Three most popular methods to solve the problem of

2022-08-07
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Three measures to solve the problem of inaccurate overprint in flexo printing due to its advantages of online post-processing, combination of various printing methods, and use of environmentally friendly water-based ink, flexo printing machine has occupied a certain market in China's high-end packaging printing field, especially in the printing of beer labels and soft pack cigarette labels. However, compared with offset printing and gravure printing, flexo printing also has some disadvantages, such as large plate deformation, which are specifically manifested in overprint inaccuracy and plate pasting

inaccurate overprinting

1. Tension control

in the printing process, due to the unstable tension, it is easy to produce a large number of waste products for convenient operation, so the tension of the paper tape should be strictly controlled. Generally, the unwinding and rewinding parts of the machine are different. Don't you know? There is a magnetic powder tension controller and a tension drive roller, and both of them have tension display. Because the paper tape has a joint, the tension will fluctuate every time the joint comes over. You can make a rule in advance to reduce the amount of waste products. If the printing parts are to be replaced, if the newly replaced paper tape is wider, the tension drive roller will be worn by the narrower paper tape in front, and the replaced wide paper will form a bridge effect in the middle of the rubber roll. The two sides of the paper tape are tight and the middle is loose, which will have a great impact on the subsequent Slitting unit. At this time, the rubber roll needs to be replaced or the surface of the old rubber roll can be ground flat. In addition, the external air inflation mandrel will become loose after a long time of use. It should be checked frequently

2. Ensure the accuracy of the printing plate and the alignment of the loading plate

during the loading of the plate, the plate is usually pasted manually, which requires a high degree of proficiency. The edge line of the printing plate must be parallel to the axis of the printing plate cylinder, and the joints should be as close as possible, otherwise it is easy to cause the plate roll jump at the joints. If a printing plate is replaced separately, the printing plate overprint is often inaccurate due to different plate making time. At this time, the electric hair dryer can be used to blow the plate soft, such as high requirements for color, and then stretch it vertically or horizontally to keep consistent with other printing plates

3. Constant speed printing

for a large number of printing pieces, under the condition of mature technology, constant speed printing should be adopted, so that the drying device can reduce the ZL of paper deformation The structure of the new clamping cylinder of the two plate injection molding machine has the same effect, which is easy to overprint. Other process parameters such as ink viscosity and tension setting can have a fixed range, so that the quality can be guaranteed

reprinted from: Chenyi printing

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