The hottest laser technology improves the quality

2022-08-08
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Laser technology improves the quality of flexographic printing

laser technology is mainly used in two aspects of flexographic printing: laser engraving ceramic roller and laser direct plate making. The application of laser technology in flexographic printing has greatly improved the quality of flexographic printing. In the American FTA's quality evaluation this year, some printing lines have reached 200 lines/inch. In addition, according to the data provided by laserlife in Australia, they use the latest Hercules laser engraving equipment, which can engrave 2000 lines/inch of embossing rollers, and 1% of the points of 200 lines/inch plates. Laser technology not only enables flexographic printing to achieve high-quality printing quality, but also uses laser engraving seamless plate sleeve technology, which can also make flexographic printing more widely applicable. The application of laser technology in flexographic printing makes the quality of flexographic printing closer to offset printing and gravure printing, which lays the foundation for flexographic printing to eventually occupy a dominant position in the packaging printing industry

laser technology improves the quality of ink transfer in flexo printing

laser technology was first used in the manufacturing process of ceramic roller. Laser technology realizes the production of high-speed roller, improves the ink transfer quality of roller, and greatly extends its service life. Domestic and foreign flexo printing machines are equipped with ceramic rollers to improve the grade of the machine and the printing effect. Even for corrugated paper printing, most people have realized the importance of using ceramic roller to improve printing quality. As an important part of flexographic press, ceramic roller has a great impact on the whole flexographic printing

the manufacturing process of ceramic roller is quite complex, and the two most critical parameters are the number of lines and the ink carrying capacity of holes. The number of lines is generally determined according to the lines of printed matter. According to the special proportional relationship between the number of printing lines and the number of wrinkle roll lines, the number of wrinkle roll lines can be determined. At present, with advanced laser engraving equipment, 2000 lines/inch can be engraved, but this kind of high-speed line will not be used in actual flexographic printing in the short term. Even a 200 line/inch print will not be equipped with more than 1400 lines/inch. Due to the small hole opening, too thin wall and poor wear resistance of the corrugated roller of ultra-high line, its service life will also be reduced. In addition, the corrugated roller of ultra-high line will also increase the difficulty of cleaning the corrugated roller. Considering various factors, we suggest that the printer should try to reduce the number of lines selected for the corrugated roller under the condition of printing permission

another important parameter in the production of corrugated rollers is the ink transfer capacity. The unit of ink transfer volume BCM is obtained by using advanced Wyko computer interferometer through tomography and integration. It is the standard measurement unit of hole volume. As a quantitative ink transfer roller, the ink transfer volume of the wrinkle roller is determined by the number of lines and hole volume. The higher the line, the higher the requirement of hole volume. When high-speed lines are used for hierarchical printing, if the ink transfer is not accurate, the printing effect will be very obvious. For roller manufacturers, they have the obligation to choose the best ink transfer volume for users, which should not be misleading. In the past, a domestic factory used a foreign manufacturer's high-speed corrugated roller because the ink transfer capacity was too high, which was more advantageous than the electronic universal testing machine with an ink transfer capacity of less than 30t. This is enough to illustrate the importance of hole volume to the production of corrugated roller

generally, each corrugated roller manufacturer has certain reference standards for the selection of hole volume, and these standards are basically the same. Manufacturers can also engrave the special hole volume required by users. We will provide a set of hole volume data for users to choose before reducing or not using various solvents. These data are based on our years of production experience, and users' use is also very successful. A more scientific method to select the volume of lines and holes is to use the corrugated roller test technology. With this test technology, you can select the best indicators of the number of lines and hole volume, see the actual printing effect before printing, and avoid unnecessary losses. Once a data is wrong, the loss is difficult to make up

how to select and match the corrugation roller correctly, how to maintain the corrugation roller, etc., these problems are more critical for users

corrugation roller is an important part of flexo printing machine, and it is also closely related to flexo printing plate and ink. When selecting and matching corrugation roller, the following factors should be considered

1. Ink type. The inks used in flexographic printing usually include water-based inks, solvent based inks, UV inks and varnishes. Different ink types will vary greatly in the ink transfer of the corrugated roller. Even if the ink of the same nature, its quality and adhesion viscosity are also different, and there will be differences in ink transfer

2. Plate materials. At present, flexographic printing mostly uses resin plates, but some still use rubber plates. The plates of these two materials have different adsorption properties to ink. In resin printing plates, there are also inked plates and non inked plates. It will have a great impact on the ink transfer quality of the corrugated roller

