What are the benefits of correctly installing the scraper blade?


Release time:

Aug 02,2021

What are the benefits of correctly installing the scraper blade?
In corrugated cardboard printing, the correct installation of the scraper is crucial for optimizing printing performance and controlling costs. In the past, due to the complex design of cardboard box printing machines and the difficulty in installing scraper blades, replacing the blades often caused the printing machine to shut down for several hours. The scraper must be carefully installed in place to ensure successful ink transfer and ensure effective printing.
If the scraper is installed properly, the service life of the scraper and the anilox roller will be extended simultaneously, while maintaining a consistent printing effect. If the scraper is not installed properly, it will accelerate the simultaneous wear of the scraper and the anilox roller, causing ink leakage in the scraper cavity, increasing the downtime of the printing machine, and wasting production time. The following will introduce the factors that affect the correct installation of the scraper one by one, such as the installation position and direction of the scraper, blade contact angle, horizontal adjustment, and pressure.
(a) Installation position and direction of scraper
When installing the scraper, the first step is to accurately position the scraper and sealing blade to achieve the best printing effect. According to the rotation direction of the anilox roller, the scraper can be installed at the top or bottom of the scraper chamber. Remember that the scraper is the last contact blade where ink is transferred to the screen roller, and the sealing blade is always installed opposite it.
If a sealing knife is used to install the scraper in the wrong position, the scraper will not have the correct contact point and will not scrape off an appropriate amount of ink before it is transferred. The tip of the scraper slope should face the scraper chamber to prevent streaks. The anilox roller and blade are designed to work together, so the correct installation and orientation of the blade are crucial for their mutual coordination.
(2) Scraper contact angle
The blade contact angle is the contact angle between the blade and the anilox roller. The ideal contact angle between the blade and the circumference of the anilox roller should be 30. If the angle is less than 30, most of the edges of the blade will come into contact with the anilox roller. If the contact surface is too large, it is difficult to scrape the ink properly; In the same situation, if the contact surface is greater than 30 degrees, it is best not to scrape the ink with the blade.
(3) Adjusting levels and pressures
If the scraper is installed correctly, it can maintain balanced contact with the anilox roller. If the scraper is adjusted correctly, it can produce a consistent ink removal effect by applying slight pressure to the anilox roller. The recommended pressure is 25 to 30 pounds or 1.7 to 2 bars. When installing the blade, tighten from the middle to both ends. Do not tighten the clamp too tightly, otherwise the blade will bend. If the installation pressure of the blades is too high, they will bend and lose good contact with the anilox roller. In this case, the anilox roller will be filled with ink. Please remember that appropriate scraper clamping pressure can not only ensure scraping quality, but also extend the pressure between the scraper and the screening roller.
If the contact between the wire roller and the scraper chamber is not parallel, it will be uneven. There are several reasons for this situation: the worm cavity is not kept horizontal, the position of the scraper in the fixture is not good, the pressure on both sides of the scraper cavity is uneven, or the bolt pressure for locking the scraper is not adjusted evenly. When this situation occurs, the operator usually increases the pressure until both the blade and the anilox roller come into contact with the anilox roller. However, additional pressure and friction can accelerate the wear of the scraper chamber and the anilox roller. Printing machine operators often try to close the scraper chamber to the anilox roller to solve the problem of ink leakage, which often exacerbates the problem of ink leakage at both ends of the scraper chamber. In fact, by selecting the appropriate ink sealing gasket and regularly replacing it, the problem of ink leakage can be prevented. Avoid increasing the pressure on the scraper to solve the problem of the scraper chamber not being level or leaking ink.
To ensure the good operation of the scraper room system, the following steps can be followed:
Before installing the ink sealing gasket, first install the scraper and sealing knife.
2. Slowly move the scraper closer to the anilox roller.
3. Ensure that the scraper and sealing knife are in contact with the anilox roller at the same time. If they do not come into contact at the same time, make system adjustments until both blades come into contact with the anilox roller at the same time.
4. Repeat the above steps on the drive side and operation side of the printing machine.
5. Set up a scraper chamber so that the movement distance between the scraper and the anilox roller does not exceed 1/8.
In the application of corrugated and cardboard printing, it is very important to install the scraper correctly to ensure that the ink is evenly transferred to the printing plate and extend the service life of the scraper and anilox roller. Only by properly training printing machine operators can the scraper work properly and reduce costs.

 

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