The influence of laser engraving technology on the development of flexo printing
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Laser technology is mainly used in two aspects of flexographic printing: laser engraved ceramic anilox rolls and laser direct plate making. The application of laser technology in the field of flexography has greatly improved and improved the quality of flexographic printing. In the FTA's quality assessment this year, part of the printed network of exhibitors has reached 200 lines/inch. According to data provided by LASERLIFE, they use the latest Hercules laser engraving equipment to engrave 2000 lines/inch anilox rolls, and 200 lines/inch plates with 1% of the dots. Can be carved. In addition to the high quality of printing quality, the laser technology uses laser-engraved seamless plate sleeve technology to make flexographic printing more widely available. 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 finalization of flexographic printing in the packaging printing industry.
Laser technology improves the quality of flexographic ink transmission
The laser technology was first applied in the manufacturing process of ceramic anilox roller. The laser technology realized the production of high-network anilox roller, and improved the quality of the anilox roller, and greatly prolonged the service life. At home and abroad, the flexo printing machine has a ceramic anilox roller installed on the machine to improve the machine grade and printing effect. Even for corrugated printing, most people are aware of the importance of applying ceramic anilox rolls to improve print quality. Ceramic anilox rolls are an important part of the flexo press and have a huge impact on the overall flexographic printing.
The manufacturing process of ceramic anilox rolls is quite complicated, and the two most important parameters are the number of screen lines and the amount of ink carried by the mesh. The number of network cables is generally determined based on the network cable of the printed matter. According to the special proportional relationship between the number of printing screen lines and the number of anilox rolls, the number of lines of the anilox roll can be determined. At present, advanced laser engraving equipment can engrave a network cable of 2000 lines/inch, but this high-speed cable will not be applied to actual flexographic printing in a short period of time. Even an anilox roll of 200 lines/inch print will not exceed 1400 lines/inch. Since the mesh opening of the ultra-high mesh wire has a small mesh opening, the mesh wall is too thin, the wear resistance is poor, and the service life is also reduced. In addition, the anilox roller of the ultra-high mesh line also increases the difficulty of cleaning the anilox roller. Based on various factors, we recommend that printers minimize the number of lines used in the anilox roll under the conditions of printing permission.
At the 5th International Printing Technology Exhibition in Beijing held in May this year, the printing effect of the 850-900 line/inch anilox roller provided by the two companies of Shanghai Ziguang and Shanxi Taihang was obtained by the flexo expert. With the praise of peers, this is the proof that we have accumulated many years of production experience to provide users with qualified products. At present, we have provided thousands of high-quality anilox rolls for many domestic flexo printing machine manufacturers and printers, and provided them with flexographic related products and technical services.
Another important parameter in the production of anilox rolls is the amount of ink transferred. The unit BCM of the ink transfer amount is obtained by using the advanced WYKO computer interferometer through tomography and integration, and is the standard unit of measurement of the mesh volume. As a quantitative transfer roller, the amount of ink transferred by the anilox roller is determined by the number of screen lines and the mesh volume. The higher the network cable, the higher the requirement for the mesh volume. The high-speed cable is used for layer printing. If the amount of ink is not accurate, the effect on the printing effect is very obvious. For anilox manufacturers, there is an obligation to choose the best amount of ink for the user, and it cannot be misleading. In the past, a domestic factory used a high-network anilox roll from a foreign manufacturer because of the problem of excessive ink transfer, which is enough to explain the importance of the mesh volume to the anilox roll.
Generally, each anilox roll manufacturer has certain reference standards for the selection of the mesh volume. These standards are basically the same. Each manufacturer can also engrave the special mesh volume required by the user. We provide a set of mesh volume data to the user before the user makes the anilox roller. These data are based on our many years of production experience, and the user's use is also very successful. The more scientific method of selecting the cable and mesh volume is to use the anilox test technology. With this test technology, you can select the best indicator of the number of mesh lines and mesh volume, and see the actual printing effect before printing to avoid unnecessary loss. Once a data is wrong, the damage is irreparable.
