What Is A CI Type Flexographic Printing Machine? What Is The Power Of Central Imprinting in This Article?

When it comes to flexographic printing machines, many industry insiders often talk about "CI" and "unit." For packing plants that are new to the industry or want to upgrade their equipment, understanding what CI is and what its core advantages lie is a first step in selecting equipment and determining the process. This article will explain the concept of central imprinting"in a simple way.
1. What exactly is Type CI? Mystery of names
CI is short for Central Impressions. The CI Flexo Printing Machine, also known as the "central impression cylinder flexographic printing machine, has a large central impression cylinder at its core, with all of the printing color groups distributed in a circular pattern.
Simple understanding: the paper roll enters from one direction, travels along the surface of the drum, and passes through groups of prints arranged in a circle along the way. When multicoloured printing is complete, come out the other side. Since all printing plates are pressed on the same large cylinder, the paper remains attached to the cylinder surface throughout the printing process in a very stable position.
Instead, they are called "flat flexo presses," in which groups of colors are arranged in straight lines and strung together. Both structures have their advantages, but in some areas, the advantages of CI model are overwhelming.
2, How does CI type work?
Take, for example, the common 6-color CI flexographic press: in the center is a large-diameter lithography cylinder surrounded by six uniform lithography units, each consisting of a mesh roller, scraper roller, plate roller and impression mechanism. The printing material is pressed against the surface of the central cylinder and is printed in six different colors at once by passing through 6 units in sequence.
Crucially, the printed material is always attached to the same cylinder from input to output without any "loose repositioning" process, which structurally ensures that the printing benchmark are exactly the same between each color group. Interference factors such as tension, elongation and deformation have been significantly eliminated.
3, What are the core strengths of CI?
1. Print accuracy is the book of your life
The biggest trump card in an overprint structure is its stability. Since all colors are completed around the same drum, the paper does not need to be stretched or positioned multiple times between different color groups, and cumulative printing errors are minimal. It can achieve stable precision, very suitable for patterns, lines, small print and other products with strict requirements.
2. Good tension control makes the film material friendlier
When printing easily stretched substrate such as plastic film and shrinkage film, due to long traction paths and high tension fluctuations, the cell types tend to have overlapping drift and color misalignment. CI paper has a short path, printing material is always glued to the drum, tension is extremely stable, is the film flexible packaging printing is the absolute mainstream solution.
3. Plenty of colours to do with
With a circular layout, the CI model can easily achieve 6, 8 or more color combinations, with little increase in body length, more compact factory space, and easy to change and move paper.
4. Drying and paper feeding integration, more consistent performance.
Central drum structure is convenient to arrange a reasonable drying system according to the circumference, uniform drying distances between colors, suitable for high-speed continuous production, as well as a variety of water-based ink, UV ink and other process combinations.
4, Limitations of Type CI: Not a panacea.
CI model also has drawbacks. Firstly, the large diameter and weight of the central embossed cylinder results in relatively high overall and maintenance costs. Secondly, for certain tissue and breathable materials, such as paper (rather than film), the circular diameter is not as adaptable and flexible as the element type. Thirdly, the thickness range substrate is limited by the adjustment of drum gap, making it more difficult for the machine to adjust when material specifications change significantly. Therefore, cardboard preprinting, labeling and so on mostly adopts the modular approach, while soft packaging film printing almost entirely choose CI.
5, Choose CI or unit type? Get a good look at the table
Tables
| Size | Type CI (Central Embossing) | Unit |
| --- | --- | --- |
|Overprint accuracy | Very high | Structurally stable | High, tension-controlled |
| Film-flexible packaging | Significant advantage, major solution | Difficult tension control, easy drift |
Multicolor expansion | More color groups save more space | Body elongation with number of colors|
Relatively high equipment costs relatively low
|Flexible mechanical regulation | Material replacement more complex | More flexible
|Typical Application | Soft Packaging Membrane, Composite Packaging | Label, Carton, Preprint |
6, Summary
The CI type flexographic printing machine relies on the the "central impression cylinder"innovative structure, the fundamental solution to multi-color overprinting process tension instability, accumulated errors of large industry pain points. This is almost the standard answer in the field of soft-wrap membranes. Understanding its principles, advantages and disadvantages is critical to selecting the right type: CI type is preferred in pursuit of ultimate coverage accuracy and film printing stability; modular production systems are often more appropriate for flexible labels and cartons in small and medium batch production. There is no absolute superiority or inferiority of a device, only its suitability for its own product. If you think about it, you won't take down the wrong path when choosing a machine.