Analysis and elimination of the exhaustion failure of the printing machine
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In the process of making a printing plate, sometimes the printing plate quality is unqualified due to the exhaustion of the printing machine. Especially in the case of making a screen printing plate, a part of the air remains between the negative film, the PS plate and the glass plate of the plate-making machine, so that the three of them cannot be closely attached together, causing the printing machine to be exposed. The light is not normally irradiated onto the photosensitive layer of the PS plate through the film, and the plate produced is mostly a flower plate. To this end, I have accumulated several solutions in my usual work, which are now summarized for your reference.
1 slap method
When the plate-making machine draws air during the normal pumping time, the operator finds that some gas remains between the bottom plate and the glass plate when pumping, or gathers or floats there, and the air extractor is exhausted. In this case, the operator can use the slap method, that is, to use the force used to make the glass plate unsuitable, and in the case of pumping on the side of the printer, the operator slaps against the concentrated area of the air. The upper surface of the glass plate, as much as possible, allows the residual air to spread out without gathering together. It is best to follow the diffused air behind the glass, try to spread them all around, so that with the effect of the air extractor, the air can be quickly driven out of the range of the film, which can do more with less. . Never go to the front of the diffused air to slap the glass, which will bring the newly scattered air back together. If the slap in the normal order still does not achieve the goal, it is better to extend the pumping time so that satisfactory results can be obtained. Moreover, the current printing machine is mostly program-controlled. In general, the second pumping will not affect the entire plate making process, so that the operator has sufficient time to slap. The similar situation occurs because the film area is large, and the operator does not check whether the film and the front of the PS plate are in close contact when the film is placed. Sometimes the negatives are placed on the base, which will also create a certain gap between them. This situation will also cause the above phenomenon, and the treatment is similar to the above.
2 tiling method
When the operator puts the film, if he is careful, he sometimes finds that the negative contact between the film and the PS plate is not strict enough. The phenomenon that the film shows is uneven on the surface of the PS plate. At this time, if the glass frame is closed and the air pumping starts, there will be an inexhaustible phenomenon in the slap method. The solution to the problem is to first set the front of the film to a good position, fix it with a transparent tape, then use one hand to press the fixed position, and the other hand gently flatten the film in order, so that the film and PS The fit between the plates is tight, then close the glass frame and press it again. A similar situation occurs, mainly because the film area is too large, or the operator has rolled up the film during the transfer of the film and other human factors have damaged the film. The precaution is to place the film in a bag before the transfer so that it does not bend, so the film will not affect the quality of the plate during the plate making process.
3 padding method
When the operator finds that the elastic force of the air cushion blanket on the printing machine is insufficient, the method of padding paper can be used to solve the problem. The pad paper used is generally 80 g double-adhesive paper. When padding paper, it should be noted that the pad paper used is preferably a whole piece, not a splicing; the pad paper is placed directly under the PS plate and cannot be slanted to the side with the air cushion blanket. Work should be based on the actual situation, slowly try to add paper, can not suddenly increase a lot of Zhang (according to my experience of up to 6), this will damage the plate machine, and sometimes even because the pad is more The glass plate is crushed. Gradually increasing the paper pad can make the glass plate have an adaptation process, which is also beneficial to the operator and is not easy to damage the glass plate. As the pad is gradually increased, the elastic force of the air cushion blanket can be increased in disguise, so that it can reach the required strength of the printing plate, and the operator can accumulate certain work experience for later use. A similar situation occurs, the main problem lies in the printing machine: 1 Because the air cushion blanket has lost the elasticity required for normal work after long-term use, the first emergency measure is to add padding paper to make up its elasticity, and then replace the air cushion later. Blanket; 2 There is a problem with the air extractor, causing insufficient air pumping, so that the air cushion blanket can not work normally. The method of treatment is to first add padding paper instead of pumping air, followed by repairing or replacing the air extractor.
4 multiple pumping methods
Most of the current printing machines are program-controlled. The characteristic is that as long as each program is set, it does not require the operator to worry. At the time set by the program, it automatically works according to the program. In this way, if sometimes the pumping time has expired, but the r gas has not been exhausted, the film has not been closely attached to the PS plate and the glass plate, and the plate printer automatically enters the next program, thereby making the plate produced. Not qualified. Therefore, the operator should pay more attention when making the printing plate. When it is found that the pumping has not been exhausted, it should be stopped immediately before the start of the next program (when the pumping time is exhausted), and the second pumping is performed. If you notice that the effect is not ideal, you can pump again. This will not affect the quality of the plate, nor will it affect the normal working order of the platen. A similar situation occurs, mainly due to machine causes and human factors. Machine reason: There is a rubber pad on the edge of the air cushion blanket. The rubber pad has a certain height and a certain hardness. When the temperature is low (such as winter), the rubber pad will shrink slightly and the hardness will be strengthened. Therefore, under other conditions, there will be a certain gap between the glass plate and the glass plate, so it will affect the normal pumping time; sometimes it will not be elastic due to the overuse of the rubber mat. Meeting the requirements of normal work will also affect the normal pumping time. If a similar situation occurs, the glass frame should be lightly pressed by hand during the normal pumping time range to increase the pressure of the glass frame, so that the glass frame can be sucked, or the temperature of the room can be increased, and the elasticity of the rubber band can be changed. Strong, weakened, or replace the rubber band. The human factor is mainly due to the fact that the negative film was not grasped in advance, and the wrong pumping time was set. The solution is to re-determine the pumping time according to the actual situation.