Non-Newtonian effect on ink transfer for gravureoffset printing

A computational simulation is carried out with the Carreau model to explore the non-Newtonian behavior of ink for gravure-offset printing. The volume of fluid (VOF) model is adopted to demonstrate the stretching and breakup behaviors of ink. The results indicate that the ink transfer ratio is much influenced by contact angle especially by the contact angle of upper plate (¿). The ink transfer of non-Newtonian fluid shows a quite different trend from that of Newtonian fluid. An oscillation or unstable behavior of the position of the minimum thickness of ink between two parallel plates during the stretching period of ink is observed for lower values of ¿. This oscillation gradually diminishes for higher contact angles at the upper plate. Moreover, the velocity of the upper plate has negative impact on the ink transfer ratio. The results are validated with available data from literature.