At present, the flexographic printing process has matured. In foreign countries, the market share occupied by Tuen has continuously expanded, and Tuen has become the most competitive printing method.
In the 1990s, China began importing flexographic printing machines. At present, there are a large number of flexible printing lines introduced in China. However, some of them have failed to be produced normally. The technical level of operators is an important factor. At present, the waste consumption rate of flexographic printing presses is basically above 10%. Some printing products with high print quality requirements have reached an astonishing level. In order to reduce consumption and increase efficiency, the author summarizes the experience of flexo printing in the past few years and communicates with everyone here.
One, dirty with dirty 1. Improper adjustment of ink compatibility Improper drying of ink, the heavy duty ink on the cylinder will gradually dry and accumulate in India, causing edges and serrations on the edge of the print. At this point can be the right amount of 1,2-propylene glycol to reduce the ink drying speed. In general, new ink drying speed is relatively fast, and the speed will gradually decrease after a period of use. Too slow drying of the ink will also cause dirt, which is due to the fact that the undried ink on the surface of the print will stick to the transfer roller and be transferred to the paper again. At this time can slow down the speed increase hot air, add appropriate amount of isopropyl alcohol or quick-drying agent in the ink to adjust. Since the ink container is not clean or the confinement of the contaminated material can cause impurities, it can be filtered by a fine gauze. Ink viscosity is too high, resulting in poor transfer, which can cause dirt on the surface of the paper to adhere to the dirt. The phenomenon is that there is a snowflake-like white spot on the work surface. These white spots are set on paper because of the reason for the paper roll cutting. Stabilizers are usually added to the ink and the viscosity can be reduced to solve the above problems.
2. Improper printing pressure adjustment There are two pressures for flexographic printing: the pressure between the anilox roller and the ram cylinder (commonly known as lateral pressure) and the pressure between the plate cylinder and the impression cylinder (personal positive pressure). Improper adjustment of any of these two pressures can result in dirty prints. If the lateral pressure is too high, the pattern or lines will not be smooth at the periphery, and the printing will be normal at the beginning of printing. The longer the time is, the more serious this phenomenon is, similar to offset printing. If the positive pressure is too high, the side of the median line (the side that faces the mouth or the tip) will grow hairy and not flat, while the other side will be normal, similar to offset long hair. Generally based on careful observation of printed products, it is not difficult to analyze the size of the two pressures.
The author believes that the lateral pressure must be small and small enough to be in contact with it. The positive pressure can be adjusted slightly to the point that it does not affect the quality of the printed matter. It is better to observe the edge of the printed product with a naked eye. For a one-way clutch press, this adjustment may seem inconvenient, but the general rule is: Reduce the side pressure, and properly increase the positive pressure will reduce dirt.
3. The squeegee wear is due to the reason of the anilox roller or the poor quality of the squeegee. In the course of use, it will cause the unseen hole on the knife edge, which will cause the ink roller to spread the ink unevenly and make the plate dirty. The phenomenon is that a trace of ink marks appears on the anilox roller, and it is better to replace the squeegee blade at this time.
4. Paper Causes Dirty Paper Dust on the surface of the paper will adhere to the plate. The greater the viscosity of the ink, the more dust that adheres. At this point, the viscosity of the ink can be reduced, and a roll of water can be placed on the paper to block the ash. If the machine is equipped with a suction device, it must be ensured that the device is working properly. If the paper roll is to be trimmed at the time of rewinding, it must be noted that the knife must be sharp, and the generation of paper hair should be minimized so as not to cause unnecessary trouble for printing. In addition, dust removal devices can also be installed on the rewinder.
Second, registering inaccurate registration is directly related to the quality of printed products and the consumption of waste products. In the case of reeled paper printing machines, overprint accuracy is a very important performance indicator. Some machines claim that the overprint error of the whole machine is within 0.1mm, which is actually very difficult to achieve. At this time, we mainly talked about improper overwriting caused by improper operation.
1. Sticky-flexion Most of the flexo presses use artificial sticking. The errors of the sticking machine, the visual error of the stick, and the inconsistent use of sticky ground can all cause the sticky version to be skewed. So sticking is a very meticulous job.
