Washing out on narrow sheets

[Guest]

Hi all. Im new on here. I work in a shop in British Columbia, Canada. I am running a 2010 sm-52 5 color with aqueous coating. My question is when i am running narrow sheets like for 4 up b/c's, I am having trouble keeping the water from coming in and washing out on the sides of the job. Not running alcohol, using alcohol substitue. Had a similar situation when running these jobs on a gto 4 color but I had an air bar that helped control that. Unfortunately, the sm- 52 doesn't have that. I have all new pan rollers but as we only got the press in April, I do not know how old the rest of the rollers are. I have no problem at all with printing full size sheets. Would running it in integrated help, or splitting up the ink train and running half the rollers help? Any feedback would be greatly appreciated. Thank's so much.

 

[Cornishpastythighs]

http://printplanet.com/forum/press-...ng-bars-what-are-they-and-how-do-you-use-them

something to get you started good luck

 

[old guy]

we used to build a water stop out of soft rubber, some times we used the fatigue mats. but up against the fountain roller to back off the water out side the sheet size. saw the pic online maybe someone sells them.

 

[Deleted member 16349]

Hi all. Im new on here. I work in a shop in British Columbia, Canada. I am running a 2010 sm-52 5 color with aqueous coating. My question is when i am running narrow sheets like for 4 up b/c's, I am having trouble keeping the water from coming in and washing out on the sides of the job. Not running alcohol, using alcohol substitue. Had a similar situation when running these jobs on a gto 4 color but I had an air bar that helped control that. Unfortunately, the sm- 52 doesn't have that. I have all new pan rollers but as we only got the press in April, I do not know how old the rest of the rollers are. I have no problem at all with printing full size sheets. Would running it in integrated help, or splitting up the ink train and running half the rollers help? Any feedback would be greatly appreciated. Thank's so much.

I would not normally offer advice on what to do on press with this kind of problem since I am not a press operator but the problem got me thinking about some related issues that I am interested in so I thought I would make some comments.

This is my view and only my view of the problem and I don't expect others will agree. Washout does not mean that the water has prevented transfer of the ink from the form roller to the plate. Washout tends to mean that there is not a lot of ink on the roller train. The light print density indicates low levels of ink on the rollers.

The interesting part of this problem for me is that the narrow sheet means that there is no great ability of the press to get rid of the water applied to the regions outside the sheet width. Evaporation will get rid of some of it. Water fed back to the ink fountain will be also possible as water and water logged ink. Anyhow, it is an indication of press design issues that do not clearly deal well with this particular problem and that is what interests me.

I am also guessing that the dampening system reaches some semi equilibrium where almost no extra water is fed into the overly wet roller train outside the narrow sheet regions.

So you print a narrow sheet. The main region of the sheet will take the water away by applying water to the sheet and with the water in the printed ink. But the edges of the sheet are in a region where not enough water is being taken away. That extra water in that location inhibits the ink feed into the press in that regions.

So my suggestion, which I have no direct experience with testing, is to try to feed more ink by opening the ink keys just at or just outside the edges of the narrow sheet. See what happens.

I am also curious to find out what happens. It may work or it may lead to other problems. You won't know until you actually test this out. Good luck.

 

[dabob]

Not being a pressman (at least for a long long time) I went and checked with our lead pressman . .. if your running an alcolor dampeners there should be some "air nozzles" that you can adjust to help dry out different parts of the water train . . or so he says . . .

 

[Ret Heidelberg Instructor]

There are no air bars on the SM52. The full roller train can carry a lot of ink. That is part of the reason that the split inking feature was introduced to print smaller formats.
It was stated that the pan rollers were new, but you should check all the settings in the dampening and inking system to make sure that nothing has been over looked. It is critical that the ink ductor be set to 4mm to the ink fountain roller. Running with the system integrated was normally to help get an ink/water balance quicker on heavier coverage, but it was suggested not to use the integration when running lighter coverage or metallic inks.

Sidebar discussion for Eric. I know that you mentioned that you were experimenting with an SM 52 as a part of your Positive ink feed research. I saw the video you posted from one of your tests that was conducted on a press. My question is how would the device work in a situation, where the entire ink train is engaged versus a split ink train option that is available as an option on the SM52? Is the Positive ink feed application work the the same regardless of the full versus split ink train. I am not a press mechanic or engineer and the video left me somewhat baffled. Just curious. Looking forward to your feedback.

 

[dabob]

My bad . .. I assumed that it would be similar to the alcolor on our GTO's and Older Speedmaster . . . .

 

[Alois Senefelder]

I despair, --- Beg, Borrow or steal some "Baldwin Water Stops" or even buy them !

