In short, the operation principle of flexographic printing machine is basically a printing method composed of cylinder and anilox roller. It is required to adopt the mechanical structure that can be quickly and easily installed when replacing the cylinder/anilox roller/scraper. The following is a brief introduction to the different ink supply systems of existing flexographic printing machines:
1. Double roll type
Although there are also two roller types without scraper, the scraper is usually used to scrape off the excess ink on the surface of the anilox roller to ensure that the correct amount of ink is provided to the layout. Theoretically, it is OK to immerse the anilox roller directly into the ink without using the hinge roller. However, the grid on the surface of the anilox roller cannot provide enough ink when it runs at high speed, which may cause the problem of flying white or ghost. In the scraper type working mode, on the one hand, the anilox roll is very easy to exchange, and on the other hand, because the positive and reverse printing is not possible, the same printing unit cannot use both front and back printing. In addition, it should be noted that the rubber roller is the source of flying ink, which may contaminate the printed matter.
2. Ink bucket type
Like offset printing and embossing, ink is supplied by the ink bucket. The space saving simplified method is adopted. Because the amount of ink used is less, it is mostly oriented to small batch production. But the exchange of scraper and anilox roller is troublesome.
3. Doctor blade chamber type
A sealed chamber is arranged between the anilox roller and the scraper, and the ink is supplied circularly. The system does not take up space; Because the chamber is closed to the ink pump, it is suitable for solvent/water-based inks that need to maintain a certain concentration.
In general, the ink system must be removed when the scraper or anilox roll is exchanged. This working mode also requires a circulating pump to keep the ink circulating. In addition, when changing the color, it is necessary to spend some time to clean the hose and pump.