Optimal design of the coat‐hanger die used for producing melt‐blown fabrics by finite element method and evolution strategies

Abstract In this article, an optimal design procedure that improves the uniformity of flow rate distribution at the outlet of the coat‐hanger die is proposed. The two‐membered evolution strategy was combined with the finite element method to optimize the design parameters of an initial coat‐hanger die geometry designed by analytical method based on one‐dimensional lubrication method. The slot gap and the manifold angle were chosen to be the optimized design parameters, and the coefficient of variation (CV) value of the flow velocity at the die outlet is regarded as the objective function. The optimal results were achieved in the 22nd generation after 100 generations' evolution, which show that the CV% value of the flow velocity at the die outlet is only 1.3631% and decreases by 68% of the initial value caused by unoptimizable die geometry. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers