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In China's printing network label printing industry, in order to effectively improve the effectiveness of anti-counterfeiting and product diversity, rotary screen printing with the label printer has gradually been promoted. For a long time, the effect of silk screen printing by label printing companies is mainly due to off-line printing on flat screens. Because flat screen printing presses and rotary label printers cannot be printed on line, there are cases where the printing efficiency is low and the position is inaccurate. What is more important is that some screen printing effects cannot be achieved by flat screens, such as Use screen printing for background color or screen printing for intermediate colors. Therefore, rotary screen printing becomes a better choice.
Rotary screen printing main features
First, it can be printed with any type of rotary label printing, high efficiency, accurate nesting. The printing speed is high, the actual printing speed of the rotary screen printing unit can reach 135 meters/minute;
Second, the printed ink layer is thick, hiding power is good, and the effect is obvious in transparent label printing;
Third, the use of low cost: Because you can connect printing, eliminating the waste of paper.
The ink is printed on the paper under the pressure of the squeegee through a stencil stencil that rotates synchronously with the paper. In this process, the paper rotates synchronously with the stencil stencil, without friction, and the service life of the stencil is improved; the screen during the printing process The principle of no deformation of the reticle results in a much smaller deformation of the print than flat screen printing.
Rotary screen printing machine classification and selection
Rotary screen printing machines can be divided into two categories according to equipment:
1. Packaging [Interchangeable units of the flexo, relief or offset printing units on the mechanical network and the printing machine, which are mainly plug-in screen printing units that come from some well-known foreign label printer manufacturers, such as Jera. Si, Niupetai, Mai Andy and some other brands, this kind of screen printing unit adopts the host's power and register system, can be flexibly selected when printing screen printing location, easy to operate. The print perimeter of such a screen printing unit typically ranges from 12 inches to 18 inches. Printing speed is within 100 meters/minute. The printing units of each printing host are different from each other and cannot be interchanged. Since the screen printing unit does not have a power and registration system, it cannot be printed off the host.
2. Another is a screen printing unit with its own power and registration system, such as RNP and STORK printing units. The silk screen unit can be flexibly installed on different rotary presses because of its small size and high speed: maximum speed of 150 m/min, with independent servomotor and register system, just coding from the printing machine The machine reads the mechanical speed and registers itself with the cursor alignment system to achieve automatic synchronization printing. The installation is simple and the operation is easy. Both satellite and crew rotary presses can be retrofitted.
Correct installation of silk screen unit
If the printing manufacturer has purchased a rotary press and needs to install a screen printing unit, the latter model will be more suitable. However, when installing this type of screen printing unit, you need to pay attention to these issues: First, the installation position, and the second is the problem of drying.
Adding a silk screen color group to a satellite rotary press is generally a position between a large wheel and an open reel. In this position, the rotary machine manufacturers can set aside a mounting position. If a rotary machine has already been purchased, this position can also be used. Extended base and wall panels. When installed in this position, it is possible to select whether the screen is to print the first color or the last color by changing the paper. Another way of adding satellites is to move the paper from the bottom of the big wheel to the left of the big wheel before putting the paper into the big wheel. Put the screen printing unit in this place and return the paper to the big wheel after printing. The paper feed position, so you can choose to print the first color or the last color. The disadvantage of this retrofit method is that the length of the paper is lengthened.
Installing a silk screen unit on a crew type rotary press is relatively simple. It is also possible to let the web machine manufacturer set aside the installation. It has been relatively simple to retrofit on existing rotary machines. It is possible to build a mounting bracket on the existing press using the wall plate of the rotary machine to guide the paper from the existing printing color group to the silk screen printing unit for silk. The web is printed and the paper is then drawn back into the web. This way the UV dryer on the web can be used (provided that the UV power on the web machine is appropriate). When the bracket is installed, the bracket can also be designed as a track, so that the screen printing unit can be moved on the track to facilitate selection of screen printing in any color.
Rotary screen printing, generally using UV ink, so the drying method using ultraviolet UV lamp drying. The printing ink layer of the rotary screen machine is much thicker than the flexographic plate and the relief plate, so the power of the UV lamp used therein is also relatively large. Generally used UV lamp power above 200W/cm. Taking a printing width of 250 mm as an example, the power of the UV lamp should be more than 5 kilowatts, generally 7 kilowatts.
Rotary screen printing machine materials are mainly screen and ink
The screen of the rotary screen printing machine includes these parts: screens, end rings, gears and plate making. All plate-making needs special plate-making equipment.
There are two kinds of screens for rotary screen printing machines. One is a woven stainless steel screen coated with a photosensitive resin, and the other is an electroformed nickel screen with no photosensitive adhesive.
Stainless steel fabrics are more convenient for printing, and generally use plane printing, and then they are bonded into circular screens. Generally, they cannot be repeated. Its net thickness is generally less than 60 microns, and its strength and print life are relatively small.
The thickness of the electroformed nickel mesh is generally more than 80 micrometers, and the structure of the electroforming method makes the strength of the mesh increase. When making the screen, the screen and the end ring are first bonded to a circular screen, and the photosensitive printing plate is coated. This type of screen can be used repeatedly for printing, which greatly saves the printing cost.
The ink used in the rotary screen printing machine is a special UV ink, which has a certain difference from the flat screen printing ink. Ink is mainly divided into two kinds: silicon and non-silicon: silicon-containing ink can not be used in the bottom of the screen printing, mainly used in surface text, pattern printing.
Finally, each printing company will consider the issue of cost. The cost of retrofitting screen printing units mainly includes these aspects: equipment costs, screen printing and plate making costs, and ink costs. With the development of rotary screen printing in China in recent years, there are already different products and manufacturers on the market for you to choose. The above mentioned content hopes to enable the majority of users to help in understanding and selecting rotary screen printing.
How to Select Rotary Screen Printing Unit for Label Printing
Rotary screen printing has always been the top screen printing method, and its printing efficiency is even more unmatched by ordinary plane screen printing, printing accuracy, and the continuity of printing are even better.