3. Type of printing plate. On the spot full plate (glazing), low line and high line. It is noteworthy that line level printing has very strict requirements on the roller line and ink transfer volume. A slight error will lead to the decline of printing quality or printing failure

4. Substrate for printing. Paper, plastic film and corrugated board have different and influence on the adsorption and color of ink. The adsorption of plastic film on ink is poor, which requires that the ink transfer volume of the corrugated roller be lower, and that of paper be higher

5. Scraping mode. The ink scraping method also has a certain influence on the ink transfer effect of the corrugated roller. When making corrugated rollers, tell the manufacturer the specific scraping methods: rubber roller scraping, forward or reverse scraping, closed scraping system

in the process of using the corrugated roller, its maintenance is very important. In the past, many people didn't pay attention to the maintenance of corrugated rollers. Or the maintenance method is improper. In particular, there is no correct understanding of the cleaning of corrugated rollers, resulting in many quality problems. After several years of development, we have gradually realized the importance of the maintenance and cleaning of the roller to improve the printing quality, especially in the printing plants engaged in narrow width and wide width flexo printing

the maintenance of wrinkle roll includes the following parts:

1 Protect the surface of the corrugated roll when replacing it, and use a leather cover when storing it

2. The replaced corrugated roller should be cleaned in time

3. Place a magnetic filter in the ink tank to avoid metal impurities scratching the roller

4. Select high-quality scraper and blade type. It is recommended to use plastic scraper to better protect the wrinkle roll

5. Use a hole microscope to detect the hole. If wear and blockage are found, measures should be taken in time

in the past, when people encountered the phenomenon of light or uneven ink, they often looked for the reason of ink, printing plate or paper, but finally found that it was caused by hole blockage and decreased ink transfer. Now when you encounter a similar problem, you may first think of the problem of the wrinkle roll. However, some corrugated paper printing plants do not pay enough attention to the printing quality themselves, not to mention the maintenance and cleaning of the corrugated roller, and the blocking of the corrugated roller seriously affects the printing quality. Such a long-term vicious cycle is detrimental to the development of the whole enterprise. If this goes on, it will also affect the overall development of flexo printing and corrugated paper printing in China. On the contrary, some large and medium-sized printing enterprises with joint venture and sole proprietorship in China attach importance to printing quality and every link in the printing process due to different management concepts and market awareness. This management experience and practice is worth learning from

generally speaking, the ceramic roller is not easy to wear. If it is found that the ink transfer volume decreases, most of the reasons are caused by the blockage of the roller hole. The existence of blockage in the hole can be clearly observed with a high-power hole microscope. Because the ink used in flexographic printing is easy to dry, it is not easy to dissolve and clean after drying, and the holes are blocked for a long time; In addition to affecting the amount of ink transfer, it will also shorten the service life of the corrugated roller. The long-term use of corrugated rollers with blocked holes will also increase the loss of ink, and there will be white exposure and dark ink during printing, especially for large-area field printing, which will have a greater impact. Therefore, it is very important to ensure the good cleaning of the embossing roller for stabilizing the printing quality

the cleaning of corrugated rollers is divided into daily cleaning and periodic cleaning

daily cleaning is to clean the wrinkle roll in time after shutdown, which can effectively prevent the ink from drying in the hole. Generally, special chemical cleaning agent is used to soften and dissolve the ink in the hole to achieve the purpose of cleaning. The specific cleaning method is to put the corrugated roller in the cleaning solution for a period of time, evenly spiral brush the surface of the corrugated roller with a special steel wire brush (copper wire brush is used for metal corrugated roller), and then rinse with water. Flexoclean cleaning agent is a kind of environmental protection product with strong pertinence and obvious cleaning effect. At present, it has been widely used in domestic flexo printing and corrugated paper printing industry. It can effectively clean water-based inks, solvent based inks, UV inks, varnishes, etc. After three years of promotion in the domestic market, many users have used fulaikeli products at present

for corrugated rollers with serious hole blockage, the effect of periodic cleaning will be more obvious. The principle of periodic cleaning is to use the principle of low-pressure spray washing the residue of baking soda impact hole to achieve the purpose of cleaning. Using our corrugation roller cleaning machine to clean a corrugation roller for narrow 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 have used our various models of cleaning machines

for manufacturers who have recently introduced flexographic printing equipment, in addition to the more reasonable configuration of corrugated rollers gb/t3098.2 (2) 000 "mechanical properties of fasteners nuts coarse rib", they also purchased corrugated roller cleaning equipment, which is undoubtedly good news for China's flexographic printing. Attaching importance to printing quality shows that flexographic printing in China has entered a virtuous cycle

source: China laser

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