Drawing, also known as drawing, starting line, when the ink performance and ink color is different, its performance is also different, the general black, blue, magenta drawing phenomenon is more obvious, and generally appear in a large area of ​​the shallow network.
Irregular drawing of blank spaces
Random wire drawing in the print blanks is characterized by an irregular ink path that is sometimes absent and has a short duration. It is usually thick. The causes and solutions are as follows.
1. There is foreign matter on the edge of the squeegee blade or under the knife. It is possible to move the squeegee forward and backward and up and down during the printing process to remove the sticking foreign matter or remove it with a bamboo stick directly on the squeegee blade (must be completed by a skilled operator to avoid unnecessary loss due to improper operation) If necessary, stop the squeegee thoroughly.
2. Insufficient ink circulation. Part of the ink in the ink tank dead space, due to not get a good circulation caused by resin precipitation, the formation of different sizes of crystals and agglomeration, or excessive drying caused the formation of the surface of the ink (summer easy to produce ink, spring and autumn because the temperature There are many cases of ink crystallization and agglomeration. As the ink is circulated, a part of the ink is crystallized or the plate roller is rotated to the blade edge, and the squeegee breaks it to form a random wire drawing. Therefore, improvements must be made in both the circulation and filtration of the ink.
(1) Cycle improvement. The first method is to tilt the ink tank to the left or right to ensure that the ink can be injected from the slightly higher end and flow out from the lower end to form a good circulation. In the second method, the ink tank is laid flat, but the ink must be injected from both ends simultaneously. In the middle of the reflow, it can also form a very good cycle, can not be injected from the single side of the ink.
(2) Filter improvements. Before the ink is used, it must be filtered for the first time. Even the new ink must be filtered. A filter of 140 mesh/inch is generally used. The filtration work of the ink circulating in the ink tank is more important. It can well filter out the resin crystals and foreign impurities formed during the use of the ink. The mesh selected should be finer. The method is to set a stocking under the ink fountain. , Form a filter bucket, after filtering for a period of time, if the filter is blocked, ink flow is not smooth, you can insert some holes in the top of the bucket with a bamboo stick to increase the ink-conducting effect. The lower part of the bucket can also be used. The role of good deposition of impurities is shown in Figure 3. Some large printing plants in Shanghai and Guangdong have used this method to control intermittent ink drawing problems.
3. Ink fatigue. This situation occurs mostly when the printing area of ​​the printing plate is relatively small. During the printing process, the resin in the ink is continuously consumed. If the solvent is continuously added without adding new ink, the resin will not be replenished, and the proportion of each component of the ink will change, thus causing ink fatigue and affecting normal use. Appropriately adding new ink will solve the problem.
Other forms of brushed
1. The phenomenon caused by the printing plate
(1) Surface treatment of printing plates. Gravure is now mostly electronically engraved. During the carving process, many small burrs are formed on the edge of the engraved mesh cavity. These small burrs also damage the squeegee during the printing process, causing the wire drawing. However, this type of drawing is limited to the dots on the printing plate and will not extend into the blank space. The new version is prone to this situation. Within a certain range, with the increase in the number of prints, drawing will gradually decrease. This requires that in the production process of the plate cylinder, on the one hand, the hardness of the engraved copper layer should be ensured, the formation of small burrs in the engraving process should be reduced, and the copper layer should be processed after the engraving; on the other hand, a standardized chromium layer should be established. The polishing process includes the type of belt used, the rotation speed of the platen, the frequency and speed of the polishing head, the polishing time, and the like. If the wire drawing phenomenon occurs in the printing process, you can also use 2# metallographic sandpaper or 600# water sandpaper or a dedicated nylon polishing net to grind and polish the surface of the printing plate, which generally solves the drawing problem.
(2) Installation of printing plates. If the printing plate runs large during the printing process, it may also cause wire drawing. This requires checking the concentricity of the printing plate and the printing plate shaft (no shaft mounting plate to check the top), checking whether the bearing and transmission parts are deformed, worn, or even the machine base is horizontal.
2. Wire drawing caused by the environment
The printing site environment must be kept clean. If there is dust in the operating environment, it may be mixed into the ink, resulting in drawing. Therefore, in the printing operation site, the number of people should be reduced as much as possible, and commuting should be performed in a clean and hygienic manner. Conditional companies can isolate the printing units, install air-conditioning facilities and dust removal equipment.
