Simulate Spinning Processes

In the spinning process, the fibres are accelerated mechanically or aerodynamically to the desired spinning speed. In recent years, a number of research activities at our institute have provided the basis for a comprehensive simulation of such spinning processes.

Project VISPI: Virtual Spinning

Validation of a Simulation Tool for Virtual Spinning

In the project VISPI, we are developing a simulation software in cooperation with a network, with which a broad spectrum of spinning processes can be virtually simulated and investigated.

Spinning is one of the oldest techniques of mankind. Classical spinning mills of the textile industry, which process fibres into a yarn, can only be found sporadically in Europe. However, globalisation also affects the production of synthetic fibres considered here. According to the industry report Chemiefaserindustrie in Deutschland (2015) (Chemical Fiber Industry in Germany, 2015), two thirds of the worldwide quantity of chemical fibers was produced in China in 2013.

In order to be able to assert themselves internationally, German fiber manufacturers are relying on »new developments with high added value in order to be able to distinguish themselves from mass-produced products manufactured in Asia«. Mechanical engineering, which belongs to this industry segment, is still strongly rooted in Germany. However, industrial research on product and process innovation is reaching its limits on a purely experimental basis, so that a trend towards virtualization is increasingly being observed.

Digital Twin Optimizes Spinning Process

Simulations save experiments, allow new insights, allow systematic parameter variations and solve upscaling problems, which can lead to serious bad investments during the transition from the laboratory plant to the industrial plant. Due to their complexity, the required simulation capability for spinning processes is currently limited to research institutions, whereby we at Fraunhofer ITWM also play a leading role in a worldwide comparison.

The LSP Chair for Polymer Materials of the Institute for Materials Science of the Friedrich-Alexander-University Erlangen-Nuremberg contributes outstanding know-how in polymer physics and materials science. Together with the LSP Erlangen, the aim is to make the corresponding simulation tools and capabilities directly available to the developing companies as quickly as possible. The provision of appropriate simulation tools can make a significant contribution to maintaining the competitiveness of fiber manufacturers and mechanical engineers in the future.

The Process: Spinning Synthetic Fibers

In spinning processes for the production of synthetic fibres, molten or dissolved spinning mass is pressed through fine nozzles, spun into fibres and then guided through a cold air flow or a spinning bath for curing. Known processes are melt spinning, solution spinning, gel spinning and dispersion spinning.

The following graphic illustrates which simulation concepts are required for the simulation of spinning processes using the example of melt spinning.

Scheme Virtual Spinning
© Fraunhofer ITWM

Scheme Virtual Spinning

A Software for Virtual Spinning Therefore Requires:

  1. a modular system with which physical models can be put together to describe the fibers - without the expertise of Cosserat rod theory (which describes a filament as a space curve with oriented cross-sections).
  2. smart, automated mathematical methods for solving boundary value problems – without manual intervention during simulation
  3. Integration of the flow simulation into the simulation of the entire spinning process with the coupling of fibers and air
  4. user guidance of the complete software adapted to the needs of the later users
Gruppenbild beim Kick-off-Meeting
© Fraunhofer ITWM

Gruppenbild beim Kick-off-Meeting des Projektes am 17. September 2019 im Fraunhofer ITWM.

Simulating in Cooperation with the LSP Erlangen

We focus on the development of mathematical numerical methods for simulation, while the University of Erlangen contributes its expertise in polymer physics to the development of a material database.

The LSP Erlangen has already investigated the molecular and rheological characterization, processing and material modeling for process instabilities in several PhD projects on melt spinning of polymer fibers.

Our institute, the Fraunhofer ITWM, has developed physical models and mathematical algorithms for the simulation of spinning processes in fundamental research projects. Using the production of glass wool and several polymer spinning processes as examples, we have demonstrated that simulations both improve fiber product properties and reduce energy costs.

The further development of the algorithms to a licensable simulation software with material database, which covers a broad spectrum of spinning processes and can be used productively by engineers after a short training period, remains a big challenge, which the proposed project takes up. The project is accompanied by the innovation mentor Prof. Stefan Schlichter and a technology advisory board consisting of industry representatives.

 

Aim of the Project VISPI

The aim of the validation project is to prove that engineers can develop, design and optimise innovative industrial spinning processes for high-tech fibres with a simulation tool.

The planned exploitation is aimed either at direct licensing by the Fraunhofer ITWM/LSP Erlangen or at distribution via external partners or a spin-off two years after the end of the project.

The BMBF funding measure »Validierung des technologischen und gesellschaftlichen Innovationspotenzials wissenschaftlicher Forschung« (Validation of the Technological and Social Innovation Potential of Scientific Research) supports researchers in systematically validating research results and opening up areas of application.

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