UV offset and UV flexo

The main difference between UV offset and UV flexo is the ink, ink and plate technology. Due to the longer ink path, UV offset printing can be achieved with up to 16 ink rollers, dampening systems, and ink tanks, which require a little more automatic control. UV flexo printing is simple because the ink path is simple and requires only a relatively simple manual adjustment.

On the other hand, especially those using digital imaging plates require high quality printing, which significantly increases the production cost of UV flexo printing. UV offset printing and UV flexo printing have their own advantages and disadvantages in particular printing requirements. There is no absolute "winner", only the most appropriate processes to meet different needs.

In the printing area, UV flexo printing has more unique advantages. It can be glazed, printed in metallic colors, and can transfer ink layers of 1 to 12 microns, which can mimic the tactile effect of screen cylinder printing. At the same time, it can handle extremely fine gradients and printing processes. The UV offset ink transfer is limited to about 2 microns, so its high quality printing advantages cannot be extended to all printing processes.

However, due to the short ink path, UV flexo printing can be converted faster than UV offset printing. Modern UV offset printing units such as XpanndTM can automatically clean multiple printing units, significantly reducing conversion time.

UV flexo printing can provide better self-visibility than UV offset printing, especially in bright colors, strong contrast colors (contrast colors).

UV offset printing still retains its solid advantages, not only in the gap in print quality, but also in simpler, more cost-effective ways to meet quality requirements. If there are high-quality requirements for processing, the platemaking source is more likely to meet the requirements and the printing variables are more standardized. UV offset printing can be easier and more cost-effective to achieve high quality printing requirements.

Modern UV offset printing units, such as XpanndTM, offer a fast transition printing combination, with low-speed setting and fast response printing on the substrate transfer function, resulting in almost the same time loss of UV offset and UV flexo printing on converting substrates. The advantages of UV flexo are compensated by the flexibility of UV offset printing management. If the UV flexo printing process is standardized locally, UV offset printing can have a clear advantage because the final printing result is also a global standard.

Flexo printing is advantageous when printing inks are frequently switched and when the substrate is unknown, because the UV offset printing system needs to coordinate ink and ink balance, and UV flexo printing can be started in real time. There are also advantages in dealing with UV offset printing in spot color printing. Because its standardization is the most advanced in the supply chain.

Modern printing presses such as AthenaTM, I-CombatTM, and XpannedTM have computer-intelligent technologies in a global or regionally standardized environment, making UV offset printing and UV flexo printing equally effective in repetitive processing because most of the variables It has been controlled by the computer. In some simpler configurations, UV flexo has obvious advantages.

The limitations of UV offset printing are not flexible enough in repeat length dimensions because of the high value and size of the printing press. Although label printers have shown from practical experience that rotary machines can use 4 to 5 sets of repeat lengths, it is sufficient to cover most of the current needs. UV flexo can print any reproducible length and the investment cost is small.

Wet offset printing is the most common printing process in the printing industry today. The basic principle is to use the ink balance between the printing area (printing ink) and the non-printing area (water) on the printing plate. The key is to maintain stability and control of the ink balance. Waterless offset printing uses a silicon coating on the printing plate to remove the ink for the non-printing area, balance control, and eliminate the use of water as a medium. Water is not used for printing, making waterless offset print dots sharper and better visible. Waterless offsets have the potential to reach higher line counts and contrasts. Wet offset printing is more compatible than waterless offset printing. Water can be considered as a cleaning plate, ink path, a bit like the self-cleaning function in printing. In water-free printing plates, dust and paper dust can damage the water-repellently-printed silicon coating, making the selection of substrates and work environment cleaner.

In general, waterless offset printing requires more demanding printer maintenance and operator skills. It is the slight mistakes in the process, and the quality of the print may vary greatly.

The problem of ink temperature has been the development of technology for many years. Waterless offset printing is still a very complicated process, and every process requires perfect control to achieve high print quality.

At printing speeds higher than 150 meters per minute, wet offset printing requires a chill roll to cool the build-up of heat in the printing unit, which can affect ink performance and ink density.

Waterless offset printing requires cooling rollers and cooling ink at any print speed, as well as cooling the plate at the center of the platen roll. Because the ink temperature is extremely sensitive to control the print quality. The working temperature of the ink is limited to a very narrow range, only 3-4°C. Above or below this temperature, the ink becomes unstable and print quality is affected. In order to achieve better control of the printing effect, the plant needs air-conditioning temperature control.

Offset is the most demanding printing process for mechanical components. When flexo printing requires only a limited amount of printing pressure, offset printing requires a great deal of pressure to be applied to the platen roller to transfer the ink. The difference in workmanship, assembly, and firmness of the offset printing press, as well as the design of the ink path and the ink management system, will affect the final print quality.

Most commercially available offset heads can achieve acceptable print quality at speeds of 30 to 40 meters per minute. To exceed the speed of 50 meters per minute, continuous good quality prints can be obtained. The XpanndTM offset printhead delivers consistently high quality printing at a print speed of 12 meters per minute. The amount of waste in the print setting is very small, and it is very close to the flexo process.

The ink interface of all parameters is controlled by the calculator interface. The ink can also be stored and recalled from the main control surface through an automatic servo remote control. The ink management system can be used repeatedly during processing, or as a new process. Set the basis. In the settings, waste and time can be greatly saved, and all ink feed parameters are controlled and can be copied!

Author/(Qiao Qiaoyun)

Source: Shanghai Packaging