Laser Technology Improves Flexographic Printing Quality

Laser technology is mainly used in two aspects of flexo printing: laser engraving ceramic anilox and laser direct plate making. The application of laser technology in the flexographic field has greatly improved and improved the flexographic printing quality. In the quality assessment of the FTA of the United States this year, some of the exhibition's print cable has reached 200 lines/inch. In addition, according to data provided by LASERLIFE of Australia, they use the latest HERCULES laser engraving equipment, which can engrave 2000 lines/inch anilox roller, and 1% of the 200 line/inch plate is also available. Can engrave. In addition to the high quality of the printing quality achieved by flexographic printing, laser technology uses a seamless engraving sleeve technology that is laser-engraved, which also allows flexographic printing to be used in a wider range of applications. The application of laser technology in flexographic printing has brought the quality of flexographic printing closer to offset and gravure printing, laying the foundation for the ultimate position of flexographic printing in the packaging and printing industry.

Laser Technology Improves the Quality of Flexo Ink Transfer

The laser technology was first applied in the production process of ceramic anilox rollers. The laser technology realized the production of high-line anilox rollers, and improved the quality of the anilox roller's ink transmission and greatly extended its service life. Domestic and foreign flexographic presses are equipped with ceramic anilox rollers on the machine to improve the machine grade and printing effect. Even for corrugated printing, most people have realized the importance of applying ceramic anilox rollers to improve the printing quality. As an important part of the flexo press, the ceramic anilox roll has a huge impact on the overall flexographic printing.

The production process of ceramic anilox roll is quite complex, and the most important two parameters are the number of mesh lines and the amount of mesh loading ink. The number of network lines is generally determined according to the printed network cable. According to the special proportion of printing screen and anilox roller number, the number of lines of the anilox roller can be determined. The current use of advanced laser engraving equipment can engrave up to 2000 lines/inch, but this high-line cable will not be applied to practical flexo printing in the short term. Even 200 lines/inch prints do not have more than 1400 lines/inch. Due to the small mesh opening of the anilox roller of the ultra-high net line, the net wall is too thin, wear resistance is poor, and the service life is also reduced. In addition, the anilox roller of the super high net line will also increase the difficulty of cleaning the anilox roller. In combination with various factors, we recommend that printers reduce the number of lines selected for anilox rollers as much as possible under the conditions of print permission.

Another important parameter of the anilox roll production is the amount of ink transferred. The unit BCM of the ink transfer amount is obtained by the advanced WYKO computer interferometer through tomography and integration, and is the standard unit of measurement for the mesh volume. As a quantitative transfer roller, the ink transfer volume of the anilox roller is determined by the number of screen lines and the volume of the mesh. The higher the cable, the higher the requirement for the volume of the mesh. High-network cable is used for printing in a hierarchical format. If the amount of ink transferred is inaccurate, the effect on the printing effect is very obvious. For anilox roller manufacturers, there is an obligation to choose the best amount of ink for the user and it should not be misleading. In the past, a high-net-line anilox roll used by a foreign company in a certain factory in the country had problems due to the high ink transfer amount, which was enough to explain the importance of the mesh volume to the anilox roll production.

In general, every anilox roller manufacturer has a certain reference standard for the selection of the mesh volume. These standards are basically the same. For the special mesh volume required by the user, each manufacturer can also sculpt. We provide a set of mesh volume data to the user before the user makes the anilox roll. This data is based on our many years of production experience, and the user's use is also very successful. The more scientific method for selecting the network cable and mesh volume is to use anilox roller testing technology. With this test technology, the best index of the number of screen lines and mesh volume can be selected, and the actual printing effect can be seen before printing to avoid unnecessary. loss. Once a data error occurs, the resulting loss is difficult to make up for.

How to correctly select the anilox roller, how to maintain the anilox roller, etc., these issues are more critical for the user.

Anilox roller is an important part of flexo printing machine. At the same time, it has a lot to do with flexographic printing plate and ink. When selecting anilox roller, we should consider the following aspects.

1. Ink type. The inks used in flexo printing are usually water-based inks, solvent inks, UV inks, and coating oils. Different ink types can vary greatly when anilox rollers transfer ink. Even if the same type of ink, its quality and adhesion viscosity are different, there will be differences when transferring ink.

2. Plate material. Flexographic printing now uses resin plates, but some still use rubber plates. The two materials have different ink adsorption properties. In the resin plate, there will also be an inked plate and a non-inked plate. For the quality of the transfer ink of the anilox roller, it will have a great influence.

3. Plate type. The full-screen (glazing), low-line, and high-line printing on the ground all have very strict requirements on the anilox roller line and the amount of ink transferred. A slight error can result in a drop in print quality or a failure in printing.

