Flexographic printing quantitative ink supply system

People who are involved in flexographic printing know that the quantitative ink supply system is one of the important factors that affect the final print quality and print product performance.
Many people compared the ceramic anilox roller, which is the main component of the quantitative ink supply system, to the “heart” of the flexographic printing press, and compared the other important component of the squeegee that forms the quantitative ink supply system with the “valve” of the heart. The "valve" valve effectively controls the amount of ink entering the "heart." The role of the two in the ink supply system is clear, and the status and importance of the entire ink supply system in printing machines is self-evident.
Ink Supply System Development Overview 1. Two-Roll System Usually, the quantitative ink supply of a flexographic printing press is completed by two rollers, referred to as a two-roll system. After the anilox roll is inked from the ink plate, another rubber squeegee roller scrapes the ink, and then the anilox roller transfers the ink remaining in the mesh to the plate to complete the entire process of ink transfer. From this two-roll system, a quantitative procedural ink supply can be achieved. This structure is still widely used in middle and low flexo printing presses, coaters and carton printers. Such a structure is still very suitable for occasions where the printing and coating quality requirements are not high.
2. Forward squeegee system When the control of the amount of ink is more precise, this two-roll system will have problems. Particularly when the printer speed reaches or exceeds 100 m/min, the hydraulic pressure generated by the high-speed flow of the ink between the anilox roller and the doctor roller tends to increase the gap between the two rollers, eventually causing excessive ink transfer to the plate. And printing materials. Taking into account the above problems and the requirement of accurate ink supply, people first proposed a positive-squeegee-type quantitative ink supply system similar to a gravure printing system. In this system, the rubber inking roller transfers the ink ribbon in the ink tray to the anilox roller, and then the scraper removes the ink not deposited in the mesh from the surface of the anilox roller, and transfers the ink in the mesh hole to the printing plate. Above, the function of quantitative ink supply was realized.
The anilox roller can use metal anilox roller, but its life is short. The ink supply system combined with a doctor blade is preferably made of a ceramic anilox roll for use as a metering roll. Scrapers are often made of steel, with the backing against the metal pad lining the pressure plate, and after being fitted to the metal frame, the bracket provides the proper working angle and pressure of the blade.
The so-called working angle is the angle between the blade and the tangent of the contact point. For a positive blade, this angle is usually between 55° and 60°. Like the two-roll system, when the printer speed is higher than 100m/min, the hydraulic pressure between the doctor blade and the anilox roller in this system will tend to separate the two, resulting in more ink transfer. To plate and printing materials. For more detailed printing, such results are obviously not allowed.
3. Reverse Scraper System A quantitative ink supply system using a reverse squeegee structure can solve this problem. The only difference in structure with the positive squeegee system is its squeegee position and its working angle. Normally, this angle is between 30° and 35°. Some manufacturers also design it as 40° up and down. With the reverse squeegee system, there is no hydraulic pressure lifting effect, so the printer can work at a higher level. Running speed.
4. Fully sealed double blade cavity ink fountain system The reverse blade structure solves problems that occur when the flexo press operates at high speed. However, whether it is a reverse squeegee, a forward squeegee structure or a two-roll system, both are open-type ink supply structures, and each ink source stores ink. After the ink on the ink roller belt passes through a certain process, some of it is used for printing, and the excess portion is returned to the ink tray.
This type of structure allows the ink to be directly exposed to the atmosphere over a large area. For the solvent-based ink, solvents are generated to evaporate into the surrounding air, causing changes in ink characteristics and environmental problems. Bubbles may also occur for water-based inks. Ultimately affect the quality of printing.
Fully sealed double blade cavity ink fountain system consists of anilox roller (usually ceramic anilox roller), two scrapers, sealing strips, ink storage containers, ink pumps, inking hoses and other components.
The characteristics of the system can be based on the following: In the quantitative ink supply system, a reverse scraper structure is used, so the printer can work at a high speed; the use of a solvent-based ink reduces the volatilization of the solvent inside the system, and alleviates the problem of environmental pollution; The foam problem that accompanies the use of water-based ink is terminated; the rubber-coated roller used in mining is excluded from the conventional structure; the system can be quickly docked with the cleaning system, and the ink-carrying elements inside the system can be completely cleaned within a short time. Washing reduces ink color change time. The use of pumps and cleaning agents for direct cleaning inside the ink supply seal system eliminates the need to remove rollers and other inked parts, which helps reduce downtime and give full play to the machine's productivity.