Troubleshooting Web Breaks In Offset Printing

On a offset web press, troubleshooting web breaks can be a daunting task. It’s a job that requires the offset pressman to have a full gamut of understanding of how the machinery operates. Here are some guidelines that along with good pressroom management, can help you get to the source of the web breaks.


First of all, these tips concern an offset pressman if he has one or more web breaks per 100 rolls. That may seem like and aggressive goal, but the reality nowadays is that paper production in combination with the equipment that is being built today give offset printing high reliability. If an offset pressman can achieve one percent, you are competitive. So I present to you, the pressman, methods troubleshooting web breaks:


1. Be Observant


The first and easiest part to troubleshoot web breaks is your tension. Start by asking yourself, “What has changed recently.” If your tension settings have changed, try to go back to what was working before the web breaks began.


Next, observe the paper. Look for ripples, wrinkles, and wander. These are the best indicators of web breaks for a pressman. Paper can take some stress. All papers have what is called a modulus of elasticity. It is capable of absorbing strain. But too much on the press will cause the offset pressman a break.


Then your next job is to see if your nips need inspection. Make sure they are clean. They are responsible for your tension and so should be in good condition. Do they show signs of wear? How about the gears driving them? This job will take careful inspection on your offset equipment. The offset pressman should also inspect wear and pressure of the nip.


In addition, have your offset pressman observe the tension. You may have indicators for this, but watch the web in all parts of the press. It shouldn’t be overly tight, but you should be able to tap it and it should give a little bounce.

2. Inspect Offset Printing Mechanics


Are your rollers on the press trammed properly? Wrinkles would give this away, but in my experience, these should be inspected periodically. This may not be a job for your pressman, but for a trained mechanic.


More important though would be your nip pressures. Nip rollers wear after a while. Be sure that you are getting a good strip by using a little grease or even ink to check them.


Then examine any slitters you are using. Dull slitters will cause small tears, causing web breaks down the line.


3. The Pressmans Job of Housekeeping


Examine all the idlers on the press for blobs of dried ink. Carefully inspect every single idler roller. Clean it well. Look for tape or any irregularity. This is a great job for the rookie pressman.


4. Offset Blankets


Blankets in poor condition will cause you tension problems. If there are any imperfections in the blanket, it could also cause a tear. If you are at this point, the offset pressman may want to consider putting on new blankets. I’m sure I don’t have to tell you, that good blankets are the heart of good offset printing.


5. The Role Of Paper For The Offset Pressman


It could be that you have a bad batch of paper. For the offset pressman, this is not always easily determined. There are a myriad of different types of paper defects that can occur, some at regular intervals. Here’s what I recommend to deal with this.


Check the identifying label. Determine through the roll number on what day the paper was made. The label should also tell you which reel and what position the roll was made from. Try different positions on the reel and on different days. Do some rolls work while others don’t? Is there a pattern you can recognize?


6. Have The Pressman Check Air Flow


If you use a heatset press oven, air flow could be responsible. Have the maintenance department check the air flow bars in side that they are not built up and that they are the correct height from the web. Make sure no air ducts have paper built up. Ensure you have proper air flow.


7. Check Your Ink And Water Balance

Too much water will cause water to accumulate at the gap. Maintain a good ink and water balance.


These are just a few point that highlight the need to explore all possibilities. However, these points are really just the start of your troubleshooting task.  To do thorough and deep troubleshooting for this problem, I highly recommend this free online troubleshooting guide, or a book I have referred to literally hundreds of times.  I gives pages of causes and solutions. It is the Guide To Troubleshooting For The Web Offset Press. You should be able to find it cheaper on amazon, but can also be ordered directly from GATF.


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Web Press Troubleshooting Guide