Filled with water velvet covered with foreign matter so that the ink color shades

In offset printing, sometimes the color of printed ink is dark, shallow, shallow, or shallow, deep (from the pressure, front-heavy, back-heavy or front-heavy), which affects the quality of printed products. The reasons for these phenomena are as follows: The effect of the ink roller and the water roller is slightly analyzed.

1. The center of gravity of the drum is biased toward the middle side of the mouth, and there is a slight depth before and after the shallow weight, ie, the weight is light and heavy; This is caused by the inconsistency in the pressure at the rinsing and dragging points when the drum rolls. Heavy pressure on one side of the network increases, dark ink; light pressure on the side, the network is reduced, the ink is light.

2. The radius of the printing surface of the drum can also be caused, for example, the lining of the drum has pleats, or the quality of the pad lining is poor, and the thickness is inconsistent, so that the pressure does not cause the ink shades to be different.

3. The pressure between the ink roller and the ink roller is too light, causing the ink to spread unevenly. In particular, the pressure between the ink roller and the ink roller and the printing plate must be evenly adjusted, and it cannot be light and heavy on both sides. Special attention should be paid to the fact that the pressure of the ink roller and the printing plate is greater than the pressure of the ink roller and the ink roller, which facilitates ink separation and transfer.

4. The diameter of the ink roller should not be too small, otherwise the amount of ink transfer can not meet the printing graphics requirements.

5. The surface of the ink roller is aged, and the hairless pores have become smooth surfaces, resulting in non-uniform ink transfer amount and easy occurrence of inconsistent ink failure before and after. The ink roller can be ground to ensure the diameter allows, roughening the surface, increasing the ink adsorption and transfer performance. Special attention should be paid to the washing of the ink after it has been printed. (Bright oil residue on the ink roller is easy to mirror the surface of the ink roller, filling the pores of the ink roller. In severe cases, the rubber on the roller will be pulled off and the ink roller will be scrapped.)

6. The water roller and the plate pressure and the pressure adjustment of the water roller and the string water roller are inconsistent, causing the water to become large and small, affecting the printing ink absorption.

7. Water roll bending caused by uneven upper water, should be replaced.

8. When the pile jacket filled with water, resulting in a foreign body charged with water roller radius changes, the water does not uniformly impact.