Study on Seam Strength: Woven and Knit or Knitted Fabrics

S M Hossen Uzzal, Planning Executive at Modele De Capital Ind. Ltd.Narayanganj, Dhaka, Bangladesh has been examining woven and knit or knitted fabrics in view to their seam strength, and we would like to present his findings.

There are so many variables in readymade garments industry such as 88 standardized types of stitches, 284 types of seams, 28 types of sewing needles with 14 types of different needle tips and other variants.  Sewing thread also varies in textile materials, inherent construction and sizes i.e. ticket number. Moreover, types of sewing machines, speeds, accessories etc also vary. Variations in fabric types are also important in these connections. The effect of some important factors on seam strength have discussed in this article.

Seam Strength for Woven Fabrics

The number of stitches per unit length is the main factor which affects the seam strength. Generally seam strength increases with the increase of stitch density but when stitch density is too high or the seam breaks by seam slippage and inverse effect on seam strength may be produced mainly due to the mechanical damage of the fabric by the sewing machine needle action. This fact is applicable to warp way stitching.

Normally seam breakage produced by sewing. Yarn breakage occurs when seam along the warp direction but fabric yarn slippage occurs when sewn along the weft direction. With the increasing the number of stitches per unit length, seam strength is reduced in many cases e.g. stitch type-401, 504 when sewn in weft direction.

With the increasing sewing thread fineness (increase in ticket number), seam strength decreases in most cases. On the other hand, with the increasing sewing needle count, seam strength slightly increases in warp way stitching but slightly reduces in weft way stitching. The influence of sewing yarn count and sewing needle count on seam strength is less than the influence of stitch type and the number of stitches per unit length.

Seam Strength for Knit or Knitted Fabrics

The effect of stitch density on seam strength in the case of knitted fabrics are more or less similar to woven fabrics expect for the fact that the seam strength increases with the increasing of stitch number per unit length  in both the course and wales sense. Seam strength in the course sense gives more strength than the wales sense.

With the increasing in sewing yarn count (fineness), seam strength decreases and vice versa. On the other hand, seam strength decreases and vice versa with the increasing in sewing needle count. The influence of sewing yarn count and sewing needle count on seam strength is less than the influence of stitch type and stitch density in both the course and wales sense.