New to the forum and have a question?

My question pertains to a problem that we have had on our Komori 440LSP since we first got it about a year ago. We have always had a problem with toning on jobs after running 4-5 thousand sheets into a run. The toning seems to happen more often in the Magenta and is consistantly on the operator side of the press. This problem also occurs in the Black,Cyan, and Yellow, but not as extreme as with the Magenta, and again it always seems to happen on the operator side of the press starting about 1/2 to 2/3 the way back on the sheet. We have had Komori and several demonstrators try to evaluate this, but we still seem to deal with this and it makes for printing on the razors edge. We have used different chemisty,( and we are alchol free, using subs), checked roller setting over and over and even gone through at least 1 to 2 complete roller changes in all four units. We have removed all isolating form roller with the exception on the D-Form, which we have locked off, and replaced the A,B,C with stationary forms. We have turned the Tresu system down to a temp. of 59 to 67 degrees to the chilled vibrators as we were told that there could be a fluctuation on temperature from the operator to the gear side of the vibrator that may be contributing to the problem. This has helped slightly by bringing the temp. down, but we don't want to get to far out of the window of proper temp. that we have been instructed to stay within. We still seem to run our water settings much higher than we feel necessary and even have the metering rollers almost or just at heavy water on the operator side of the press to compensate. We have also adjusted the skew and it is presently at 7-8.
If anyone has experienced this problem and could give us some input we would appreciate it very much. Glad to be aboard.

poly or metal plates??
do you have the same problem when running with IPA?

When we trialed low IPA, one of the founts gave us the same problem you are having, from the half way mark of the sheet to the tail edge would tint slightly and you would have to keep turing up your water to stop it, or simply change plates.. this would only happen after a few thousand sheets
I spoke to the suppliers and it seems we were not the only shop having that problem on poly plates..

Another thing, what type of roller wash are you using?

We are using metal plates and have quit using IPA as of over a year ago and gone strickly with subs.

Here's one thing to check. Even if you have non oscillating ink forms (a.b,c) make sure they are not moving laterally with the oscillating roller(copper on my L528). It doesn't take much movement of the form rollers laterally to cause a toning effect about 2/3's of the way back from gripper. I have had one roller cause this but if all four (including d) are to moving can cause you to print on razors edge. Hope you solve your problem.

I agree with what Bruce said. Check the form rollers for movements. A slight oscillation of 1/16 of an inch in between the roller brackets will cause the toning.
Good luck.