Analysis of Reasons Caused by Newspaper Printing

Breaking paper is a headache for newspaper printing. Whether it is manual paper-cutting or automatic paper-cutting, it takes more than 10 minutes to cut a piece of paper. Frequent paper breaks can make operators miserable.

The author was fortunate to have contact with UNISET and COLORMAN of manroland and conducted some research. Now we will discuss some of the reasons for the occurrence of paper breaks.

1, edge cracking, side bumps.

If you find it timely and deal with it immediately, this fault will not cause serious problems.

2, the paper itself has a problem

If the quality of the paper is unqualified or improperly stored, the center of gravity of the paper roll may shift, resulting in eccentricity. It is generally believed that when the eccentricity of the paper roll exceeds 5 mm, it is unqualified, and the eccentricity is liable to cause breakage.

Under normal circumstances, tension and braking force balance. When using an eccentric paper roll, due to the change in the radius R of the paper roll, the paper is subjected to an oscillation that gradually decreases in oscillation period and gradually decreases in amplitude. Comparing each short period of time, the greater the starting speed, the greater the stress inside the paper.

3, the speed change is not normal

4, too much tension

There is a tension limit on the paper. When increasing the tension, try to keep it away from the limit tension. At high speeds, a very small change can also create very large stresses that can cause web breaks.

5. When the paper feed must be stopped immediately due to other reasons, the paper winder breaks the paper tape.

6, long boot, deposition of ink stain on the roller.

For example, the tension of Manroland's COLORMAN offset press is controlled segmentally. When turned on for a long time, the deposition of ink scale increases the radius of each roller, so that the tension also increases.

Furthermore, there are many paper guide rollers between the drum and the power roller, and the ink deposit on the upper surface also increases the tension.

When tension reaches the limit, the machine's paper breaker will break the paper protectively.

Source: "Printing Technology"

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