#560
Author: Edgar B. Gutoff, P.E., Sc.D.,
Email: ebgutof@coe.neu.edu
Subject: It is possible the lines are caused by combined or multiple pick-out.
It is possible that the lines you see are caused by combined or multiple pick-out. W. W. Pulkrabek and J. D. Munter, in their article "Knurl Roll Design for Stable Rotogravure Coating", in Chem. Eng. Science, vol 38, pages 1309-1314 (1983), point out that this is least likely to occur when the gravure pitch times the sine of the helix angle equals the natural ribbing frequency, which is a function mainly of the volume factor of the gravure cylinder. What this means is that the quality of the coating depends on the gravure pitch or line frequency, while keeping the volume factor constant in order to keep the coverage constant. In a graph that they show, the quality was usually improved at lower line frequencies. You may wish to try this.
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