For optimum print results, fine adjustments of the doctor blade is an indispensable prerequisite.
Flat angles create a big contact area, thereby increasing hazing and drag-outs. Angles that are too steep produce chattering. Therefore, a precise adjustment of doctor blade angle is crucial for an optimal contact zone. For this purpose, Daetwyler Swisstec offers the respective angle measuring instruments for cylinder circumferences of 250 – 700 mm and 700 – 1500 mm respectively.
The operating of the instrument
For working with the setting gauge instrument, the respective machine has to be switched off. As a first step, put the setting gauge for doctor blade angle the closest possible on the cylinder. The push the setting gauge over the cylinder to the doctor blade till the protractor arm lies strongly paralell on the doctor blade (holding device). The doctor blade angle will be measured by the tangent of the cylinder. Read the blade angle on the angle scale and if necessary set the doctor blade once again. As an empirical value in gravure printing, the contact zone angle of doctor blade should be situated between 55° and 65°.