How to extend the service life of doctor blade and printing plate

Squeegee blades play an important role in gravure printing. Proper use of squeegee blades can not only saturate the ink color of printed products, but also minimize printing quality accidents.

When the gravure press runs at high speed driven by the motor, the doctor blade also swings accordingly. The structure of the squeegee swing mechanism of gravure printing machines produced by different manufacturers is different. For example, the YS620 rotary gravure printing machine produced by Shanzhang Light Industry Machinery Factory in A factory, the scraper swing is driven by a special micro motor, and the 800 type gravure printing machine produced by Zhejiang Haining People's Machinery Factory, the scraper swing is driven by the transmission gear Driven. Regardless of the type of swing structure, we must achieve one goal: scrape off excess ink, while reducing the friction of the blade of the doctor blade and the printing plate to extend the service life of the doctor blade and the printing plate.

Squeegee selection

If the squeegee is not elastic, it cannot be quickly restored to its original position, and the knife wire, squeegee powder, and copper plate powder generated when the pendulum is left on the printing plate will have a great influence on the color of the printed product.

A doctor blade containing a certain proportion of C, Cr, Mn, and Si should be selected. The blade thickness is usually 0.1 to 0.18 mm. The squeegee is too thick and has no elasticity, and the ink is not cleaned. When it is reflected on the printed product, it often appears foggy.

If the squeegee is too thin, the squeegee will easily leave a mark on the printing plate. Under the action of friction, the squeegee will gradually wear out, which will inevitably affect the quality of the print. We noticed that when printing a large area full-page white background, the use of too thin scrapers often shows longitudinal streaks.

The hardness of the doctor blade also affects the print quality. The squeegee is iron, and the gravure is chrome-plated on the surface of the copper cylinder. Because the hardness of copper is 200-300HV and the hardness of chromium is 700-900HV, it is best to choose a squeegee with a hardness of 450-600HV, so that it will not damage the printing plate , And not easy to leave a knife mark, you can also scrape off the excess ink on the layout.

The blade of the scraper should be rounded, which is conducive to protecting the printing plate. Because the surface of the printing plate is arc-shaped, if the blade edge is also arc-shaped, it is not easy to damage the printing plate, and it is also easy to scrape the ink, to ensure that the non-graphic area is clean and does not stagnate ink. If the blade tip is flat, because the flat edge is very sharp, it is easy to damage the printing plate and affect the scraping effect, which affects the printing quality.

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