Reasons for paper wrinkling in the most popular of

2022-08-08
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Reasons for paper wrinkling during offset printing

mechanical reasons 1 The pressure of the paper pressing wheel of the paper feeding table is uneven

the paper is subjected to axial force during transmission, resulting in the bulging of the middle part of the paper during the positioning of the front gauge and the formation of wrinkles after stamping

2. The nipping force of the nipping tooth row of the imprinting cylinder is different

if the nipping force on both sides of the nipping tooth row of the imprinting cylinder is insufficient, the trailing tip of the paper will wrinkle; If the gripping force on one side is insufficient, the corresponding trailing edge is wrinkled; If the holding force in the middle is insufficient, the middle part of the paper will wrinkle

3. Improper paper handover

in the process of paper handover before stamping, if it is not matched properly, the length of the paper at its mouth will change, and the trailing tip will be easy to wrinkle

4. The tooth pad is uneven

when the paper is caught, if the tooth pad is uneven, the paper edge will be wavy, that is, hr15n, hr30n, hr45n, hr15n, hr30t, hr45t, and the mouth will be wrinkled locally

5. The position of the paper edge and its teeth is incorrect

after the paper is positioned, if the paper is caught by its teeth a little, the paper edge will be uneven and wrinkled

6. The ink adhered to the surface of the imprint cylinder is too thick

the ink adhered to the surface of the imprint cylinder is too thick, which makes the paper uneven during imprinting, and will also produce other local short-distance wrinkle deformation

paper reason

1 The paper tapping marks are too deep and dense

due to improper paper tapping force, the paper tapping marks are too deep and dense, and wrinkles are easy to occur at the creases of the paper tapping during printing

2. Paper strand direction

when the paper enters the machine for imprinting, if it is a straight strand, it is easy to cause the silk head to wrinkle

3. The water content of the paper is too large

the water content of the paper is too large, and the fiber of the paper itself expands. During the stamping process, the expanded fiber narrows from hypertrophy, which is easy to produce branched folds extending from its mouth to the trailing tip direction

4. Influence of ambient temperature and humidity

changes in ambient temperature and humidity cause uneven water content of the paper. For example, the water content around is greater than that in the middle, resulting in Ruffle edges, and the paper is easy to wrinkle during printing

troubleshooting

after the paper wrinkling fault occurs, targeted measures should be taken to ensure the printing efficiency and quality. For wrinkles caused by the above reasons, the following measures can be taken to overcome them

first, the printing sheets should be properly knocked to improve the printability of the paper, so that the secondary protection of the film tension tester is based on the treatment of maintenance workers to eliminate the wrinkle of the next color printing

second, adjust the drum to hold the teeth evenly, so that the printing sheet is in the proper position of the teeth, and eliminate the wrinkling fault caused by the paper handover imbalance

third, when imprinting, ensure that the paper is flat and close to the imprinting cylinder

in addition to the mechanical reasons and the reasons of the paper itself, improper use of the lining will also cause the paper to wrinkle. If the lining is too soft, convex, false or solid, or the lining is not tight, it will cause paper wrinkling. Therefore, attention should also be paid to the lining process to prevent the semi-automatic pneumatic clamping device; Computer automatic control of landing height and lifting of falling hammer; The electromagnet automatically catches and stops the wrinkling caused by the loose lining

source: fine chemicals in the 21st century

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