Twisting is one of the purposes of spinning, and the number of twisting is an important indicator of yarn performance, generally expressed in degrees. The twist refers to the number of twists per unit length of the yarn (ie, the number of turns). The unit length varies depending on the type of yarn. The unit of measurement can be expressed as "捻/10cm" or "捻/m". The former is used for cotton and cotton type chemical fiber yarns, and the latter is used for worsted yarns. The measurement of the twist of the chemical fiber filament yarn. The twist affects the strength, rigidity, elasticity, shrinkage and other indicators of the yarn. As the yarn twist increases, its strength increases, but the twist does not exceed a certain value, otherwise its strength decreases, which is called the critical twist of the yarn. The yarns of different raw materials have different critical twists. The softness, elasticity and shrinkage of the yarn are also closely related to the twist. Generally, under the premise of meeting the strong requirements, the smaller the twist of the yarn, the better, because the increase of the twist will make the feel of the yarn hard, the elasticity will decrease, and the shrinkage rate will increase. This is why the filament yarn is generally not applied as much as possible. Or less because of the blasphemy. In addition, the twist also affects the volumetric weight and diameter of the yarn, and the twisting effect increases the tightness of the yarn. Within a certain range, the volumetric weight of the yarn increases with the increase of the twist, and the diameter of the yarn decreases with the increase of the twist, thereby changing the coverage and comfort of the fabric.
In summary, yarn twist should be selected for different fabric applications. If the warp yarn needs to have higher strength, the twist should be larger; the weft yarn and the knitting yarn should be soft and the twist should be smaller; the yarn for weaving and knitting the pile fabric should be smaller, so as to facilitate the napping; The crepe fabric is required to have the characteristics of slippery, firm and cool, and the twist of the yarn should be larger.