Factors affecting the transfer of ink by the anilox roller

The author has worked with Mr. Xia Yixing of Xiamen Astor Company and Mr. Ye Ting of Shanghai Aokeli Printing Machinery Co., Ltd. Discussed how the anilox roller should play a better role. Among them, the anilox roller's ink transmission elements were discussed. Later on, this topic will be paid attention by colleagues in the industry, so it is triggered to write this article.

With the development of flexographic printing, the ink transfer method of its printing equipment has undergone continuous improvement and improvement with the development of science and technology. If it still stays at the level of the original metal smooth roller and metal anilox roller, it is difficult to meet the standard requirements for the amount of ink transfer required for various types of printing products developed in Japan. At present, flexographic printing has been able to produce high-quality prints. It is also recognized that ceramic anilox rollers are indispensable in the development of flexo printing. It is a unit that produces ceramic anilox rollers. It is not yet possible to achieve uniform data and consistent ink delivery, resulting in more ink delivery for the same number of anilox roller lines.

(BCM is the standard of ink transmission in Britain and America, Western Europe (except for the UK, CM3 / M2, its conversion method is 1BCM = 1.55CM3 / M2) or the number of lines and ink transmission of different anilox rollers are the same, which affects the use and communication In order to grasp the relationship between these elements and the amount of ink transferred, we can use the anilox roller handily.

The elements of the amount of ink transferred by the anilox roller are: the number of anilox roller mesh lines, the ratio of the opening to the mesh wall, the shape of the mesh hole, the depth of the mesh hole, the operating speed of the smooth roller on the surface of the mesh hole, the angle of the mesh wire, and the shape of the dot.

1. Line number of anilox roller

The number of lines of the anilox roller, that is, the distribution of cells in a unit length, can be calculated according to the number of cells distributed per unit area. The unit length here refers to per inch (2.54 cm), such as 200 lines / inch, that is, for every 200 cells (800 cells / cm), there are 10,000 cells. In the same way, there are 250,000 net holes in 500 lines per talent. Because the single area is the same and the number of the same holes is different, the mesh holes have different sizes, the amount of ink stored is large, and the amount of ink transferred is also large; the opposite is the case for small ones, so the amount of ink transferred by the high line is less than the amount of ink transferred by the low line. Some units have done exploration experiments. The anilox roller with 1000 lines / inch is used to transfer ink. As a result, the density value of the ink does not meet the "international" requirements. Here is a problem: the number of anilox roller lines should be selected reasonably, not as high as possible.

At present, there is still a tendency to increase the line number of the anilox roller, which specifically reflects that the machine line with a high number of anilox roller has good quality. â‘¡ When buying the machine, pay more attention to the configuration of anilox roller with high thread count. â‘¢The anilox roller is processed to 1200 lines or even 2000 lines, and the quality of the anilox roll is exaggerated. â‘£Coil corrugated box printing and slotting choose 350 lines / inch or higher ceramic anilox roller, etc. The author believes that it is wrong to measure the quality and printing performance of the anilox roller by the number of lines of the anilox roller. The number of lines of the anilox roller is exactly the amount of ink. Under normal circumstances, the number of lines is high and the amount of ink is small. The lower the number, the more ink.

The different number of lines of the anilox roller gives flexo workers control over the amount of ink, and also creates conditions for products with high printing quality and high screen lines. Metal anilox rolls can generally only be processed to 300 lines / inch, so before the 1980s, the maximum can only print 120 lines / inch flexographic printing, and later can print 175 lines / inch printing, ceramic anilox roller function But no. Here is also a question, how high is the line number of ceramic anilox roller? At present, according to the author's knowledge, the highest domestic line is 1,000 lines, and the 1200 lines abroad, and how will the 2000 line be realized. The key is that the amount of ink transfer is very small, which is not up to the use requirements. When selecting the line number of the anilox roller, in addition to the conventional principles (base material, text, image line number, ink), it should be emphasized that each unit chooses to adjust in practical application. With the improvement of anilox roller processing technology in the future. The ink storage capacity of the anilox will increase, and the number of lines used by the anilox roller can be appropriately increased, but please use it with caution when using an anilox roller with more than 1000 lines.

2. Ratio of opening to net wall

This element (see Figure 1) has a certain relationship with the transfer of ink volume, the depth of the mesh hole and the increase in the ratio of the number of plate lines. Unite.

figure 1

The anilox roller transmits ink from the mesh cavity and the mesh cavity is concave, so there must be a mesh wall between the mesh cavity. The ratio of the opening to the width of the mesh was 5: 1 in this case. 31% of the anilox roll. There is no ink on the anilox wall, especially in the case of using a squeegee, if the anilox roller is used as the plate cylinder for gravure printing, then the print is a flat mesh, so it can be seen that the anilox roller is transmitted through the mesh Ink is ink. It is not surface ink transfer, so this part of the wall is not ideal for transferring ink. If the high light dots fall on the wall, you will not get ink.

