High Shear Anilox Cell Discharge Mechanics in Flexographic Aqueous Dispersion Application
Liquid release from anilox cells under high shear depends on dynamic viscosity below forty centipoise and cell depth ratios under thirty percent.
Reverse Angle Doctor Blade
Metering Component
Steel or plastic strip positioned against the rotation of anilox or gravure rolls removes excess ink from the surface. A reverse angle doctor blade sits at an obtuse angle to the direction of the roll movement to provide a clean wipe. This configuration prevents the hydraulic pressure of the ink from lifting the blade away from the cylinder.
It is a standard feature in modern flexographic printing chambers.
Mechanical Action
Pressure applied to the holder forces the tip of the reverse angle doctor blade into contact with the ceramic or chrome surface. Because the roll turns toward the blade, the wiping action is more aggressive and consistent than a trailing blade.
Wear Profile
Friction between the two surfaces leads to the gradual thinning of the contact edge. A reverse angle doctor blade must be changed regularly to avoid the formation of burrs that could scratch the expensive cylinder. If the blade pressure is too high, the heat generated can cause the ink to dry prematurely in the cells.
The choice of material for the blade depends on the abrasiveness of the pigments and the speed of the press. Carbon steel offers a sharp wipe but may corrode when used with water based inks.