|
6.0 Seam Performance
The seam performance of sewing threads depends on Sewability, seam security and End use requirement
6.1 Sewability
The ability to produce a seam with a minimum amount of thread breakage and damage to the thread during the sewing operation.
6.2 Seam Security
In relation to its end use requirements, once the thread has been sewn in to a seam the performance characteristics of the seam in the garment.
6.3 End use Requirements
Seam strength, appearance (luster, size), abrasion resistance, stitch and impact.
7.0 Production of Sewing Threads
Sewing threads has to meet the above said quality requirements and the flow chart furnished below shows the typical sequence for the production. Care has to be taken from the selection of the raw material to the finishing so as to meet requirements. Figure1 shows a typical sewing thread flow chart. 
8.0 Seam quality
It is the study and control over the seam strength, slippage, puckers, and seam appearance.
8.1 Seam failure
When seam is under transverse strain, the pulling force becomes more then fabric frictional resistance in stitch geometry then the stitch assembly permits the yarns being pulled to slip out which is termed as seam slippage. This slippage depends on fabric construction, raw material, type of seam-stitch density and sewing thread tension.
Higher inter yarn frictional force and high cover of the fabric will restrict the movement of the sewing thread. For slippery fabrics, high extensible thread would facilitate the slippage at much lower load.
Seam efficiency = {Seam tensile strength /fabric tensile thread} X100
Higher the seam efficiency better will be the quality. Generally it will be in the range of 85-90%. Type of stitch, type of seam, strength of sewing thread and wear of the sewing thread will affect Seam efficiency.
|