Expert tips on how to control the ink balance of the offset press

Therefore, in actual printing, the operator mainly controls the balance of ink and water based on experience. The key to the balance of ink and water is to control the size of the water, and the size of the water always changes with the change of the amount of ink, which is commonly said that water follows the ink. 1. Pre-press presetting For advanced offset printing machines, it is equipped with plate reading devices (such as Heidelberg CP2000, Komori PSS, etc.).

It can provide ink preset data, and can automatically complete the setting, in fact, this preset is also error, therefore, most of the offset printing machine ink balance presetting is based on experience, pre-adjustment pay attention to the following points: (1) Observe the distribution of the printing plate, the layout area is large, the water consumption is large, and the reverse is small. (2) The paper has high smoothness and less water consumption, and vice versa.

3) In yellow, magenta, blue and black four-color printing, the amount of water in the black version should be small but not large. (4) The amount of water in gold and silver ink printing should not be too large. (5) The printing speed is fast, the environmental humidity is high, and the water consumption should be small but not large.

Specific adjustment method: (1) First of all, adjust the gap between the ink fountain and the ink fountain roller to make the ink output uniform, and at the same time, according to the printing plate, make individual adjustments to the gap between the ink fountain and the ink fountain roller. (2) The teeth of the ink fountain roller (or the arc of the ink fountain roller) should be matched with the ink fountain gap and ink color.

When printing light colors, the ink fountain gap should be smaller, and the ink fountain roller should be more toothy. When printing dark colors, the ink fountain gap should be larger, and the ink fountain roller should be less toothy. (3) Turn on the water and ink transfer switches, and force the water and ink supply.

Be sure to pay attention to the presetting, the water and ink should not be too large, especially the amount of water should not be too large (you can feel the amount of water on the surface of the water roller with your hands). 4) The pre-adjusted water and ink are basically uniform. [Expert tip] For J2205 machine, when the water transfer roller of the two-color wetting device hits the water, it is opposite to the two-color printing plate cylinder, so the two-color printing plate is often dirty, so special attention should be paid to it.

2. Ink and water balance control in the printing process 1. Cleaning and maintenance of the printing plate Before printing, the printing plate should be cleaned with water to remove the protective film on the surface of the new printing plate. When applying the glue solution, it should be flat, otherwise, it will destroy the non-** part of the sand mesh of the printing plate. [Case 5-1] The operator on the printing machine turned on the printing plate and started the test printing after the printing machine, only to find that the full plate was dirty.

There is also a factory printing machine operator to take the printing plate to install the machine, do not clean the printing plate, directly drop the water roller, the result of the layout dirty, at this time, the operator with the sponge block absorbs water and adds to the surface of the water roller, resulting in an increase in the amount of water. [Pro Tip] Both of these operations are illegal operations! 2. Judgment of the amount of water in the printing plate As mentioned above, an important aspect of the balance of ink and water is the control of "water", so the identification and control of the amount of water is the first element of the balance of ink and water.

The principle of offset ink transfer is that oil and water are incompatible. Because the plate is flat.

Because the printing plate is different from the embossed gravure hole printing, it is flat, and the characteristics of the blank part are different, the first is lipophilic, the blank is hydrophilic, the first water on the printing plate and then the ink, you can ensure that the ** part has ink, the blank part has no ink, so that it can be transferred to the substrate by pressure.

In other words, the focus of offset printing is to adjust the balance of ink and water. If it is not adjusted well, it will cause the dots to expand or shrink, resulting in pasting or whitening.