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Influence of scraping knife to print color, all in the details
Nov 25, 2016

1. Printing distance

Scraping knife and plate cylinder position determines the scraping knife point of contact and imprint the distance. In General, the long distance, Internet point in the ink dries easily, ink transfer rate is lower, the print equivalent of ink were partly reduced. Instead the distance is short, the ink transfer rates are relatively high, but it also will make some small lines to reflect to the printing substrate.

Print the length of the distance according to the printing speed, viscosity, depth of network quality, layout adjustment. Most scraping knife about 1/4 installed in the upper part of the plate cylinder position.

2. the squeegee pressure, angle

Scraping knife contact angle blade and a printing plate roller contact point the tangent of the angle with the blade. When scraping knife scraping, will actually scrape ink part within the network. Squeegee pressure larger or when the blade angle is steeper, Internet point in the ink being struck more, transfer of the ink was smaller, color depth of Dodge. Less pressure, angle the blade flat, point within less ink being struck, transfer of the ink is relatively big, color depth is also bigger, but graphic edges appear blurred.

Scraping knife at the time of Assembly, must ensure that its cutting edge line parallel to the printed version of the bus, or because the ends of the print distance, angle and pressure differences that make both ends of the plate pattern color inconsistencies.

(1) the squeegee angle. According to experience, the contact angle of the blade to 55 degrees is ideal. Blade installed properly, the blade bending load should be about 5 °, so installing the contact angle of 60 °. But in the actual production process should not stick angles can be adjusted according to the actual situation to ensure printing quality.

(2) the squeegee pressure. Blade and plates on the cylinder pressure is set according to the actual needs, General scraping knife pressure setting in 20~25kg/m, make the blade plate movement to maintain a certain flexibility and blade job. Ensure effective scraping in the printing process and control the amount of ink without scraping the doctor blade and the surface of the contact pressure should be as light as possible, to reduce unnecessary wear of the printed edition of the blade.