Selection and Management of Anilox Rollers in Flexographic Printing

With the development of flexo printing, the application of anilox rollers has become more and more popular.

However, the correct selection of anilox rollers and the maintenance, cleaning and preservation of the anilox rollers have not been properly understood and mastered.

The anilox roll has three main parameters, namely: lines per inch, cell angle, and cell volume. All three parameters are noticed by both the user and the supplier when ordering or processing a new anilox roll. However, from the user's point of view, it is OK to accept the new anilox roller according to the above three parameters. However, after a period of time, the state of the cell site will certainly change, including the surface abrasion and abrasion of the cell site. Or there is a dry accumulation of ink residue or debris in the net cavity, the volume of the net hole is reduced, and the ink also overflows from the worn hole wall, resulting in inconsistent ink density of the corresponding ink area. Therefore, from the perspective of users, in addition to paying attention to the above-mentioned three parameters during the acceptance, the fourth variable factor, namely the change in the state of the cyberspace, must be constantly observed in the future.

How to properly choose anilox roller

It is often thought that reducing the thickness of the ink film layer can reduce the amount of VOC (volatile content) released, and therefore advocates the use of an anilox roller with a shallower mesh. Well, after the ink layer will bring more VOC release, but the thickness of the ink layer is mainly determined by the volume of the network point, and the depth of the shape of the network point is only one aspect. For example, the ink layer printed by an anilox roller with a shallow dished space of 500 lines per inch and an anilox roller with a deeper steep network with a density of 1,000 lines per inch may be almost the same as the ink volume of its respective cell space. Density may also be indistinguishable. Therefore, the concept of anilox rollers tending to use shallower cells is not appropriate. The main consideration is to select the largest LPI (line per inch) for the best ink transfer and the best ink drying. For optimal density.

The best choice of anilox roller should start from the construction list for each print. This kind of construction order must provide all information according to the needs of each print, including the relevant parameters required by the printing press after obtaining the customer's consent for the signing. Since the anilox rolls are often used interchangeably in the printing press, it is important to specify the number of lines per inch (LPI) and the volume of the cells (BCM) of the anilox roll.

For example: When a printing unit prints a red version in a printing unit, it uses an anilox roller of 600LPI and 1.8BCM. When printing in the next printing unit, the red version of the anilox roller has only 500LPI, 3BCM and 700LPI, and 1.5BCM. Two options are available. At this time, the nearest anilox roller should be selected: 700LPI, 1.5BCM anilox roller.

For new prints may not have a history file, it is best to create a characteristic test record green, including using a standard set of plates and a specific set of inks to test the resulting ink density with different anilox rollers. The printing plate should include certain field areas and various sizes of positive texts and sets of images. Should also be able to measure the quantitative reading of the ink transfer and dot gain, trapping and tune range and other values, in order to prepare for the future adapt to different prints, as the basis for the selection of anilox roller parameters.

If unusual print jobs are encountered (new product prints, new substrates, new ink systems, etc.), the existing list of anilox rolls may not be sufficient to provide the necessary parameters. At this time, the printer should consider ordering a composite anilox roll. The so-called composite anilox roller has a variety of different LPI and BCM ribbon combinations on the same anilox roller, so that you can see a variety of differences in one test. the result of. As regards the width and the number, depending on the design requirements, there is a so-called "standard" composite anilox roll supply, but more is tailored to the user's own requirements. In order to ensure the success and effectiveness of the test, the following points should be noted:

Test strips of different parameters should be kept at a sufficient distance so as not to overlap or interfere with each other and influence the conclusion clearly.

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

The first and last test strips (ie both ends) of the drum should be the same in order to see if the pressure across the test drum is uniform.

II. Classification Management of Inventory Rollers

The number of anilox roll stocks in the printing plant grows with the development of the business. For the convenience of use, the most appropriate anilox roll is selected according to the requirements of different prints, and a list of stocked anilox rolls should be listed.

If this list is only classified by LPI, only the number of lines of the anilox roller can be known, and the volume of the cell (BCM) can not be known. When selecting, the necessary parameters cannot be provided. For example, the same 800LPI anilox roller may be 1.0BCM, while others may be 1.8 or more BCM, the printing ink transfer volume is very different, so the list of inventory anilox roller in addition to record In addition to the LPI of the anilox roll, BCM parameters must also be recorded separately. In addition, due to the long service period and maintenance of the anilox roller, the surface or net wall of the anilox roller is worn or blocked by the ink residue, and the printing effect is also very different. Therefore, it should also be noted when preparing the list of inventory anilox rolls.

When ordering the anilox roller from the manufacturer, the user should clearly specify the processing parameter requirements, including the number of lines per inch, the volume of the cells, the engraving angle, and the width of the unsculpted webbing (if so drawn). In addition, because there are always certain differences in processing, it is better to process the anilox roller in batches even if the same LPI and BCM are processed.

Three. Anilox roller maintenance

The correct maintenance of the anilox roller should start from confirming the current use of the anilox roller, including the status of the relevant components on the printing machine, such as gears, bearings, and squeegee blade systems. This confirmation processing can be combined with the daily maintenance of the machine. Or troubleshoot the process at the same time. Carefully use magnifiers to carefully observe the surface of the drum and the condition of the cells, as well as the relevant machine parts, and record them in words, for example:

Bearing wear, loosening of the anilox roller assembly, resulting in uneven embossing in the take-up direction, worn or hardened teeth, incorrect overprinting, repetitive horizontal streaks on the reel, damaged surface of the anilox roller, The change in the volume of the cells in the relevant parts will affect the uniformity of the printed ink, due to improper or insufficient cleaning of the anilox roll or damage to the anilox roll, affecting the ink color, and the appearance of streaks or ink leak marks or stains.

If such defects are found at the time of printing preparation, it will inevitably delay production and increase losses. Regular inspections and maintenance should be performed during daily equipment maintenance.