Analysis of Causes of Wrinkling Failures in Books and Journals

Based on experience, the author analyzes the causes of wrinkling in the printing of books and publications as follows.

First, paper problems cause wrinkling of printed products

1. uneven distribution of paper moisture content: if the surrounding water content is greater than the middle part (that is, when the charge side), it will produce wrinkling phenomenon of the drag part; if the water content around is less than the middle part (ie tight edge paper), it will The middle part is wrinkled.

2. The moisture content of the paper is too large; if the moisture content of the paper is too large, the deformation of the pressure during the imprinting process will produce branching wrinkles that extend from the gargle to the tip.

Second, mechanical adjustment factors cause wrinkling of printed products

1. The paper feeding roller has uneven pressure on the paper feeding roller or uneven feeding belt tension: due to improper pressure adjustment of the paper feeding roller or uneven feeding belt tension, the paper is affected by the axial force in the conveying process. Or askew, it will cause wrinkles when imprinting.

2. Improper Paper Transfer: Before the paper enters the imprinting system, the flatness of the paper is damaged in the handover process, so the paper is creased during the imprinting process.

3, the impression force of the impression cylinder grippers is inconsistent or uneven.

4. The ink on the surface of the embossing cylinder is too thick to make the paper unsmooth.

In the printing process, once the printed product is found to be wrinkled, it should be immediately stopped to analyze the cause of wrinkling. The method of observing the wrinkle rule of the product is generally adopted. The reason for the paper is that the wrinkling position of the product is changed, and the position of the wrinkle caused by improper mechanical adjustment is basically fixed. It is also possible to use other types of paper for the trial printing method. If the wrinkling site is not changed, it can basically be determined as a mechanical factor. If there is a change, it is a paper factor. After the cause of the wrinkling is analyzed accurately, the drug can be prescribed. The solution is as follows:

1, wrinkling caused by paper factors

Hang the paper on the paper dryer for about 6 hours to make the water content of all parts of the paper consistent.

2. Wrinkling caused by mechanical adjustment factors

One of the reasons: Tighten and tension the various transport belts, adjust the pressure of the transport rollers not too large or too small, and do not tilt.

The second reason is to adjust each handover link to ensure the balance and reliability of the handover process.

The third reason is: level the dental pad, then turn the machine to the position of the jaws, and insert the positioning screw between the positioning screw and the positioning block.

0.3mm thick paper, and then a piece of paper with a basis weight of 80g/m2, tested the force of the tusks from the middle to the sides, and it was appropriate to use the force to force the teeth to adjust. Paper grip force remains uniform.

The fourth reason: use gasoline to clean the ink on the surface of the impression cylinder.

From the above analysis, it can be seen that the causes of product wrinkling in book printing are various. Therefore, we need to conduct comprehensive analysis and accurate judgments in order to achieve rapid and accurate troubleshooting.

Reprinted from: Shenzhen Printing Network