Any user of Kodak XD positive thermal plates experiencing tramlines on the plates, i know there are huge amount of variables in Web offset printing and the CTP process, i am keen to hear of anyone who has issues with XD plates
All marks are perpendicular to the the grip edge. They travel in straight lines from the Grip to the Tail of the plate.
The mark is occurring on different batches of plates and on different presses.
Typically the mark appears after a run of 40000 impressions
There is no evidence of gauging and all rollers in contact with the cylinder under impression are clean and without buildup.
We have eliminated the plate setters and processors as potential causes and are focussing on ink and plates as they are common on all our presses.
These look like contact marks as they do not apear on the plate bends
Do the marks appear on all plates? I ask because it's a bit odd that the mark in your image is inline with the screen angle. Is this the Yellow (or Black) plate? Is it in line with the other screen angles or is the mark constant in angle compared with the gripper angle.
Also, it's not just the line up the center that appears abraded but also two halftone dots to the left the halftone dots also appear to have the same abrasion - based on how the dots are malformed.
Do the said "Tramlines" also run through the Non-image area of the plates, running from the Lead Edge to Trailing Edge ? -- then look for faint marks in the Anodizing.
Regards, Alois
Last edited by Alois Senefelder; 09-03-2010 at 04:12 PM.
Reason: ********
To answer your question first Alois, yes the lines do apear in the non image area of the plate, and secondly Gordo the lines do apear in all plates CMYK and at 90 degree to the edge.
My next step is to isolate the plates by using a batch with the number 5000 out from the previous batch number to ensure about 3 months seperation in production.
WE have a tank system for our ink for all presses except 1, for this press i will retain the old batch of plates and trail ink from a different vendor and also get the milling analysed to ensure a "gloss mill" as per the manufacturers specifications.
As an aside i will also look at the time diferential between when the plate was made and when it went on the press, we do not gum our plates as such but have a prebake solution that includes Arabic gum, this protects the image from the heat in the oven, in the old days i have seen "gum blindness" on litho plates where the gum crystalises after 1-2 days and acts as an abrasive on the plate prior to being taken off by press chemestry.
To answer your question first Alois, yes the lines do apear in the non image area of the plate, and secondly Gordo the lines do apear in all plates CMYK and at 90 degree to the edge.
If the line appears on all press units then it's likely not a press problem. If the lines only appear on one press unit then it may be a press issue. Can you rotate the plate 90° and image? If the line still appears in the same direction then it is not the plate but likely a processor issue. But if the line changes its orientation 90° then it's likely a problem with the plates.
To answer you question first Gordo, we have imaged the plate vertically as opposed to horizontally, no visible marks post processing under a 200x lupe, after 48.000 copies lines appear.
And to answer your question Alois, the lines are uniform in width but appear at random intervals on the plate and there is no corresponding piling/build up on the blanket or debris in the forme rollers etc.
We have send a sample via Kodak NZ (i must mention their service has been outstanding) to their plant in China.
As an aside changing to an new batch this morning for one of our presses has produced no "tramlines" so far, the press is up to 430.000 good copies.....
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Originally Posted by maas
