Once, when the company printed color prints, it suddenly appeared that the printed matter was difficult to print and the ink color was difficult to reach the original document's standard. The crew's adjustment of the pressure of the machine and the adjustment of the ink volume of the ink fountain all had little effect.
Later, it was found that multi-color offset printing presses had such problems that monochromatic, double-colored, or even four-color printing was difficult to achieve. Because the problem does not occur long, the order of the printing processes is correct and the operation specifications are normal. Therefore, the problem of the printing press can be basically eliminated. The PS version was re-baked and the machine was tested. The failure persisted, and the field density of the film and printed matter was repeatedly compared. No abnormality was found.
So checking the printing process, in the printing section, drying the PS version of the high sensitivity will make the ink performance decreased, and how much exposure to the PS version of the sensitivity plays a decisive role. Reburning PS version, pay attention to reduce the exposure, try on the machine, a little improvement but still not meet the requirements.
Due to the fact that it was midsummer, the air conditioning in the printing room was bad, and the temperature in the room had far exceeded the temperature of the liquid suitable for development. Although the PS version of the development machine has a temperature control device, but only applies to the outside temperature lower than the temperature of the liquid, if the outside temperature is higher than the temperature of the developer liquid, the liquid temperature will be consistent with the outside temperature, resulting in the liquid temperature is too high As a result, the sensitivity of the PS version is too high. It has been verified that the liquid temperature is higher than the proper development temperature. After maintenance, the temperature of the liquid is maintained at a suitable temperature, and the problem is solved.
(Shanxi Xinhua Printing Company Wu Shengqiang)
Reprinted from: Printing Technology