Closed Scraper System Operation and Adjustment
1. Install and adjust the ink chamber
According to the instructions of the closed squeegee system manufacturer, the ink chamber is mounted on the flexographic printing press and the upper and lower blades are gently contacted with the anilox roll. In addition, check whether the contact between the upper and lower blades and the anilox roller is even and consistent. In fact, many problems that occur during the printing process are caused by incorrect ink chamber positions or incorrect installation of seals.
Place the ink chamber so that it is parallel to the centerline of the anilox roller and centered relative to both ends of the anilox roller. In this 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 an appropriately sized scraper.
Next, start the loading mechanism and, if necessary, readjust 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 re-aligned to prevent irreversible damage.
Finally, if the closed scraper system uses a pneumatic installation method, check that the distance between the doctor blade and the anilox roller is appropriate, otherwise damage may occur when the anilox roller comes into contact with the doctor blade. In addition, if the blade is not in uniform contact with the anilox roller, serious leakage problems may occur.
2. Ink supply and idling
After the ink chamber is adjusted, start the ink pump and start injecting ink into the ink chamber. It is important to keep in mind that the speed of the ink pump cannot be too fast, otherwise it will cause over pressurization and leakage. The amount of ink or varnish pressed into the ink chamber can be as little as the amount required for the job.
Once the ink chamber is filled with ink or varnish, you can activate the idle button. If you use a metal spatula, you may emit a loud buzzing sound. Use some high-quality spatula or use a non-metallic spatula. Effectively reduce and reduce this noise.
3. Visual inspection
After the system has been running for a while, carefully check the posture of the system, the tube, and the ink pump. The operation of the system should be smooth; the pipes cannot be tangled together and cannot fall under the ink pump; the height of the return pipe cannot be lower than the surface of the ink or varnish in the bucket. In addition, check the backflow of the ink or varnish, and adjust the speed of the circulation pump if necessary.
4. Adjust blade pressure
First, reduce the pressure of the ink chamber on the anilox roller. This is the first step in adjusting the squeegee pressure. A strong “ink flow†may appear on the surface of the time-consuming anilox roller. Next, carefully increase the pressure or slowly turn the pressure regulator handle until the “ink flow†on the surface of the anilox roll disappears. At this time, the squeegee pressure reaches the optimum state, the so-called “knuckle pressure†state, not only The best operating performance, but also caused by the least wear and tear.
Closed scraper system cleaning
When using a closed scraper system, cleaning is a very important part and is the most easily overlooked part. The cleaning procedure is roughly as follows.
(1) Close the ink pump and allow the ink or varnish to flow naturally.
(2) Rinse the closed scraper system with clean water or a special cleaning solution. Note that the cleaning solution must not be used repeatedly. Otherwise, the ink and varnish can only be diluted or diluted, but it cannot be thoroughly cleaned.
(3) Remove the ink chamber and clean it off-line. This saves time and money.
(4) The anilox roll should also be thoroughly cleaned, otherwise the residual ink or varnish may be dried 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 using water-based ink or varnish, the effect of cleaning the anilox roller with hot water is also 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.