Shanghai Aucley is an investment company of Australia's LASERLIFE company. Laser Rich has advanced Hercules high-precision laser engraving equipment. Laser to Rich Company produces high quality anilox rolls in strict accordance with the ISO9002 standard, and there will be a WYKO test report when each anilox roll is delivered to the user. For high-network anilox rolls, lasers are enriched with advanced YAG laser engraving to pursue more accurate ink transfer. In addition to achieving higher network cables, YAG engraving is important for greatly increasing the amount of ink carried. YAG engraving is the most advanced laser engraving method. Many of the world's largest anilox roller manufacturers use YAG to engrave high-network anilox rolls.
In the second half of this year, the advanced laser engraved ceramic anilox roller production line introduced by Shanghai Aokeli will be put into production. In addition to providing high quality products for domestic users, it can also greatly shorten delivery time, reduce costs, and timely Users solve related technical problems.
How to properly select the anilox roller, how to maintain the anilox roller, etc., these problems are more critical for the user.
The anilox roller is an important part of the flexo printing machine. At the same time, it has a great relationship with the flexographic printing plate and the ink. When selecting the anilox roller, the following factors should be considered.
1. Ink type. The inks used in flexographic printing usually include water-based inks, solvent inks, UV inks, and glazing oils. Different ink types can make a big difference when the anilox roller transfers ink. Even if the ink of the same nature, its quality and adhesion viscosity are different, there will be differences when transferring ink.
2. Plate material. Resin plates are often used in flexographic printing, but some still use rubber plates. The plates of these two materials have different adsorption properties for inks. In the resin plate, there will also be a distinction between the inking plate and the non-inking plate. For the quality of the anilox roller, it will have a great impact.
3. Plate type. The full-page (glazing), low-network and high-network line printing on the ground has very strict requirements on the anilox roller network and the amount of ink transferred. A slight error will lead to a decline in printing quality or printing failure.
4. Printing substrate. Paper, plastic film, corrugated cardboard have different effects on the adsorption and color of the ink. The plastic film has poor adsorption to the ink, and the amount of ink transferred by the anilox roller is required to be lower, and the paper requires a higher amount of ink.
5. Scrape method. The ink wiping method also has a certain influence on the ink transfer effect of the anilox roller. When making an anilox roll, tell the manufacturer the specific way to smear: rubber roller squeegee, forward or reverse squeegee, closed squeegee system?
During the use of the anilox roller, its maintenance is very important. In the past, many people did not pay attention to the maintenance of the anilox roller. Or the method of maintenance is not appropriate. In particular, there is no correct understanding of the cleaning of anilox rolls, and many quality problems arise. After several years of development, we have gradually realized the importance of maintenance and cleaning of anilox rolls to improve the quality of printing, especially for printing companies that are engaged in narrow and wide flexo printing.
The maintenance of the anilox roller includes the following parts:
1. Protect the anilox roller surface when replacing the anilox roller. Use a leather case when storing.
2. The replaced anilox roller should be cleaned in time.
3. Place a magnetic filter in the ink tank to prevent metal impurities from scratching the anilox roller.
4. Use high-quality scraper and knife edge type, it is recommended to use plastic scraper to better protect the anilox roller.
5. Use a mesh microscope to detect the mesh. If wear and blockage are found, take measures in a timely manner.
In the past, when people encountered light ink or uneven ink color, they often searched for ink, printing plates or paper. Finally, they found that the mesh was clogged and the amount of ink transferred was reduced. Now, the first thing that comes to mind when encountering similar problems is the problem of the anilox roller. However, some corrugated printing factories, they themselves pay insufficient attention to the quality of printing, not to mention the maintenance and cleaning of the anilox roller, and the obstruction of the anilox roller seriously affects the printing quality, so the long-term vicious circle is not good for the development of the whole enterprise. of. This will also affect the overall development of China's flexo and corrugated printing. On the contrary, some of our domestic joint ventures and wholly-owned large and medium-sized printing enterprises, due to different management concepts and market awareness, they attach importance to printing quality and every aspect of the printing process. This management experience and practice is worth learning.
