Analysis: How to do a good job in ink and color change in offset printing
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In the offset printing process, especially the monochrome offset printing machine, regardless of Y, M, C, BK four-color printing, the trademarks, packaging and decoration often need to wash ink and color, cleaning the ink system of the entire offset printing machine, and then Put on a new ink. The ink-washing device wiper is composed of a rubber knife, an ink receiving groove and a loose adjusting screw. Ink washing process: Put the gasoline and car wash water on the ink roller, install the scraper in the ink tank, and tighten the adjusting screw so that the rubber knife has a 40° angle corresponding to the offset roller surface of the offset press. Contact, longitudinal and lateral movement of the ink roller, the old ink and gasoline on the inking system are continuously scraped through the rubber knife into the ink collection tank.
Washing and color changing is clean and thorough, which plays a key role in the accurate grasp of printing hue. The ink color can be positive and the ink color is bright and accurate. In the actual ink washing and color changing operation, the following points should be noted:
1. The ink squeegee device must be installed on the offset printing machine when the ink is changed, or if the ink roller needs to be cleaned due to other factors, the eccentric pin on both ends of the ink receiving groove is placed on the installation. The adjusting nut is fixed in the opening of the square iron block of the wall plate fixed in the opening groove of the support shaft on the offset printing machine wall plate. Then start the offset printing machine, and turn the adjusting nut so that the blade of the rubber rubber knife slowly contacts the surface of the squeezing roller, and the contact pressure of the adjusting screw at the left and right ends is evenly required, and the rubber knives and the squeezing roller are evenly contacted at every part. Fully scrape the ink.
2. When cleaning the ink, in order to thoroughly and cleanly remove the ink accumulation and ink marks on all the ink rollers, it is preferable to pour the gasoline from the upper portion of the ink injecting member on the ink roller near the ink fountain portion, thus cleaning the crucible. The waste ink flows into the ink collection tank from the upper part of the rubber knife edge, and after a period of cleaning, the ink roller can be washed.
3. After the ink roller and ink fountain of the inking unit are cleaned, wipe it clean and clean it with a cloth head that is clean, soft, clean and has no fiber fluff and good water absorption.
4. The position of the wiper of the cleaning ink washing mechanism should be accurate, and the rubber blade and the surface of the ink roller should be kept at the same distance and the same contact pressure.
5. After cleaning, the speed of the cloth should be stable and fast. The offset printing machine should not let the cloth roll into the ink roller during operation.
6. Washing and changing colors requires the operator to maintain a uniform amount when pouring gasoline from the upper ink roller. Do not let the gasoline splash around.
7. The workshop is strictly prohibited from smoking and open flames to prevent fires when changing ink and color.
8. The operating status of the offset printing machine must be safe to scrub the ink roller.
1Beware of the cuffs, hands and corners of the top, which are caught in the rollers or rollers, causing personal injury.
2 Operators' jackets are not allowed to carry box rulers, keys, coins, pencils, pens and other hard objects and ink shovel and tools for repairing machines to prevent them from falling into the ink roller and causing accidents.
9. Washing and color changing In general, there are two cases, one is to change the light ink to the dark ink, and the other is to replace the dark ink with the light ink.
1 light color ink for dark ink method
It is easier to change the ink of light color into dark ink, which is also time-saving and labor-saving for the cleaning of the ink roller. First, use the ink shovel to shovel the light ink of the ink fountain. Just use the squeegee to clean the light ink on the ink roller, and clean the ink, paper and other debris left on the ink roller.
2 dark ink changed to light color ink
Offset ink wash and color change, dark ink is replaced by light ink. At this time, the cleaning of the ink roller is relatively high, it is difficult to clean, and the ink roller is cleaned to a higher degree. It requires that the light ink cannot be dark ink. Dirty, if the old ink on the cleaning roller is not completely clean, it will affect the color and hue inaccuracy. The light ink will have the shadow of dark ink. Therefore, the ink fountain, ink roller, ink shovel, etc. must be cleaned. Then use the ink shovel to apply the ink to the ink roller, start the offset printing machine, evenly paste the light ink on the ink roller, and then pour the gasoline to clean it. If it is not clean, it can be repeated once until the ink roller is clean.