In offset printing, sometimes the ink color of the printed product is dark before light or light before dark (shown from the pressure as heavy before light or light before heavy) affecting the quality of the print. For the reasons for these kinds of phenomena, we will start from the cylinder , The influence of several aspects of ink roller and water roller is briefly analyzed.
1. The center of gravity of the roller is biased toward the middle of the mouth, and the front depth is shallow and the front is light, and the front is light and the front is light. This is caused by the inconsistent pressure between the mouth and the tip of the roller when the roller is rolling. On the side with heavy pressure, the dots increase, and the ink color is dark; on the side with light pressure, the dots shrink, and the ink color is light.
2. The radius of the printing surface of the cylinder can also be caused. For example, the pad of the cylinder produces pleats, or the quality of the pad is poor, and the thickness is inconsistent, so that the pressure does not cause the ink color to be different.
3. The pressure between the ink roller and the ink inking roller is too light, which causes uneven ink transfer, and suddenly increases and decreases. In particular, the pressure between the inking roller and the inking roller and the printing plate must be adjusted evenly, not light on one side and heavy on the other. In particular, pay attention to the pressure of the inking roller and the printing plate is greater than the pressure of the inking roller and the inking roller, so that the ink is separated and transferred.
4. The diameter of the inking roller should not be too small, otherwise the amount of ink transfer can not reach the demand for printed graphics.
5. The surface of the inking roller is aging, and no capillary holes have been changed to a smooth surface, resulting in uneven ink transfer and prone to inconsistent ink color failure. This type of ink roller can be ground under the condition that the diameter is allowed, so that the surface is roughened, and the absorption and transfer performance of the ink is increased. Special attention should be paid to the ink roller after printing the gloss oil. (Glossy oil remaining on the ink roller is easy to mirror the surface of the ink roller and fill the pores on the ink roller. In severe cases, the rubber on the ink roller will be pulled out, causing the ink roller to be scrapped)
6. The inconsistent adjustment of the pressure between the water roller and the printing plate and the pressure between the water roller and the water roller cause the water to rise and fall, which affects the adsorption of the ink on the plate.
7. The water supply caused by the bending of the water roller is uneven and should be replaced in time.
8. When installing the water-fleece cover, there are foreign objects loaded to cause the water roller radius to change, which affects the unevenness of the water.
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