Thread: Heidelberg GTO 52 CRISIS

Typically if you run board weight paper at a text weight setting you will get smashed blankets and this will be noticed rather quickly. While it is possible that the settings are off they usually wont result in streaks. If its too low it will result in low printing pressure which can be corrected by increaseing pressure. If its high it will result in smashed blankets. Usually streaks will be because the bearer pressure is too low and you can get chatter from the gears or gap streaks from contact from plate to blanket coming on and off with each revolution.

Originally Posted by Grant B

I thought that perhaps the pressure adjustments were not adjusting properly and could be stuck at a low value. It has not been mentioned if this is occurring on a single unit or on all units. I've seen that pattern when board weight stock has been run through at text weight settings.

We had the same problem for 2 months when we switched to a new CTP system. After trying every adjustment and fix we switched to soy ink from the oil base and a new fountain and the problem was gone. I don't know where you are located but here in So California we must use low voc solvents and cleaners. We also found these were contaminating our DDS rollers and contributing to the head marks just like in your pics. We finally found a combination that works fine and never had it return.

I have seen this many times with that type of plate, usually it's not a problem on the printed piece and we just forget it. If you get toning on live copy, then work on it with:

1) blanket packing.
2) pressure of water forms.
3) fountain solution mixture.

My GTO's don't like loose bodied inks. The thicker the better. I also get streaks if my alcohol% is too low. Also can come from running too slow. HTH

I agree with your other posts. Does look like pressure streaks, check your packing and bearer pressures. Check your rollers and their durometer. I would also take some deletion fluid and wipe the non image area and see if it doesn't streak in this area. Wipe in the area where the streaks are showing up. Just trying to think outside the box. Maybe the processor isn't cleaning the back-round out properly. Make sure your roller nips are a little heavier to the vibrator than to the plate. Most times when we have plate issues it appears to be a press issue but ended up a processor issue or lazer issue on the trend setter. We had problems like this on Akiyama presses and went over everything like your saying pressure, rollers, checking gears. Had mechanics checking everything. Nothing in the pressroom seemed to solve the issue. Now we don't have the issue and we really didn't do anything in the pressroom to solve it. That's why I always go after the prep dept. If you haven't changed anything in the pressroom. The season is changing do you keep the place heated and how about your tap water, maybe something has changed - hard or soft water --etc.

Good Luck,
Hope I get a chance to visit Ireland some day. Still have a relative in County Roscommon.

jtdoonz