Flexo printing is a kind of relief printing, and the material of printing plate is flexible resin plate.
The three key areas of flexography are trademark label, plastic flexible packaging and folding paper boxes (such as milk boxes).
a complete set of flexo printing units is generally a reel winder.
offset printing belongs to lithographic printing, and PS plate is used as printing plate material.
books and paper packaging are generally offset printed. There are two types: lithographic type and reel type.
There are two other popular printing methods-gravure printing or screen printing
The main object of gravure printing is also plastic soft packaging, but the ink thickness of gravure printing is better than that of flexo printing. For example, instant noodle packaging bags and cigarette boxes are basically gravure printed;
Compared with flexography, gravure roller plate has long plate-making cycle, high cost and pollution, which is suitable for long-run printing. Flexographic printing is low cost and simple to make, which belongs to green plate making, but the print run of flexographic printing should not be too large.
screen printing is generally used to print special materials. Such as cloth, metal and leather, are also commonly used in the production of post-press special effects.
of course, there are usually a combination of various printing methods in practical applications.
the principle of any kind of printing is inseparable from color separation and dot. Many things can be realized by different printing methods, but the arrangement of specific technology depends on the quantity of products, economic cost, customer requirements and the length of production cycle.
flexography is a direct printing method, which is called flexography because it uses an elastic and convex image printing plate. The flexographic printing plate is glued to the printing plate cylinder, and the printing plate is fed with ink by an engraved metal anilox roller. Because flexography has great elasticity, it can transfer liquid or fat ink to almost all kinds of materials, and flexography is light pressure printing.
According to the characteristics of flexographic printing, the manuscript suitable for flexographic printing should be selected:
1. Various patterns suitable for flexographic printing, such as lines and color blocks, should be designed with spot color as the best.
2. It is difficult to achieve flexographic printing of excessively small words and lines (especially the requirements of highlighting), and it should be avoided in design.
3. The design should avoid strict registration requirements.
4. We should also consider the characteristics of the printing press and whether the original can be truly restored by ink. Half-tone manuscripts should avoid designing and selecting large-area high-gloss manuscripts and pictures.
5. The size of the manuscript should avoid high-magnification reduction and enlargement, because these will cause the loss of hierarchy.
Flexographic printing has unique flexibility, economy, and is beneficial to environmental protection, and meets the hygienic standard of food packaging printed matter, which is one of the reasons for the rapid development of flexographic printing technology abroad. However, from the current situation in China, offset printing is more popular, gravure printing has occupied a large market in the packaging industry, and flexographic printing started relatively late. Although it has indeed made great progress in recent years, it still lags far behind the international advanced technology level.
From the perspective of manuscript design and plate-making process, flexographic printing process is self-contained and has its own unique features. Its plate-making process is basically as follows:
manuscript → electronic color separation or photography → positive and negative images → back exposure → main exposure → development and washing → drying → post-processing → post-exposure → plate sticking
Compared with offset printing, there are mainly the following differences: < p Offset printing is 1% ~ 99% (or 2% ~ 98%) and flexography is 3% ~ 95%.
2. The outlets are enlarged (5%). Offset printing is 15% ~ 2%, and flexography is 3% ~ 4%.
3. Number of screening lines. Generally, the maximum offset printing is 175 lines/inch, while the number of flexographic screening lines generally does not exceed 15 lines/inch.