JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
Print ISSN : 0021-9592
Transport Phenomena and Fluid Engineering
A Critical Condition for Overfill-to-Starve Transition of Doctor-Bladed Liquids in Gravure Coatings
Hidenobu MiuraAyumi TsuruokaMasato Yamamura
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2017 Volume 50 Issue 4 Pages 262-267

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Abstract

The present study measured free surface profiles of doctor-bladed fluids on engraved roll surface in order to quantify the volumes of fluid retained in tri-helical grooves. The fluid overfilled the grooves to cover the entire surface of the roll at low roll speeds; whereas, it exhibits a concave surface profile in each groove at high speeds, i.e. a starved configuration with a partial filling of the groove. The overfill-to-starve transition was observed with decreasing the static liquid pressure and the depth-to-width aspect ratio of grooves, or increasing the blade thickness and the fluid viscosity. The dimensionless volumes of residue on the roll obeyed a master curve with respect to a balance between the pressure-driven and viscous drag flows. An empirical equation was newly derived based on the one-dimensional lubrication approximation, which allowed us to predict an optimum condition in stable gravure coating operations.

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© 2017 The Society of Chemical Engineers, Japan
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