Common paper failures during printing (below)

3 Reasons for the formation of such pleats in large gull-shaped pleats (1) The corners of large water-papers are curled up, and grippers are not good.
(2) Paper grippers on one side of the paper are too light.
(3) Paper angles float.
(4) The side specified position is not proper, and the paper corner touches the paper notch.
Treatment method: After the paper is knocked and processed, it will be printed on the machine. For the looser gripper teeth, it needs to be readjusted. The floating angle of the paper is mainly irresistible.


(Figure 2-4) Large pleats

[Case 2-7]
A factory J2105 machine printing middle school textbooks, color inserts. Using 128g/m2 coated paper printing, shortly after the official opening of printing, it was found that occasional external folds, after careful observation by the outside of the specified position, concluded that the paper in the pull side pull pull the paper, the paper angle and the feeder table The gaps collide, causing pleats to appear.
Approach:
The lateral rules are properly displaced to avoid the gap.
[Expert Tips]:
Similar to this kind of phenomenon, the captain should deal with it in advance and cannot wait until the problem arises.

4 Arc-shaped pleats This type of pleats is mainly caused by: the middle part of the gripper teeth is too loose, causing the phenomenon of unstoppable paper, which is pulled out during printing to generate pleats.
Treatment method: Calibrate the gripper force. If the pad is too smooth, it can be replaced with a new one.


Figure 2-5 Arc pleats

child

[Case 2-8]
A factory used a four-color offset press to print a corporate advertising brochure, and found arc-shaped folds in places where portraits were printed in the latter half (not every one).

[case analysis]:
According to the conventional treatment method, the force of the paper teeth is checked, but in this case, the gripper has a good grip strength. Later, the black density of the part where the folds are found is high, especially the red ink density is too high, resulting in this. The peeling force is increased, and the gripper is slightly unsuitable and the above failure will occur.

Approach:
Re-plate, put the portrait of the person in the mouth or the front half of the paper, the fault disappears.

[Expert Tips]:

The portrait of a person or a product with strict fit requirements, such as a portrait of a person or a smaller picture, is usually best placed in the front half of a mouthwash or printed paper. In addition, if the density of ink is high, it should not be printed in the latter half.

5 large distribution pleats

The reason for this type of pleats is that (1) the impression cylinder gripper has two or more loose at one place, and even cannot hold the paper.
(2) The tooth gaps of the paper-feeding teeth are uneven, which causes the paper edge of the paper to become a wavy curve, and the length of the paper is shortened when the printing cylinder grips the paper and presses against the paper. Pleat.

Treatment method: Check the impression cylinder gripper force.


Figure 2-6 Large scattered pleats

Source: Ke Yin Network