Compared with traditional offset printing, UV printing has the advantages of bright colors, wide range of printing materials, novel products, and a vast market. It is suitable for the printing of high-end business cards, boutique packaging, high-end commercial albums, and special desk calendars. However, UV offset printing has a certain degree of complexity and diversity, which brings certain difficulties and problems to operators. If operators do not systematically grasp the processes and technologies of UV offset printing, they tend to ignore some problems that are not easily noticeable. , which led to the emergence of a variety of print quality problems. When the full version of magenta was printed on the ground, an ink stick problem occurred. The specific situation was that the width of the ink stick was 8 mm, the width between the ink sticks was 12 mm, and the ink bars were evenly distributed and distributed into a curtain. After troubleshooting all possible causes, the author finally found that the main reason came from the UV system of the offset press. Below, analyze the process and the final solution.
Equipment troubleshooting
The ink stick problem encountered this time was very similar to the usual “gear bar” seen at the first sight, so the author first checked from the equipment perspective. Through the detection of certain parameters of the printing equipment, the radial runout errors of the impression cylinder, the blanket cylinder, and the plate cylinder are all within 0.01 mm. At the same time, there are no signs of wear on the transmission zero stage gears of each cylinder. The road is also very smooth, thereby eliminating the possibility of roller problems.
Then, the ink roller parameters of each color group were adjusted, but after the completion of the test, it was found that the ink stick problem still exists, so the possibility of ink roller problems can also be ruled out.
Subsequently, the glazing unit was also inspected and found that the radial runout error of the A-side anilox roller support sleeve of this unit reached 0.08mm, which has greatly exceeded the amount of error required by the printing equipment. The author believes that this may be the trigger for ink sticks. The main reason for the problem. As a result, the support sleeves and support bearings were replaced. However, it is disappointing that this situation is still not the “virtual culprit” of the ink stick problem. The issue of ink sticks still exists when the printer is switched on.
Electrical troubleshooting
After eliminating the "suspicion" of the printing equipment, the company's electrician conducted investigations from the electrical point of view, including the replacement of the main motor pulse potentiometer, spindle signal encoder and the host main drive, and even the main source of power transmission source motor, but the issue of ink sticks is still not solve.
Supplies troubleshooting
Taking into account the paper, ink may also be the cause of the ink stick problem, I changed the company's different types of paper and different manufacturers of ink, but the problem of ink sticks still exists when the power-on test. Afterwards, the rubber blankets, printing plates, and gaskets were investigated one by one. It was found that there was no slack in the blankets, the plate friction was moderate, and the pads were medium and soft, all of which did not cause problems with the ink bars. produce.
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