2. Poor machine transmission Flexo presses are high-speed machines. After a certain period of use, the top wires, keys, pins, etc., between the components of the drive train will loosen, directly affecting overprinting. Therefore, it is important to regular maintenance of the machine milk, the use of rotating belt or shaking the impression cylinder to see if it is loose. The most common is that the embossing roll is loosened or the keys are worn. In the printing, it is shown that the gauges of the group run wildly irregularly, especially when the state of Zhang Guo is just turned on, the rules cannot always be stopped at one position, and the influence after printing is normal is small. (To be continued)
In the 1990s, China began importing flexographic printing machines. At present, there are a large number of flexible printing lines introduced in China. However, some of them have failed to be produced normally. The technical level of operators is an important factor. At present, the waste consumption rate of flexographic printing presses is basically above 10%. Some printing products with high print quality requirements have reached an astonishing level. In order to reduce consumption and increase efficiency, the author summarizes the experience of flexo printing in the past few years and communicates with everyone here.
One, dirty with dirty 1. Improper adjustment of ink compatibility Improper drying of ink, the heavy duty ink on the cylinder will gradually dry and accumulate in India, causing edges and serrations on the edge of the print. At this point can be the right amount of 1,2-propylene glycol to reduce the ink drying speed. In general, new ink drying speed is relatively fast, and the speed will gradually decrease after a period of use. Too slow drying of the ink will also cause dirt, which is due to the fact that the undried ink on the surface of the print will stick to the transfer roller and be transferred to the paper again. At this time can slow down the speed increase hot air, add appropriate amount of isopropyl alcohol or quick-drying agent in the ink to adjust. Since the ink container is not clean or the confinement of the contaminated material can cause impurities, it can be filtered by a fine gauze. Ink viscosity is too high, resulting in poor transfer, which can cause dirt on the surface of the paper to adhere to the dirt. The phenomenon is that there is a snowflake-like white spot on the work surface. These white spots are set on paper because of the reason for the paper roll cutting. Stabilizers are usually added to the ink and the viscosity can be reduced to solve the above problems.
2. Improper printing pressure adjustment There are two pressures for flexographic printing: the pressure between the anilox roller and the ram cylinder (commonly known as lateral pressure) and the pressure between the plate cylinder and the impression cylinder (personal positive pressure). Improper adjustment of any of these two pressures can result in dirty prints. If the lateral pressure is too high, the pattern or lines will not be smooth at the periphery, and the printing will be normal at the beginning of printing. The longer the time is, the more serious this phenomenon is, similar to offset printing. If the positive pressure is too high, the side of the median line (the side that faces the mouth or the tip) will grow hairy and not flat, while the other side will be normal, similar to offset long hair. Generally based on careful observation of printed products, it is not difficult to analyze the size of the two pressures.
The author believes that the lateral pressure must be small and small enough to be in contact with it. The positive pressure can be adjusted slightly to the point that it does not affect the quality of the printed matter. It is better to observe the edge of the printed product with a naked eye. For a one-way clutch press, this adjustment may seem inconvenient, but the general rule is: Reduce the side pressure, and properly increase the positive pressure will reduce dirt.
3. The squeegee wear is due to the reason of the anilox roller or the poor quality of the squeegee. In the course of use, it will cause the unseen hole on the knife edge, which will cause the ink roller to spread the ink unevenly and make the plate dirty. The phenomenon is that a trace of ink marks appears on the anilox roller, and it is better to replace the squeegee blade at this time.
4. Paper Causes Dirty Paper Dust on the surface of the paper will adhere to the plate. The greater the viscosity of the ink, the more dust that adheres. At this point, the viscosity of the ink can be reduced, and a roll of water can be placed on the paper to block the ash. If the machine is equipped with a suction device, it must be ensured that the device is working properly. If the paper roll is to be trimmed at the time of rewinding, it must be noted that the knife must be sharp, and the generation of paper hair should be minimized so as not to cause unnecessary trouble for printing. In addition, dust removal devices can also be installed on the rewinder.
Second, registering inaccurate registration is directly related to the quality of printed products and the consumption of waste products. In the case of reeled paper printing machines, overprint accuracy is a very important performance indicator. Some machines claim that the overprint error of the whole machine is within 0.1mm, which is actually very difficult to achieve. At this time, we mainly talked about improper overwriting caused by improper operation.
1. Sticky-flexion Most of the flexo presses use artificial sticking. The errors of the sticking machine, the visual error of the stick, and the inconsistent use of sticky ground can all cause the sticky version to be skewed. So sticking is a very meticulous job.
2. Poor machine transmission Flexo presses are high-speed machines. After a certain period of use, the top wires, keys, pins, etc., between the components of the drive train will loosen, directly affecting overprinting. Therefore, it is important to regular maintenance of the machine milk, the use of rotating belt or shaking the impression cylinder to see if it is loose. The most common is that the embossing roll is loosened or the keys are worn. In the printing, it is shown that the gauges of the group run wildly irregularly, especially when the state of Zhang Guo is just turned on, the rules cannot always be stopped at one position, and the influence after printing is normal is small. (To be continued)
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