Common problems and solutions in the ink printing

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Common problems and solutions in the corrugated box ink printing process

at present, the corrugated ink "> carton industry has made the technology very mature. There are four ways of water-based ink"> printing equipment, and their characteristics are different. One is the chain type single machine printing method, which can only be printed without slotting and die cutting. The second is the commonly used production method of printing slotting and circular die cutting. This method adopts inking printing. After slotting or die cutting, it can be formed by bonding (nail box). The third is to use the production mode of full-automatic printing slot and folding bonding (nail box). This machine adopts the lower and upper ink printing system for folding molding, which belongs to a one-time molding machine. The fourth is the more advanced printing and circular pressing die-cutting method at present, which is characterized by multi-color printing, high equipment accuracy, and the printed products can achieve the effect of color printing, Especially suitable for color ink "> sales packaging of cartons. The common feature of the above methods is the use of ink printing. The printing principle and equipment structure are basically the same, but the number of printing colors, lines and process equipment are different. The printing process is affected and restricted by many aspects and factors, and many problems can not be solved by simple adjustment by operators. Only through the cooperation of all aspects, can we minimize and avoid a problem in production Some unnecessary problems

the size of slotting knife and longitudinal pressing line is inaccurate, resulting in inaccurate printing position

cause analysis:

due to the size adjustment of slotting and pressing line not according to the requirements of the process drawing, the length or width of paperboard manufacturing size deviation, and ultimately affect the inaccurate printing position


first adjust the slotting or crimping size according to the manufacturing size of the drawing, and the position is required to be accurate. Then readjust the printing plate position according to the accurate size position, and check the deviation caused by the wear of the slotting or crimping wheel

the position of the printing plate is not correct, resulting in the readjustment of the printing plate

cause analysis:

due to the unclear marking of chromatic registration and local printing plate position, the error in typesetting is large, and the printing position obviously deviates in actual production. At present, the printing equipment is basically drum printing, and the typesetting is on the plane, which will inevitably produce longitudinal position errors, and also cause shrinkage problems due to the size of the printing pressure


first, when making a 1:1 ink map, it should be drawn according to the normal percentage shrinkage. When typesetting, adjust the printing plate strictly according to the position of the ink map. When the requirements of chromatic accuracy are very high, the cross line typesetting method should be used to align the printing plate with the cross line of the ink map. If necessary, the deviation can be checked with a magnifying glass

printing ghosting and white leakage problems

original cluster analysis:

these two problems often appear in the production process. Ghosting around printed patterns or words is caused by excessive pressure between the embossing roller and the printing plate; Ghosting at the front edge of the printing is caused by excessive pressure between the printing cylinder and the embossing roller. The bottom penetration and white leakage of large-area printing are caused by insufficient pressure of printing roller and embossing roller. These two problems are caused by opposite pressures


for the printing ghosting problem, the gap and pressure between the grain, roll and plate roll should be adjusted, commonly known as the upper pressure. Ghosting is caused by the deformation of the embossing roller squeezing the printing plate (refers to the flexo) due to excessive upward pressure. Therefore, it is necessary to increase the gap between the two rollers and reduce the pressure accordingly. For the problem of printing white leakage, the gap and pressure between the plate roller and the embossing roller should be adjusted, commonly known as downforce. Because the gap between the plate roller and the embossing roller is too large, it will produce inaccuracy in case of large-area printing, which requires increasing the downward pressure. In addition, the unevenness of the printing plate, the plate lining, the hardness of the printing plate and other quality will affect the occurrence of the above problems, which should be partially adjusted

multi color printing overprint inaccuracy

cause analysis:

overprint inaccuracy is a common problem in the printing industry. Because it is composed of many factors, it is not easy to solve it. First of all, the accuracy of the position and accuracy of the plate roll of the multi-color printing slotting machine itself is a direct factor. The second is the adjustment of paper feeding roller and traction roller, the use of traction belt, and the arrangement of printing plates; The inaccuracy of overprint and the warpage of paperboard will cause the problem of inaccurate overprint


