Ink supply device automatically presets - possibilities and limitations (on)

The main purpose of this article is to explain the key parameters in the preset process to get the best results. There are two stages in the automatic presetting of the ink supply device:
1. Determine area coverage;
2. Calculate the setting value of the ink volume control element.
For this reason, the system must clearly understand the relationship between metering and inking. In order to calculate the ink metering value, the system must take into account the press parameters, such as the lateral ink, ink backflow, and stable weather conditions that are important for good results. Although spot colors are more difficult to handle, standardization, color management, regular maintenance, and calibration of equipment components plus a stable production environment can provide good presets, and reduce preparation time and paper waste.
Ink supply device settings For a long time, the ink area screws or ink spoons were manually adjusted according to the senses. In the early 1980s, Mann Rolland introduced his own electronic plate scanner, which determined the ink supply preset based on the area coverage value. Although the system has limitations, it is indeed better than the previous one. The beginning.
Less than two decades later, automatic ink supply presets have grown considerably. More and more printers automatically determine the area coverage value directly from the print, rather than the plate scanner, even though the plate scanner has been greatly improved. This saves time and eliminates sources of error. Even so, the result is still not ideal.
In order to get a good print quickly and effectively, it is necessary to clarify some important issues.
â—‹1 What does an automatic ink supply preset mean?
â—‹2 What processes are required to reach the automatically preset value?
â—‹3 How to perform a good preset feature?
The first is the calculation phase In order to understand the possibilities and limitations, to accurately calculate the preset values, the calculation phase should be carefully considered. The computing system must process the input values ​​zone by zone, first the area coverage itself, and secondly the required ink volume. However, giving only the required amount of ink is not enough for the computing system - in order to calculate the correct preset value, you must know the relationship between ink setting and ink.
Then, in two steps, the ink supply amount calculated by the ink film thickness is calculated according to the specified ink amount, and the nominal ink film thickness on the substrate is calculated. The correct setting of the ink metering elements is calculated from these nominal ink film thicknesses and area coverage. When the area coverage, the substrate characteristics, and the transfer characteristics of the printing press are known, a certain amount of ink film thickness can be obtained by adjusting a certain ink key to obtain a certain amount of printing ink.
The next task is to optimize the system must be able to generate accurate values ​​as accurately as possible from the above described relationships, so the software of the computing system is quite important. The software used by Manroland also includes technical parameters of the printer, such as the effect of transverse cross-inking or ink flow in ink fountains, which are often ignored by other systems. The best results obtained by the calculation program in the computing system still depend on the quality of the input value, so the correlation between the quantities is also a factor in the calculation.
The area coverage data obtained by the color separation scanner scans the surface of the printing plate optically and analyzes the area of ​​the image and non-graphics to obtain the area coverage data; the area coverage can also be directly obtained by the prepress processing through the CIP3 interface. Rate data, this method is now more and more widely used. After eliminating readings or sources of error from numerical database values, you need to observe the results of using the calibrated ink supply.
The use of a calibration ink supply must distinguish between the basic print colors (yellow, magenta, cyan, black) and spot colors. For printing basic colors, common standards have been defined long ago, such as FOGRA. However, many printers have developed their own standards. In order to reduce uncertainty, useful recommendations that have been used for many years are now strictly applied to the production process, but with the necessary color matching.
The nominal ink volume of a spot ink in general is usually a color value (for example, Lab), and the color management system is required to be able to correctly compensate for any difference in the production of the sample. In order to reduce the uncertainty of the color value of the spot color ink, the only compensation method is strict standardization or the use of a printability meter to measure the characteristic line. For spot colors, if the printability meter is not used or the ink supplier does not provide the relevant data, the only solution is to make a rough evaluation. In this case, the pigment of the ink and the nature of the substrate are decisive. effect. (To be continued)