First, pay attention to the observation sample
1 Sampling inspection in printing . Shortly after entering the official printing, there will be some changes in the amount of ink supplied and the amount of water that will be determined at the time of printing. It should be frequently sampled and re-adjusted. When the printing speed remains the same, and the ink supply amount and the water supply amount are all in a stable state, the sampling inspection is performed at a ratio of 500 to 1000 sheets/time per print.
2 Clip the warning tape. In official printing, as a symbol, a slender warning strip should be inserted as a symbol to facilitate the inspection in the post-process.
Second, pay attention to changes in water
1 Pay attention to the change in water supply at the beginning of official printing. The amount of water applied during the trial printing and the amount of water entering the official printing will change somewhat. Be sure to pay attention to the presence or absence of ghosting and water scorpion while paying attention to mediating the water supply of the printing plate.
2 Pay attention to the change of water in the formal printing process. Pay close attention to the heat generated by the main body of the machine and the influence of the ventilation condition in the workshop on the water supply. The alcohol dampening plate should pay attention to the dampening system cooling device, control the temperature of the dampening solution, and the water is too small, which will make the printing plate dirty. Excessive water will cause the ink to emulsifie, which will bring a series of problems. For example, the print is dull, the paper is stretched and the overprint is not allowed, and the drying of the ink is delayed.
Third, pay attention to changes in ink
1 Pay attention to the ink of the ink fountain. The ink of the ink fountain is transmitted from the gap between the ink fountain roller and the ink fountain blade, and is naturally extruded by the self weight of the ink. Therefore, the amount of ink in the ink fountain directly affects the output of the ink. Therefore, pay attention to keep a certain amount of ink in the ink fountain. In addition, printing inks have thixotropic properties. If it is placed in the ink fountain for a long time, the fluidity will gradually deteriorate. Therefore, it is often necessary to use an ink knife to stir in the ink fountain or to install an ink agitator.
2 Prevent the ink from drying on the machine. When the machine is stopped for a long time, such as eating or resting, the ink on the ink roller and the surface of the ink in the ink fountain are dried. A dry inhibitor can be sprayed on where it is desired to prevent dryness.
3 Note that the ink is uniform, and the density of the printed matter changes depending on the amount of water, room temperature, and machine speed. It should always be checked against the standard proofs. Take care to prevent uneven ink.
4 Keep the pH value of the dampening solution. After adding the auxiliary agent to the ink, it will easily affect the pH value of the dampening solution. If the pH value increases, the plate will be dirty, so pay special attention.
Fourth, pay attention to the back of the dirty
The back smudging is caused by the slow drying of the ink, the excessive thickness of the ink layer, and the high smoothness of the paper, so that the ink on the surface of the sheet sticks to the back side of the previous sheet.
Five, pay attention to ghosting failure
The so-called ghosting is the misprint of the image printed with a plate, and the double and triple images can be seen on the printed sheet. There are many reasons for ghosting, such as paper, fangs, rollers, blankets, printing speed, ink viscosity and other factors are very complicated. The following methods can be used to check the cause and handle it.
1 Print twice, observe the overprinting accuracy, check and adjust the paper feeding force of the side gauge, paper feeding, pressure roller and paper pressing machine.
2 Check the tension of the blanket, the new blanket is easy to loosen, pay attention to the tightening, but not too tight.
3 Check the drum liner and printing pressure.
4 Check the paper suitability. The paper has poor fit, especially in paper that is wavy at the mouth of the mouth, which is prone to ghosting, so it is necessary to check.
5 reduce the viscosity of the ink. The viscosity of the ink is high, and the paper cannot smoothly peel off the blanket, which makes the tip of the paper unstable, resulting in ghosting. The viscosity of the ink can be appropriately lowered.
6 adjustment of tooth decay. Poor adjustment of the cavities and improper maintenance are a major cause of ghosting. Therefore, the adjustment and maintenance inspection of the cavities should be done regularly so that they can always maintain a good working condition.
Six, pay attention to check the overprint situation
Remove 20~30 prints in succession, and then pry open the paper edge to check whether the front gauge and side gauge are positioned accurately (two overprint inspections can be performed).
Seven, pay attention to other work
1 ink replenishment, agitation and replenishment of the wetting fluid.
2 remove dirty work. Since the ink residue, paper powder, paper wool and the like are adsorbed on the printing plate or the blanket and reflected on the paper, it is necessary to remove the dirt. In addition to dirty work, it should be stopped. Unless there is a device that can remove dirt during operation. It is absolutely forbidden to remove dirt directly by hand during operation.
3 cleaning blankets, wiping and gluing operations. When the ink, paper powder, and powder powder are accumulated on the blanket to affect the transfer of the ink, the blanket must be stopped for cleaning, and safety should be taken during operation. Wiping and gluing should also be safe.
4 Pay attention to the abnormal phenomenon of the printing machine. Pay attention to the sound, heat, vibration, smell, etc. when the machine is running. Always check the ammeter to keep an eye on the abnormality of the press.
Eight, pay attention to confirm the number of prints
At the end of the printing, it should be confirmed whether the number of prints matches the production order. If there are any missing copies that need to be printed, the production management personnel should be notified to make timely arrangements for reprinting.
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