A New Approach to Fiber Spreading: Higher Precision, Less Waste in UD Tape Production

Unidirectional (UD) tapes are essential components in lightweight composite applications, from automotive parts to aerospace structures. Their mechanical performance and reliability depend heavily on the precise alignment and uniform distribution of fiber rovings within a polymer matrix. Even minor inconsistencies during the spreading process can lead to defects, reduce material performance, and increase production costs. Optimizing UD tapes to enable lighter, more energy-efficient structures with reduced material consumption also helps manufacturers comply with the European Union’s binding objective of becoming climate-neutral by 2050.

In conventional manufacturing, achieving uniform fiber spreading is a persistent challenge. Variations in the initial width of fiber bundles, combined with the high mechanical forces applied in traditional systems, can result in uneven tape thickness, fiber breakage, and higher scrap rates. These factors make the spreading process one of the most critical steps in producing high-performance UD tapes.

The Forced Conveying Method

The new method replaces conventional deflection with a single spreading roller equipped with helical grooves. As the roving passes over the roller, the grooves progressively separate filament bundles while relaxation zones between grooves allow the fibers to release stress. A centering roller upstream ensures concentric entry, and guiding rods downstream stabilize the tape and allow inline width monitoring. This configuration provides a more controlled, gentle, and repeatable spreading process.

Key features of the method include:

• Gentle handling of fibers to reduce breakage and preserve mechanical performance

• High reproducibility across different roving widths and production speeds

• Simplified process control, since fewer parameters strongly influence tape quality compared to conventional spreading

• Scalability, making it suitable for industrial production lines

By controlling parameters such as wrap angle, roller diameter, groove pitch, and feed rate (rovings’ forward speed through the roller), the method allows for precise spreading of rovings without compromising fiber integrity.

Experimental Validation

Extensive testing confirmed the effectiveness of forced conveying. High-filament carbon fiber rovings were processed through the new setup and compared to conventional methods. The roving width was recorded before and after spreading using inline imaging, while load cells simultaneously measured the tensile forces acting on the fibers.

The results demonstrated:

• Significantly improved width uniformity, even when input rovings exhibited variability

• Drastic reduction in tensile forces acting on the fibers

• Consistent reproducibility over long production runs

• Minimal adjustment needed for variations in fiber properties

These findings show that the method is robust, reliable, and adaptable to different fiber types, tow sizes, and industrial conditions.

Industrial Benefits, Relevance and Sustainability

For industries like automotive, aerospace, and renewable energy, these enhancements offer tangible benefits. Uniform fiber spreading directly impacts composite performance by supporting stronger, more predictable composite parts and enabling designers and engineers to optimize material use while maintaining stringent mechanical specifications.

Homogeneous UD tapes reduce the risk of dry regions or weak interfaces, ensuring predictable mechanical properties in high-performance components. Lower scrap rates and less fiber damage translate into cost savings, higher efficiency, and more sustainable production.

The method’s adaptability also supports environmental goals by minimizing waste and energy consumption. Its ability to handle diverse input rovings without extensive reconfiguration makes it particularly attractive for manufacturers aiming to combine high quality, efficiency, and sustainability.

Future Perspectives

The forced conveying technique also opens the door to further innovations. Future work could include automated and adaptive spreading systems, integration with inline quality monitoring technologies, and scaling to accommodate larger production lines or different fiber types. By addressing one of the central challenges in UD tape production, this method enables the manufacture of lighter, stronger, and more reliable composites for next-generation industrial applications.

Project partners

The work was carried out by Competence Center CHASE GmbH ↗ in collaboration with Institute of Polymer Processing and Digital Transformation, Johannes Kepler University Linz ↗, Covestro Thermoplast Composite GmbH ↗, and LIT Factory, Johannes Kepler University Linz ↗.

The paper was published in Journal of Engineered Fibers and Fabrics, Volume 20: 1-8, 2025, the authors are Stefan Kohl, Christian Marschik, Gernot Hochleitner, Thomas Kranzl and Gerald Berger-Weber: Forced convyeing as a novel method for spreading fiber rovings - CHASE PDF ↗