In the gravure printing process, we often encounter that part of the color of some layouts is lighter than the normal color, and this phenomenon becomes more and more serious with the increase of the number of prints, which directly affects the print quality. After stopping the machine for observation, it is found that the graphic part of the layout is worn, the opening of the inking hole becomes smaller and the depth becomes shallow, resulting in the reduction of the single area of ink transfer in the mesh hole, the total ink transfer volume also decreases accordingly, and the general trend of ink color change becomes lighter, so as to reduce the printing resistance.Improve The Printing Resistance Of Gravure Plate  In Production

       After analysis, the main factors affecting plate wear are: surface friction, plate making quality of gravure, pressure of doctor blade, printing pressure, linear speed of plate roller and embossing roller, performance of ink and paper, etc. Although the impact of these factors on plate wear is inevitable, how to reduce the impact of these adverse factors on plate is very necessary to improve print quality, reduce printing cost and shorten printing cycle.Improve The Printing Resistance Of Gravure Plate  In Production

1、 Factors affecting the printing resistance of gravure plate

1. Surface friction is the main reason to reduce the printing plate resistance

      Printing is inseparable from pressure. Under pressure, friction will inevitably occur, resulting in the wear of the plate surface. The greater the pressure, the greater the friction, and the more serious the plate wear.Improve The Printing Resistance Of Gravure Plate  In Production

There are mainly the following forms of friction on the surface of the printing plate cylinder:Improve The Printing Resistance Of Gravure Plate  In Production

(1) Friction between the doctor blade and the plate cylinder.

(2) Friction between plate cylinder and impression cylinder.Improve The Printing Resistance Of Gravure Plate  In Production

(3) The thickness and particles of pigments and fillers in the ink, the loose structure and texture of the substrate surface and the falling off of dust can produce additional friction.

2. The plate making quality of gravure affects the printing resistance of printing plateImprove The Printing Resistance Of Gravure Plate  In Production

(1) The hardness of chromium layer shall be high

      The quality of chromium layer is the basis of printing plate resistance. The chromium layer has low hardness and is easy to be scratched by hard particles, so it is better to have higher hardness during chromium plating. In the printing process, the printing plate is constantly worn by various factors, such as low hardness of chromium layer and thin coating, which will reduce the printing resistance of the printing plate.Improve The Printing Resistance Of Gravure Plate  In Production

(2) The finish of chromium layer shall be high

      The chrome layer on the surface of the plate cylinder has a high finish. The scraper can scrape the ink under light pressure to reduce faults. If the surface is rough, it is difficult for the doctor blade to scrape the ink, which is easy to produce printing failure.Improve The Printing Resistance Of Gravure Plate  In Production

(3) The circumferential runout of the printing plate cylinder during printing should be small

      If the processing accuracy of the plate cylinder is poor, the dynamic balance is poor, or the cylinder shaft, bearing and transmission gear are worn or deformed, there will be runout during printing, causing the printing knife line. Therefore, the circumferential runout of plate cylinder printing should be small.

(4) The surface of the cylinder should be checked and wiped frequently

      Hard objects adhering to the surface of the plate cylinder will directly damage the plate cylinder and cause printing failure. Therefore, always check and wipe the drum.Improve The Printing Resistance Of Gravure Plate  In Production

      In gravure production, the layout is required to be flat, the chromium layer is smooth, the thickness is uniform, and has good wear resistance. According to the requirements and types of printing quality, the correct choice of laser engraving gravure or electric engraving gravure can avoid unnecessary waste and save cost.Improve The Printing Resistance Of Gravure Plate  In Production

3. Printing resistance of doctor blade and printing plate

      The angle and pressure of the doctor blade have different wear effects on the printing plate. The angle of the doctor blade is small, which has less wear effect on the printing plate, weak scraping effect, thick ink, strong covering power and good luster, but it is not easy to scrape clean.Improve The Printing Resistance Of Gravure Plate  In Production

4. Printing pressure and printing plate resistance

      Printing pressure has a great influence on plate wear, printing quality and the structure of printing machinery. The printing pressure is too small, and the picture and text transfer in printing is incomplete, which reduces the ink transfer rate and makes the imprinting false; If the printing pressure is too high, the local ink is excessive, resulting in inaccurate printing tone and distortion of graphics and text. Improve The Printing Resistance Of Gravure Plate  In Production

      In addition, the gear and drum shaft bear too much pressure and friction, which is bound to aggravate the wear of the printing plate and affect the printing quality. Therefore, on the basis of ensuring that the imprint is strong enough, the use of small printing pressure (i.e. ideal printing pressure) as far as possible will help to reduce the wear of the printing plate.Improve The Printing Resistance Of Gravure Plate  In Production

5. The linear speed of plate roller and embossing roller shall be the same

      According to the requirements of gravure printing process, when the printing plate and embossing cylinder are rolled, not only the transmission should be stable and the instantaneous transmission ratio should be constant, but also the linear speed of the two cylinder surfaces should be consistent. However, due to the wear of the surface of the embossing cylinder, the radius of the embossing cylinder will change during printing. Improve The Printing Resistance Of Gravure Plate  In Production

      By V = w × R shows that the linear velocity before and after wear and at the lowest point is inconsistent, which will produce speed difference and cause relative slip. The greater the speed difference of the printing surface, the greater the friction, Improve The Printing Resistance Of Gravure Plate  In Production

     And the wear of the printing plate also intensifies. Therefore, making the linear speed of the surface of the printing plate and the embossing cylinder as consistent as possible in the printing process and reducing the speed difference caused by wear will help to reduce the wear of the plate.Improve The Printing Resistance Of Gravure Plate  In Production