In general, ceramic anilox rolls are not easily worn, and if the amount of ink transferred is found to be reduced, most of the causes are caused by clogging of the anilox roll mesh. The presence of a blockage in the mesh can be clearly observed with a high-power mesh microscope. Since the ink used in flexographic printing is easy to dry, it is not easy to dissolve and clean after drying, and the mesh is blocked for a long time; in addition to affecting the amount of ink transferred, the service life of the anilox roller is also shortened. The long-term use of the anilox roll blocked by the mesh will also increase the loss of the ink, and the phenomenon of whiteness and inelasticity during printing may occur, especially for large-area solid printing. Therefore, it is very important to ensure good cleaning of the anilox roller for stable printing quality.
The cleaning of the anilox roller is divided into daily cleaning and periodic cleaning.
Daily cleaning is the cleaning of the anilox roller in time after shutdown, which can effectively prevent the ink from drying out 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, and use a special wire brush (copper wire brush for the metal anilox roller) to uniformly spirally brush the surface of the anilox roller, and then rinse with water after washing. 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 the domestic flexo printing and corrugated printing industry. It can effectively clean water-based inks, solvent inks, UV inks, glazing oils, etc. After three years of promotion in the domestic market, there are many users who use Fulai Keli products.
For anilox rolls with a serious mesh plugging, the effect of periodic cleaning is more pronounced. The principle of periodic cleaning is to use the principle of low pressure spray baking baking soda powder to hit the mesh residue to achieve the purpose of cleaning. Use our anilox roller cleaning machine to clean an anilox roller for narrow-width flexo printing machine. The cleaning process takes only 3-5 minutes, the cleaning effect is obvious, and the operation is simple. Nearly 100 flexo and corrugated printing plants in China use various types of washing machines we produce.
For the newly introduced manufacturers of flexographic printing equipment, in addition to the more reasonable configuration of the anilox roller, they also purchased the anilox roller cleaning equipment, which is undoubtedly good news for China Flexo. Paying attention to printing quality, it shows that our country's flexographic printing has entered a virtuous circle.
The impact of laser technology on the development of flexo printing
Another important application of laser technology in the field of flexography is in plate making. Laser-engraved seamless plates enable continuous printing of flexographic printing, extending flexographic printing to a wider range of packaging and printing applications. The application and promotion of direct plate making technology using laser on photosensitive resin materials has created conditions for the final realization of high quality in flexographic printing.
At first, laser technology only engraved some lines and characters on a sleeve plate made of rubber material. Due to material limitations, the engraved network cable was not very high. This plate sleeve can only print some solid or simple text, such as cigarette tipping paper and exercise book lines, wrapping paper, wallpaper, etc. Later To achieve higher-level continuous color printing, in order to achieve higher printing network, several manufacturers of flexographic materials in the world are developing a resin material that can be laser-engraved. After several years of hard work, companies such as DuPont and BASF have introduced this material. With these materials and laser engraving equipment, the plate network cable can reach 200 lines/inch and above and 1% dot percentage. The actual printing effect of the machine is also recognized by the industry, and the printing quality is close to the offset and gravure levels. In China, because this technology has just been promoted, it is still immature in terms of technology and market. It takes a period of exploration and practice and will not be popularized in the short term. In addition, the high plate-making costs caused by the plate-making materials and plate-making equipment have also affected the development of laser direct plate-making in China to some extent.
Flexographic printing is a special printing method that relies more on supporting materials and technologies. Its development will be restricted by various factors. China's flexo printing has only developed in recent years. Although it has received many attentions, the talents who are truly proficient in this printing method are limited, and the technical and industry standards for flexographic printing are not yet complete. In addition, excessive dependence on imported supporting printing materials will lead to excessive printing costs, which is not conducive to the future development of flexographic printing in China.