In particular, when the pressure of the four ink rollers and the ink roller is too light, it is easy to produce a dark fault in front of the ink.
Solution: The low-speed offset printing machine can evenly adjust the eccentricity to adjust the pressure between the rollers. The high-speed machine can evenly adjust the ink roller without eccentricity, and can be replaced with a thicker rubber roller. The pressure of the four ink rollers and the ink roller can be adjusted from front to back depending on the contact width between them.
6. The effect of the roller on the darkness before the imprinting
Since the plate, eraser, and embossing three cylinders do not reach the static balance, during the printing process, the center of gravity on the circumference is often dark in ink, and the radius of the printing surface of the cylinder is inconsistent. This may cause darkness or darkness in the ink, and it is also possible. Dark before producing ink.
Solution: The above is a drawback in the design and manufacture of offset printing machinery. It is difficult for the printing operator to solve the problem in the normal printing process. Only when the system is to be overhauled, will the rebalanced cylinders not be reprocessed. Operators sometimes increase pressure in lighter ink spots, but these are temporary measures and have little effect.
7. The poor lipophilicity of the blanket
Printing blankets require maximum adsorption and transfer of ink while minimizing moisture absorption, as well as good oil and acid resistance. As the printing process is often in constant contact with moisture, ink, paper, etc., it may be adsorbed on the surface of the blanket to form a film layer, which changes their wetting properties, that is, the oleophilic ink transfer performance is weakened and hydrophilic. Sexual enhancement. This is also prone to shortcomings. At the same time, blanket light, heat aging, will make the blanket surface soft, sticky, or even cracks, so that the ink transfer performance is reduced, prone to inconsistent print ink color depth.
8. Inadequate ink deployment, high viscosity, low flow, caused by the deep before and after the blot
Solution: In order to make the ink have a good printability, it is necessary to add some auxiliary materials in an appropriate amount according to the requirements of the print. The viscosity of the ink is large. To add the ink, the printing companies commonly use 0-6 and 05-01 resin varnish to improve the viscosity and fluidity of the ink. No. 0 varnish has a large viscosity, when the ink adhesive material does not have enough adhesive force to appear on the plate or the printing plate often has the disadvantages of floating ink, greasy, etc., can be properly added 0 varnish to improve performance.
No. 6 varnish is a slightly yellowish, dry, vegetable oil that has been refined by heating and has a certain viscous oily fluid. No. 6 varnish has two functions:
1 Dilution in the ink, also play a role in reducing the viscosity of the ink;
2 Reduces the concentration of the ink, increases the flowability and development of the ink, and enhances the printability of the ink.