Spunbond Processes

Spunbond processes are industrial processes for the production of nonwovens.  Filaments are created by melting polymer and processing it through spinnerets. These filaments are then cooled, stretched  and swirled by air, and deposited on a perforated conveyor belt as laydown. Typical problems arising in the design of Spunbond processes are:

• How to minimize the energy demand to create the airflow?
• How to produce a nonwoven that is as uniform as possible while running on a fast-moving conveyor belt?

Simulation with FIDYST

To answer these questions the Fraunhofer ITWM starts by simulating the complete Spunbond plant with the commercial Computational Fluid Dynamics (CFD) solver ANSYS FLUENT. Next, the scientists from the Fraunhofer ITWM use their software FIDYST (Fiber Dynamics Simulation Tool) to simulate the filaments in airflow. Analysis of the laydown on the conveyor belt is then provided by the simulation tool SURRO. After a reference case has been completely simulated and validated against the industrial partner's measurements, further experiments based on simulations can be computed.

Process Optimization

To optimize the Spunbond process the Fraunhofer ITWM analyzes the reference case and from this provides design proposals for modifications of the Spunbond line. Structural alterations, which would idle the production line for several hours, can then be tested by computer simulations. Parameters of the process can systematically be sampled to find optimal operating points for production. Material properties can then be predicted before the proposed changes are implemented. Typical problems arising in the upscaling of pilot plants can thus be reduced or completely avoided.

Further Information:

• S. Gramsch, D. Hietel, R. Wegener. Optimizing spunbond, meltblown, and airlay processes with FIDYST. Melliand International, 21(2):115-117, 2015.
  
• R.Wegener, N.Marheineke, D.Hietel. Virtuelle Produktion von Filamenten und Vliesstoffen. In: Mathematik im Fraunhofer-Institut Problemgetrieben - Modellbezogen - Lösungsorientiert. Hrsg. H.Neunzert, D.Prätzel-Wolters, Springer, 105-165, 2014.
  
• A.Klar, N.Marheineke, R.Wegener. Hierarchy of Mathematical Models for Production Processes of Technical Textiles. ZAMM, 89(12): 941-961, 2009.