Yarn: it is the general term of yarn and thread. And has a strong continuous strip, including single yarns and strands.

Single yarn: Processed by the short fibers, making the short fibers or wires along the axial direction and twisted.

Ply yarn: it is made of two or more single yarns combined and twisted. Its strength and wear resistance are better than that of single yarn. At the same time, ply yarn can also be combined and twisted in a certain way to obtain compound twisted ply yarn.

What is twisting?

If one end of the strip is held, the other end is rotated, and the yarn can be formed, which is called twisted.

For short fibers, the twisted is the necessary means of making the fiber strip as a yarn. It is generally necessary to condense the fibers into a fibrous strip before twisting, and the outer fibers of the fibers are extruded into the inner layer. Thereby, the strip is obtained in the longitudinal direction of the fibers.

For long silk yarns and strands, twisted can form a tight structure that is not easily damaged by lateral force, and twisting can also form a variant wire and a fancy line. How many of the twisted and twisted direction not only affect the hand feel and appearance of the fabric, but also affect the intrinsic quality of the fabric.

After the strip is twisted, the outer fibers produce a tilted helical roll back, the fiber torsional deformation, the gauze is tightly bored, and the structural form and mechanical physical properties of the fiber collective are changed. (As shown below)

When there is an encirclement angle, the fiber has centripetal pressure on the yarn. The greater the encirclement angle, the greater the centripetal pressure. Due to the existence of centripetal pressure, the outer fiber is extruded to the inner layer, which increases the compactness of the yarn and the friction between the fibers, thus changing the structural form and physical and mechanical properties of the yarn, which is the essence of twisting yarn.

Twist direction: indicates the direction of twisting

Twist direction refers to the inclined direction of the fiber 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 yarn tends from the lower right corner to the upper left corner, and the inclined direction is consistent with the middle of "s", which is called s twisting or smooth twisting; The twist direction of yarn tends from the lower left corner to the upper right corner, and the tilt direction is consistent with the middle of "Z", which is called Z twist or backhand twist. Generally, Z-twist is used for single yarn and S-twist is used for ply yarn.

The twist direction of the ply yarn is expressed according to the twist direction successively twisted. For example, the twist direction of single yarn with Z twist, initial twist with S twist and compound twist with Z twist is represented by zsz.

The twist direction of yarn has a great influence on the appearance and hand feel of fabric. By combining the twist direction of warp and weft yarn with fabric organization, fabrics with different styles such as appearance and hand feel can be woven.

Measurement method of twist

Common twist test methods have two types of direct counting methods and untwisting twisting methods. Short fiber, strand trials generally use direct counting methods, while the fine yarns use a doubling ousted method, in addition, there are second and three-time untwisting twisting method, slip method, etc.

Direct counting method

Under certain tension, clamping both ends of the known length yarn, one end is fixed, the other end is rotated around the axial direction, until the single yarn or single yarn in the line, is completely parallel the number of twists retracted is the twist of the yarn sample length.

Untwisting twisting method

Under certain tension, clamping both ends of the known yarn length, one end is fixed, the other end is rotated around the axial direction, and the number of twists and reverse twisted are returned to the starting length, The number of twists is twice the twice of the length within the length of the yarn sample.

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AY04 Electronic Twist Tester

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