Irregular drawing of blank spaces
Random wire drawing in the print blanks is characterized by an irregular ink path that is sometimes absent and has a short duration. It is usually thick. The causes and solutions are as follows.
1. There is foreign matter on the edge of the squeegee blade or under the knife. It is possible to move the squeegee forward and backward and up and down during the printing process to remove the sticking foreign matter or remove it with a bamboo stick directly on the squeegee blade (must be completed by a skilled operator to avoid unnecessary loss due to improper operation) If necessary, stop the squeegee thoroughly.
2. Insufficient ink circulation. Part of the ink in the ink tank dead space, due to not get a good circulation caused by resin precipitation, the formation of different sizes of crystals and agglomeration, or excessive drying caused the formation of the surface of the ink (summer easy to produce ink, spring and autumn because the temperature There are many cases of ink crystallization and agglomeration. As the ink is circulated, a part of the ink is crystallized or the plate roller is rotated to the blade edge, and the squeegee breaks it to form a random wire drawing. Therefore, improvements must be made in both the circulation and filtration of the ink.
(1) Cycle improvement. The first method is to tilt the ink tank to the left or right to ensure that the ink can be injected from the slightly higher end and flow out from the lower end to form a good circulation. In the second method, the ink tank is laid flat, but the ink must be injected from both ends simultaneously. In the middle of the reflow, it can also form a very good cycle, can not be injected from the single side of the ink.
(2) Filter improvements. Before the ink is used, it must be filtered for the first time. Even the new ink must be filtered. A filter of 140 mesh/inch is generally used. The filtration work of the ink circulating in the ink tank is more important. It can well filter out the resin crystals and foreign impurities formed during the use of the ink. The mesh selected should be finer. The method is to set a stocking under the ink fountain. , Form a filter bucket, after filtering for a period of time, if the filter is blocked, ink flow is not smooth, you can insert some holes in the top of the bucket with a bamboo stick to increase the ink-conducting effect. The lower part of the bucket can also be used. The role of good deposition of impurities is shown in Figure 3. Some large printing plants in Shanghai and Guangdong have used this method to control intermittent ink drawing problems.
3. Ink fatigue. This situation occurs mostly when the printing area of ​​the printing plate is relatively small. During the printing process, the resin in the ink is continuously consumed. If the solvent is continuously added without adding new ink, the resin will not be replenished, and the proportion of each component of the ink will change, thus causing ink fatigue and affecting normal use. Appropriately adding new ink will solve the problem.
Other forms of brushed
1. The phenomenon caused by the printing plate
(1) Surface treatment of printing plates. Gravure is now mostly electronically engraved. During the carving process, many small burrs are formed on the edge of the engraved mesh cavity. These small burrs also damage the squeegee during the printing process, causing the wire drawing. However, this type of drawing is limited to the dots on the printing plate and will not extend into the blank space. The new version is prone to this situation. Within a certain range, with the increase in the number of prints, drawing will gradually decrease. This requires that in the production process of the plate cylinder, on the one hand, the hardness of the engraved copper layer should be ensured, the formation of small burrs in the engraving process should be reduced, and the copper layer should be processed after the engraving; on the other hand, a standardized chromium layer should be established. The polishing process includes the type of belt used, the rotation speed of the platen, the frequency and speed of the polishing head, the polishing time, and the like. If the wire drawing phenomenon occurs in the printing process, you can also use 2# metallographic sandpaper or 600# water sandpaper or a dedicated nylon polishing net to grind and polish the surface of the printing plate, which generally solves the drawing problem.
(2) Installation of printing plates. If the printing plate runs large during the printing process, it may also cause wire drawing. This requires checking the concentricity of the printing plate and the printing plate shaft (no shaft mounting plate to check the top), checking whether the bearing and transmission parts are deformed, worn, or even the machine base is horizontal.
2. Wire drawing caused by the environment
The printing site environment must be kept clean. If there is dust in the operating environment, it may be mixed into the ink, resulting in drawing. Therefore, in the printing operation site, the number of people should be reduced as much as possible, and commuting should be performed in a clean and hygienic manner. Conditional companies can isolate the printing units, install air-conditioning facilities and dust removal equipment.
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