4. Printing substrate. Paper, plastic film, and corrugated board have different effects on ink absorption and color. The plastic film has poor ink adsorption, requiring the anilox roller to transmit less ink, and the paper requires higher ink transfer.

5. Scraping method. The method of scraping ink also has some influence on the ink transfer effect of the anilox roller. When making the anilox roller, tell the manufacturer specific ways to wipe the ink: rubber roller scraping, forward or reverse scraping, closed scraping system?

During the use of the anilox roller, its maintenance is very important. In the past, many people did not attach importance to the maintenance of anilox rollers. Or it is improperly maintained. In particular, cleaning of the anilox roll is not properly understood and many quality problems have arisen. After several years of development, we have gradually realized the importance of the maintenance and cleaning of anilox rollers for improving the quality of printing. This is especially true for printing plants that perform narrow and wide flexo printing.

Anilox roller maintenance includes the following sections:

1. Protect the anilox roller surface when changing the anilox roller. Use a leather case when storing.
2. Replace the anilox roller for timely cleaning.
3. Place a magnetic filter in the ink tank to prevent metal impurities from scratching the anilox roller.
4. Select high-quality scraper and knife type. It is recommended to use plastic scraper to better protect the anilox roller.
5. Use a mesh microscope to inspect the mesh. If any wear or blockage is found, take measures in time.

In the past, people often encountered ink, printing plates, or paper when they encountered light ink or uneven ink. Finally, they found that they were caused by blocked meshes and reduced ink transfer. Now the first thing that comes to mind when you encounter similar problems is the problem of anilox rollers. However, some corrugated paper printing plants do not pay enough attention to printing quality, let alone maintain and clean the anilox roll, and the anilox roll blockage seriously affects the printing quality. This long vicious cycle is not conducive to the development of the entire enterprise. of. If this continues, it will also affect the overall development of China's flexo and corrugated paper printing. On the contrary, due to the differences in management concepts and market awareness, some large and medium-sized printing companies with joint ventures and wholly-owned enterprises in China have attached importance to printing quality and each link in the printing process. This type of management experience and practice is worth learning from.

In general, the ceramic anilox roll is not easy to wear, if you find that the amount of ink transferred decreases, most of the reasons are caused by the blockage of the anilox roller mesh. With the high-power mesh microscope, it can be clearly observed that plugs are present in the mesh. Because the ink used in flexo printing is easy to dry, it is not easy to be dissolved and cleaned after drying, and the mesh is blocked for a long time; in addition to affecting the amount of ink transferred, the life of the anilox roll will be shortened. The use of anilox rollers that have been blocked by mesh for a long period of time will also increase the loss of ink. The phenomenon of whitening and ink coloration will occur during printing, especially for large-area field printing. Therefore, it is very important to stabilize the printing quality that the anilox roller is well cleaned.

Anilox roller cleaning is divided into daily cleaning and cycle cleaning.

Daily cleaning is the cleaning of the anilox roller in time after shutdown, which can effectively prevent the ink from drying in the mesh. Generally, a special chemical cleaning agent is used to achieve the purpose of cleaning by softening and dissolving the ink in the mesh. The specific cleaning method is to place the anilox roller in the cleaning solution for a period of time, use a special wire brush (a copper wire brush is used for the metal anilox roller) to spirally brush the surface of the anilox roller, and rinse with water after cleaning. The cleaning agent of FLEXOCLEAN is a kind of environmentally friendly product with strong pertinence and obvious cleaning effect. It has been widely used in domestic flexographic and corrugated paper printing industry. It can effectively wash water-based inks, solvent inks, UV inks, and varnishes. Thanks to our promotion in the domestic market over the past three years, there are many users who currently use Fu Lai Ke Li products.

For anilox rollers with severe mesh jams, the effect of periodic cleaning is more pronounced. The principle of periodic cleaning is to use the principle of low-pressure spray washing baking soda powder to hit the mesh residue to achieve the purpose of cleaning. Using our anilox roller cleaning machine to clean an anilox roller for a narrow web press, the cleaning process takes only 3-5 minutes, the cleaning effect is obvious, and the operation is simple. Nearly a hundred flexo and corrugated paper printing plants in China are using various types of washing machines we produce.

For the newly introduced manufacturers of flexo printing equipment, in addition to the more rational configuration of the anilox roller, they also purchased anilox roller cleaning equipment, which is undoubtedly a good news for Chinese flexo printing. Paying attention to printing quality shows that China's flexographic printing has entered a virtuous cycle.

Source: China Laser Network