Minimizing the print quality limitations during selection of anilox roll line frequency in flexographic half tone printing

Abstract

Flexographic printing technology prints liquid ink on absorbent as well as non-absorbent substrates. Owing to developments in plate and anilox roll manufacturing technology, now we can comfortably print half tone with resolution of 100 LPI (Lines per Inch) and above. This has helped flexographic printer to reproduce monochrome continuous tone and full color graphic original, matching performance of lithographic and gravure printing technologies. But unlike other printing technologies in flexographic printing screen frequency of plate i.e. image carrier and engraving line frequency of anilox roll collectively affect smoothness and uniformity of reproduced half tone image. In this experiment three line frequencies of anilox roll and five screen frequency of image carrier are selected and their effect on print characteristics is studied using plot of theoretical dot area against apparent dot area. Considering high cost involved in manufacturing anilox roll this experiment is aimed at identifying optimum combination of screen frequency and line frequency required in minimizing secondary moire and maintaining print quality.