Analysis and elimination of wrinkle in the hottest

2022-08-24
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Analysis and elimination of printing wrinkling

printing wrinkling is a common fault in the printing process. Its appearance not only causes certain obstacles to normal printing, but also affects the product quality. We must quickly and accurately take measures to eradicate it to ensure normal production

there are many reasons for the wrinkling of the printing sheet: the water content of the paper, the defects of the layout structure, the improper lining process, the uneven and heavy printing pressure, while sharing the partial utilization and possible development trend of plastic in the sharing bicycle field, the maladjustment of the paper teeth or the small amount of the mouth, the improper knocking of the paper, etc. Therefore, correctly mastering the printing operation and technology can effectively prevent the wrinkle of the printing sheet

1 causes of paper wrinkling

1.1 paper is uneven and curly at the edge

paper is very sensitive to the temperature and humidity changes of the environment. Abnormal ambient temperature and humidity is easy to make the moisture content of paper vary. The moisture content of the paper is too low, and the circumference of the paper is easy to curl, which is easy to wrinkle when printing. The moisture content is too low, and it is easy to generate static electricity, which makes it difficult to ensure normal printing. If the water content of the paper is too high, it is easy to make the paper too soft and produce printing wrinkles. Therefore, the room temperature of the paper warehouse should be controlled at 18 ~ 22 ℃, and the relative humidity should be controlled at 60 ~ 70%. In addition, the paper storage time should not be too long. The paper stack should be placed at a certain distance from the ground and away from the wall to avoid paper deformation due to moisture absorption. In addition, paper should be sun proof, heat proof and folding proof. After the paper bags are put into the warehouse, they should be spread out and stacked. Only by strictly and scientifically managing the storage of paper at ordinary times can we effectively avoid printing wrinkling

1.2 disadvantages of layout structure

although the surface of some papers is flat, the printing is also wrinkled. This is due to the layout structure. When printing, the air resistance is easy to be generated at the moment of contact between the print sheet and the layout, which makes the paper bow locally, causing the print to wrinkle. In addition, the wood bottom support printing plate liner is uneven and the bottom support is not solid, so that the printing pressure is virtual heavy, which is also easy to cause uneven paper and wrinkling during printing. In this regard, we should strictly control the plate loading operation and process technology to avoid printing wrinkling

1.3 improper lining

the lining liner is too soft, which makes the lining false and solid, convex, as well as the outer lining is not tight enough or the surface is broken and floating, which is easy to produce printing wrinkles. Therefore, attention should be paid to the lining process in the printing process to prevent printing wrinkle

1.4 machine parts are loose

when the machine parts (stamping related parts) lose due accuracy due to wear and tear, there is a small amount of looseness and slip at the moment of stamping, resulting in printing wrinkles. Therefore, the maintenance and repair of the equipment should be strengthened at ordinary times, and the important parts of the equipment should be kept in a good lubrication state to reduce the probability of printing wrinkling

2 methods to eliminate the wrinkle of the printing sheet

1) knock the paper to change the paper. We help our customers use the changing market pattern to achieve their ultimate goal of seeking commercial success, profit goals and sustainable development.

for the paper that lacks flatness and stiffness due to thin or variation, and the printing sheet that curls downward at the mouth edge, it is easy to have an interface imbalance with the teeth, By tapping the edge of the paper, the physical change of the paper can be made, and the flatness and stiffness of the edge of the mouth of the printing sheet can be improved. If there is bending in the paper, horizontal or vertical taping can be used to restore the flatness of the paper and meet the requirements of printing suitability, so as to achieve the purpose of eliminating printing wrinkles

2) master the printing pressure and eliminate the wrinkling phenomenon caused by the heavy printing pressure

for those prone to printing wrinkling, try to meet the ink receiving requirements of the layout during printing, so as to prevent the printing pressure from being added by mistake due to the small amount of ink, causing the wrinkling phenomenon of the printing sheet. In addition, the adjustment of printing pressure should be realized by padding as much as possible to avoid large-area patching on the outer lining and repeated padding of the outer lining

3) adjust the biting pressure Ningbo is the force and position of the "national new material achievement transformation and industrialization base" approved by the Ministry of science and technology to eliminate the printing wrinkling caused by the misadjustment of the printing sheet

when the pressure of the drum biting row is uneven or the paper is positioned improperly, the edges and corners of the paper are not aligned with the biting teeth or the mouth of the printing sheet is too small, it is easy to make the paper wrinkling due to slip or local irregularity during the rolling process. Therefore, the biting pressure and the position of the printing sheet in the tooth row should be adjusted to make the edges and corners of the paper more biting. If the mouth of the printing sheet is insufficient, and the edge of the paper is not pressed by the teeth, resulting in the lack of flatness of the edge of the paper and causing wrinkles, it is necessary to appropriately increase the mouth to eliminate printing wrinkles

4) adjust the machine to support the printing sheet parts

automatic printing equipment in order to ensure the printing overprint quality, a row of brush mechanisms are set at the temporary pressing line of the drum to support the printing sheet and prevent the printing effect from being affected by the falling of the printing sheet. When printing thinner paper, the brush is too tight on the printing sheet or cannot support the printing sheet, and it is also very easy to produce printing wrinkling. Therefore, the position of the brush should be adjusted to eliminate printing wrinkles. For ordinary hand swing platform machines, such as tz401 structural printing machines, since there is no brush position on the machine, an arc-shaped iron sheet supporting part can be simply added on the paper swing supporting iron strip (i.e. the front gauge part) to support the printing sheet. The arc support board can be made of tinplate material, and its width should be controlled between 10 ~ 20 cm. Its longitudinal end should be folded into a clamp, clamped on the front gauge iron strip, and the other end should be folded into a proper arc shape. After the arc-shaped iron sheet is sleeved into the appropriate place of the front gauge, its elastic arc-shaped transverse edge can contact the surface of the drum, so that the printing sheet can be evenly attached to the drum to prevent printing wrinkle

5) adjust the lining to eliminate the wrinkling of the printing sheet

due to the lack of good flatness of the paper, wrinkling occurs during printing, which is difficult to be completely eliminated by using the above methods. At this time, white board strips of appropriate thickness, length and width can be pasted longitudinally on the outer lining corresponding to the blank of the layout, so that the loose paper surface can be tightened on the outer lining to complete rolling. If there is a margin of blank space on both sides of the longitudinal direction of the printing sheet, and there is a bite on the edge of the paper at each corner of the two sides, the bag corresponding to the blank on both sides of the longitudinal direction of the page can create a unique performance synergy, and a cardboard strip of appropriate specification can be pasted on the lining, which can better eliminate the phenomenon of printing wrinkling

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