In addition, the wear of gears can also be misprinted by the public. Check the easy-to-wear gears regularly and refuel the gearbox.
3. Tension is not suitable Flexographic press tension control system should include tension detection, tension adjustment and Zhang Guo hospitality and other parts. Common tension control methods include friction discs and sub-brakes. If the air pressure (hydraulic), current adjustment is too large or too small will affect the overprint. Different textures of paper and tension at different printing speeds have some changes. If you are using a manual Zhang Guo controller, be aware that as the paper roll decreases, the main roll tension also decreases. This is because the smaller the paper roll, the smaller its required necrosis (braking force).
In addition, the poor control of rewinding Zhang Guo during the production of paper or during the roll-up process of yesterday may also cause instability of the tension and affect the accuracy of overprinting. The normal paper roll is flush with the edge of the paper roll with poor tension, or the paper core is skewed.
4. If the pressure is too high, the plate will be deformed and overprinting will occur. This is often the case when two spot color overprinted words are negative. One-sided pursuit of black ink and increased pressure will make the void space narrower and the two-color overprint more difficult (for this type of work, two plate plate design must be specially dealt with; Or only, known as the expansion of the plate version; after the printed Yin Yin slightly smaller, used to register with the previous version, known as the forming version).
5. There is no tension adjustment device for the flexo printing machine. If there is no tension adjustment device between the color groups of the unit type flexo press, during the pattern making, local tension will be formed in a certain area, which will affect overprinting with other color groups. This kind of situation is the same in the same discipline, but when the frontier continues to land, this effect will manifest itself, especially when low-speed printing thin paper.
6. Axial overprinting is inaccurate. This is a non-existent situation. Most problems are mechanical, such as shafts and walls, and plate roller bearings that are damaged. In addition, too much paper humidity can cause misprints.
Third, the ink sticks Because the printing plate cylinder of the flexo printing machine is not shoulder iron like the offset printing machine, so the flexo printing machine is most likely to produce the ink stick. The causes of ink sticks mainly include the following aspects.
1. The rack bars are the most common and appear in rows of rows in the direction of the paper feed due to gear wear or poor meshing between gears. If the gear is replaced and the oil cannot be solved after refueling, the pressure must be readjusted so that the plate roller gear and the platen roller gear can achieve the best meshing position, thereby eliminating the toothed bar.
2. The knife bar flexo machine can perform single warp. The knife 2 of the knife is slightly higher than the shoulder iron of the knife. If Knife 2 is the main height, the whole machine vibration will occur when the machine rotates, so that the cover is one. So the cutter must be carefully adjusted. In addition, the paper threading path can be changed as appropriate. For example, wear more or less to wear a paper roller, so that when the cutter cuts paper, the blank part of the cylinder or the printing cylinder of the printing plate is opposite, so as to avoid the ink bars generated by the vibration of the machine. Generally, after several trials, it is possible to determine the proper threading path. When the circumference of the cylinder changes, the threading path must also change.
3. Improper pressure regulation, whether it is positive pressure or lateral pressure adjustment is too large, will make the version of the rotary drum port and the screen in the imprinting roller with the impact of the emergence of ink bars. For a one-way clutch press, such ink sticks are common and difficult to remove.
4. The platen roller shaft is not fixed tightly and the platen roller shaft is not fixed tightly, and the ink bar will be generated at high speed. A fixed position of the anilox roller also has an effect.
5. Ink viscosity and machine speed The ink viscosity and the presence of ink bars are not directly related to whether or not. However, when the ink viscosity is small, the amount of ink is small, and the visual sense of the bar is obvious; the viscosity is large, the ink is deep and full, and the ink bar is inconspicuous. In addition, the speed of the machine is also related to the ink bars, but the two are not proportional. Sometimes the speed is low and the ink bars are small; sometimes the speed is high and the ink bars are small. This is related to the smoothness of the machine at different speeds. In most cases, the speed is high and the ink bars are small.
Fourth, paper wrinkles Paper wrinkles more common in thin paper printing. The main reason is:
1. Tension adjustment is too large. The unwinding tension of thin paper should be small. If the tension is too great, the paper will wrinkle.
2. The tape is tight on both sides. The paper roll is not centered with respect to the position of the machine, causing the paper tape to become loose and tight, and when it passes around the paper feed roller, the paper tape shifts toward the loose side of the paper edge.
3. Stick foreign objects such as inks on the roller.
The paper roller is not fixed tightly, causing looseness in the shaft and causing wrinkles.
