Hi Erik, Yes - the press, since installing this upgrade seems less stable. Color fluctuating and density targets randomly changing themselves throughout the press runs.
Jud
In general, close loop systems work by looking for an error. The error is the difference between the target value and the actual value. The magnitude of the error or delta e is used to drive the system for correction. There are usually PID settings which represent Proportional, Integrative and Differential parameters. Each of these parameters has a gain which one sets. It may be that these are not set correctly.
Closed loop systems can be unstable even though the process is not. If the gains for these parameters are set too large, then the system will overshoot and fight itself.
If you turn your closed loop system off while you are running, does the process seem to settle down. If it does, it kind of implies that you are overcorrecting. Reduce the gains down to low levels.
Also in printing on press, the coverage is a factor. High coverage would respond better with larger gains but low coverage will need lower gains in order to not over correct.
If your press is still unstable when you turn off the closed loop control system, then you have a press issue.
Offset is normally a stable process. It may not be consistent but it is stable. This means that if you don't touch it, it should stay where it is most of the time.
I would think there are some manuals and other info that came with the system. You need to read it. I don't know how advanced your system is but one should not think that the engineers who made the system understood everything. You need to know what their system does.
It can't hurt to start with low gains and carefully work up keeping the coverage issue in mind.
Good luck.
