Prinergy 4 Web Growth Compensation Help!!!!

[bogdan.gheorghiu]

Hi all,

Our company use a Prinergy Evo 4.0 workflow with a Magnus 800 CTP. For some weeks, we have been having this problem: it was impossible to made a good set-up for an web growth compensation.

To be more specific: our press is a Komory SP - 4 towers , 8 colors, sheet fed print mashine has a specific deformation of image printed in paper format 720 mm x 960 mm. On the bottom of the sheet the registration of colors is very good, but on the top of the sheet the misregistration is about 0.5 mm. You can see the image attached for a good understanding.

We try various formula to set-up this kind of deformation but we always obtain an equal compensation on the bottom and on the top of the sheet.

The guys from Kodak Romania are not helpfull and in this moment we try to obtain some help otherwise.

Thanks a lot.

 

[maxon]

web growth

web growth

Bogdan, I've sent you a PM.

PrepsPro compensation aside, web growth is just what it is - WEB growth usually seen with newsprint shrinking, not sheetfed. Anyway, you should check pressroom conditions - temp, humidity, new blankets correctly packed, also drying, anything that can affect paper (moisture variability). Is it getting worse at higher speeds with your Komori ? Have you tried changing paper, see how it comes out ?

Are you absolutely sure your Magnus machine is in spec wrt geometry and plate loading, have you carefully measured the exposed plates ? ... Although I can't imagine how an external drum machine would give such geometry errors, just a thought.

 

[bogdan.gheorghiu]

Thanks for reply.

To be more specific, I need a good syntax for Prinergy Ev 4.0.6.6 to realize an anamorphic distorsion. I've studyed helps, but nothing.
I have license just for PrepsPlus, because we use web growth compensation with Prinergy.
And yes it's a matter of pressroom conditions and paper quality, but we must compensate software.

Thank again

 

[maxon]

Bogdan, the real cause seems to be the Komori machine, don't waste time and effort looking for workarounds. Is your sheetfed machine mechanically sound, properly tested and set up ? You must trust your pressmen they know what they're doing, eventually ask an offset service guy to come over and investigate this matter.

Has anyone else on this forum ever encontered such thing, I believe Bogdan would apreciate a second opinion.

 

[Joe]

Bogdan, the real cause seems to be the Komori machine, don't waste time and effort looking for workarounds. Is your sheetfed machine mechanically sound, properly tested and set up ? You must trust your pressmen they know what they're doing, eventually ask an offset service guy to come over and investigate this matter.

Has anyone else on this forum ever encontered such thing, I believe Bogdan would apreciate a second opinion.

Can't help with Prinergy but I know with Apogee X it is possible to set different web growths at different points on a sheet by editing a web growth text file. If you can find the file Prinergy is using to do the web growth possibly you can manually edit it to accomplish the same thing.

Edit: I just happened to meet with a Kodak rep today and indeed there is a control file that you can adjust to do exactly what you are looking for.

 

[colorfun]

Komori SP (not LP) machine is very specific press that has this problem known. It is not something that you can call machine failure. This is tower-based sheetfed machine (like akiyama). The risk of misregister is bigger when you use thin papers.
However, you can minimalize it by:
-using waterless printing (no water means less misregister)
-using paper with proper fiber direction
-thicker paper if possible...
-software (apogee, heidelberg 100%)
regards
szymon

Bogdan, the real cause seems to be the Komori machine, don't waste time and effort looking for workarounds. Is your sheetfed machine mechanically sound, properly tested and set up ? You must trust your pressmen they know what they're doing, eventually ask an offset service guy to come over and investigate this matter.

Has anyone else on this forum ever encontered such thing, I believe Bogdan would apreciate a second opinion.