How to equip flexographic press with anilox roller

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How to match the roller of flexographic printing press

most prints have both field, line and continuous image adjustment. In order to meet the needs of all kinds of printing products, users must not adopt the practice of matching several embossing rollers with several printing units on the flexographic press. Taking the narrow width unit flexographic press as an example, at present, most of the imported in China are 6+1 type, that is, six color groups are dedicated to multi-color printing, and the last unit can both print and UV glazing

we suggest that for prints with no more than 150 lines, this 6+1 flexo press should be equipped with 9 embossing rollers. Among them, four wrinkle rollers with 700 lines and ink layer thickness of 2.3bcm (1billion cubic microns/inch) and 60 ° are used for hierarchical printing; Three embossing rollers with 360 ~ 400 lines, about bcm6.0 and 60 ° are used for field printing; Two 200 thread, bcm15 or so, 60 ° corrugated rollers are used for gold printing and polishing. If water-based gloss is used, 360 line roller should be selected, so that the oil layer is slightly thinner, and the printing speed will not be affected by the drying problem of gloss. Water based light oil does not have the special smell of UV light oil. The device of the wrinkle roll during printing can be determined through test and comparison. The thickness of the ink layer that the operator can observe during the test mainly depends on the number of lines of the wrinkle roll and the BCM value

what problems should be paid attention to in the use of corrugated rollers

the corrugated rollers we mentioned here refer to laser engraved ceramic corrugated rollers, which are made of high temperature resistant and wear-resistant coating materials in aerospace and aviation, according to a certain density, depth, angle and shape. This kind of corrugated roller is characterized by high cost and wear resistance. If used properly, its service life can be as long as several years; If used improperly, not only the service life will be shortened, but also the corrugated roller will be scrapped

in the process of use, the position of a corrugation roller on the printing machine depends on the specific print, and the position of the corrugation roller varies with different print, so the line roller is often changed during printing. At present, most of the narrow width machines use solid steel corrugated rollers, which are very heavy. When installing the imperial corrugated roller, pay attention to avoid touching the surface cover of the corrugated roller against other metal objects. Because the ceramic coating is very thin, it is easy to cause permanent damage after collision. In the process of printing and cleaning the machine, the ink should be avoided from drying on the striping roller. The special detergent recommended by the water-based ink manufacturer should be used, and the stainless steel brush should be used to ensure that the cleaning is clean and thorough. And form the habit of often observing the wrinkle roll hole with a high-power magnifying glass. Once it is found that the ink is deposited at the bottom of the hole and has a gradually increasing trend, it should be cleaned in time. If the above methods do not work, ultrasonic or sand blasting can be used, but it must be carried out under the guidance of the roller manufacturer

under normal use and maintenance conditions, there is no need to worry about the wear of the corrugated roller. The easily worn components in the ink transfer system are mainly the doctor blade. Compared with it, the wear of the ceramic coating of the corrugated roller can be said to be minimal. The ink layer will become thinner after the roller is slightly worn

what's the matter with plate shrinking

as we all know, flexographic printing has a phenomenon of unidirectional elongation along the direction of printing paper. The proportion of elongation is related to two factors: the diameter of the plate cylinder (including double-sided tape) and the thickness of the printing plate itself. The larger the diameter of the plate cylinder is, the smaller the thickness of the plate is, and the smaller the elongation to the high-performance, multi-purpose side. A concept that needs to be clarified here is that the elongation phenomenon is not caused by pressure in printing. In fact, the elongation deformation has occurred when the flexible printing plate is adhered to the plate cylinder through double-sided adhesive. Therefore, when designing ink drawings, we need to shrink the plate, and the proportion is obtained by looking up the table according to the actual plate thickness and the actual printing length. If you use computer plate making, you only need to give a one-way reduction instruction before designing the ink separation. If the film is made by hand, a deformer is needed, and the film with proportionally reduced version can also be obtained

what is the relationship between the number of printing lines and the number of wrinkle rollers

in many articles introducing flexographic printing technology, the ratio of the number of printing lines to the number of wrinkle rollers is set as 1:3.5 or 1:4. According to the practical experience and the analysis of the award-winning products selected by the American Flexographic Printing Technology Association (FTA) in recent years, the author believes that this value should be higher, including the measuring instruments that have made significant improvements in the structure and material of the original horizontal tensile testing machine and other products, resulting in changes in performance and technical characteristics, which are about 1:4.5 or 1:5. For individual fine prints, this proportion may be even higher. The reason is that the most difficult problem to solve when printing layered plates with flexographic printing machine is point expansion. The use of a higher number of lines of the corrugated roller, and the ink layer is thinner than solving the problems such as lack of utilization evaluation and too long cycle of formulating new material standards. The point expansion deformation is easier to be controlled. When printing, if the ink color is not strong enough, a water-based ink with high color concentration can be selected to ensure the quality of the print

how to design flexographic inks that are easy to overprint

in the printing process, a key indicator that people often pay attention to is overprint, because the waste caused by inaccurate overprint often accounts for a large proportion of all waste products. Although flexographic printer manufacturers have provided a good foundation for accurate overprint in the process of design and processing, and the automatic monitoring system also provides a guarantee for accurate overprint, the technical level and proficiency of operators also have a great impact on the overprint accuracy. If we can make some adjustments for the convenience of overprint when designing ink drawings, we can greatly reduce the difficulty of printing and reduce the scrap rate

the simplest way is to use anti white words as much as possible when designing the original ink manuscript, or excavate between the two colors to form an anti white outline, or cover the edge of the overprint of the two colors with the third kind of slightly thick dark outline. For the printing of finer prints, trapping technology can be used, and the amount of trapping depends on the accuracy of the printer, the quality of the paper used for printing and the level of the operator. Trapping processing is easy to realize on the computer. If there is no computer, there is only ready-made color separations. You can use a special trapping modifier to input the value of trapping volume, and the machine will automatically generate a trapping processed film. If there is no trapping processor, you can put a transparent spacer between the color separation film and the copy film, and expose it with a single point light copying machine, and you can also get films with similar effects

source: packaging Expo

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