Effect of slot‐die configurations on coating gap dependence of maximum and minimum wet thicknesses

Abstract The dependence of the maximum and minimum wet thicknesses on the coating gap is derived for the slot‐die coating process, under different slot‐die configurations. Analytical expressions for the wet thickness and its derivative with respect to the coating gap are obtained using a simple flow model. The results indicate that, as expected, the minimum wet thickness increases linearly with the coating gap; however, the maximum wet thickness demonstrates a counterintuitive trend of decreasing as the coating gap increases, when a specific slot‐die configuration is assumed. Moreover, the results are also validated by numerically solving the complete two‐dimensional (2D) Navier–Stokes equation.