Common cleaning methods and problem analysis of th

2022-09-23
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Common cleaning methods and problem analysis of the corrugated roller

in order to make the corrugated roller transfer ink accurately and quantitatively, not only the physical parameters of the corrugated roller should be configured correctly, but also the maintenance of the corrugated roller is very important. Especially in high-quality color layered printing, in order to maintain the accurate transmission of ink volume, the wrinkle roller must be cleaned frequently. Some domestic flexographic printing plants have not paid attention to this aspect, which not only shortens the service life of the corrugated roller, but also makes it difficult to obtain high-quality prints

in the past, there have been many discussions and discussions on the cleaning methods of corrugated rollers. Ink manufacturers, chemical manufacturers, and printing machine manufacturers have launched various chemical cleaning agents, cleaning machines, and cleaning processes for how to remove the ink dirt in the roller holes. However, these introductions mostly involve the cleaning ability, and the negative impact of different ways on the corrugated roller is less discussed

the flexographic printing machine with laser engraving roller and ink scraper blade system with ink groove can run at high speed, so it needs to use fast drying ink. To clean the ink tank, first drain the ink in the tank, and then use clean water or mixed water with chemical detergent that has passed the reform and opening-up tide to circulate it in the ink circulation system. The inking hole of the laser engraving roller is coated with silicone resin, and the surface of the roller can be soaked with commercial cleaning agent. According to the inspection of the main roller manufacturers, the surface moisture absorption will change after continuous soaking for 24, 48 and 72 hours. Then use a proper brush at least once a day to put the shaft sleeve on the brushing roller, which is a more effective cleaning method

after careful observation, it is often found that the middle of the wrinkle roll can be cleaned, and there are still ink deposits at both ends of the hole. The ink tank system can generally inject new ink into the middle of the roller with an ink pump, and distribute the ink to the whole surface of the roller by centrifugal force. Therefore, the new ink in the middle of the wrinkle roll can wash away the stored ink and keep the holes clean, while the holes at both ends of the wrinkle roll, especially under the condition of high-speed wire, are easy to be blocked by the ink, so it needs to be cleaned with more effective chemical cleaners

the following cleaning methods are widely used in the industry today. These methods are more effective in removing the ink from the hole, but each method may have side effects on the wrinkle roll, so a unified method has not been formed so far

● ultrasonic cleaning method

dip the corrugated roller into a tank filled with chemical cleaning solution and equipped with an ultrasonic cleaning system, which is a frequency converter that sends high-frequency sound waves. The frequency converter vibrates the solution, produces bubbles, and produces inward "explosion". A series of inward explosive forces drive the ink out of the hole and flow away with the cleaning solution. Some ultrasonic cleaning systems have a device to rotate the wrinkle roll, otherwise it needs to be rotated manually. The cleaning time depends on the size of the roller and the blockage of the ink. It usually takes 30 minutes to 24 hours, or even longer. During this time, the roller is under high-frequency ultrasonic vibration for a long time

after ultrasonic vibration for a period of time, extremely small cracks will appear on the surface of the ceramic roller. The accumulation of cracks provides an additional channel for the porous ceramic coating, and gradually corrodes the substrate

most high-quality corrugated rollers are coated with a moisture-proof barrier protective layer before the ceramic coating, and some manufacturers use single-layer or multi-layer additional protective layers to further delay corrosion. The ultrasonic cleaning system cannot be distinguished from the impact of the international trade war. In addition, the domestic environmental protection policy has pressed the ink or protective layer tightly. In the process of vibration, the protective layer falls off due to vibration. Therefore, when the printing machine uses high pH chemical cleaning agent, the protective layer will fall off, that is, the beginning of corrosion

● soaking tank

dip all or part of the wrinkle roll into the tank of high pH cleaning solvent, which can dissolve the ink. The new structure is to spray the solvent to the rotating roller through high pressure, forcing the ink to escape from the hole. Although this method is more effective, if used for a long time, the solvent will penetrate the protective layer, making the solvent penetrate through the ceramic pores and corrode the steel body

after testing, the use of general chemical solvents, soaking time within 24 hours, will not affect the surface tension and hydrophilicity of the roller

● pressure cleaning

sodium carbonate or baking soda is used as cleaning agent for pressure cleaning. High voltage generator (such as sand cleaning system) is required in some devices, and the ceramic coating may fall off the roll body during cleaning. The pressure setting should not exceed 30 pounds/inch. The selected pressure can not only do a good job of cleaning, which is the work on the different samples of the correction point, but also can not damage the wrinkle roll

flexographic printers have learned that the chemical cleaners currently sold are more effective in decomposing ink. This is the reason for choosing this method, but the impact of long-term use and excessive use of chemicals should also be considered. If this cleaning method is used for a long time, the corrugated roller may be damaged

(author Liu Jiao)

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