Determinants and maintenance points of plate print

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The factors that determine the printing quality of the plate printer and the key points of maintenance

the plate printer is one of the necessary equipment for offset printing. The printing quality of the plate printer mainly depends on the following two factors:

1 Whether the vacuum pumping system of the plate printer works normally. Whether the film surface and sulfuric acid paper carbon powder surface are closely matched with the photosensitive film surface of other printing plates of PS plate

2. When gallium iodide lamp, xenon lamp, purple fluorescent tube and other light sources are exposed, whether the illumination on the whole panel is uniform, and whether the illumination in the middle and around is consistent and uniform is the standard to measure the performance and quality of the printer. The most common fault of the offset vacuum printer is that the film surface of the film, the carbon powder surface of the sulfuric acid paper and the photosensitive film surface of the PS plate are not closely matched enough, and the air is not pumped properly, which will seriously affect the printing quality. Because the vacuum pumping can not reach a certain vacuum degree, the air leakage phenomenon is serious, especially for the electric four-color film with the drying belt line. If the pumping is not solid, the drug film surface of the film can not be closely absorbed and matched with the PS version photosensitive film, and the small dots, fine lines and fine layers of the PS version will be lost. The main reason is that the pressure of the accumulator must be ensured to be in the normal task state. There is a gap between the film surface and the photosensitive film of the PS version, which is not compact and solid. During exposure, the image and text points of the PS version are tilted in the void, which can not be close to the photosensitive film of the PS version. If the gallium iodide lamp is exposed from above, the photosensitive film of the points in the void will be decomposed by light after exposure, and then after the automatic and manual development process of the PS version, Weak points and pictures in the void contact will be lost. Currently, various experimental specifications generally require that the accuracy of parameter testing should not be less than 1/3 of the allowable error of experimental conditions

in addition, the plate printer, like other printing equipment, must be properly maintained frequently in order to be in good working condition for a long time. Therefore, the following points must be achieved:

① maintain the integrity of the function of the air extraction system. The vacuum pump shall be inspected once a week. The vacuum oil level shall always be aligned with the oil level line. All oil must be replaced after one year of operation

② wipe and moisten the frame of the blanket with glycerin once a week. When the machine is not in use, cover the blanket on the glass plate table with a cloth curtain to prevent dust and sundries

③ the surface of the glass plate table must be kept clean. When wiping, clean it with a soft brush, and then wipe it with degreasing gauze and anhydrous alcohol

④ the lamp curtain used to block the scattered ultraviolet light and avoid the sun exposure to human skin and eyes is composed of two layers of cloth, which is a white polyester cloth to reflect light. The young people are covered with a layer of red velveteen cloth to protect them from ultraviolet rays. The inner layer will affect the effect of reflecting ultraviolet rays due to yellowing over time, dust, oil and other reasons, resulting in an increase in exposure time. At this time, it is best to replace a layer of white polyester cloth

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