Anilox Roller Correctly Use the Pit Avoidance Guide, please remember it carefully! !

Anilox Roller Correctly Use the "Pit Avoidance Guide", please remember it carefully! !

The anilox roller, commonly known as the mesh line roller and ink transfer roller, is engraved with countless mesh holes or mesh grooves of the same size, shape and depth on the roll surface to control the quantitative output of ink or coating volume. The emergence of anilox rollers not only simplifies the structure of the ink delivery system, but also allows for better control of ink layer thickness and printing speed. So, how should a small anilox roller be chosen correctly? What are the common problems in use? In this article, let's take a look.

anilox roller ink transfer performance

Before choosing an anilox roller, let's first understand the ink transfer performance of the anilox roller. In the printing process, the ink transfer performance of the anilox roller is mainly presented by the amount of ink load, which is a very critical role, which will directly affect the final printing effect. The so-called ink capacity is the ink storage volume of the mesh in a unit area. At present, the more commonly used units to express ink capacity are cm³/m² and BCM. Among them, cm³/m² is the total volume of the roller surface mesh hole per square meter; BCM means 1 BCM = 1.55 cm³/m².

Affected by different process parameters, the parameters that determine the ink transfer performance of anilox rollers are mainly as follows:

Mesh shape and angle

The mesh has the function of ink storage and uniformity. The commonly used mesh shape is hexagonal and the mesh angle is 60°. This setting is conducive to improving ink supply and avoiding or reducing the formation of turtle patterns in the print. Because the structure and angle of the mesh will directly affect the circulation of the ink, under normal circumstances, the circulation of the mesh cannot be blindly pursued, otherwise the ink in the mesh will be thrown out of the mesh, and the mesh will not store ink and the ink volume will be small. Under special circumstances, such as when transporting some high-viscosity inks, some structures that can make the ink flow well in the mesh, such as S-shaped mesh, spiral mesh, etc.

Mesh depth and opening

After determining the number of network cables, the width of a single mesh is determined. Mesh width, that is, the sum of the mesh opening and mesh wall width. Normally, the width of the mesh wall accounts for about 5%~10% of the width of the mesh, which needs to be determined according to different applications. The shallower the mesh, the smaller the mesh volume, and the smaller the ink transfer. The mesh is too deep, the larger the ink transfer, but the mesh is easy to block, the ink is not easy to transfer, not easy to clean, usually the mesh opening ratio (mesh depth and opening ratio) is about 28%~33% more suitable for ink transfer.

How to choose anilox rollers

When choosing anilox rollers, consider comprehensive factors such as the fineness of the printed product, substrate material, plate matching, ink type, and cost factors.

1. Select the number of anilox rollers according to the fineness of the printed product

If the two fields are overprinted or the printing layout is small, you can choose an anilox roller with a higher number of mesh lines; Text and line versions can choose the appropriate anilox roller according to the size of the text and the fineness of the lines; For the printing of color screen line prints, the number of net lines of the anilox roller should be determined according to the number of lines of the printed product itself.

2. Select the number of anilox rollers according to the printing material and printing requirements

In the process of label printing, commonly used printing materials include paper, film, etc. Among them, paper includes corrugated cardboard, coated paper, self-adhesive paper, etc., and film includes PE, BOPP, etc. Different printing materials have different ink absorption amounts. For example, the ink absorption capacity of paper is large, and the drying of ink on paper mainly depends on the absorption of paper. The film is not absorbent to ink, and the drying of ink mainly depends on volatilization. Therefore, the selection of anilox rollers should be based on the ink absorption of the substrate material to choose anilox rollers with different number of lines.

3. Select the number of anilox roll lines according to the number of lines on the printing plate

Practice has proved that in order to obtain high-quality prints, the number of net lines of the anilox roller should maintain a certain proportional relationship with the number of printing plate and screen lines, that is, the number of screen lines of the anilox roller should generally be 4~8 times the number of printing plate plus screen lines. For field printing, if the number of net lines of the anilox roller is too low, the ink supply is too large, and the edge of the printing plate will cause ghosting on the edge of the printed product due to ink accumulation; If the number of network cables is too high, the ink supply is insufficient, and the printing field density is not enough, it will make the printed product bloom. Therefore, in actual work, the number of net lines of the anilox roller must be reasonably selected according to the amount of ink supply.

4. Choose the anilox roller mesh shape according to the ink type

For some inks and coating liquids with high viscosity, an open mesh shape should be selected as much as possible, so that the ink medium can bring better leveling effect when transferred to the substrate and ensure the uniformity of the print.

Common problems with anilox roll use

The anilox roller will encounter some problems during use, affecting ink transfer, thereby affecting the quality of the print.

A bright line appears in the circumferential direction of the roller surface

This problem is mainly caused by scraper scratches. If the impurities and dry ink are present in the ink circulation system, friction will form between the squeegee and the anilox roller, and then there will be circumferential scratches on the surface of the ceramic area, which is manifested as a circumferential bright line. The solution to this problem is to thoroughly clean the ink tank, closed scraper cavity and ink circulation system in time, strictly control the scraper pressure, ensure the flatness and straightness of the scraper blade installation, and choose high-quality scraper blades.

There are dents in the circumferential direction of the roller surface

This problem is often caused by abnormal contact between the squeegee and the anilox roll or the embedding of hard objects. Solutions to this include: checking whether the scraper is installed properly; Check whether there are impurities or chips in the scraper edge; Remove dry ink or impurities in the ink tank or cavity in time.

The roller surface is partially dented or the end face ceramic falls off

This problem is often caused by external forces. The solution to this includes: preventing hard objects from contacting, colliding and knocking with the roller surface; The anilox roller effectively protects the roll surface during loading, unloading or handling; Master the correct method of cleaning anilox rollers.

Spots or water ripples appear on the roller surface

This problem is often caused by residual ink on the mesh wall and bottom of the mesh, uneven wear of the roller surface and scraper, or improper cleaning methods. The solution to this includes: choosing the right method to clean the anilox roller in time and effectively; Proper installation and use of scrapers; If you use ultrasonic cleaning, minimize the number and time of cleaning, it is not recommended to use ultrasonic cleaning methods for high mesh wire anilox rollers to avoid mesh wall breakage.

Irregular bulges appear on the roll surface

This problem is mainly caused by solvent erosion in inks or cleaning chemicals. Solutions include: detecting the composition of the ink; Do not use strong acid and alkaline cleaning agents; After using the cleaning agent, the residual solution must be cleaned with clean water immediately; Minimize the use of aluminum-based anilox rollers.

The amount of ink transferred decreased

This can be caused by worn mesh, clogged mesh, or decreased ink color density. Solutions to this include: inspecting the mesh, if it is severely worn, it is recommended to rework; If the mesh is blocked, the anilox roller should be effectively cleaned in time; Check for differences in ink composition or batch.