Using Evolution Strategy to Design the Coat Hanger Die of Melt Blowing Process

The uniformity of melt blown fabrics is mainly decided by the coat hanger die. So searching out optimal coat hanger die geometry to distribute the molten polymer uniformly across the die outlet width is a major interest of some textile and chemical engineering researchers. An optimizing design procedure was proposed based on multi-membered evolution strategy (ES) and finite element method (FEM) in this paper. The slot gap and the manifold angle of the coat hanger die were chosen to be the design variables and the CV% value of the flow velocity at the die outlet was regarded as the objective function. The design variables were optimized according to the multi-membered ES and the objective function was calculated by FEM. Two different multi-membered ES (2, 6) and (2+6) were applied. The optimum values of the CV% were about 1.772%, while the CV% value of the initial die geometry was 21.32%. The uniformity of the flow rate across the die outlet width was improved evidently.