Details:
Summary:
The anilox roll is the primary means of ink delivery to the flexographic plate. The engraved cell geometry on the roll determines the volume of ink carried and also the amount of ink released to the plate. Understanding the ink release process is a key to having from highlights to solids on same plate. A new method has been developed in order to obtain detailed information concerning the percentage of ink released from the anilox roll to the flexographic plate. White light interferometry was used to measure the anilox roll in various states, un-inked, inked and after printing to obtain the quantity of ink released. A series of experiments where then undertaken using a printability tester to study the ink release to solid and half tone plates for varying anilox volumes and cell geometries. The influence of anilox to plate pressure and printing speed were also evaluated. Micro interaction of the plate coverage and the anilox was found to control the ink release. The amount of ink released is a function of coverage, cell geometry (particularly open area) and pressure. This interacts with the relative size and geometry of the dots on the plate. As a first approximation, 40% of the ink is released by the anilox to the plate when printing a 100% solid. This is not the case when printing half tones and highlighting the difficulties of having a half tone and solid on the same plate. The ink release was found to be independent of printing speed.