Fault analysis of imprint shortening in the hottes

2022-10-22
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Fault analysis of "imprint shortening" in the printing process

the phenomenon of imprint lengthening or shortening is common in the printing process. Most of these faults are related to factors such as paper, printing pressure, the nature and material of the lining, teeth holding, etc., but the author encountered a special case

fault phenomenon

a four-color offset press has been in good operation, but when converting printing operations, a set of printing plates just installed appeared the phenomenon that the imprint of the second color printing plate (cyan plate) was significantly shortened

fault analysis and troubleshooting

repeatedly check the pressure, teeth, lining, and found no problems. Re sun the blue version, install it, and then try to print. The fault is still there, so it is suspected that there are serious problems with the machine. The author listened carefully to the introduction of the relevant operators in the workshop, and carefully checked the printing sheet. It was found that the axial and radial length of the blue print were significantly shortened, while the other three-color overprint was very accurate. After that, I made a simple inspection of the machine and basically found no problems. According to the situation of the printing sheet and the machine, it is not sure that it is the fault of the machine, or it may be caused by other reasons. Therefore, in order to avoid causing unnecessary trouble, we did not adjust the machine blindly. When studying the specific operation details with the relevant operators in the plate printing and printing workshops, the author believes that there are no problems with the operating procedures and processes of the operators, and the film is completely accurate

so what's the problem? It turned out that this set of printing plates was baked a week ago and has not been used due to production scheduling. Before going online, the printing staff found that the green version could not be used because it was injured when participating in the lithium industry in the Americas, so they made up a new one. In the work, we often encounter the situation that the printing plate is damaged and the sun is replenished. There was no problem originally. However, it was a rainy day a week ago, and the air was very humid for several days in a row, so it may be that the original film stretched due to moisture, resulting in the lengthening of the impressions of the four printing plates. After that, the weather improved, and the temperature and humidity control measures in the printing workshop were not very effective. When the blue version was supplemented, the green version imprint became shorter due to the drying and shrinkage of the film due to the weather. In order to confirm this judgment, we found the scratched printing plate and the newly baked printing plate to compare with the film, and found that the scratched printing plate was indeed longer than the impression of the film and the newly baked printing plate. Then, we took off all the black, magenta and yellow printing plates on the official working machine of Jinan experimental machine factory after the 2017 Spring Festival, and compared them with the printing plate, and the results confirmed the author's judgment. After re printing, test printing and troubleshooting

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