Details:
Summary:
The performance of the anilox roll controls the ink transfer in flexographic printing. One of the critical regions is the filling of the cells in the ink chamber. This is undoubtedly influenced by the ink flow in and the pressure distribution within the ink chamber. A parametric study was carried out on the effect of ink rheology, press speed and chamber geometry on the flow in a flexographic press ink chamber. The modelling was carried out using a proprietary finite volume Computational Fluid Dynamic (CFD) software, FLUENT. A power law approximation was used to simulate the non Newtonian nature of the ink. The predominant force driving the flow within the chamber was found to be the flow induced by the anilox roll. The cross flow produced by the ink supply was found to have a negligible effect. The primary parameters dictating the flow pattern were found to be the interaction between the ink viscosity and the press speed. All the pressure required for ink transfer is generated at the doctor blade. The doctor blade angle strongly dictated the static pressure generated at the tip of the doctor blade while the Pseudoplastic nature of the ink resulted in an appreciable loss in doctor blade static pressure. A reduction in chamber size increases the ink pressure at the doctor blade tip.