Daily maintenance and problem solving of anilox rolls.

- Jun 09, 2020-

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Dimples appear on the roller surface in the circumferential direction


This problem is often caused by abnormal contact between the doctor blade and the anilox roller or embedding of hard objects.


The solutions to this include: check whether the scraper is installed properly; check whether there are impurities or gaps in the blade of the scraper; and remove the dry ink or impurities in the ink tank or cavity in time.


The roller surface is partially depressed or the end surface ceramic is off


Such problems are often caused by external forces.


The solutions to this include: preventing hard objects from contacting, colliding, and knocking with the roller surface; anilox rollers effectively protecting the roller surface during loading, unloading, or handling; and mastering the correct method of cleaning the anilox roller.


Bright lines appear in the circumferential direction of the roller surface


This kind of problem is mainly caused by scraping the scraper.


The use of a scraper to scrape ink is likely to cause impurities to remain in the ink chamber and ink tank, or the ink cannot be cleaned and dried and clumped. If the impurities and the clumped ink are present in the ink circulation system, the scraper and the net Friction is formed in the middle of the textured roller, which will cause circumferential scratches on the ceramic surface, which appear as bright lines in the circumferential direction.


The small bright lines generated at the beginning will appear as a very shallow line on the printed product. This is because the mesh wall will become wider after being damaged. The widened mesh wall will block the mesh on the side, resulting in the side mesh The ink is not completely released. If the scratch is serious, the bright line will become wider and deeper. After the mesh of the bright line part is completely destroyed, a circumferential groove will be formed on the roller surface, and excessive ink will be transferred to the printed product in the groove. A darker line will appear on the printed product.


The newly processed anilox roll is more prone to ceramic and mesh scratches when it is first started. This is because the new anilox roll surface ceramic is not as smooth as the anilox roll that has been used for a while. During the operation, some ceramic powder will be generated due to the contact force between the blade and the anilox roller. If these powders remain in the closed ink chamber or ink pipe and are not removed in time, they will be more likely to cause circumferential damage.


The solution to this is as follows:


(1) Thoroughly clean the ink tank, closed blade cavity and ink circulation system in time. In particular, after the cleaning, the dead corners of the ink tank and closed blade cavity should be checked to prevent impurities and dry clumped ink from re-entering.


(2) Strictly control the blade pressure. If the blade pressure is too high, the contact surface between the blade and the anilox roller will also increase, and the possibility of impurities and dry clumps of ink scratching the anilox roller will also be greatly increased.


(3) Ensure the flatness and straightness of the blade installation. If the blade is not installed straight, it will affect the scraping effect or damage the surface of the anilox roller. Uneven pressure will cause the blade to be wavy, which will cause scratches on the surface of the anilox roller.


(4) Use high-quality scraping blades. The use of imported scraper blades can reduce the risk, and the blades of domestic blades are prone to gaps during use.


(5) When applying the newly processed anilox roller, the initial printing speed should not be too high, the use time should not be too long, to avoid the resulting ceramic powder embedded in the scraper and the anilox roller to cause friction. Therefore, it is generally recommended that the initial printing speed should not exceed 60 m/min. After 6 hours of running-in time, the machine is stopped, the blade and ink block are replaced, the ink tank and cavity are thoroughly cleaned, and then the official printing is performed.


Mottled or water ripples appear on the roller surface


This problem is often caused by residual ink on the mesh wall and the bottom of the mesh, uneven wear of the roller surface and the blade, or improper cleaning methods.


The solutions to this include: selecting the correct method and timely and effective cleaning of the anilox roller; installing and using a scraper correctly; if using ultrasonic cleaning, minimize the number and time of cleaning, it is not recommended to use ultrasonic cleaning method for high-net wire anilox roller, Avoid breaking the mesh wall.


If you must use ultrasonic cleaning anilox roller, you need to pay attention to the following: reduce the ultrasonic power. To reduce the frequency of ultrasonic cleaning, it is generally recommended to clean once every 6 months.


Strictly control the time of each cleaning. According to the requirements of ultrasonic operation, the anilox roller needs to be soaked in the potion for a period of time to soften the residue in the mesh hole, and then the ultrasonic generator is turned on, and the ultrasonic working time must be strictly controlled. When the roller is put into the washing machine, the ultrasonic generator is turned on, which will cause great damage to the anilox roller.


After ultrasonic cleaning, thoroughly remove the residue of the medicine on the roller surface. It is recommended to clean the anilox roller with water after cleaning, and then wipe the roller surface with alcohol to quickly evaporate the medicine.


Irregular bulge on the roll surface


This kind of problem is mainly caused by the solvent corrosion of ink or cleaning liquid.


The solutions to this include: detecting the composition of the ink; not using strong acid and alkaline cleaning agents; after using the cleaning agent, the residual solution must be washed immediately with clean water; and the use of aluminum-based anilox rollers should be minimized.


Decreased ink transfer


This problem is caused by mesh wear, mesh clogging, or a drop in ink color density.


The solutions to this include: detecting the mesh, if the wear is severe, it is recommended to re-process; if the mesh is clogged, the anilox roller is effectively cleaned in time; check the ink composition or batch for differences.