At present, some ceramic anilox roller processing units, according to the characteristics of ceramics with high hardness and good wear resistance, minimize the area of ​​the mesh wall and improve the effect of ink transfer. The method is to increase the ratio of the opening to the mesh wall, that is, 7: 1, 8: 1 or even more than 10: 1. According to the scope of the network cable, some units introduce a higher ratio of 200 lines / inch for the lower network cable and 800 lines / inch for the higher network cable. This is scientific. It is possible that all the wire numbers are in a ratio. It is also impossible that the ceramic wall has high hardness and good wear resistance, and the mesh wall can be unrestrictedly thin. The mesh wall is not very vertical, and its top is extremely thin. It can be seen from Table 1 that most of them are less than 0.01 mm (the thickness of the newspaper is 0.07mm). To affect the service life. According to the number of lines, the ratio of the opening to the mesh wall, the thickness of the mesh wall is known.

Table 1 (Unit: micron)

3. Net shape

figure 2

This element (Figure 2) is still being improved after the successful research of ceramic anilox rollers. From the figure, it can be seen that the volume of the anilox tends to expand, why should it be expanded? Isn't the shape of the first net hole beautiful? The strength of the mesh wall is also high. From the third shape, the strength of the wall is greatly weakened, and from Table 1, there are many mesh wall thicknesses that are less than a meter, but people still tend to expand the mesh hole volume. : ① The role of the anilox roller is to transfer ink, and the amount of ink transferred by the anilox roller should be increased as much as possible. ② The depth of the net hole cannot be very deep, and the volume of the net hole should be enlarged as much as possible within the effective depth. ③As mentioned before, the anilox roller is a dot ink transfer, not a surface ink transfer, and the flexographic printing ink transfer system, only one anilox roller touches the plate roller. Although the mechanical structure is simple, compared with the four upper plate rollers in lithographic printing which are in contact with the printing plate, and compared with the surface ink transfer, the anilox roller must have sufficient ink transfer amount to achieve normal printing. ④It is beneficial to choose high anilox roller to transfer ink, and the shape of mesh hole is one of the keys. ⑤ It is helpful to increase the ratio of the number of printing plate lines to the number of lines of the anilox roller. The ratio starts at 1: 3, and the application example of ceramic anilox roller is improved, which is generally more than 4.5. The purpose is that the highlight dots on the printing plate can get enough coverage of several ink dots on the anilox roller, so as to ensure that the highlight dots are enough The inks make the halftone products rich in layers and strong in three-dimensional. According to the data, the ink storage capacity of the second type of hole can be increased by 10% to 15%, and that of the third type can be increased by 20% to 30%. The shape of the net hole is related to the service life of the ceramics, so the selection can be appropriately selected according to the actual needs according to the advantages and disadvantages of various aspects.

4. Net depth

This element is also one of the keys. According to the data, the depth of the cell is 23% to 33% of the opening width, and the ideal is 28%. This parameter is worth discussing. According to this parameter, the depth of the mesh hole of the ceramic anilox roller of 1000 lines / inch is less than 0.01 mm, which is almost the same as the top of the mesh wall, and the amount of ink transfer is very small. So this parameter is more suitable for metal anilox roller. Because the metal anilox roller adopts the method of electronic engraving or the mechanical extrusion method of the hob, the depth of the mesh hole needs to be separated from the mesh hole due to the cutter and the hob, so it is impossible to exceed 1/2 of the opening width. It is also impossible to expand the content, so it is concluded that 28% is an ideal conclusion.

The ceramic anilox roller is processed by laser beam, and there is no requirement for tool detachment, so its processing depth can be increased by an appropriate amount, and it can also meet the requirements of use. For example, the same mesh can be formed by ablating the mesh twice or more times, so as to achieve the desired depth, but this depth has not yet been unified, and an optimal value should be unified in the future.

In addition, the ink in the cell is based on the principle of the velocity gradient of hydrodynamics. The speed of the liquid near the cell wall is 0, that is, it is stationary, which is often called the wall effect, so the general ink release is 2/3 of the cell capacity ~ 4/5.

The depth of the anilox is largely restricted by the number of lines of the anilox roller, and according to the number of lines, the ratio of the opening to the anilox wall, the ratio of the opening to the depth, and the depth can be calculated.

Example: Coiling roller is 1000 lines / inch. The ratio of the opening to the mesh wall is 7: 1, and the ratio of the opening to the depth is 1: 1; from this, the depth of the mesh hole T = 25.4 / 1000 * 7/8 * 1 = 0.022

5. Mesh surface smoothness

This index is very important during the period of the metal anilox roller, except that the shape of the same cavity is clear and uniform. The surface is smooth, and a layer of chromium is also required to increase the surface hardness of the anilox roller. On the other hand, the smooth mesh ink is easy. Early ceramic anilox rolls had very poor surface finish due to technical conditions (see Figure 3). Under high magnification magnifying glass, the lava at the time of the explosion. The uneven surface affects both the release of ink and the capacity of ink. Therefore, the cleaning fluid and equipment of ceramic anilox rolls should be cleaned at the historic moment, but the anilox rolls should also be cleaned, but the requirements are not high.

image 3

Some units apply high and new technologies such as ion implantation technology and nanotechnology to change the performance of the ceramic layer, so that the originally loose ceramic molecules become denser, thereby improving the surface finish of the mesh hole and easy to clean and improve the service life.

