Twist and twisting of yarn

　　Twisting is to cause the two cross-sections of the yarn to rotate relative to each other. At this time, the fibers in the yarn that were originally parallel to the yarn shaft are inclined into a spiral line. For short fibers, twisting is mainly to increase the strength of the yarn. The twisting of the filament can not only increase the strength of the yarn, but also produce some effect. The amount of yarn twist and the combination of yarn in the fabric have a great impact on the appearance and performance of the product.

　　Indicators of twisting properties include: twisting that indicates the degree of twisting, twist coefficient, and twisting direction that indicates the direction of twisting.

　　Twist: The twisting angle of the yarn wire is twisted by one circle to make a twist. The number of twists within a unit length of a yarn is called twist. my country’s cotton yarns are made of special twists, that is, they are represented by twists within the length of 10 cm; combed yarns and chemical fiber filaments are made of metric branch twists, that is, they are represented by twists within each meter; in addition, There is also an imperial branch twist expressed as the number of twists per inch.

Twisting coefficient: Twist cannot be used to compare the twisting degree of yarns of different thicknesses, because the same twist, the inclination of the fibers of thick yarns is greater than that of thin Shingle. In actual production, twist coefficients are commonly used to represent the degree of twisting of the yarn. The twist coefficient is a relative value that indicates the degree of twisting of the yarn by the bonded line density, and can be used to compare the degree of twisting of yarns of different thicknesses. The twist coefficient can be calculated based on the twist of the yarn and the thread density of the yarn.

　　Twisting direction The twisting direction refers to the inclination direction of the fibers in the single yarn or the single yarn in the strand after the yarn is twisted. It is divided into Z twist and S twist. After twisting, the twisting direction of the yarn wire is inclined from the lower right corner to the upper left corner, and the inclination direction is consistent with the middle of “S” is called S twist or hand twist; the twisting direction of the yarn is inclined from the lower left corner to the upper right corner, and the inclination direction is ” The middle part of Z” is consistently referred to as Z twist or backhand twist. Generally, Z-twisting is often used for single yarns, and S-twisting is used for strands.

　The twisting direction of the strand is expressed in the twisting direction successively. For example, the single yarn is a strand with Z twist, the initial twist is S twist, and the repeated twist is Z twist, and its twist direction is represented by ZSZ.

　　The twisting direction of the yarn has a great impact on the appearance and feel of the fabric. The twisting direction of the warp and weft yarn can be combined with the fabric structure to create the appearance and feel Fabrics of different styles.