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.
Capillary Viscometry
Fluid Measurement
Precision measurement of liquid resistance through a narrow glass tube determines the kinematic viscosity of paper coatings and adhesives. Practitioners use capillary viscometry to calculate how gravity drives a fixed volume of fluid through a calibrated orifice at a controlled temperature. The time taken for the liquid to pass between two etched marks provides the raw data for the calculation.
This method relies on the known dimensions of the glass instrument to convert time into centistokes.
Laminar Flow
Internal friction within the fluid creates a velocity gradient that resists movement against the capillary walls. While capillary viscometry excels with Newtonian fluids like oils and some clear varnishes, it requires careful handling when used for pigmented coatings. The narrow diameter of the tube prevents the turbulence that would skew results in larger vessels.
Quality Control
Consistency in adhesive application depends on maintaining a specific flow rate under the standardized conditions of the lab. Operators employ capillary viscometry to verify that incoming batches of binder meet the specification required for high speed laminating. If the viscosity is too high, the glue fails to wet the surface properly.
Conversely, a low viscosity leads to excessive penetration into the paper substrate. Results remain valid only if the temperature is held within a fraction of a degree.