Squeegee leakage problem in printing process of flexible printing equipment

Squeegee leakage during the printing process of flexible printing equipment is a very common problem. There are many reasons. If the handling is not good, improper combination of various details can lead to the result that the scraper is missing or even unable to print.

1. The lack of co-pressing pressure may leave a slight gap between the doctor blade and the anilox roller. This causes excess coating oil to remain on the roller and is therefore applied to the plate, and when the printing press is at rest Polishing oil will leak out.

2. One or two doctor blades, possibly with seals or blade splints, have been worn or contaminated. These parts should be checked once a week and cleaned as needed. If you do not apply the coating at any time, you should lift the cavity and lubricate the seals. If the blade wears excessively, it may be necessary to use different types of synthetic, long-life, or ceramic blades, or use non-segmented blades if quality standards permit. Causes of wear that should be avoided are abrasive pigments (such as titanium oxide in water-based opaque white paint; UV opaque white paint can be used as an alternative) and anilox rollers with incorrect surface finishes or abrasive sculpting patterns.

3. The speed of the printing press may be too high, causing turbulence and cavitation of the coating oil (formation and collapse of the low-pressure area in the flowing liquid), thereby instantaneously pushing the doctor blade back.

Smearing is a phenomenon that can occur both at the upper and lower blades, even when the seal is tight and the blade has sufficient pressure. Leakage is not its cause.

4. If the blade pressing pressure is too high, the two doctor blades will bend in their length direction so that the side of the blade does not come into contact with the roller. Trying to repair this loosening of the contact line by increasing the build-up pressure will only worsen the problem.

5. The open anilox roll engraving part (ART, ART-TIF) has no mesh wall and therefore cannot form a tight seal with the blade. So even when the printer is at rest, low-viscosity coatings can leak.

6. Excessive pressure (filling pressure) in the squeegee cavity may squeeze the coating out of the cavity.

7. Centrifugal drift may occur on the shadowing rollers, especially when the texture resolution is less than 50 lines per inch and the use of low viscosity coatings. Centrifugal force drives the coating along the endless groove, allowing the coating to collect at one end. It is advisable to use different engravings and enamels or higher viscosity coating.