How CI Flexo Printing Machines Operate Explained Simply

The working principle of a CI flexographic printing press can be summarized as follows: the central impression cylinder is the center, driving the continuous movement of the flexible substrate. Multiple printing units are synchronized around it to complete the ``ink supply, ink transfer, imprint, drying"and other processes, finally achieving precision, multi-color printing of a pass.
1.Core Transmission: Role of the Central Impression Cylinder
The central impression cylinder is the "hub"of the whole machine. Its smooth surface and diameter are significantly larger than other cylinders.
It rotates at a constant speed, steadily propelling the flexible substrate (such as plastic or paper) pressed against it, ensuring that the substrate does not stretch or deflect throughout the process.
All printing units (usually in groups of 6-10) are arranged in a circle around it. Each set of plate cylinders directly press the central drum, no separate impression roller is required. ii. Key steps: Four-step Multi-Color Printing
The process is constantly automated and every step is seamlessly integrated. It is divided into four steps:
Substrate Supply (Unwinding)
Flexible substrates are rolled out by an unfurling mechanism, and tension control system regulate tension to ensure that the substrates are smooth and evenly drawn, preventing creases or fractures.
Ink Transfer and Impression
Each printing unit is individually monochrome printed. Its core is the anilox roller, plate cylinder and central roller.
The anilox roller pulls ink out of the ink tank, and the doctor blade to remove excess ink, precisely controlling the amount of ink delivered.
Ink is transferred from the circuit the anilox roller to the image portion of the flexible version.
The plate cylinder presses the central impression cylinder, transferring the plate ink to the moving substrate.
Instant Drying (Curing)
After printing each color, the substrate immediately enters the drying unit of the corresponding color unit (hot air drying or UV curing) to quickly set the ink to prevent color mixing and staining during subsequent overprinting. Finished Product Rewinding
After printing and drying all colors, the substrate is rewound into a large volume through a winding mechanism, pending subsequent secondary processing, such as sectioning and bagging.