Selection and management of anilox roller in the h

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Selection and management of corrugated rollers in flexographic printing

with the development of flexographic printing, the application of corrugated rollers is becoming more and more popular

however, how to select the corrugation roll correctly and the maintenance, cleaning and preservation of the corrugation roll have not been understood and mastered

there are three main parameters of the wrinkle roll, namely, the number of lines per inch, the hole angle and the hole volume. These three parameters will be noticed by both users and suppliers when ordering or processing new corrugated rollers. However, from the perspective of the user, it is OK to accept the new wrinkle roller according to the above three parameters, but after a period of time, the state of the hole will certainly change, including the surface of the hole is worn, scratched or there is dry ink residue or debris blockage in the hole, the ink capacity of the hole is reduced, and the ink also overflows from the worn hole wall, resulting in inconsistent ink density in the corresponding ink area. Therefore, from the perspective of users, in addition to paying attention to the above three parameters during acceptance, they should also often pay attention to the fourth variable factor in the future, that is, the state change of acupoints

I How to choose the corrugation roller properly

it is often believed that thinning the thickness of the ink film can reduce the release of VOC (volatile content), so it is advocated to use the corrugation roller with shallow holes. Yes, the later ink layer will bring more VOC release, but the thickness of the ink layer is mainly determined by the volume of the hole, and the depth and shape of the hole is only one aspect. For example, the ink layer printed by the corrugated roller with shallow dished holes of 500 lines per inch and the corrugated roller with deep and steep holes of 1000 lines per inch may be almost the same because of their respective hole volumes, and the ink layer density may not be very different. Therefore, the concept of preferring to choose the corrugated roller with shallow holes is not appropriate. The main consideration is to choose the maximum LPI (number of lines per inch) to obtain the best density under the condition of ensuring the best ink transmission and the best ink drying

the best selection of corrugated rollers should start from the construction order of each printed piece. Get rid of the old theoretical dilemma. Pay attention to the usual protection and maintenance of this construction order. According to the needs of each print, provide all information, including the relevant parameters required for the printing machine after obtaining the signed sample agreed by the customer. Since the corrugated rollers are often used interchangeably in the printing press, it is important to specify the parameters of the number of lines per inch (LPI) and the volume of holes (BCM) of the corrugated rollers

for example, when printing a red plate in a printing unit, 600lpi and 1.8bcm corrugated rollers are used. When printing in the next printing unit, there are only 500lpi, 3bcm, 700lpi and 1.5bcm corrugated rollers for the red plate. At this time, the corrugated rollers with the closest parameters, namely 700lpi and 1.5bcm, should be selected

for new prints that may not have historical files, it is best to establish a characteristic test record, including using a set of standard printing plates and a set of specific ink volume, and testing the ink density with different embossing rollers. The printing plate should contain a certain field area and various sizes of positive text and sets of images. It should also have measurable and readable quantitative ink transfer and dot expansion, trapping, and tone range, which can be used as the parameter basis for selecting the wrinkle roller when adapting to different prints in the future

if you encounter unusual printing tasks (new varieties of printing, new substrates, new ink systems, etc.), the existing list of corrugated rollers may not be sufficient to provide necessary parameters. At this time, the printing plant should consider ordering a set of composite corrugated rollers. The so-called composite corrugation roller is a banded combination of multiple different number of lines (LPI) and cavity volume (BCM) on the same corrugation roller, so that a variety of different results can be seen in one test. As for the width and quantity of the belt, it varies according to different design requirements. At present, there are 57 so-called "standard" composite corrugated rollers in Urumqi pedestrian overpasses, but most of them are processed and customized according to the user's own requirements. In order to ensure the success and effectiveness of the test, we should pay attention to the following points:

the test bands with different parameters should be kept at a sufficient distance to avoid overlapping or interference, which will affect the making of clear conclusions

the width of each test strip should be sufficient to reflect the printing effect to be observed

the first and last test belts (that is, at both ends) of the drum should be the same, so as to observe whether the pressure at both ends of the test drum is uniform

II Classification management of stock corrugation rollers

the stock of corrugation rollers in the printing plant increases with the development of business. In order to effectively select the most suitable corrugation rollers according to the requirements of different prints during use, a list of stock corrugation rollers should be made

if this list is only classified by LPI, only the number of lines of the wrinkle roll can be known, and the volume of its hole (BCM) can not be known, so the necessary parameters cannot be provided when selecting. For example, for the same 800lpi corrugated roller, some may be 1.0bcm, while others may be 1.8 or larger BCM, and the ink transfer volume of its printing is greatly different. Therefore, in addition to the LPI of the corrugated roller, the inventory list of corrugated roller must also record its BCM parameters. In addition, due to the long service life and good maintenance of the corrugated roller, the wear of the surface or wall of the corrugated roller hole or the blockage by ink residue are also different, and its printing effect is also very different. Therefore, when preparing the inventory list of corrugated rollers, it should also be noted

when ordering the corrugated roller from the manufacturer, the user should clearly put forward the requirements for processing parameters, including the number of lines per inch, hole volume, engraving angle and the width of the non engraved sideband (if any). In addition, because there will inevitably be certain differences in processing, even if the same LPI and BCM are used for the processing of corrugated rollers, it is best to order processing in batches

III Maintenance of the corrugated roller

the correct maintenance of the corrugated roller should start from the confirmation of the current use of the corrugated roller, including the status of relevant parts on the printing machine, such as gears, bearings, doctor blade system, etc. this confirmation processing can be carried out simultaneously in combination with the daily maintenance work of the machine or the process of troubleshooting. Carefully observe the surface and holes of the drum with a magnifying glass, as well as the relevant machine parts, and record them in words, for example:

bearing wear, wrinkle roll assembly looseness, resulting in uneven impression in the direction of winding, tooth wear or hard injury, inaccurate overprinting, repeated transverse regular stripes on the winding, damage to the surface of the wrinkle roll, so that the hole volume of relevant parts changes, Affect the uniformity of the ink color of the printing sheet. Due to the improper or insufficient operation of cleaning the roller or the damage of the roller, affect the ink color, and there are stripes or ink leakage marks or stains

if such defects are found only in the printing preparation time, it will inevitably delay production and increase losses. Regular inspection and maintenance should be carried out in the daily equipment maintenance work

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