Coating with Patterned Rolls and Rods, 1995 Coating Fundamentals Symposium Proceedings
Knurled and gravure rolls, and microgravure and wire-wound rods (Mayer rods) are widely used to apply thin coatings at relatively high speeds. The main advantage of patterned rolls and rods over smooth ones is that the metering function - coat weight control, in other words - is largely performed by the volume of the pattern (equivalently the wire diameter of Mayer rods). This requires that the web be suitably pressed, as by a deformable roll backing it, against the roll or rod, so that liquid is transferred uniformly from the grooves or cells to the web. Usually it also requires control of feed rate to the nip, as by a flexible doctor blade. But then the need to maintain a uniform gap along the length of the rolls is eliminated.
Coating with Patterned Rolls and Rods, 1995 Coating Fundamentals Symposium Proceedings