The industrial applications of dry spinning processes range from textiles and nonwovens to lightweight components. In a typical dry spinning process, a diluent polymer mixture is extruded through the nozzles of a spinning plate and aerodynamically dried in a spinning duct. The solidified fibers are taken-off at the end of the duct and thereby stretched.In several years of research and development, the Fraunhofer ITWM, Kaiserslautern/Germany, has created a simulation tool that handles dry spinning processes with hundreds or thousands of fibers.
It covers both the full interaction of all fibers with the surrounding gas flow and the diffusion of the diluent in each individual fiber. The result is both the complete aerodynamics of the gas flow (velocity, temperature, diluent distribution) as well as all relevant state variables along the fiber (diameter, speed, temperature). Thereby, the diluent concentration is resolved radially in the cross sections of the fibers.
The simulations performed at the ITWM enable an in-depth analysis of the processes and their optimization through variation of the process and geometrical parameters. For example, the duct geometry can be optimized to reduce turbulence and improve the quality of the fibers. In particular, the upscaling from the laboratory to industrial scale can be achieved by the use of simulations. Significant cost savings are realized by reducing or avoiding expensive structural modifications.