Reasons for paper wrinkling during offset printing (2)

Paper wrinkle treatment

1. Treatment of used paper

When the printed product is found to be wrinkled, we must first carefully observe the position, size, shape, etc. of the wrinkled paper, and judge and analyze it to see if the paper is wrinkled, or both are wrinkled, and all the paper is wrinkled. Some wrinkled and wrinkled, or only some paper wrinkles. Look at the big folds, the dark folds, or the creases at the mouth; then, check the white paper for serious paper problems such as whether it is flat or not. At the same time, if you look at other machines and use the same paper to print the same thing, whether it is also wrinkled. If the products printed on the machines have wrinkling, the paper is obviously not good, or it is too new or too wet. It needs to be replaced by paper, or white paper can be used to replace the bite. Whether or not the test paper continues to wrinkle, it is not possible to use a paper-knocking method to knock out the white paper and make it stiff and soft. Then try printing again to see if wrinkles can be eliminated. If it still does not work, use a paper machine to dry the white paper and print again.

2. Processing of printing machinery

When the same paper printed on the other machine is not wrinkled, it indicates that the machine is mechanically defective. After the white paper is torn down, the position of the paper wrinkles does not change, and it can be concluded that there is a problem with the machine, and it is necessary to inspect and adjust the bite condition of the embossed teeth and the teeth. Under normal circumstances, adjusting (embossing or oscillating) individual teeth will work, and sometimes it will be different. Simply adjusting individual teeth will not help at all, and you will need to loosen all the teeth and adjust them again. During the adjustment process, if there is any The tooth chip or tooth pad is seriously worn, and it must be replaced in time until the mouth is consistent and the bite force is consistent.

3. Handle the drum lining accordingly

When printing a large-format thin paper, a wrinkle is found. After a series of treatments such as paper change, down-counting, knocking, paper-hanging, and tooth adjustment are still ineffective, the lining inside the blanket cylinder can be treated as follows: Remove the liner from the rubber to reduce the pressure between the rollers. If it continues to wrinkle, take out its lining completely, and then use a blade to split the pad paper. When dividing, keep a piece close to the roller, the paper clip is not cut off, and the gap from the print to the tip is The center of the room is a tangent line, which is cut open. In this way, when the printing is performed, the area under pressure is correspondingly smaller, and the wrinkling phenomenon will disappear.

4. Emergency treatment of paper wrinkles

There are many ways to deal with paper wrinkling. Sometimes the paper is wrinkled. The inspection is that the two ends of the impression cylinder are seriously worn. When processing, the two ends can be attached with a wide-shaped tape to be used. Sometimes the paper wrinkles are too heavy between the rollers, and the pressure on the rollers can also be reduced slightly, and sometimes there are some special situations. For example, some prints are in urgent need of a cycle, and when they are printed, they are found to be wrinkled. The reason for the wrinkling is that the drums and unevenness of the paper are caused by the individual biting paper of the impression cylinder, and this monotonous tooth is useless. If all the embossed teeth are tuned again and again, the time will be delayed. For the sake of emergency, this tooth piece can be used. First remove it temporarily. In this way, when it is reprinted, it will not be affected by this tooth and the paper will no longer wrinkle. After the batch is completed, the tooth is placed again, and a full adjustment is made. There is also a situation where the wrinkling position is at the corner of the paper, because the paper is upturned, and when the pull tab is pulled, the upturned paper angle happens to collide with the oscillating tooth pad, such as the movable pull gauge. It will lead to changes in rules, causing trouble for the next round of printing. In this regard, an emergency measure may also be taken. That is, the toothpaste that is inconvenient is temporarily unscrewed with a wrench, so that it is no longer wrinkled and the printed product is printed. After that, put the pad again and readjust it.