Under the premise of ensuring the printing quality, the highest printing quantity that a printing plate can print is called the printing plate's resistance force. The level of gravure resistance of gravure printing plates is directly related to the economic benefits of gravure printing, and is also the key to reducing costs, increasing production, and ensuring quality.

In the gravure printing process, we often encounter some parts of the layout of the color lighter than the normal color, and with the increase in the number of prints, this phenomenon is more serious, a direct impact on the quality of prints. Observed during the shutdown, it was found that part of the layout graphic was worn out, the opening of the ink hole became smaller and the depth became shallower, resulting in a decrease in the area of ​​the ink-passing ink cell and a corresponding decrease in the total ink transfer amount. The overall change in the ink color faded. Reduce the resistance force. After analysis, the main factors affecting the wear of the printing plate are: surface friction, gravure plate making quality, squeegee pressure, printing pressure, linear speed of printing plate cylinder and embossing roller, performance of ink and paper. Although the influence of these factors on the wear of the printing plate is unavoidable, how to reduce the influence of these undesirable factors on the printing plate is necessary to improve the quality of the printing product, reduce the printing cost, and shorten the printing cycle.

First, the factors that affect the gravure printing plate

1. Surface friction is the main reason to reduce the printing plate's resistance to printing. Printing can not be separated from the pressure. With pressure, friction is bound to occur, causing the plate surface to wear. The greater the pressure, the greater the friction and the more severe the wear of the printing plate.
There are mainly the following forms of friction on the surface of the plate cylinder:
(1) The friction between the squeegee and the plate cylinder.
(2) The friction between the plate cylinder and the impression cylinder.
(3) The coarseness and granules of the pigments and fillers in the ink, the structure of the surface of the substrate, the looseness of the texture, and the shedding of the dust may generate additional friction.

2. The gravure plate quality affects the printing plate's resistance to printing. (1) The hardness of the chromium layer is high. The quality of the chromium layer is the basis of the printing plate's resistance to printing. The chromium layer has a low hardness and is easily scratched by hard particles. Therefore, it is better to have a higher hardness when chrome plating. In the printing process, the printing plate is affected by various factors, and is constantly subject to wear. For example, the hardness of the chromium layer is low, and the thin coating can cause the printing plate to have a reduced printing resistance.
(2) Chromium finish is high The chromium finish on the surface of the drum is high. The scraper can scrape the ink under light pressure to reduce the failure. If the surface is rough, it is difficult for the squeegee to scrape the ink, which is prone to print failure.
(3) When the printing roller is printing, the circumferential runout should be small. If the platen roller has poor processing accuracy, the dynamic balance is not good, or the roller shaft, bearings and transmission gears are worn or deformed, the runout will occur during printing, which will cause the printing knife line. Therefore, the printing roller is less likely to beat circumferentially when printing.
(4) The surface of the roller should be inspected and wiped on the surface of the roller to prevent it from directly damaging the plate cylinder and causing printing problems. Therefore, always check and wipe the roller.
In gravure production, the layout is required to be smooth, the chromium layer is smooth, uniform in thickness, and has good wear resistance. According to the requirements and types of quality of printed materials, the correct choice of laser engraving gravure or electric engraving gravure, this can avoid unnecessary waste and save costs.

3. The squeegee and the printing plate are resistant to the force The different angles and pressures of the squeegee have different wear effects on the printing plate. The smaller the angle of the squeegee, the less wear on the printing plate, the weaker squeegee effect, the thicker printing ink, the strong hiding power, the good gloss, but not easy to clean.

4. Printing pressure and printing plate resistance The printing pressure has a great influence on the printing plate wear, and also has a great influence on the printing quality and the structure of the printing machine. The printing pressure is too small, the transfer of graphics and texts in printing is not complete, the ink transfer rate is reduced, and the imprinting is weak; if the printing pressure is too high, the local ink is excessive, so that the prints are inaccurate in color and the graphic and text are distorted. In addition, gears and roller bearings are subjected to excessive pressure and friction, which will inevitably aggravate plate wear and affect the quality of printed products. Therefore, on the basis of ensuring that the imprinting is sufficiently robust, using as little printing pressure as possible (ie, ideal printing pressure) will help reduce the wear of the printing plate.

