False twisted elastic yarn is a type of elastic yarn that utilizes the thermoplastic properties of synthetic fibers such as polyester and nylon. It is heated and shaped during fiber twisting and curling deformation to fix the twisted and curled state, resulting in a fluffy, elastic, and untwisted elastic yarn. Due to the slight torque and good elasticity of the yarn, it is called false twisted elastic yarn.

The fiber is twisted to a certain shape and then untwisted, and the yarn maintains the looseness of the twisted state, but without twist. The traditional processing method adopts the three-step method mentioned above, while currently it is completed in one step on a false twist elastic yarn machine. Its fibers have good torsion and elasticity, so it is possible to develop crepe fabrics and elastic fabrics with good crepe effect.

In order to achieve a comfortable effect and ideal bundling of the product due to the fluffiness of the false twisted elastic yarn, and to achieve good weaving effect on the fabric, people add a certain degree of twist on the false twisted elastic yarn machine to form solid twisted false twisted elastic yarn. At present, the real twist and false twist elastic yarn can be completed on the false twist one-step method of adding elasticity machine.

Mixing false twisted elastic fibers with other single fibers and twisting them together, due to the gap overfeeding, the surface of the mixed fibers has regular bamboo segments, which are completely covered by the skin fibers, rather than the skin fibers and core fibers being twisted side by side. This is the bamboo segment yarn(Slub yarn) developed in the market.

The length range of bamboo nodes in bamboo fibers is 1-15cm, and the number of bamboo nodes per meter can be adjusted within 3-10. The tightness of bamboo nodes can be adjusted due to tight clamping without slipping, or due to loose clamping, slipping can occur.

Made from MOY (medium speed spinning) polyester or POY (pre oriented yarn, high-speed spinning) polyester as raw materials, through stretching and false twisting on a one-step machine. In the stretching section, the coarse and fine sections of the yarn are produced due to different stretching, and the deformation of the yarn in the false twisting section achieves both coarse and fine appearance and fluffy performance. The produced elastic yarn with coarse and fine sections is called uneven false twisting yarn.

In the processing of yarn, two types of twists, positive and negative, are formed in the twisting and untwisting zones. Therefore, overall, the positive and negative twists cancel each other out and become "untwisted", while there are positive and negative twists in some parts of the yarn, resulting in mixed twisted false twisted deformation yarn, which has two types: single strand type and mixed fiber type.

Single stranded type refers to single filament mixed twisted false twisted yarn. In the twisted section of the yarn, the fiber is tightly wrapped and presents finer twisted nodes, while in the untwisted section, the yarn body is fluffy and presents thicker nodes. The length of the twisted nodes and thicker nodes can be adjusted. Mixed fiber type refers to the combination of two types of single filament mixed twisted false twisted yarn to form a dual color effect, heteroshrinkage effect, and three combinations of irregular polyester yarn, cationic polyester yarn, and colored yarn with two types of fibers.