Virtual Bobbin Dyeing and Optimization

Reduce Rejection Rate of Colored Bobbins

The quality of the dyeing of bobbins is decisively related to the homogeneous density of the yarn. We are developing an algorithm that simulates a virtual bobbin on the basis of the setting parameters and can calculate its density. This optimizes the settings of the winding machines and improves the final coloring.

Faulty dyeing in the German textile and clothing industry results in costs of 8.8 million euros, which the industry can no longer accept in light of the increasing price competition from East Asia. The aim of a multidisciplinary project called DensiSpul at the German Federation of Industrial Research Associations - AiF (Arbeitsgemeinschaft industrieller Forschungsvereinigungen) is to reduce the rejection rate of poorly colored bobbins by at least 15 percent through the use of simulation. The success of the project could mean annual savings of approximately 1.3 million euros in Germany. Our institute is collaborating on the project with the Institute for Textile Technology (ITA) at RWTH Aachen University and the Society for the Advancement of Applied Computer Science (GFaI).

Institut für Textiltechnik und Lehrstuhl für Textilmaschinenbau und RWTH Aachen — © Peter Winandy
Institut für Textiltechnik (ITA) of RWTH Aachen University

Winding Process Determines Color Quality

In 2012, a total of approx. 361,000 tons of fibers were processed in the clothing and home textiles sector in Germany. Approx. 30 percent of these fibres are wound on bobbins in Germany and then dyed in a dye bath. When dyeing bobbins, the most important thing is the uniformity of the dyeing through of the yarn bobbin in order to guarantee high quality for subsequent processing. The dye penetration in turn depends decisively on the homogeneity of the density distribution of the wound yarn and thus on the setting parameters of the winding machine.

© Fraunhofer ITWM
CFD-Simulation einer virtuellen Garnspule im Färbebad

Aim: Reduce Rejection Rate by at Least 15 Percent

One of the aims of DensiSpul is to develop a system that generates recommended settings for the winding machines on the basis of a simulation. Together with the other project partners, we are developing an algorithm to simulate a virtual bobbin based on the machine setup parameters. We then calculate an optimized density of the virtually wound bobbin for the subsequent dyeing process. The CT imaging of actual wound bobbins is always a priority focus for the validation of the material models. Ultimately, from the optimized virtual bobbin, the recommended setup parameters for the winder can be determined.