Control the offset ink ink balance method (1)

The theory of ink balance is not difficult to understand for general offset press operators, but it is not easy to follow the ink-water balance theory in practice. This is because the operator does not have enough time to use the instrument to perform the measurement. Different models have different operating methods. In addition, printing is performed under dynamic conditions, and there are too many factors that affect the balance of ink and water. Therefore, in actual printing, the operator mainly controls the ink and water balance based on experience. The key to ink and water balance is to control the size of the water, and the size of the water always changes with the amount of ink. This is what the ordinary saying goes.

Prepress Prepress

For advanced offset printing presses, there are printing plate reading and reading devices (such as Heidelberg CP2000, Komori PSS, etc.). Can provide ink preset data, and can automatically complete the set, in fact, this preset is also error, so, most offset ink ink balance preset experience-based, pre-tuning attention to the following points :

(1) Observe the distribution of the printing plate graphic and text. The area of ​​the layout picture is large and the amount of water consumption is large, and vice versa.
(2) Paper has high smoothness and low water consumption, and vice versa.
(3) In the printing of yellow, magenta, cyan, and black colors, the amount of water in the black plate should not be too large.
(4) The amount of water in gold and silver ink printing should not be too large.
(5) Printing speed, environmental humidity, and water consumption should not be large.

Specific adjustment method:

(1) First adjust the gap between the ink fountain and the ink fountain roller to make the ink output uniform. At the same time, according to the situation of the printing plate graphic, adjust the gap between the ink fountain and the ink fountain roller individually.
(2) The teeth of the ink fountain roller (or the ink fountain roller rotation) should be matched with the ink fountain gap and ink depth. When printing light colors, the ink fountain gap is small, and the ink fountain roller has more teeth to go. When the dark color is printed, the gap between the ink fountains is large, and the ink fountain roller has less teeth.
(3) Turn on the water and ink switch to force water and ink. Do not pay too much attention to water and ink when presetting, especially if the amount of water cannot be too large (you can feel the amount of water on the surface of the water roller by hand).
(4) Pre-adjusted water and ink are basically uniform.

[Expert Tips]

For the J2205 model, the water transfer roller of the two-color dampening device is opposite to the two-color printing plate cylinder when it passes water. Therefore, the two-color printing plate is often dirty, and should be particularly noticeable.

Second printing ink balance control

1, printing plate cleaning and maintenance

Before printing, the printing plate is washed with water to remove the protective film on the surface of the new printing plate. When the printing is stopped in the middle, it is necessary to dip water or glue to protect the non-graphic part, and the downtime is long. When the glue is applied, it must be flat. Otherwise, the non-graphic part of the plate will be destroyed.

[Case 5-1]

When a staff in a factory prints a copy, they forget to apply the glue to the new printing plate. The operator on the printing machine will try the printing after the printing plate is on the machine, only to find that the full version is dirty. At this time, use a cleaning solution to clean the printing plate. As a result, the dirtier the cleaner it is, the more reprinted. There is also a printing plant operator who used a printing plate to install the machine. Instead of cleaning the plate, the water roller is directly dropped. As a result, the layout is dirty. At this time, the operator adds water to the surface of the water roller with the sponge, resulting in a large amount of water. Increase.

[Expert Tips]

Both of these operations are illegal operations!