Shinohara 52 dampening problems

[pmc swp]

We run a 2 colour Shinohara 52, 2003 year Model. It has a 3 roller refrigerated alcohol dampening system. We've had it around 2 years and have had continuous trouble with the dampening system. We currently have a problem whereby after achieving ink water balance on a job and we stop the press and re-start for any reason, the 2nd unit will get an extra flood of water causing the image to wash-out temporarily, returning to normal after about 30 sheets.

We have just replaced and re-set all ink and water rollers on this deck and the problem persists. We run 10% alcohol.

We've noticed that if we set the water form roller harder to the steel than you might normally the result improves but is not entirely eliminated.

This happens on the first unit but to a much lesser degree. Visually the settings appear to be the same on each unit but these presses use 2 different diameter water form rollers. 58.5mm on unit 1 and 55mm on unit 2. Any thoughts?

 

[turbotom1052]

although not familiar with the Shinohara presses i cant help but to wonder why there would be a variation in roller sizes from one printing unit to the other on a press with a unitized design. Id begin by verifying that this is in fact correct. My next thought would be to go to the settings menu of the press and look for the pre-dampening settings. Most modern presses have a provision for setting just how much pre dampening goes on at press startup. If you find the tab for pre dampening compare it to the other unit. If its higher then drop down the pre dampening a bit. Might take some trial and error but you should be able to find a setting thats more consistent with the other unit.
Does the press have the ability to run the dampening either intergrated or segregated from the inker?
if so are both units set the same way??? Theres another area you might want to look into.

 

[Lithogreen]

Turbotom: Yes the Shinohara does run two different sized water form rollers. They do this to try and aliviate the banding issue they get from their dampening system. Nice thought on shinoharas side but doesn't solve the problem.

PMC:
As Turbotom noted, check plate predamp settings (one setting for all decks which is a pain) If you are running metal plates check to see poly plate dampening isnt selected.

I have had this flooding issue but only when printing alcohol free. You are running 10% IPA so you should not be having this issue unless shore hardness is incorect or settings are amis.
The way around it, if in fact all your rollers are the correct shore A hardness and set correctly, is to run the metering roller slightly tighter and run your damp dials higher to compinsate.
If this doesnt solve your problem some of the consolse have the ability to adjust metering roller speeds as per the speed of the press.. set this so that the metering roller spins slower during paper feed then speeds up once the sheet starts to run at production speed.

 

[spigot]

If your rollers are the correct size and shore, and set correctly (i use a 4mm stripe, 5 is ok)
Then it will be in the computer settings. If its only happening on one unit watch its metering roller to see its not spinning faster than the others, or if the speed compensation profile hasnt been fiddled with.

 

[Dean Graphic Services]

water problems

water problems

Make sure your not in the poly plate mode. This will add more water before going on impression.

 

[spharris]

damp trouble

damp trouble

like it was said before look at your water settings on the console example H M L they will have a number value see if both units same..... try dropping down on the unit that is washing out you might check the synchonization point I know i am not spelling it right...( the starting point when the water kicks in when the press speeds up)... I think around 30% they have a setting you can check and or change too I once had a komori after power spike just clear all my water setting to zero had too chase stuff until I check settings reset everything and life was good again hope this help ...you might have some watch rollers in that unit when you start back up to make sure its not stripping problem