Print product gargle dirty solution

JS2102 double-sided offset printing machine can complete double-sided printing at one time, with high speed and high efficiency. However, when the machine is used for printing, the gargles of the printed products often cause dirty lines. The width of these dirty lines is 3 to 5 mm, and it is about 12 mm from the gargle, which seriously affects the quality of the product. The following author focuses on the cause and solution of this failure from the aspects of the structure and adjustment of the machine.

There are three main reasons for the dirty line of the mouthwash.

1. The upper rubber roller is equipped with cavities so that the upper plate cylinder cannot advance. Otherwise, the plate or roller body will be crushed by the tusks. In the operation of the machine, the plate is affected by the impact friction of the ink roller, the plate grain is damaged, the hydrophilicity is reduced, and the blank part is easy to stick ink. The ink is transferred to the printing product through the rubber roller. , causing dirt.

2. Ink roller is small, ink layer is too thick. This machine is mainly used for books and periodicals printing. The design of inking equipment is relatively simple. There are 14 ink rollers, only 2 ink rollers, and 1 water roller, which is compared with the inking device of single-side machine (such as J2108 machine. There are 2 water rollers, 21 ink sticks, and 4 ink rollers. The ink performance is obviously worse, and the book printing itself uses a large amount of ink. If the operator also blindly increases the ink volume, the ink roller The ink layer on the top is too thick, and the ink layer on the printing plate is easily pressed and spread. At the same time, the rotating ink strand breaks and splashes, which makes the printing plate dirty. This is also the reason why the mouthwash is easy to get dirty.

3. The pressure between the ink roller and the printing plate is too high. Some operators mistakenly believe that there are fewer ink rollers and the pressure should be greater. This is incorrect. Too much pressure will exacerbate the runout and friction of the ink roller at the mouth of the plate, making it easier to get dirty at the mouth. In severe cases, it will also make the printing plate's resistance to printing force drop. Most of the double-sided machines now use PS plates and air-cushion blankets with high flatness, and the amount of ink carried by the two inking rollers is large, so even if the pressure between the ink roller and the printing plate is small, the ink can be guaranteed. Passed correctly.

Based on the above reasons, the following solutions can be taken.

1. By taking the screws to push the plate cylinder as far as possible, so that the tine just hit the plate, while the next plate cylinder by the front rubber roller about 10mm, careful not to borrow too much, otherwise the upper and lower plate printing The size of the plate cannot be uniform, which makes it difficult to print and print.

2. Adjust the pressure of the ink roller on the plate to reach 4mm (indentation width, the same below). The pressure of the water roller should be adjusted to be larger than the ink roller, and it can be adjusted to 6mm.

3. Pay attention to the fact that the ink layer is not printed thickly when printing, so that the word can reach medium darkness. If the reflection density is only measured, the solid density of the 52 g/m2 offset paper can reach 1.4. This density gives readers good visual effects and is also conducive to printing.

In addition to the correct adjustment of the machine, the operator should also pay attention to mastering the ink-water balance during printing. The ink additives should not be added too much. The pH of the fountain solution should be controlled at 5-6. In the summer when the temperature is high, you can add some ice cubes in the fountain solution to cool down. In this way, the fault of dirty mouth will not happen.