Practice has proved that the poor surface finish of the mesh hole causes the anilox roller to gradually reduce the amount of ink transfer, and ultimately the use and product quality. One company printed a batch of the same product before and after, with the same printing plate, ink and base material. But the color difference was found, and it was found that the amount of ink transmission was reduced after the anilox roller was blocked. A corrugated box printing unit. Due to the blockage of the anilox roller, the production was stopped, and now this indicator has been paid attention to by the manufacturing unit.

6. Anilox roller running speed

The amount of ink transferred by the flexographic printing anilox roller changes with the printing speed. As a flexo worker, you should clearly understand and master this feature. The single-blade system has a high speed and a large amount of ink transfer; the double-blade seal system is the opposite, with a high speed and a small amount of ink transfer.

Flexographic printing started late in China, and currently there are not many skilled operators. Many units gradually increase the printing speed after running in. With a single blade system, if the color difference is found to be deeper, measures should be taken to reduce the amount of ink transfer, increase the line number of the anilox roller, or lower the ink hue.

7. Network cable angle and network cable shape

The anilox roller is flat and dot-to-ink, so the anilox has an angle. Anilox wire has 30 °, 45 °, 60 °, but the actual metal anilox roller is 45 °, and the laser engraved ceramic anilox roller is 60 °. 60 ° has the best intensity and large ink transfer. The ink transfer system of flexographic printing is developed from a metal anilox roller to a ceramic anilox roller, and the metal anilox roller is easy to process at 45 °, and the half-color is formed to meet the requirements of the anilox roller at 45 °, so the metal and ceramic anilox The angle of the roller wire is not unified.

In the development of anilox rolls, many dot shapes have been used. Hexagonal, quadrangular, grooved, diagonal, dotted, etc. Groove-shaped, diagonal-line type is suitable for coating, but has been eliminated.

The dots of 45 ° dots have more nets than hexagons and quadrilaterals, which is not good for ink delivery, and the dots are also eliminated. At present, the shape of the dots of the metal anilox roller is a quadrangular shape, and the screen linearity is 45 °. The dot shape of the ceramic anilox roller is hexagonal, and the angle of the wire is 60 °.

Among the above 8 points, except for the 6th point, which has nothing to do with processing, 3 points of the remaining 7 points are constant (number of anilox roller lines, angle of the anilox line, and shape of the dot), 4 points (the ratio of the opening day to the anilox wall, mesh shape. The depth of the hole and the surface finish of the hole) have not been agreed by the processing units. Therefore, the amount of ink transferred by the ceramic lines of the same number of lines is inconsistent.

Table 2: Line number of anilox roller

According to the data, the anilox rollers with different thread counts transmit the same ink (Table 2), such as BCM7-8, and the anilox roller thread count is 200-3BCM3.5. The number of lines of the anilox roller can be in the range of 400 to 700 lines. This selection and communication. If printing halftones, BCM requires 3.5 line selection or 700 lines? Will choosing 400 lines violate the proportional relationship between the number of plate lines and the number of network lines? Will moire appear?

The laser light sources for processing ceramic anilox rollers include CO 2 and YAG. In the future, other light sources will appear. The light source is different, and the characteristics of the mesh hole are also different. As mentioned above, due to the different processing parameters of ceramic anilox rollers, the amount of ink transferred is also the same.

Therefore, the author's point of view is: 1. The current units should understand the principle, function and BCM of the palm roller; 2. According to the current BCM of the reticle roller is not unified, and a large number of lines BCM, It should be based on BCM, and the number of anilox roller lines cannot be used as a basis for adjusting the amount of ink; 3. In practice and application, it is more reasonable to choose and be good at adjusting BCM ink. Communication is a reference; A type of ink transfer (BCM), the amount of ink changes with the screen line also changes with it, so that it can adapt to the use and selection of the anilox roller and carry out communication.

   The Leather Mobile Phone Cover with the protect function , and you could put the card slots ,it more convient you life .It could fit all phone size , Like S, M and L size (4.7-5.5).We sell Pu/genunine Leather Phone Case ,Card Slot Phone Case,folio Phone Case , Card Slot Back Cover,Leather Mobile Phone Cover,Universal Leather Case.

  We employ the most creative designers and tech brilliant engineers to make the best cases. We believe our high-quality products with competitive prices will satisfy your needs.  

The productive process :

Make the Products Mould –Cutting the fabric –Do the half products – Finish products – Cleaning –QC- Package – Shippment .

Leather Mobile Phone Cover

Leather Phone Case,Leather Phone Cover,Leather Mobile Phone Covers,Custom Leather Phone Case Cover

Guangzhou Ysure Electronic Technology Co., Ltd. , https://www.ysurecase.com