Paper wrinkling in the process of the hottest prin

2022-08-05
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The phenomenon of paper wrinkling in the printing process and its elimination

the calibration and zeroing of the extensometer in the printing process: measuring the standard length, paper wrinkling (wrinkle) is one of the most common faults, and the economic loss is relatively large. There are two main reasons for this kind of fault: one is caused by the paper itself (mostly in non coated paper), and the other is the improper adjustment and use of the machine, The causes and treatment methods are further analyzed according to the shape below. 7. The tensile machine is protected twice a month on average

1. Small sporadic pleats

reasons for this kind of pleats:

(1) lotus leaf edge after moisture absorption of the paper (the water content of the paper itself is uneven or the relative humidity in the workshop is high, and the water content of the paper is low)

(2) ink stacking cylinder on the back of the printed piece printed on both sides (the ink accumulated on the surface of the impression cylinder is too thick, resulting in local pressure changes)

professional technical support of Jinan new era assay instrument Co., Ltd. welcome information processing methods:

hang the paper again; If it is printed on both sides, be sure to wash the embossing cylinder frequently

2. Thin straight pleats that do not protrude (pleats are in the middle of the paper)

the main reason for this kind of pleats is the deformation (tight edges) around the paper

treatment method:

hang the paper again. If some printing plants do not have the equipment to hang the paper, the uncut printing paper to be printed can be shaken one week in advance, placed in the printing workshop to adapt to the temperature and humidity around the machine, and then cut and put on the machine during printing

3. Big crooked pleats

reasons for this kind of pleats:

(1) the edges and corners of the watery paper are cocked up, and the paper teeth are not good

(2) the gripper at one side of the paper is too light

(3) paper corners float

(4) the side gauge is improperly positioned, and the paper corner touches the notch of the paper gripper

processing method:

paper is printed on the machine after anti knock processing; The loose paper teeth need to be readjusted. The paper angle floats mainly because the teeth cannot hold the paper

[case]:

a factory j2105 machine printed middle school textbooks with color inserts. 128g/┫ coated paper was used for printing. Shortly after the official printing, it was found that pleats occasionally appeared outside. After careful observation, it was concluded that when the paper was pulled by the side gauge ball, the paper angle collided with the gap of the paper feeding tooth table, resulting in pleats

treatment method:

the side gauge shall be properly displaced to avoid the notch

[expert tips]:

if this phenomenon is similar, the captain should handle it in advance and should not wait for the problem to occur

4. Circular arc pleats

the main reason for this kind of pleats is that the middle part of the paper teeth is too loose, resulting in the phenomenon that the paper cannot be held, and the pleats are pulled out during printing

treatment method:

correct the paper gripper force. If the tooth pad is too smooth, replace it with a new one

[case]:

a factory used a four-color offset press to print an enterprise's advertising brochure. It was found that there were arc-shaped folds (not every one) at the place where the portrait was printed in the latter half

[case analysis]:

according to the conventional treatment method, it is necessary to check the gripping force of the paper teeth. However, in this case, the gripping force of the paper teeth is good. Later, it was found that the black density of the part where the pleats appear is large, especially the red ink density is too large, resulting in the increase of the peeling force here. If the paper teeth are slightly inappropriate, the above fault will occur

handling method:

re plate making, place the portrait in its mouth or the front half of the paper, and the fault disappears

[expert tips]:

for most portraits of people or products with strict matching requirements, it is better to put them in the mouth or in the front half of the printing paper when making up, for example, portraits of people or small pictures, by taking advantage of the policy of made in China 2025. In addition, those with high ink density should not be placed in the back half of the printing paper

5. Large scattered pleats

reasons for this kind of pleats:

(1) two or more paper teeth of the imprint cylinder are too loose at one place, and they can't even hold the paper

(2) the paper delivery tooth pad is uneven, resulting in the edge of the paper at its mouth not being in line and becoming a wavy curve. When the imprinting cylinder holds the paper at its mouth for imprinting, the length of the paper is shortened, and large loose folds are generated from its mouth

treatment method: check the paper holding force of the paper holding teeth of the imprint cylinder

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