DTY, ATY and ACY: Which Textured Yarn for Which Fabric
Three families of textured yarn — false-twist crimp (DTY), air-jet loop (ATY/Taslan) and elastane-core air-covered (ACY) — deliver different hand, stretch and end-use. This guide separates the production logic of all three and shows which is right for sportswear, swimwear and linings.
Flat, lustrous filament yarn (POY or FDY) on its own is too lifeless, too slippery and too low in bulk for most knit fabrics. What gives a fabric its bulk, cover, stretch and hand is the texturing step applied after spinning. In the world of polyester filament there are three major routes for that step, and although all start from the same POY feedstock, they produce very different yarns: false-twist DTY, air-jet ATY (Taslan) and air-covered ACY. Which one you choose determines how the fabric stretches, how it recovers and where it belongs.
DTY — false-twist crimp, real stretch
DTY (draw-textured yarn) is the single largest category of polyester filament yarn and the backbone of knit-fabric supply. The draw-texturing machine simultaneously draws, false-twists and heat-sets the POY: the yarn is heated under high twist in a primary heater (typically ~190–220 °C), cooled, then untwisted — but the crimp memory is permanently set into the filaments. The result is a bulky, elastic, covering yarn. The physics of the process is detailed in our sibling guide dty-textured-yarn; for the spinning POY/FDY distinction see melt-spinning-poy-fdy. The friction-disc surface/yarn speed ratio (D/Y, typically ~1.6–2.2) and an optional second 'set' heater (typically ~160–180 °C) tune the yarn's character: 'set' yarn is stable and soft, 'non-set' yarn is high-torque and high-stretch.
ATY/Taslan — air-jet loop, spun-like look
ATY (air-textured yarn), also known in the industry by the Taslan trade name, uses an entirely different physics: no twist, no heat-based crimp. Over-fed (overfeed, typically ~5.5–36%) filaments are passed through a turbulent air jet; the jet throws the filaments out into random loops and arcs and locks them into the yarn body (jet pressure typically ~7–10 bar, speed typically ~300–500 m/min). These surface loops give the yarn a matte, hairy, spun-like hand and cover — but not a true permanent stretch. ATY is chosen not for DTY's elastic crimp but for a dry, full, cotton- or linen-like hand; it is preferred when a woven feel is wanted without pilling risk. The air-texturing jets typically come from suppliers such as Heberlein.
ACY — elastane-core air-covering, permanent stretch
ACY (air-covered yarn) is structurally distinct from the other two: it is a covering yarn. An elastane (spandex/Lycra) core is fed under tension while one or two polyester filaments (usually DTY) are wrapped and knotted around the core with the help of an air jet; SSM-type air-covering jets are used for this. The result is a composite yarn that carries the high-recovery, permanent stretch of elastane but looks entirely polyester on the surface and dyes like polyester (disperse dye, typically ~130 °C). Unlike crimp-derived DTY stretch, ACY stretch comes from the elastane core — which is why the % elongation is far higher and the recovery far stronger. ACY is a bulkier, less constrained alternative to mechanical covering (conventional/single/double covering) or twist-covering.
Which yarn for which fabric
- Sportswear & activewear: When multi-directional stretch and recovery are needed, ACY (elastane core) provides two-way stretch; when one-way bulk, sweat management and cover are enough, DTY is used as the main yarn. For moisture handling see the moisture-wicking-finishing guide.
- Swimwear & shapewear: Because high recovery under chlorine and constant stretch is essential, ACY (polyester/elastane) dominates; the body yarn is usually DTY and the stretch component is the elastane core.
- Linings & shirting taffeta: When a smooth, light, low-cost and low-stretch result is wanted, flat FDY or fine DTY is preferred; ACY's stretch is usually unnecessary.
- Cotton/linen-feel fabrics: When a matte, full, dry spun-like hand and woven-like stability are sought, ATY/Taslan is the alternative to DTY's lustrous elastic character.
Comparison: DTY vs ATY vs ACY
| Dimension | DTY (false-twist) | ATY / Taslan (air-jet) | ACY (air-covered) |
|---|---|---|---|
| Process principle | Draw + false-twist + heat-set | Over-feed + turbulent air-jet loop | Air-jet wrapping of filament over elastane core |
| Feedstock | POY | Flat filament (POY/FDY) | Elastane core + DTY/filament sheath |
| Typical parameter | D/Y ~1.6–2.2; heater ~190–220 °C | Jet ~7–10 bar; overfeed ~5.5–36% | Tensioned elastane core + jet wrapping |
| Hand / appearance | Bulky, elastic, covering | Matte, hairy, spun-like | Polyester surface, bulky, covered core |
| Stretch source | Crimp memory (moderate stretch) | Low / no stretch (loop bulk) | Elastane core (high, permanent stretch) |
| Typical use | General knits, sport, outerwear | Cotton/linen-feel, woven, fill | Swimwear, shapewear, two-way-stretch sport |
In short: all three are born from the same polyester filament but pull different levers. DTY gives bulk and moderate stretch through crimp; ATY gives a spun-like hand through air loops but does not stretch; ACY takes its stretch from a separate elastane core and dresses it in polyester. When you see a notation like 'DTY 150/48 SIM' or 'ACY 40D elastane / 75D DTY' on a TDS, you can now read what it means for the fabric's hand and stretch behaviour. For the crimp physics behind texturing see the dty-textured-yarn and fiber-cross-section guides, and for the dye side see disperse-dyeing-process.
Frequently asked questions
What is the difference between DTY, ATY and ACY?
DTY gives crimp and true stretch through false-twist texturing (the most common performance yarn); ATY/Taslan gives a matt, staple-like hand through air-jet looping; ACY air-covers an elastane core and delivers lasting stretch.
Which textured yarn is right for which fabric?
DTY for sportswear and general performance knits; ATY for a cotton-like matt hand and linings; ACY for swimwear and products needing high stretch.