Central impression printing machine, or CI, flexo printing machine means that decks are arranged around a single, large-diameter impression cylinder.
In a modern flexographic press, each print unit comprises of:
Anilox roller: a cylinder of highly engineered metal and/or ceramic, which is laser engraved with minute cells of a given angle, line screen, and volume to deliver the required fineness of print,
Chambered doctor blade system: a device that delivers a measured amount of ink to the cells of the anilox roller Plate cylinder: which the printing plate is mounted upon Impression cylinder: a sleeve that supports the substrate as the printing plate is pressed against it
Inking system: ink holding tank, ink pump with delivery and return ink lines, plus other elements to ensure the maintenance of ink supply and viscosity
Between the print units, driers may be installed so that subsequent colors can be applied to the substrate without merging into those previously printed.
These driers may utilize hot air, infrared or ultra-violet light, depending on the application.
During the printing process, the ink is pumped into the ink chamber of the doctor blade system. Two blades within the ink chamber, the barrier blade, and the doctor blade, seal either end and confine the ink to the chamber while it is in contact with the anilox roller. As the anilox roller rotates, the cells in contact with the doctor blade system collect ink, and then any surface excess is removed as the roller passes under the doctor blade. As the anilox rotates, its surface comes into contact with the raised areas of the printing plates mounted on the plate cylinder, transferring the ink. The printing plate then rotates and transfers the image onto the substrate.
CI Flexo Printing Machine Applications:
The applications of CI flexo printing include the manufacture of flexible and aluminum packaging, pre-print liners and labels, plastic and paper bags, heavy-duty paper sacks, and shrink sleeves.
Process advantages:
The flexo printing press offers users a number of advantages, not least that the most readily available inks are water-based and therefore easier to work with and faster to dry.
The manufacture of flexo printing plates is relatively straightforward and the process is also easily adaptable to a wide range of substrates.
The high print quality and registration accuracy of CI (Central Impression) flexo printing are well established, while recent developments among in-line flexo printing presses have meant that flexographic presses are now able to compete against gravure and litho machines in areas such as fiber-board packaging manufacture.