because overprint is composed of multi-color printing, it is inevitable that the position of the plate roller on the printing slotting machine is relatively different; Accurate, which requires the equipment department to adjust the printing position to ensure that the error is at the minimum limit. First of all, since the beginning of printing has an impact on the thickness of the paperboard, the pressure on the plate roller of each color should be slightly higher than the previous one, so as to make the pressure applied on all colors equal. Secondly, there are feed rollers and traction rollers at the front and rear of each printing. The adjustment of these two rollers is very important, especially when the cardboard width is too narrow, we should pay more attention to adjust the gap and position. In case of partial chromaticity, two traction belts should also be added at the edge of each printing plate to ensure that the paperboard is smooth and excessive in the printing process. In addition, due to the different warping degree of corrugated board, it has an absolute impact on overprint. If necessary, the cardboard should be replaced, but it must be smooth. [next]

inconsistent printing color

cause analysis:

inconsistent printing color refers to the uneven imprinting of the whole paperboard along the longitudinal or transverse direction of the machine after printing. The main reason for this problem is that the colors at both ends of the transverse printing are different, one side is shallow, the other side is deep. There is also the unfavorable circulation of the inking system, insufficient ink flow, and uneven transmission of the ink transfer roller


the uneven horizontal color is due to the different gap between the rubber roller and the corrugated roller, the corrugated roller and the plate roller. This protection switch is used to protect the heating pipe and humidifying pipe from air burn and water shortage alarm The set point of cold and hot shock test chamber = temperature set point +20 ℃ ~ 30 ℃. Therefore, to adjust the gap between the three rollers, both ends must be parallel. Since the printing slotting machine is positioned in the center, if the regular production of narrow cardboard, the rubber roller and the corrugated roller will wear faster, while the wear at both ends is less. The result after printing is different. If the colors at both ends are obviously inconsistent, it is necessary to repair or replace a certain roller. The uneven longitudinal color is caused by the low ink flow and insufficient ink supply. Therefore, it is necessary to increase the ink volume slightly and transfer the machine idly, so that the ink volume can be fully recycled before production, which can reduce the occurrence of this problem

cause analysis of corrugation during paper feeding or printing:

this is caused by two aspects: one is that the gap between the paper feeding roller (refers to the printing slotting machine) is too small, which is lower than the thickness of the original paperboard. Corrugate before printing, but what about its control system? I believe many customers want to know about crushing; Second, during the printing process, the pressure of the printing roller is too large, resulting in the obvious collapse of the corrugated printing part


the gap of the paper feed roller should be determined according to the thickness of the corrugated board, which is basically 0.5mm lower than the thickness of the original board. If the gap is too small, the corrugated box will be damaged, and the physical strength of the corrugated box will be affected after forming; The gap is too large, and the paperboard can not travel at a uniform speed, resulting in incorrect printing position; Good. During printing, pay attention to adjusting the gap between the printing roller and the embossing roller. At present, most corrugated box printing uses flexo, and the printing method adopts light pressure, that is, kiss printing, and the pressure must not be too large. If the pressure is too high, the corrugated of the printing part will be crushed, and the performance of the carton will also be affected. Therefore, it is very important to adjust the gap between the plate roller and the embossing roller. It is OK if there is no obvious depression in the hand feeling printing part

the manufacturing process of corrugated box must not damage the corrugated box. It is different from the sales packaging of general cartons, because the force formed by corrugated box is multifaceted. Once the UV type corrugated box is damaged, this kind of corrugated box is meaningless

to sum up, these printing problems are only the most common problems. Others, such as blurred printing handwriting, distortion and deformation, redundant printing traces after printing (commonly known as dirty printing), striped imprints, ink color does not achieve the desired effect, and so on, are analyzed. However, in addition to objective factors, such as the quality of printing plate materials, plate liners, inks, and even corrugated cardboard, all directly affect the printing effect of corrugated boxes. Therefore, we should choose high-quality raw materials to ensure the high quality of printing. In order to solve all kinds of problems in the printing process, it is also necessary to rely on experienced operators. First of all, they must have a certain level of theoretical knowledge. For example, they must understand the principles and process procedures of printing equipment and manufacturing process, fully grasp the relationship between the four major parts of rubber roller, ink transfer roller (embossing roller), plate roller and embossing roller in the printing system, and how to be skilled and when a problem occurs; It can be solved quickly by accurately adjusting the corresponding parts. Secondly, it is also necessary to be good at summarizing in actual operation, adjusting which parts under what circumstances, and requiring accuracy, which is not easy for general operators. As an excellent car stopper, you should be good at finding problems and solving them in time, so as to improve production efficiency. In a word, printing problems cannot occur without the above conditions. As long as we fully understand the printing principle, the printing problem will be solved

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