GTO - 52-4

Hello. The jacket of the printing cylinder was replaced on the 3rd printing block. After that, the image does not align. On the long side of the sheet, the image at the end of the print is longer. And in general, it is difficult to combine crosses and a picture on different types of paper throughout the impression. Thank you, I ask for help what to do?

 

The image doesn’t align now because the circumference in unit #3 is different somehow. You either;
A) changed the impression cylinder jacket pack
B) somehow skewed the new jacket when installing it
C) did not tighten it correctly
These are some of the possibilities, how you go about fixing it is entirely up to you.

 

How to determine the correct shirt tension??

 

It’s an acquired skill, Andrei. Simply put, tension the jacket as you would tensioning the plates (image plates that go on plate cylinder). Before that step, you must clean behind the lead clamp (gripper pad rail), clean tail clamp bar and be sure you have not removed the mylar packing adhered to the back of new jacket. While hanging jacket, it’s very important to use the pressing bar that should have come with the press. It has wing bolts that fasten to threaded holes along side undercut at lead edge. Before tensioning the jacket, be sure to measure edge from a fixed pint to be sure the jacket is running absolutely true to cylinder. Once done, tension jacket to heavy resistance, use 10mm spanner to bounce along lead and tail edges to be sure there is no “hollow” sound.

 

You could also use the impression force of blanket. What i mean is before you put jacket on, turn the impression as you would hang a plate then put dial impression at highest force, install jacket and turn once or twice before you tension jacket. That should remove any air trapped. Also you could buy 3 more identical jackets and change them so you have same jacket on all units. Torque wrench could help though i dont know for sure to what Newton you tighten