The flexographic printing plate undergoes deformation during the printingprocess that is dependent on the engagement, plate characteristics and the image.Previous work has shown that the individual dot, particularly in the highlightregion experiences two forms of distortion that both result in tone gain. Theseare expansion of the surface of the dot and "barrelling", where the compressionof the dot by the pressure in the printing nip causes the shoulder to make contactwith the printed surface. This paper examines the influence of geometry (dotsize and shape) on tone gain behaviour.A model of the dot structure was created using a finite element modellingsystem. The model allowed the study of the deformation of the dot with time asa load is applied simulating its passage through the printing nip junction.Numerical experiments were designed and used to establish the influence of thegeometric characteristics with the minimum number of calculation runs. An L16orthogonal array investigation was carried out where the dot geometry wasderived from interferometer measurements on plates having different linerulings, dot depth and plate thickness. The simulations were run over a range ofengagements and this also allowed the interaction of these parameters to bestudied. The results highlight the importance of the dot structure on the plate andits likely impact on tone gain during printing.
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