Screen Printing Scraper Application Technology

In screen printing, controlling the squeegee is a very important process technology. In order to operate the squeegee correctly in printing and achieve the intended purpose, manufacturers have created a variety of squeegees for customers to choose.
The function of the squeegee is to transfer the ink from the inside of the screen to the surface of the substrate, and the flowing ink is disconnected according to the resilience of the screen. The scraper consists of the hardness of the scraper, the sharpness of the front of the scraper, and the angle of the scraper.

The use of a three-layer squeegee, that is, three sandwiched polyurethane squeegees, allows unbiased ink transfer. It is preferable that the two outer layers have a hardness of 70° to 75° and a hardness of 900 in the intermediate layer. The outer layer of the scraper can play a soft role on the substrate. Low hardness scraper will not damage the screen, but also print smoothly. The single-layer high hardness scraper (80°, 90° scraper) is not suitable for a single, large amount of screen printing, and the screen is quickly damaged. In screen printing, when changing screens, try to shorten the time of change. In the case of continuous printing, it is best to use a squeegee of 70° to 75°.

Experience exchange: Application technology of screen printing squeegee (with photos)

The three-layer squeegee, which has a middle layer of 90° hardness placed in the center, is designed to resist the printing of the substrate. The pressure of the squeegee acts on the leading edge of the squeegee. With the movement of the scraper. When the pressure on the squeegee disappears, the moving ink is disconnected. The scraper's pressure is transferred to energy and concentrated at the very front of the scraper. Through a magnifying glass, you can see energy similar to solar energy. Although the operating pressure of the squeegee is small each time, a large number of printings are continuously performed. This solar energy-like energy increases exponentially. Under the pressure of the squeegee, if the substrate is offset, the center of the squeegee pressure will move and the ink will not pass through the screen, which will not effectively move the ink.

The front of the scraper must be very sharp. Test method. Swiping with your finger, there is a feeling of opening your fingers. This sharp blade is suitable for screen printing with midtone patterns. Otherwise, the squeegee must be ground and the squeegee and handle must be installed correctly. There must be no problems such as skewness or parallelism. Always inspect the scraper to ensure the correct angle and sharpness of the scraper.

Setting the squeegee angle is a very difficult task. The reason is that if the front surface of the squeegee bends on the printing surface, the measured angle is an incorrect base point. Therefore, in order to control the correct angle of the squeegee, the use of a three-layer squeegee becomes a reason. Scraper allows a wide range of angles. If the angle of the squeegee is measured from the horizontal plane, the angle of the squeegee on the screen printer is set at printing, the effective squeegee angle is very large; the smaller the effective angle during printing, the less controllable the ink transfer is. When screen printing is used to adjust the midtone pattern, a good printing result can also be obtained without changing the angle of the squeegee.

The pressure of the squeegee during printing is not as great as possible. Excessive pressure becomes a disadvantage. In the actual printing. Scraper at both ends of the scraper rises l/4 pressure. Therefore, when adjusting the pressure of the squeegee, it should be noted that the squeegee pressure should be moderate and the squeegee pressure should be uniform.


Source: Japan Screen Printing 2005.2