Three factors affecting the printing quality of th

Three factors affecting the printing quality of corrugated boxes

corrugated box packaging has developed rapidly in recent years, and the printing quality is a major technical problem in the process of carton processing. How to print high-quality carton products with ordinary printing machines mainly depends on the following three aspects

I. selection of plates

the printing plates of corrugated boxes mainly include flexo, rubber plate, silk plate, etc., of which flexo and rubber plate are the most widely used. Flexo is made of plastic soft materials, which has the advantages of soft texture, high printing resistance, clear text and pictures, and poor damage to corrugated board. Compared with flexo, offset plate has high hardness and low printing resistance. However, it has low cost, economic price, convenient manual or machine engraving, and has a high share in the field of ordinary cartons. Therefore, after receiving the order prints, we should choose flexographic printing for the products with high requirements for patterns and words, large field printing area and large quantities according to the actual situation; For ordinary cartons with low requirements for patterns and words and small batches, offset printing is generally used to achieve the purpose of economic and practical 20 ~ 70hrc

second, the adjustment of the gap

the adjustment of the gap and pressure of each roller of the printing machine is the key to ensure the quality of printing products. Due to the improper adjustment of the gap between the paper guide printing plate and the impression, there will be some quality problems that are difficult to avoid, such as line thickening, dot expansion, illegible handwriting, edge ghosting, dirty edges, field whitening, overprint deviation and other quality defects. This requires the operator to adjust the size of each gap according to the thickness of plate making

first of all, it is the adjustment of the ink roller and the wrinkle roller. There should be no gap here, and the pressure adjustment is difficult to determine. Its pressure can be put into 80mm 215; 200g Niuka paper strip, which can be pulled is suitable. If the pulling is easy, the pressure is small; If it cannot be pulled, the pressure is too high. For printing when the field printing area is large or the paperboard surface paper is thick and uneven, the pressure can be appropriately reduced, so as to thicken the ink layer of the corrugated roller to meet the large-area ink supply; When the handwriting is small and the line is thin, the pressure should be slightly increased to reduce the ink supply, so as to achieve the purpose of clear printing

secondly, it is the adjustment of the gap between the wrinkle roller and the plate roller. The pressure here directly affects the printing quality of the print. The gap pressure should be adjusted according to different plates. Compared with flexo, offset is a little more stressful. The adjustment of this pressure gap must be the same at both ends of the wrinkle roller and the plate roller, otherwise the printing quality will be affected and the plate will be damaged. Specific operation method: pay great attention to the pneumatic or spiral manual printing machine. You can use a 6mm ~ 8mm gauge to debug. First start the printing machine, inking, slowly pressurize, and take the whole layout as the benchmark. The pressure on the flexo should be light. In the process of ink transmission, try not to deform the plate due to pressure. For those that cannot transfer ink locally, do not increase the pressure to solve it, but stick double-sided adhesive tape as the underlay here to achieve the required thickness, which will reduce the pressure on the whole printing plate and improve the printing resistance. If the pressure is too large, it is easy to have defects such as ghosting, blurred handwriting, ink accumulation, burrs, brightness, etc

therefore, in practical operation, it is difficult to obtain high-definition and high-quality prints without good technical quality and operation experience. Thirdly, the gap between the printing plate and the impression roller is 4 The system is controlled and adjusted by microcomputer. While ensuring the printing effect, we should try to increase the adjustment of the gap as much as possible. Because too much pressure will destroy the strength of the paperboard, and there will be quality defects such as imprinting and spreading, fuzzy layers and so on. In practice, due to the inconsistency between the flatness of corrugated board and the smoothness of paper, So it's very important in the printing process "We not only know that it is difficult to set up a research and development center in Shanghai to do this. Therefore, it is required to control the flatness of the paperboard as much as possible in the process of paperboard production to meet the requirements of printing. For overprint products with more than two colors, the requirements are higher. If the front color printing pressure is large and the color is deep, then the back color will have problems such as unclear printing and incomplete graphics. We should appropriately reduce the front color pressure, increase the back printing pressure, and adjust to the best Effect

III. use of guide strips

offset strips or die-cutting elastic strips play a very important role in printing, especially in some prints with small specifications and small printing area. It is an effective method to solve overprint inaccuracy and printing cutting dislocation. The length of the guide strip should be equal to or greater than the width of the cardboard. Stick the guide strip on both sides of the printing plate and print it outside the rough edges of the cardboard cutting, which can make the cardboard get the whole process control in the printing process and effectively avoid the occurrence of inaccurate overprint, inaccurate printing and cutting and other problems

information source: corrugated box