5. The linear speed of the plate roller and the embossing roller must be the same according to the requirements of the gravure printing process. When the plate and the impression cylinder are being rolled, not only the transmission is stable, the instantaneous transmission ratio is constant, and the linear speed of the surface of the two rollers is required to be uniform. . However, due to the wear of the surface of the impression cylinder, the radius of the impression cylinder changes during printing. It can be seen from V=W×R that the linear velocity before and after the wear and at the lowest point are not uniform, so that a speed difference occurs and relative slippage occurs. The greater the speed difference of the printing surface, the greater the friction and the increased wear of the printing plate surface. Therefore, the linear velocity of the surface of the printing plate and the impression cylinder in the printing process is as consistent as possible, and the speed difference caused by the wear is reduced, which will help reduce the wear of the plate.

6. The effect of paper properties on the printing plate The printing properties of the paper determine whether the printing process can proceed smoothly and whether high quality prints can be obtained.
Paper's smoothness, ink absorption, and surface strength are important print properties of paper. In the case of normal pressure, paper with low smoothness will be printed with imprinted prints due to unevenness of the surface. In order to obtain clear graphic information and increase the pressure of printing, although it made up for the lack of imprinting, it increased the degree of wear of the layout. The surface strength of paper is not high enough, and the viscosity of the ink is high. In the printing, powders and naps are easily generated and adhere to the impression cylinder and printing plate. This not only affects the transfer rate of the ink, but also aggravates the rough surface of the printing plate. Degrees will also aggravate the wear of the layout. Therefore, the use of smooth, flat, high-strength, paper powder less paper, or frequent cleaning plate cylinder, will help reduce the printing plate wear phenomenon.

7. The effect of the ink's performance on the printing plate For different printing machines, inks with different properties should be used. If the pigment of the ink pigment is large, it will act as an abrasive and will aggravate the wear of the printing plate. Although the viscosity of the ink is relatively high, a clear dot can be obtained. However, if the paper strength is not enough, the phenomenon of falling powder and pulling hair easily occurs, which also aggravates the wear of the printing plate. Therefore, choosing a suitable ink is beneficial for reducing the wear of the printing plate and improving the printing quality.

Second, improve the printing plate resistance to print

A better version of the drum has a higher resistance to printing forces, and the gravure drum has a print resistance of typically more than one million. The surface chrome layer is thinned and can be re-chromed for continued use. High-quality printing plates provide a reliable guarantee for printing. The improvement of the resistance to printing force depends not only on the printed version, but there are many external factors that directly or indirectly affect the printing plate's resistance to printing. Here, the operational aspects of the printing process are summarized as follows:

(1) Under the premise of guaranteeing the printing quality, use the minimum pressure to reduce the friction between the plate cylinder and the impression cylinder; clean the ink tank and the plate cylinder regularly.
(2) Under the premise that the ink on the surface of the printing plate can be scraped off, the smaller squeegee pressure and angle of the ink knife are used as much as possible to reduce the abrasion of the squeegee to the printing plate.
(3) Filter the ink and eliminate the static electricity on the surface of the substrate, so as not to damage the surface of the substrate due to electrostatic adsorption of coarse particles or the surface of the substrate.
(4) Strictly control the drying of the ink and avoid premature drying and damage of the printing plate on the surface of the printing plate.
(5) When there is no ink on the surface of the printing plate, the squeegee should not be scraped for a long time, because the layout is not smooth, and the printing plate is easily damaged.
(6) Avoid various abnormal damages of the plate cylinder from the process.

In short, there are many factors that cause plate wear during printing, and these factors also exist objectively. If the printing plate is seriously worn out, it should be diligently handed and grounded to observe and eliminate it one by one. This will reduce the unfavorable factors that will lead to plate wear. This will result in fewer downtimes and fewer plate changes in the printing process, ensuring that production runs smoothly and effectively. Improve productivity.