Installation and adjustment of closed scraper systems
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
In recent years, the application of closed scraper systems in flexographic printing has been increasing. In order to help flexographic printing operators to understand the closed scraper system, this article will introduce the installation, adjustment and cleaning of closed scraper systems. Some tips and advice. It must be noted here that when performing the following operations, it is important to follow the recommendations and guidelines of the closed scraper system supplier and refer to the operating manual.
Basic features of the closed scraper system
The ink scraping method of the closed scraper system is shown in Fig. 1. The basic features of the system mainly include the following aspects.
(1) It adopts unique chamber structure and double-layer sealing design, which has better inking effect and saves ink.
(2) Effectively controlling the large amount of solvent evaporation in the ink, improving the working environment and reducing air pollution. Since most of the area where the ink is located is sealed, only a very small portion of the contact with the anilox roll is exposed, thereby greatly reducing the amount of solvent volatilization.
(3) The adaptability to the printing speed is good, regardless of the printing speed, the amount of ink transfer is fixed, so the printing quality is stable.
(4) A combination scraper can be used, and the scraper can be replaced quickly and simply.
Of course, there are still some problems with the closed scraper system. For example, the contact angle of the closed scraper and the degree of freedom of the pressure are small, the uniformity of the scraping ink is required to be high, and the sealing property is required to be good, otherwise the ink leakage is likely to occur. In addition, the cleaning operation after printing is troublesome, especially the ink or varnish remaining at the dead corner is more difficult to remove, but the application of the automatic cleaning device solves this problem to some extent.
Scraper and seal installation
1. Cutting scraper
At present, there are many types of scrapers. Regardless of the type of scraper used, it is first necessary to carefully check the scraper for small burrs, small gaps or other defects, which may adversely affect the printing or glazing process. Moreover, the blade of the scraper must be clean.
Always wear protective gloves and safety glasses when cutting the blade, and use a special cutting tool to ensure that the cut edges are straight and tidy. More importantly, it is necessary to ensure that the length of the scraper after cutting is appropriate.
2. Install a new scraper
Loosen the screws on the holder, put on protective glasses and gloves, carefully remove the old blade from the holder and the ink chamber, and send it to the designated area for proper disposal.
Next, use a soft cloth and a special amount of special cleaning agent or hot water to gently wipe off the dried ink or varnish remaining in the holder. This is to make the new blade fit straight into the ink chamber. To prevent leakage of ink or varnish during operation.
When installing a new scraper, make sure that it is of the right length and that there are no defects, then tighten and secure the tool holder. If the scraper is bent or loosened, it will not only affect the service life of the scraper, but also the seal strip is prone to leakage. Leakage at the seal is often caused by excessive pressure on the anilox roll by the scraper. Therefore, it is important to ensure that the seal and scraper are properly installed.
3. Installation seal
Carefully check that the width of the seal is appropriate. Some seals often have small burrs or have been damaged during the cutting process. Sealing strips of different materials have different sealing properties. Therefore, it is necessary to consult with the supplier and know which type of sealing strip should be picked and why it should be used. The accuracy of the dimensions of the seals must also be ensured. Even a 1/4 inch deviation will seriously affect the sealability. Therefore, it is necessary to ensure that the seals match the closed scraper system used.
In addition, the surface of both ends of the anilox roll used in conjunction with the closed scraper system should be unengraved, that is to say, the surface of the end of the netting roll that is in contact with the sealing strip is smooth, which minimizes the sealing. The strip is worn and can effectively prevent the ink or varnish from leaking from the sealing strip during the transfer process. The main function of the sealing strip is to block the leakage of ink or varnish. Therefore, be sure to check the position of the seal and the scraper before starting the printing.
Operation and adjustment of the closed scraper system
1. Install and adjust the ink chamber
Install the ink chamber onto the flexographic press as directed by the manufacturer of the closed scraper system and gently contact the upper and lower scrapers with the anilox roller. In addition, check whether the contact between the upper and lower blades and the anilox roller is balanced and consistent. In fact, many of the problems that occur during the printing process are caused by incorrect ink chamber locations or incorrect seal installation.
The ink chamber is placed so that it is parallel to the centerline of the anilox roll and its position is centered relative to the ends of the anilox roll. In the process, be sure to remove the seal and replace the scraper with two stainless steel blades of the same width. After adjusting the position of the ink chamber to the center, the blade can be replaced with a properly sized scraper.
Next, start the loading mechanism and, if necessary, re-adjust the base until the ink chamber is parallel to the anilox roller. If the doctor blade or ink chamber contacts the anilox roller, the system must be realigned to prevent irreversible damage.
Finally, if the closed scraper system is pneumatically mounted, check that the distance between the scraper and the anilox roller is appropriate, otherwise damage may occur when the anilox roller and the scraper grip are in contact. In addition, if the blade is not evenly contacted with the anilox roller, serious leakage problems may occur.
2. Ink supply and idling
After the ink chamber is adjusted, the ink pump is activated to start injecting ink into the ink chamber. It is important to keep in mind that the ink pump should not be operated too fast, otherwise it will cause excessive pressurization and leakage. The amount of ink or varnish that is pressed into the ink chamber may be slightly larger than the amount required for the job.
Once the ink chamber is filled with ink or varnish, the idle button can be activated. If a metal scraper is used, it may make a loud humming sound. Some high quality scrapers or non-metallic scrapers can be used. Effectively reduce and reduce this noise.
3. Visual inspection
After the system has been running for a while, carefully check the attitude of the system, tube and ink pump. The operation of the system should be smooth; the tubes should not be entangled and should not fall under the ink pump; the height of the return tube should not be lower than the surface of the ink or varnish in the barrel. In addition, check the return of the ink or varnish, and adjust the speed of the circulation pump if necessary.
4. Adjust the blade pressure
First, reducing the pressure on the anilox roll in the ink chamber is the first step in adjusting the pressure of the doctor blade. A strong "ink flow" may occur on the surface of the anilox roll. Next, carefully increase the pressure or slowly rotate the pressure regulating handle until the “ink flow” on the surface of the anilox roller disappears. At this time, the blade pressure reaches the optimum state, the so-called “kissing pressure” state, not only the blade It has the best performance and minimal wear.
Cleaning of the closed scraper system
When using a closed scraper system, cleaning is a very important part and one of the most overlooked. The cleaning steps are roughly as follows.
(1) Turn off the ink pump and let the ink or varnish flow back naturally.
(2) Rinse the closed scraper system with clean water or special cleaning solution. Note that the cleaning solution should not be used repeatedly. Otherwise, it can only dilute or dilute the ink and varnish, but it cannot be thoroughly cleaned.
(3) Remove the ink chamber and clean it offline, which saves time and money.
(4) The anilox roller should also be thoroughly cleaned, otherwise the residual ink or varnish may dry on its surface. Ultrasonic or high-pressure automatic cleaning system can be used for cleaning, which can reduce the damage to the anilox roller. When water-based ink or varnish is used, the effect of cleaning the anilox roller with hot water is better. If the ink or varnish has dried on the surface of the anilox roll, it can be removed with a soft cloth or a special brush.