 pixel at 2540, and 55 pixel at 4000). But it depends on the UV power of the tubes.
    few yaers ago, with the stronger tubes it was 16 pixel at 2400. As I know, the power of the UV tubes today is limited to a lower value. (and of course it will continue to decline after a few hundred of working hours)

    The new inert system from DuPont (DigiCorr or Flow) can keep 6pix/2400 (7/2540, 15/4000), very close to Kodak's flexcell

    but only with a real test-print can be find the best minimal dot.


    Ap

  5. #5
    Junior Member ecrm is on a distinguished road
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    Thanks AP,

    Do you have the formula for the calculation?
    Generally I only use 150lpi & 175lpi with 2540dpi & 4000dpi.

  6. #6
    Donor Apa_Cska is on a distinguished road
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    there is no formula... it depends on the plate processing technology.

    f.eg. the DuPont Fast plate can keep higher pixels only.

    The min. percentage at given screen ruling easy to calculate.

    2540 dpi, 175 lpi => microcell contains 210 pxel (100 % ) => the 23 pixel means more than 10 percent, and 8% with 150 lpi

    approximately....

    so run a testprint around this values in very small steps (1/256), and find the best printouts (the minimum density)

    good luck!

    Ap

  7. #7
    Junior Member ecrm is on a distinguished road
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    Hello AP,

    I'm not sure what do you mean in term of "plate processing technology"
    I am processing "normal" digital flexo plate with Esko CDI and BASF Combi F III.
    (Just normal round dot at this point, no AM/FM or HD screen).

    Cheers,

  8. #8
    Junior Member ecrm is on a distinguished road
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    Hey,

    I found a references calculation [URL="http://the-print-guide.blogspot.com/2010/04/how-to-calculate-halftone-dot-sizes-in.html"]here[/URL]:


    According this, 1% dot at 150lpi is about 17 micron. Would this be too small?


    Cheers,

  9. #9
    Donor Apa_Cska is on a distinguished road
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    yes

    Yes, it is

    the standard UV tech cannot keep 17 micron, but the Kodak's flexcell can keep even smaller (and the DuPont's new digiflow also)
    But you can compensate it in th RIP more or less.
    Last edited by Apa_Cska; 05-07-2012 at 08:03 PM.

  10. #10
    Junior Member ecrm is on a distinguished road
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    I am using Esko frontend. I've spend few days looking at the structure of the dots, it seem like 1% to 3% dot doesn't form very well on the plate. I'm not sure if this got something to do with the plate or CDI itself.

    I am testing normal round dot at 150lpi at the moment, I will test HD screen once I am happy with what I consider as normal/regular screen.

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