ad

Automatic Register - How It Works And Where It Falls Short



Automatic registration is one of the foremost achivements in automation for the offset printing industry.  Gone are the days when a pressman had to run to each printing unit and manually crank on a shaft or compensator to line up the colors.  Automatic registration has become almost a second thought.  On startup, the press will line up all colors to within hundredths of a millimeter.  Here is a video demonstration of how it works.


An Innovative Improvement
This gift to pressmen has brought about more possibilities.  For example, many web presses today have an automatic registration system that combats piling.  Small adjustments are made throughout the print run to move the plate cylinders in unison just slightly.  These small adjustments minimize piling problems as no one particular part on the blanket builds up quickly.

Some Improvements Yet To Be Made
Though these systems are fully automated, there are a few procedures that automatic register has failed to deal with.  I hope we can see improvement in these areas in the future.
1.  Marks must show clearly.  If they begin to fade because of piling or poor ink and water balance, they will stop functioning properly.
2.  Paper calibrated properly.  Most cameras that read register marks are too sensitive to changes in paper color.  A slight difference in shade and it will not read them properly.
3.  Plates mounted correctly.  Usually plates have to be mounted and lined up to one side of the cylinder for them to align properly.  If not done properly, the systems usually are not able to cope with such moves quickly enough.  True, it happens due to our own stupidity, but hey, we have to deal with the stupidity of computers sometimes too, right?
4.  Backup.  This is an important one.  I have yet to see a system that will line up the register both sides of the  sheet, one to the other.  This is probably the most common issue and needs to be resolved.  I can't image how it could be done, but the company that comes up with the solution will get a gold star in my books.

The Biggest Challenge
Probably the biggest challenge to automatic register is simply knowing the software.  A system that runs on automatic needs little attention.  But when it doesn't work right, it takes the guy that knows how the program works to get it going again.

3 comments:

  1. Erik Nikkanen9:07 AM

    I would add that good web tension control into the first print unit is very critical for allowing any automated register system to work to its fullest potential.

    ReplyDelete
  2. Erik: What is the solution in case the tension control on the first unit is not good? We have serious registration problems on our web press because of this...

    Please let me know @ yogamoorthy@gmail.com

    ReplyDelete
    Replies
    1. Although there's obviously a big difference between web and sheet fed print we experience the same displacement of "fanning" so much so between k y units we've had to displace the size .0002 to the k plate or go old school and pack the k plate with your rice paper or dividing sheets used to separate your plates in prepress

      Delete