Bulking false twist

In false twist texturing (FTT), shown schematically in Figure 7, a device twists yam upstream of its location as the threadline passes across a heater, and the yam untwists downstream from the device and is wound up. If the yam is not heated downstream from the twist device, it has bulk and high elasticity (stretch). If the yam is heated downstream from the twist device, it has bulk, but much less stretch. FTT machines initially used two steps to sequentially draw and texture. Later machines combined those steps to simultaneously draw and texture (92). Initial machines used pin spindles as the false twist device. Texturing speeds were about 150 m/min and slowly increased to about 300 m/min. As POY quaUty and stmctural stabiUty improved, new... 

False-twist texturing depends on setting fibers in a kind geometry and then changing to another, which generates elongation that can be recovered by bulking. Another method is to set fibers in the required crimped form. This was the basis for stuffer-box and other methods. 

False-twisting is most widely used for texturing fine tex yarns. In the first step, they are heated to about 220°C and 185°C in the cases of nylon-6,6 and nylon-6, respectively. This is followed by twisting to introduce 30-40 turns/cm using spindle or friction devices. The yarn is then cooled and untwisted. The resulting product is characterized by good elasticity. If bulk is required, the yarn is either subjected to a second heat-twist-untwist step or treated with steam or hot water in an autoclave. 

Set yarns False-twist yarns stabflized to produce bulk. 

Set Yarns False-twist yams stabilized to produce bulk. 

Textured Yarns n Yarns that develop stretch and bulk on subsequent processing. When woven or knitted into fabric, the cover, hand, and other aesthetics of the finished fabric better resemble the properties of a fabric constructed from spun yarn. Also see Texturing. The ten types of textured yarns are Bulked Yarn -Qualitative term to describe a textured yarn. A bulked yarn develops more bulk than stretch in the finished fabric. Coil Tarn - A textured yarn that takes on a coil or spiral configuration when further processed. A coil yarn can be either a torque yarn or a nontorque yarn. A coil yarn can be formed by the false twist or edge crimp... 

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