Causes and solutions for wrinkle failure
(1) The local tension is too large. For example, if the unwinding tension is set too large, it will cause wrinkle failure, and the more the paper goes backwards, the more serious the failure will occur, and even the paper breaks. The solution is to reduce the set value of the tension of each part.
(2) The equipment does not match the substrate. Flexo printing machine has a printing material to the range, if thick paper printing flexo printed tissue, wrinkling is likely to cause problems, especially in the more common of several color groups. The solution is to consult the manufacturer of flexo printing machine, and timely replace a set of impression cylinders suitable for printing thin paper and paper feeding and paper-feeding rubber rollers (the surface material is generally cyanide rubber), so that the hardness of the rubber roller can meet the thickness requirements of the printing material. . Under normal circumstances, when printing a film, a rubber roller with a hardness of HS70 is selected; when printing thick paper, a rubber roller with a hardness of HS80 is selected, and sometimes the hardness can reach HS85 to HS90.
(3) The corner of the correcting device is too large. This phenomenon occurs mostly in the printing stage of the same batch of work. Because the corner of the correcting device is too large, the two sides of the paper are inconsistently elastic, and the loose side is prone to wrinkle failure. The solution is to let the flexo press run for a period of time. After the correcting roller is aligned, set the system to the "automatic" working state. To prevent this failure from occurring on the next roll of paper, a mark is typically placed on the unwinding inflation shaft to ensure the accuracy of the lateral position of each roll.
(4) Paper absorbs moisture from the air. This phenomenon only occurs in the outer layer of the paper roll. As long as you walk through the paper or cut off the paper and then reconnect it, normal production can be resumed. Therefore, in the process of paper transportation and storage, it is necessary to ensure that the outer packaging of the paper roll is intact, and then remove the outer packaging when the machine is on, to avoid excessive absorption of moisture in the outer layer of the paper roll and cause wrinkle failure.
(5) There is a raised foreign matter on the surface of the impression cylinder or the paper guide roller. This phenomenon occurs mostly in the start-up phase, as long as the dry ink block or foreign matter on the surface of the impression cylinder and the paper guide roller is carefully inspected and cleaned at the time of starting up.
(6) The difference in parallelism between the plate cylinder, the impression cylinder or the paper guide roller. This phenomenon occurs mostly on devices that have been used for a long time. The solution is to carefully check and adjust the parallelism of each roller during the annual maintenance of the equipment. It is required that the parallelism error of each roller of the same color group does not exceed 0.03 mm, and the rollers of the adjacent two color groups or the rollers of the same color group and the tension roller The parallelism error between the two does not exceed 0.05 mm.
Causes and solutions for silt paper failure
Flexo-printing machine die-cutting generally adopts a simple circular die-cutting method. This die-cutting method can not only die-cut the finished product, but also cut a large sheet. The occurrence of silt faults is mostly caused by the paper line speed of the paper feed roller being greater than the line speed of the die-cutting paper, which can be divided into the following two cases.
(1) Caused by a die cutter. The diameter of the new die cutter is usually larger than the thickness of the substrate.
The theoretical diameter is 3‰~4‰, and it is incremented step by step (that is, the diameter of the blade of the first, second and third station die cutters gradually increases). If the diameter of the die cutter blade after wear is close to the theoretical diameter, there will be a paper jam and a failure to open. Although this failure can be alleviated by replacing the sponge strip (the sponge strip is easy to age after a period of use, the elasticity will become smaller), but the smaller the diameter of the knife roll will cause the meshing gear to collide and the die-cut dimension is inaccurate, thus affecting normal production. Therefore, the best solution when this happens is to recreate a new die cutter.
(2) caused by the die-cutting roller. When the flexo press is shipped from the factory, the manufacturer will use it according to the actual use of the user.
The case is to determine the diameter and the amount of enlargement of the die-cutting bottom roll, generally increasing step by step (ie, the diameters of the die-cutting rolls of the first, second and third stations are gradually increased). For the die-cutting process with the roll-to-roll function or the self-adhesive die-cutting process with the rewinding function, due to the existence of traction, there is generally no paper-crushing failure, as long as the diameter of the first-stage die-cutting bottom roller is enlarged. It is small or close to the theoretical size, and the die-cutting bottom roller can be adjusted step by step. For other non-traction die-cutting, the diameter of the die-cutting roller should be 2‰~4‰, and the thicker the paper, the larger the amount of magnification.
Generally, there are mainly two types of paper jams caused by die-cutting rolls.
(1) When the thick paper is cut by the die-cutting bottom die of the die-cut thin paper, and the thickness of the paper exceeds a certain range, a paper-crushing failure occurs before the die-cutting station. If you only use this type of paper for a short period of time, you only need to stick a thin layer of self-adhesive on the die-cutting roller to eliminate it; but if you want to use this paper for a long time, you need to re-make the appropriate die-cutting roller.
(2) If the size of the outer diameter of the die-cutting bottom roll after grinding is too small, a paper failure will occur, and a new die-cutting roll needs to be reworked. Therefore, when grinding the die-cutting bottom roller, it is necessary to ensure that the outer diameter of the die-cutting bottom roller meets the requirements of the magnification.
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