I'm not sure about other offset printing processes, but with our press, we use take-off bars, or perhaps some refer to them as run-off bars. I've never used them on a sheetfed press, but on our web presses they save us major headaches. I'm not talking about the ones that control ghosting - that's a different subject I've covered. These are simply strips of printed image along the edge of the running paper. In our case, they are about 3 mm wide. The picture below gives you an idea of what we use.
For us, this controls three very important things.
1. They control ink buildup on the edges.
I've worked on 5 different brands of offset web presses. Four of them we could never get the ink keys on the edge of the fountain to close enough to stop the ink flowing down the ink train. The problem would be compounded as the ink would continually build up on the edges of the rollers with nowhere to go. This led to spitting and a mess on the sides of the offset printing unit. Take-off bars solved this problem.
2. They stop paper piling on the edge of the paper.
A rather unexpected result of adding this take-off bar was that they stopped paper buildup that happens on the edge of the paper and builds up on the blanket. The best way to get them off was to shut down and scrub with water. They would even smash these blankets in these areas. Now with these bars on the edges, we no longer have this buildup. If you have been trying to troubleshoot piling on the edges, this is a good place to start.
3. They keep the edges of our water train clean.
When the ink is no longer building up on the edges, the dampening system fares much better. No longer do the edges of our water pan roller or water form roller build up with ink.
I think most pressmen know about this since every place that I have worked at know about this, but I just wanted to share with anyone that may not be doing this yet. Was it a helpful tip for you? "Like" it on the the Facebook link above or Google +1 it. Thanks for looking. More to come.
Related Articles:
What Causes Blanket Piling?
The Perfect Temperature to Minimize Blanket Piling
How We Greatly Reduced Blanket Piling
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| The right of the printed sheet shows we print a little ink on the edge. |
1. They control ink buildup on the edges.
I've worked on 5 different brands of offset web presses. Four of them we could never get the ink keys on the edge of the fountain to close enough to stop the ink flowing down the ink train. The problem would be compounded as the ink would continually build up on the edges of the rollers with nowhere to go. This led to spitting and a mess on the sides of the offset printing unit. Take-off bars solved this problem.
2. They stop paper piling on the edge of the paper.
A rather unexpected result of adding this take-off bar was that they stopped paper buildup that happens on the edge of the paper and builds up on the blanket. The best way to get them off was to shut down and scrub with water. They would even smash these blankets in these areas. Now with these bars on the edges, we no longer have this buildup. If you have been trying to troubleshoot piling on the edges, this is a good place to start.
3. They keep the edges of our water train clean.
When the ink is no longer building up on the edges, the dampening system fares much better. No longer do the edges of our water pan roller or water form roller build up with ink.
I think most pressmen know about this since every place that I have worked at know about this, but I just wanted to share with anyone that may not be doing this yet. Was it a helpful tip for you? "Like" it on the the Facebook link above or Google +1 it. Thanks for looking. More to come.
Related Articles:
What Causes Blanket Piling?
The Perfect Temperature to Minimize Blanket Piling
How We Greatly Reduced Blanket Piling
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