Yarn Twist

Yarn Twist

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Yarn Twist refers to the measure of the spiral given to yarn in order to hold the constituent fibres or threads intact.

The Textile Institute defines Yarn Twist as follows: “Yarn Twist is the spiral disposition of the components of a thread which is usually the result of the relative rotation of the two ends”.

There are two types of Yarn Twists defined according to the direction of the twist:

1. S- Twist: A single thread of yarn has the S-twist if, when it is held in the vertical position, the fibres inclined to the axis of the yarn conform in the direction by slope to the central portion of the letter “S”.

2. Z-Twist: A single thread of yarn has the Z-Twist if, when it is held in the vertical position, the fibres inclined to the axis of the yarn conform in the direction of slope to the central portion of the letter “Z”.

The amount of the twist is also of cardinal concern as it refers to the number of turns or twist per unit length in the twisted condition. The following formula is used to calculate the twist amount:

If “n” is the number of turns or twists and “I” is the length of the yarn then the twist, represented by “T” is:

T = n/I