There are three printing pressures for flexographic printing presses. These three printing pressures will have a great influence on the print quality of products. They are indispensable and are described as follows:
1. Inking device pressure: This pressure is the pressure between the inking roller and the metal anilox roller. Its main function is to control the amount of printing ink, and evenly transfer the ink. If the pressure between the two rollers is large, the amount of ink on the metal anilox roller will be small; otherwise, the amount of ink will be greater. At the same time, if the pressure between the two rollers is too small (ie, the gap is too large), once the critical point of the web height is reached, the anilox roller loses the effect of ink transfer, resulting in uneven ink-eating on the printing portion of the printing plate. The amount is not easy to control, and eventually the printed product is overprinted with thick ink resulting in ink sticking, poor clarity, blemishes in the dots, lines spread, and false hairiness.
If the pressure of the two rollers is too tight (small gap), the amount of ink on the metal anilox roller is relatively reduced, the dots can be printed clearly, and the characters and lines can be printed clearly and stably, but the ink volume and gloss are lacking. At the same time, it is necessary to prevent the metal anilox roller and the ink roller from being bent at both ends due to the excessive pressure between the two rollers, the printer gear jumping, the tooth fracture, and the like.
The principle of the size of this printing pressure should generally be determined by the characteristics of the product. The pressure between the two rollers of the cable product may be relatively large; the fine text, the line pressure may also be slightly larger; the characters of large characters and the field may be relatively small.
At the same time, the size of the pressure is related to the size of the printing area. Generally, the printing area is larger and the pressure can be lighter to increase the amount of ink, thereby increasing the density and vividness of the field and the brightness. Generally smaller or more delicate printing area, the pressure will be slightly larger to reduce the amount of ink to improve the clarity of the print. This pressure must be horizontally tangent to both ends of the anilox roll, and there should be no deviation, otherwise it will affect the print definition and printing effect.
2. The pressure of the ink transfer device: The function of the printing pressure between the metal anilox roller and the plate roller is to uniformly transfer the ink on the metal anilox roller to the printing surface of the printing plate (embossed printing portion).
Whether the printing pressure is correct or not has a great influence on the resolution of printed dots. The pressure is too heavy, the pressure of the anilox roll on the printing plate is large, and the image dots after printing are enlarged. (Word, line version thicker or double-shadow), high-profile office can be expanded into 20% network points, the middle tone network point jumped up, dark tone level darkened, low-key level of the network and off, 6 percent to the Internet almost For the field.
From the magnifying glass, it can be observed that each mesh has a double image overlapped (1 to 60%). 60% of the Internet has become unsightly, and it is solid. The products printed in this way have lost tone levels, poor image clarity, poor tone reduction, and unbalanced three colors. At the same time, due to over-printing pressure, the printing plate's printing rate is reduced, and the printing is easy to pile up. Dirty and dirty and other drawbacks.
The pressure is too light to eat on the printing plate. Of course it cannot be printed.
The best printing pressure: adjust the pressure between the anilox roller and the plate roller at the same size, and make the ink layer on the anilox roller come into horizontal contact with the plate surface. Of course, this â€œjust in contact with the round cutâ€ can only be obtained through long-term practice.
3. Impression device pressure: This pressure refers to the printing pressure between the plate roller and the platen roller. The pressure to make the ink layer obtained on the printing plate correctly transferred to the printing material is the final key to flexo printing. It directly affects the quality of the printed product.
The pressure between the two rollers is too large, the printed dots are spread out, the middle color is light, and the surrounding circles are deep circles, which have a great influence on the image level (words and lines are printed and printed on both sides). The dark tone level is easy to blur and the pressure is too high. Light, no printed image on the printed material.
The correct pressure adjustment allows the embossing roller and the plate roller to adjust the pressure at both ends of the same, the two are in round-horizontal contact. When the printing part of the printing plate is in contact with the printing material, the dots do not substantially enlarge, the characters and lines are clear, and the printing is not the best. At the same time, in the printing process, it is also necessary to adjust it at any time according to the specific conditions of printing so as to maintain the best state.
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