Print wrinkle failure is a common failure phenomenon in the printing production process. Analysis of various phenomena of wrinkling failures of printed products, the reasons are many, including the abnormal moisture content of the paper, as well as the source of the defects of the printing plate structure; there are reasons for the improper lining process, and there are also uncomfortable printing pressure; It may be caused by poor adjustment of the gripper or too small amount of gripper, or caused by improper paper knocking method. Therefore, careful analysis of various wrinkling failure phenomena and correct grasp of printing operations and process technology are effective measures to prevent wrinkling of printed products and ensure product printing quality.
1. Analysis and preventive measures of the phenomenon of wrinkle failure of printed products
1. Wrinkle failure caused by curling of paper edge
We know that paper is very sensitive to changes in the temperature and humidity of the environment. If the temperature and humidity of the printing environment are not normal, it is easy for the paper to expand and contract. If the moisture content of the paper is too low, the paper is easily curled around, and it is easy to wrinkle during printing. If the moisture content of the paper is too low, it is also easy to produce static electricity and it is difficult to achieve normal printing. If the moisture content of the paper is too high, it is easy to make the paper too soft and produce embossed wrinkles. Therefore, we should focus on strengthening
For the scientific management of paper, the room temperature of the paper warehouse should be controlled between 18-22 degrees, and the indoor relative humidity should be controlled between 60-70%. For the paper-packed products entering the warehouse, they should be unpacked and spread out as soon as possible. The stack of paper should be high off the ground and away from the wall to prevent the paper from absorbing moisture and deformation. In addition, the paper must be protected against heat, folds and pressure, which is not only a basic requirement for better prevention of warpage and deformation of the paper, but also an essential measure to prevent wrinkling of printed products.
2. Wrinkles of printed products caused by defects in the structure of the printing plate
Some papers have good flatness, but wrinkling problems still occur during printing. This is due to structural reasons. For example, when printing a relief plate with solid lines and lines, the air resistance is easily generated when the printed sheet contacts the plate surface during the imprinting process, causing the printed sheet to bulge and wrinkle. In addition, the uneven bottom pad of the wooden bottom plate and the bottom plate are not solid enough, so that the printing pressure is heavy, and it is easy to produce the wrinkles of the printed product. For this reason, the line plate technology should be installed to reduce the line layout. Pressure to avoid the occurrence of wrinkle failure of printed products.
3. Puckering phenomenon caused by uncomfortable lining
The lining is a medium for imprint transfer. When the inner and outer linings are too soft, the linings are prone to bulge after compression, and the linings are not tight enough. The surface lining paper is cracked. The lining surface Undesirable situations such as repeated padding or air control, and the tail of the pad sticker are not sticking and floating, are prone to wrinkles. Therefore, attention should be paid to the packaging process technology during the printing process to prevent the occurrence of wrinkle failures caused by the loose and unpressurized packaging and uneven surface.
4. Wrinkles caused by wear and loose equipment parts
When the key parts of the machine, the machine parts with the linkage roller used for imprinting are worn out and lose their due precision, causing the machine to slip due to a small amount of looseness during imprinting. This is also a printing of certain layouts, paper The source of wrinkles. Therefore, we should pay attention to strengthening the maintenance and repair of the equipment, so that the key parts of the equipment maintain good lubrication and high precision to prevent the occurrence of poor axial or radial loosening between components and reduce the occurrence of wrinkles. Opportunity.
2. Several treatment methods for wrinkles of printed products
1. Knock the paper to improve the printability of the paper.
For paper that is thin or lacks flatness and stiffness due to deformation, such as the curling edge of the printed sheet, the paper edge must be knocked to physically change the paper to improve the printed sheet mouth The flatness and firmness of the paper edge. For the phenomenon of curling in the paper surface, the method of horizontal knocking or vertical knocking can be used as appropriate to make the printed sheet obtain the required flatness for printing to achieve the purpose of eliminating wrinkles of the printed product.
2. Adjust the printing pressure to eliminate the wrinkles caused by uncomfortable printing pressure.
For flexible paper that is prone to wrinkling of printed products, try to meet the requirements of the amount of ink on the printing surface when printing, in order to prevent the printing ink from being printed due to the lack of ink on the printing surface and causing the printing to wrinkle. In addition, the adjustment of the printing pressure should be achieved through the lower pad as much as possible, and the foot pad should be balanced with the foot pad. It is necessary to avoid large-area patching on the outer lining or even dug the outer lining repeatedly, which is also effective in preventing wrinkling of printed products. Method.
3. Adjust the pressure of the roller gripper and the position of the gripper to eliminate the problem of wrinkles caused by the misalignment of the printed sheets. ·
When the pressure of the roller gripping paper is uneven or the positioning of the printed sheet is unsuitable, the edges of the paper are not aligned with the teeth, and the amount of the printed sheet is too small, it is easy to make the printed sheet in the rolling process, due to the slippage Unevenness causes wrinkles of the printed product. To this end, the pressure of the teeth and the position of the printed sheet in the row of teeth should be adjusted to make the edges of the paper enter the teeth. The occurrence of printing slippage to eliminate the wrinkling failure of printed products.
4. Adjust the brush device of the machine to make the printed sheet's plain clothes tightly adhere to the roller to eliminate the wrinkling of the printed article caused by the falling of the printed sheet.
In order to ensure the printing quality of the automatic printing machine, there is a row of flat paper brushes at the position of the printing line of the cylinder. When printing soft and thin paper, if the brush is too tight and squeezes the printed sheets on the surface of the cylinder, it is easy to cause printing. Product wrinkling. The brush should be adjusted loosely to eliminate the wrinkle failure of the printed product.
In short, as long as we conscientiously sum up experience in practice, conduct detailed analysis and research on various fault phenomena of wrinkling of printed products, and implement various preventive measures, from the source of the fault to carry out technical and process control checks, It can minimize or avoid the wrinkling failure of various features of the printed products, and ensure the printing quality of the products.
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