Simulations of lateral stress variations in a flexographic print nip

Abstract Contact printing, calendaring, and coating of packaging paperboard are standard industry processes that utilize rolling nips. The pressure pulse, maximum pressure, and duration have been extensively studied regarding its effect on the substrate and how it can be changed and controlled to achieve the desired effect. The present study considers lateral variations of the stress in a rolling process. A parametric study of the surface roughness, substrate stiffness, cylinder cover stiffness, and changed nip engagement or impression is performed using Finite Element Modelling. The simulation shows that a smooth surface does not completely negate the effects of the structural thickness. The impression has the most significant impact, and the combination of roughness and non-linear material means that the pressure distribution can change drastically, not just the maximum pressure pulse. Additionally, different combinations of settings can achieve the same mean pressure pulse but have very different stress distributions. E.g. changing the surface roughness will have a significant effect on the pressure variations, but the effect on the pressure profile shape is negligible.