DTY is a stretch yarn formed by POY filaments after being stretched by a stretching machine. The yarn is elastic, soft to the touch, and fluffy in appearance. DTY can be processed into differentiated yarns such as machine-wrapped, empty-wrapped, plied, and composite yarns. The specifications range from 12d to 70d, with f numbers (6 to 68). 70d/48f and 50d/48f and their plied yarns are mainly sold to seamless underwear manufacturers.

During the spinning process, POY fibers are partially stretched to obtain precursors with uniformly oriented molecular chains, achieving the characteristics of post-process elasticization and deep processing. Compared with POY, HOY has greater stretching and higher molecular chain orientation. It can be directly used for weaving textiles or processed to obtain elastic materials with specific properties. FDY means that the fibers are fully stretched during the spinning process and heated and shaped by hot rollers to achieve good thermal stability. FDY can be used for further processing, such as the production of SCY (single-covered yarn) and DCY (double-covered yarn), twisted two-ply yarn, or air-textured yarn, and can also be used directly in fabric production. Fine denier specifications (such as below 12d) are suitable for stockings or light and transparent fabrics, and other specifications are widely used in many textile fields such as knitting, weaving, and warp knitting. This type of fabric has good heat shrinkage stability, a neat and smooth feel, and a silky feel.