3. Tension is not suitable Flexographic press tension control system should include tension detection, tension adjustment and Zhang Guo hospitality and other parts. Common tension control methods include friction discs and sub-brakes. If the air pressure (hydraulic), current adjustment is too large or too small will affect the overprint. Different textures of paper and tension at different printing speeds have some changes. If you are using a manual Zhang Guo controller, be aware that as the paper roll decreases, the main roll tension also decreases. This is because the smaller the paper roll, the smaller its required necrosis (braking force).
In addition, the poor control of rewinding Zhang Guo during the production of paper or during the roll-up process of yesterday may also cause instability of the tension and affect the accuracy of overprinting. The normal paper roll is flush with the edge of the paper roll with poor tension, or the paper core is skewed.
4. If the pressure is too high, the plate will be deformed and overprinting will occur. This is often the case when two spot color overprinted words are negative. One-sided pursuit of black ink and increased pressure will make the void space narrower and the two-color overprint more difficult (for this type of work, two plate plate design must be specially dealt with; Or only, known as the expansion of the plate version; after the printed Yin Yin slightly smaller, used to register with the previous version, known as the forming version).
5. There is no tension adjustment device for the flexo printing machine. If there is no tension adjustment device between the color groups of the unit type flexo press, during the pattern making, local tension will be formed in a certain area, which will affect overprinting with other color groups. This kind of situation is the same in the same discipline, but when the frontier continues to land, this effect will manifest itself, especially when low-speed printing thin paper.
6. Axial overprinting is inaccurate. This is a non-existent situation. Most problems are mechanical, such as shafts and walls, and plate roller bearings that are damaged. In addition, too much paper humidity can cause misprints.
Third, the ink sticks Because the printing plate cylinder of the flexo printing machine is not shoulder iron like the offset printing machine, so the flexo printing machine is most likely to produce the ink stick. The causes of ink sticks mainly include the following aspects.
1. The rack bars are the most common and appear in rows of rows in the direction of the paper feed due to gear wear or poor meshing between gears. If the gear is replaced and the oil cannot be solved after refueling, the pressure must be readjusted so that the plate roller gear and the platen roller gear can achieve the best meshing position, thereby eliminating the toothed bar.
2. The knife bar flexo machine can perform single warp. The knife 2 of the knife is slightly higher than the shoulder iron of the knife. If Knife 2 is the main height, the whole machine vibration will occur when the machine rotates, so that the cover is one. So the cutter must be carefully adjusted. In addition, the paper threading path can be changed as appropriate. For example, wear more or less to wear a paper roller, so that when the cutter cuts paper, the blank part of the cylinder or the printing cylinder of the printing plate is opposite, so as to avoid the ink bars generated by the vibration of the machine. Generally, after several trials, it is possible to determine the proper threading path. When the circumference of the cylinder changes, the threading path must also change.
3. Improper pressure regulation, whether it is positive pressure or lateral pressure adjustment is too large, will make the version of the rotary drum port and the screen in the imprinting roller with the impact of the emergence of ink bars. For a one-way clutch press, such ink sticks are common and difficult to remove.
4. The platen roller shaft is not fixed tightly and the platen roller shaft is not fixed tightly, and the ink bar will be generated at high speed. A fixed position of the anilox roller also has an effect.
5. Ink viscosity and machine speed The ink viscosity and the presence of ink bars are not directly related to whether or not. However, when the ink viscosity is small, the amount of ink is small, and the visual sense of the bar is obvious; the viscosity is large, the ink is deep and full, and the ink bar is inconspicuous. In addition, the speed of the machine is also related to the ink bars, but the two are not proportional. Sometimes the speed is low and the ink bars are small; sometimes the speed is high and the ink bars are small. This is related to the smoothness of the machine at different speeds. In most cases, the speed is high and the ink bars are small.
Fourth, paper wrinkles Paper wrinkles more common in thin paper printing. The main reason is:
1. Tension adjustment is too large. The unwinding tension of thin paper should be small. If the tension is too great, the paper will wrinkle.
2. The tape is tight on both sides. The paper roll is not centered with respect to the position of the machine, causing the paper tape to become loose and tight, and when it passes around the paper feed roller, the paper tape shifts toward the loose side of the paper edge.
3. Stick foreign objects such as inks on the roller.
The paper roller is not fixed tightly, causing looseness in the shaft and causing wrinkles.
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