POY, DTY, And FDY

Definition and differences in process

POY is a filament yarn that has not been sufficiently drawn after spinning and has only been partially oriented at the molecular level. It is handled as an intermediate material for downstream drawing or false-twist processing, and it is not often used on its own as yarn for final products.

DTY is a textured yarn made by drawing and false-twist processing POY and similar yarns, giving them crimp. Crimp refers to the fine waviness in the yarn, which adds bulk and stretch. FDY is yarn that has been fully drawn during the spinning process and, in principle, does not require additional drawing.

• POY: an intermediate yarn that is nearly undrawn and intended for further processing
• DTY: textured yarn with crimp created by drawing and false-twist processing
• FDY: relatively smooth filament yarn that has been fully drawn

Hand feel and appearance characteristics

DTY tends to include air pockets due to crimp, and is generally a bulkier, softer yarn with a more matte appearance. Because it is easier to achieve stretch and recovery, it is well suited to creating fullness and stretch in knit fabrics.

FDY is characterized by smoothness and moderate luster that take advantage of filament continuity. In woven fabrics, it is easier to achieve a clear surface and drape, but the actual appearance and hand feel vary greatly depending on cross-sectional shape, yarn thickness, twist, woven or knitted structure, and dyeing and finishing.

Because POY is an intermediate yarn, its final fabric hand feel cannot be judged from POY alone. Processing conditions into DTY and similar yarns affect crimp, stretch, dyeability, and bulk.

Main applications

DTY is used for fabrics that require softness, bulk, and ease of movement, such as underwear, cut-and-sew garments, sportswear, leggings, and knit linings. It can be designed from lightweight to heavyweight fabrics, and is used both on its own and in combination with different yarns in mixed knitting or weaving.

FDY is used in applications that take advantage of surface smoothness and stable weaving or knitting performance, such as linings, blouses, dresses, jackets, outerwear, and bags. Nylon FDY is also used in woven fabrics that benefit from its suppleness.

Selection and handling notes

When selecting fabric, check not only the yarn category but also the fiber type, total linear density, filament count, twist, structure, fabric weight, and finishing process. Even when stretch is expected, performance cannot be judged from DTY alone, so confirm the fabric's stretch recovery and dimensional stability through testing.

Fabrics made with polyester or nylon generally tend not to shrink much, but dimensional changes can still occur depending on heat, knitted or woven structure, finishing, and washing conditions. Before mass production, it is important to perform washing tests and pressing tests to confirm compliance with the specified conditions.

For stretchy knit fabrics made with DTY, care is needed to avoid over-stretching during cutting and waviness during sewing. Align the grain and let the fabric relax, and adjust differential feed and presser foot pressure, as well as the elasticity of the sewing thread, to match the fabric; this helps reduce puckering and seam failure.

Differences from similar terms

POY, DTY, and FDY are not names of woven or knit fabrics; they are terms mainly indicating the manufacturing and processing stage of synthetic filament yarn. Even with the same DTY, the fabric's appearance and performance differ if the knit structure, such as jersey or tricot, is different.

False-twist textured yarn is a general term for yarns given crimp by false-twist processing. DTY refers to a representative false-twist textured yarn made by combining drawing and false-twist processing. Filament yarn is also a general term for yarn made from continuous long fibers, and POY, DTY, and FDY are differences in processing stage and form.

Frequently asked questions