 

[Deleted member 16349]

Sidebar discussion for Eric. I know that you mentioned that you were experimenting with an SM 52 as a part of your Positive ink feed research. I saw the video you posted from one of your tests that was conducted on a press. My question is how would the device work in a situation, where the entire ink train is engaged versus a split ink train option that is available as an option on the SM52? Is the Positive ink feed application work the the same regardless of the full versus split ink train. I am not a press mechanic or engineer and the video left me somewhat baffled. Just curious. Looking forward to your feedback.

I was designing a prototype for the SM 52 but at this time there is no plan to test. Just to clear up that situation. It would be nice to tested it on that press but I don't have a suitable site.

As to the question about positive ink feed. What positive ink feed does is feed ink into the press in a way that is independent of water, roller train temperature and press speed. It is also independent of the design of the press and roller settings. So if the entire ink train is engaged versus a split ink train, there is no difference in what the positive ink feed does on average.

The positive ink feed does not guarantee constant density but it is more like the providing consistent "average" print density, since it is based on the average out put of ink on the paper for the SID control patch. Variations of print density about the average are related to the design of the roller train of the press.

This is where things get interesting for people who are interested in testing different roller train configurations or dampening methods. Since the ink feed is stable with positive ink feed, then one can test different roller configurations to reduce the variation about the average to smaller values. This would be needed if one was trying to make the press print more consistently around the plate circumference.

 

[Alois Senefelder]

Press Roller Train Arrangements.

In my opinion the merits of Erik's ITB are dubious.

Salient Points.

1) The Multi Roller Inking Train configuration is the de facto type used on most conventional litho presses,

the primary ink flow with this design is to the 1st/2nd plate inkers. The other design is the Drum Type train

which feeds ink to the 3rd/4th plate inker.

2) The de facto dampening system used on modern litho presses is "direct to plate,water first". This method

renders the 1st plate inker largely in capacitated as a plate inker. This roller train arrangement meets at

the plate nip a film of fountain solution, where the F.S. iinput rate is at least equivalent to all the water loss paths.


Regards, Alois

 

[Deleted member 16349]

Press Roller Train Arrangements.

In my opinion the merits of Erik's ITB are dubious.

Salient Points.

1) The Multi Roller Inking Train configuration is the de facto type used on most conventional litho presses,

the primary ink flow with this design is to the 1st/2nd plate inkers. The other design is the Drum Type train

which feeds ink to the 3rd/4th plate inker.

2) The de facto dampening system used on modern litho presses is "direct to plate,water first". This method

renders the 1st plate inker largely in capacitated as a plate inker. This roller train arrangement meets at

the plate nip a film of fountain solution, where the F.S. iinput rate is at least equivalent to all the water loss paths.


Regards, Alois

According to Heidelberg, the single form roller Anicolor press prints better, more consistently around the plate cylinder and can get to colour in a much shorter number of sheets than their conventional presses. Go figure.

Alois, you live in the past.

 

[Guest]

First off, I would like to thank everyone for there responses. It is very nice to see people helping out other people in the trade. Because I also run evelopes, it is impossibe to put take off bars on to help keep the water away. So what I did is go thru all the rollers in the magenta unit (as retired heidelberg instructor mentioned) very carefully as that is the unit giving me the most grief. Roller settings weren't to bad except for the ink ductor to the ink fountain roller. All units were only about 2mm instead of the require 4mm. Once that was done and some very minor tweaking on all the other rollers, I started to run the press and magenta toned in like crazy. As it turned out, because of the water problem, I was squeezing the pan roller more than I had to and increasing the dwell on the pan roller. So then I reset the pan roller to specs, dropped the water down about 20% and now runs fantastic. Repeated this on other 4 units, ran a 5 color job and all was very well.

Since I am able to run the water so much lower to keep the print clean, I am pretty sure that not as much water will be introduced to the non-image area allowing me to run narrow sheets without washing out. Time will tell.

Thank's again for all your input and help, Richard

 

[Alois Senefelder]

Past, present and future.

No Erik,

I do not live in the past, I live in reality of today where most day to day printing takes

place in SMEs that can't afford to buy a Heidelberg Anicolor press.


Regards, Alois

 

[turbotom1052]

if you print on narrow sheets often you may want to fabricate yourself some air bars. Not very hard extremely effective. If its only an occasional job on a narrow sheet I would suggest cranking down the metering roller about a half turn tighter and just running your water speed up a little higher. One you get running Id suggest that any time the excess water starts to show itself on the edges of your form, you should clear the feed board, turn off the water, and run the press up on speed for about 30 seconds to aid in evaporating the excess fountain solution before starting up again.