EFFECT OF TWIST ON YARN STRENGTH.

EFFECT OF TWIST ON YARN STRENGTH:-

Short staple fiber:-

Twist is important into a staple yarn binds the fibers together and provide corhence to give strength to the yarn. Firstly, with the increment of twist, the lateral force holding the fibers also increases which allows more fibers to contribute to the yarn strength. But,secondly when twist increases from the optimum level , the angle of fibers made with the axis of the yarn also increases , which makes the fibers contribute the less to the yarn strength. The influence of increasing twist on the strength of a staple spun yarn shown in Fig. 1.

Fig.1 Strength of yarn versus twist level for staple spun yarn.

CONTINUOUS FILAMENT YARN:-

In case of filaments yarn, a small amount of twist is needed to hold the filament fibers together. Therefore increase in twist will decrease the strength of filament yarn. This is due to the fact that the filaments are stronger than short staple fibers so less twist is needed to impart strength in filament yarns. Theoretically the maximum strength of a continuous filament yarn is possible when the filaments are oriented parallel to the axis of the yarn. Since the filaments are variable strength, so the primary function of twist is to provide support to weaker filament, thus resulting in an increase in the yarn strength. The influence of increasing twist on a contribution filament yarn is shown in Fig.2.

Fig.2 strength of yarn versus twist level for filament yarn.

EFFECT OF TWIST ON YARN SND FIBERS PROPERTIES:-

The twist level has an effect on the properties of yarn as well as fabric. The following parameters are effected by twist, 

1. Hand feei.

2. Moisture Absorption.

3. Wearing Properties.

4. Aesthetic effect.

5. Moisture wicking.

6. Air permiabilty.

7. Luster.

Types of fabrics with Respect to Different types of twist:-

Soft surface fabrics have slack S twist:-

1. Smooth surfaced fabrics have optimum twist. This stimulates strength, smoothness, and elasticity.

2. Crepe fabrics have maximum number of twist .

3. Poplin have two single yarn that are Z twisted individually and placed together using S twist.

4. Sewing thread has three S twisted single yarn , which are the Z twisted together. Tear resistance of the thread will be higher.

Ref:-https://textillearnear.net