Investigation of seam strength combining different woven fabrics and stitches

Sewing is an indispensable process during the manufacture of many garments or technical fabrics. Seam strength is influenced by the strength of the sewing thread, the type of seam and other sewing parameters, as well as fabric parameters. Factors that can potentially influence seam strength include stitch density, needle size, sewing thread count, warp and weft yarns, etc.

To investigate seam type and fabric parameters, a high-tenacity sewing yarn can be used that is unlikely to break. Such a yarn can be made, e.g., from meta- or para-aramid. Meta-aramid exhibits heat and flame resistance and is thus frequently used for protective clothing.

Here, we present investigations on seam strength on five different fabrics – viscose, polyester and two cotton woven fabrics as well as a polypropylene nonwoven – in accordance with EN ISO 13935-2 (Textiles – Seam tensile properties of fabrics and made-up textile articles, Part 2: Determination of maximum force to seam rupture using the grab method). The seams were produced using stitch types 301 (straight stitch) and 304 (zigzag stitch) at a stitch density of 5 stitches/cm on a Juki DX3, using the meta-aramid yarn “Coats® Firefly™”. The process had to be adjusted by correcting the upper thread tension and the alignment of the bobbin to avoid sewing errors.

The results showed that, as expected, thread breakage as a failure mode was eliminated, which allowed for a comparison between the selected stitches and the various woven fabrics, some of which broke, while seam yarn slippage was detected in others. This investigation will help other researchers to evaluate the inherent seam performance of woven fabrics by minimizing thread-related failures and isolating the effects of fabric structure and seam design on the overall seam strength.