Unit #1 Registration Issues

Good Day Everyone,

We are experiencing an odd problem on 2 of our QMDI's at the same time regarding registration on UNIT #1

We are running CYAN in UNIT# 1 and we have a peculiar situation where, at the bottom of the sheet, the register is OUT to the LEFT on the bottom LHS of the sheet and OUT to the RIGHT on the bottom RHS of the sheet. The bottom middle of the sheet seems to be fine. It seems like the image (cyan) tails outwards as you move further down the sheet but in opposite directions. The image on the TOP HALF of the sheet looks perfectly fine. (please see attached pictures)

So we cannot move the registration of the plate to the LEFT or RIGHT in the REGISTRATION menu as this corrects one side and makes the opposite side worse. Also it takes the image at the top of the sheet out of register.

Please see attached pictures. Any advice / assistance would be greatly appreciated . I look forward to your valued input on the above problem.

Thanking you in advance - Shawn

 

Just a query!

Could this problem be as a result of PAPER STRETCH?
We just noticed that when we are backing up the job, this registration problem is NOT happening - same set of plates but very different results!
We are running the front of the job on one press and the reverse side on the other. So we ran half of the FRONTS and then swopped over the paper to the other press and ran the backup and vice versa.

It is quite clear, that the sheets that have already gone through the presses once, are printing much better on the reverse side.
If it is indeed due to paper stretch, is this a problem with too much moisture in the paper? We have had quite a bit of rain over the past week and the paper we are running arrived at our shop approximately 5 days ago during rainy conditions also.

This is just my observation - I could be totally wrong but I just thought I would share this as a possible cause of the problem. To me this seems the only logical / plausible explanation as to why the register would be out in opposite directions on the sheet and also only for the first colour and worse at the tail end of the sheet compared to the head of the sheet.

Your input would be greatly appreciated.

Thank You!

 

Shawn
I believe the issue is referred to as 'fanout' and I found a great article about it below the suggestion.

I forwarded your post to an associate. Their input is:
Affecting the bottom but not the top ?? I would change the blanket. Compression layers could be defective. Next swap the black to the first unit to see if that changes anything. This is what bussels are for. But not just one side.

http://offsetpressman.blogspot.com/2011/08/what-causes-fanout-and-what-you-can-do.html

 

Always look for answers inside your own questions. 2 different machines at the same time. whats different ? Machines are different. Is the ink the same batch? Are you running the same lot of paper. Did you spin a load to see if the problem moves from gripper to tail? 1st units are notorious for "movement" "fanout " etc etc.

I doubt you have 2 blankets with compression layer problems (both on the same unit of 2 different presses) I use this analogy solving press problems all the time. Its not rocket science.....but it is a science. Also not sure of the DI quality parameters , but if those pictures are the worst registration issues you have .....Its not that bad, you have to cheat register all the time, more so on older presses. Small type with no overprint or trap, its a game.

 

Make sure all your grippers are clean & check the plate tensioning.
It can be very difficult on a DI to get perfect registration on every job all the time due to many factors (paper, ink, atmosphere, temperature, machine speed, image / ink on sheet, cleanliness of machine)