Flexo Printing Technology

In the history of modern printing for more than 100 years, the screening technology has increased from optical screening to electronic screening from 30 to 40 years ago. The size of the network points ranges from coarse to fine networks, and the distribution of network points has a random distribution from regular to random. All these technological improvements and reforms eliminate moiré patterns, make the tone even flatter, and expand the scope of print reproduction. In general, the purpose is to improve the quality of printing. However, corresponding to this, it is necessary to develop compatible recording speeds and higher resolution devices. However, the development of things tends to undergo unexpected changes. As a result of reverse thinking, some famous merchants are already working hard to develop low-resolution screen-printing screening technologies. According to past experience, in order to reproduce a certain tone in a device with a low resolution, the necessary resolution is 10 times or more than the number of lines (for example, the number of screen lines for 100 lines, the output resolution should be above 1000 DPI. In general, the resolution of the output of 150~175 lines must be between 2000~3000DPI). Now with the new IntelliDotSpeedScreen screening technology from OPTRONICS International Corporation, TurboScreening developed by Saturn Asia Pacific Co., Ltd. can achieve high network cable with low resolution output (eg, 150 to 175 lines at 1000 DPI). One of the most realistic meanings for flexo printing is the SambaScreen from BARCO and the HybridScreen from PPC, both of which are the latest screening methods for flexo printing. For flexo printing, since the dots of the highlights are not easily printed, the reproduction of the highlights is not complete. The above two screening methods are used, and this problem can be completely improved.

Both Samba and Hybrid networks are a kind of AM/FM hybrid screening method. Because the position of the network points in the traditional screen determines the structure of its sharpness, the expansion of some halftone dots in the middle tone is small, while the random dots are in the high-light part. The effect is better, because the positions of the highlights need to be optimized, and the smallest dots must be able to ensure a perfect match between the texture and the screen. The random dots in the highlights and shadows are smaller. Therefore, this combination of AM and FM screen is suitable for flexographic features. The difference between the two is that the SambaScreen network uses the FM frequency modulation network for highlights and shadows, while the intermediate tone uses the traditional AM amplitude modulation network. It smoothly transitions from a random point to a traditional point (5% to 10% from 90. %~95%) is calculated automatically by the digital, rather than simply interpolated by the respective density. The HybridScreen screening method is a screening method in which FM and AM coincide with each Other over the entire density range. With the above two screen printing methods, the smaller and more stable dot enlargement allows the flexo-printed prints to clearly reproduce the fine dots of the highlights, and the layers are more abundant.

Ink transfer system and a new generation of anilox roller
In order to stably supply the low viscosity (5~500) ink to the flexographic plate, the anilox roller ink transfer system is an ideal printing method. In general, the anilox roll is sculpted on the surface of ceramics. According to the different types of cells, it has cubic, conical, oblique, and other shapes. According to the shape, the number of lines, the depth, etc., the ink supply amount and the ink holding amount are calculated. High-quality ceramic magnetic anilox roller has strong wear resistance. From its processing, laser engraving uses conventional carbon dioxide laser engraving method and YAG laser engraving method using multiple impacts, and the latter is currently a type of mesh engraving. The highest preparation method is that each mesh is struck twice by a laser beam, the first hits the engraving, and the second hit increases the depth of the mesh. Double-clicking on the shaped mesh creates a smooth wall with a fast and uniform ink transfer, ensuring print quality. In terms of its composition, the anilox roller inking system has two methods. One is to use a counter roll method in which the peripheral speed is very slow, and the other is a squeegee method in which an ink is scraped with a squeegee like gravure. The anilox roller blade installation method clockwise and counterclockwise. Recently, the ink slot squeegee method was introduced. The two positive and negative squeegees are not only accurate, but also maintain ink volume. Since the ink tank is used, the scattering and evaporation of the ink can be suppressed, and the ink supply can be stabilized according to the printing speed.

In recent years, a graphite carbon fiber material newly developed in the aerospace industry has been welcomed in the manufacturing industry due to its light and hard characteristics. Invented in 1994, the carbon fiber core was soon applied to the flexo-printed anilox roller core, becoming a new generation of more advantageous anilox roller. Although steel rolls have long been the most preferred material for anilox rolls due to their physical properties such as strength, mechanical processing properties and durability, they are replaced by such carbon fiber roll cores instead of the conventional steel roll cores. Its strength is 2 times that of steel rollers and its weight is 1/10 that of steel rollers.

The anilox roller of this carbon fiber core has been tried out and has the following advantages:

1. Due to the special lightness of the carbon fiber anilox roll, it is easy to handle in the roll change and labor is reduced.

2. The carbon fiber anilox roll is not easily damaged during roll change, which saves a large amount of money for re-engraving the new roll.

3. In the driving part of the printing machine, the total weight of the carbon fiber anilox roller is 1/10 of the weight of the steel roller, which is beneficial to reduce the friction between the rollers and the service life of the anilox roller is accordingly increased, thereby reducing the downtime. , increased productivity.