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Sewing Thread Elongation: Basics, Effect of Sewing and Seam Performance

One of the lesser-understood areas in sewing thread technology; sewing thread elongation has been an important basis for comparing different threads.

The elongation of thread has a direct effect on sewability and seam elasticity. Therefore, this feature is often the focus of attention. It is usually specified as maximum tensile elongation in percent. The maximum tensile elongation is described as a sewing thread’s change in length until it breaks or tears. This is caused by the tensile strength lengthwise (in relation to its original length). The elongation behavior of sewing threads depends on the selection of the raw material, the construction, and the production method. For example, cotton threads have an inherent lower elongation than synthetic threads (polyester etc.).

Basics of Elongation – Breaking Point

Elongation – Breaking Point: Elongation at break is defined as the amount (expressed as a % of its original length) that a thread is extended at its breaking point.

Elongation is how far a thread stretches before reaches its breaking point. Elongation at break is expressed as a percentage of its original length. If a thread measuring 100 cm can be stretched to 125 cm, at which point it breaks, it is said to have 25 percent elongation at break.

high bulk textured yarn
Industrial Sewing Thread
Heavy Duty Sewing Thread
Industrial Sewing Thread

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The relationship between strand twist coefficient and elongation at break

When the twist coefficient of cotton sewing thread increases, the elongation and deformation of the fibers increase, which affects the ability to bear tensile deformation in the future; in addition, when the twist coefficient increases, it is difficult to slide between fibers. Both of these are factors that reduce the elongation at the break of the yarn. However, when the twist coefficient increases, the fiber inclination angle increases, and the inclination tends to decrease when it is pulled so that the cotton sewing thread increases. Generally speaking, within the generally used twist coefficient range, favorable factors dominate, so as the twist coefficient increases, the elongation at the break of cotton sewing thread increases.

When the strands and single yarns are twisted in the same direction, the average twist amplitude of the fibers increases with the increase of the twist coefficient, and the elongation at the break of the strands increases; when the strands and single yarns are twisted in reverse, at the beginning The average twist amplitude decreases with the increase of the twist coefficient, and the elongation at break of the strands decreases slightly, and then increases with the increase of the average twist width, and the elongation at break of the strands also gradually increases. In addition, the twisting of the strands improves the structure of the yarn, changes the distribution of the twist amplitude, etc., so that the elasticity of the yarn and the ability to withstand repeated loads are improved to a certain extent!

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Effect of Elongation While Sewing

However, figures representing elongation at break give little indication of a sewing thread’s behavior during sewing. As far as practical sewing applications are concerned, a far more important consideration would be elongation measured at loads normally experienced during sewing operations.

Different sewing tensions elongates thread differently. The loop is affected by applying more tension. The stretch will become more and affect the loop formation. The loop formation will be larger if stretched less at certain sewing tensions. It will become difficult to catch and will improperly form the stitch if it stretches more.

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Thread Elongation at Break in Seam Performance

The selection of a thread based on its elongation properties plays a major role in achieving seam stretch, which is the prime indicator of a quality finished product.

Seam performance depends on seam stretch. If the percentage elongation at the break of a thread is less, the amount the seam can stretch before it breaks will also be less. This, in turn, affects seam performance. Hence, it is better to have a thread with optimal elongation properties to obtain good seam performance. Optimal elongation should not be too high, or too low. Elongation should be balanced or controlled as needed, and specific needs can be met by threads with different construction and manufacturing techniques.

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Other factors that can support seam

Along with thread elongation, other factors that can support seam elasticity are:
A correct determination of stitch density, stitch type, and seam type.

Generally, the higher the thread elongation, the better is the seam elongation, and in turn, the seam performance.

Read More: sewing wikipedia