Removal of horseshoe marks of PS version
in offset printing, we often encounter the situation that the PS version, especially the regenerated PS version, is not flat enough and has horseshoe shaped convex and concave marks, which seriously affects the quality of offset printing. Where there are hoof marks. Because the photosensitive adhesive film of PS version cannot be closely absorbed with the words, lines and dispensing film of sulfuric acid paper or film, and there is a certain gap at the same time, it is easy to cause false words, lines and dots, and PS version cannot be printed on the machine
1. Causes and solutions of horseshoe impression formation
there are two kinds of PS plates commonly used in offset plate making and printing; First, printing high-grade and fine packaging decoration, trademarks, four-color sleeve mold temperature is the main factor to control the cooling and finalization of products. The original PS plate used for printing color cover is of high price, good quality and relatively flat surface; Second, it is used to print low-grade books, periodicals and forms. Now a considerable number of enterprises can produce recycled PS versions of miscellaneous parts. This kind of plate has low price, unstable quality, the surface of the regenerated PS plate is not smooth enough, and there are many horseshoe marks
because the regenerated PS version has been regenerated for many times by the original PS version. In the process of regeneration, the PS version is only about 0.4mm thick in the processes of disassembly, cleaning, grinding, electrolytic corrosion, coating the photosensitive film of the regenerated PS version, drying and so on. For example, the split PS version has a large size and thin plate. P at the end of April this year, the s version is often regenerated repeatedly in the process of regeneration, which is easy to cause horseshoe marks on the regenerated PS version during operation. PS version in the process of transportation, it is best to store it vertically like glassware, and handle it carefully, so as to reduce horseshoe marks
in addition, the operator who is drying the PS version should have a careful and serious working attitude. When taking out the PS version from the packing box, he should handle it gently. When he finds that there is a horseshoe mark on the PS version, the circuit of the single chip microcomputer control system is shown in the figure. A small bamboo board can be used to poke up from the back of the PS version. If possible, press it on the platform to make the PS version as flat as possible
2. Adjust the vacuum pump of selenium plate machine
when we encounter uneven horseshoe marks on the PS plate in our actual work, we should readjust the pressure of the vacuum pump before printing, so that the pressure increases when vacuuming. Extend the inspiratory time before the exposure of the PS version, and let the vacuum pump pump pump the air and absorb enough to absorb the solid. In this way, the photosensitive film surface of the PS version can closely fit the words, dots and lines on the sulfuric acid paper or film. The points of the PS version exposed are clear, bright and clean, and the dots are solid and solid, meeting the quality requirements of offset printing
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