Twist direction of yarn

A technological characteristic of OE-rotor spinning is the presence of wrapper fibers (Fig. 3.19). When fibers are attached to the end of the twisted yarn in the rotor groove (a), they wind around the yarn end with one fiber end in the direction of yarn twist and with the other fiber end opposite to the direction of yarn twist (b-d). Such wrapper fibers, also called blurbs, are characteristic for OE-rotor yams. The resulting yarn appearance is attractive in some products, for example, blue Jeans. In other products, these wrapper fibers are unwanted. In yarns for cut-pile carpets, wrapper fibers are disadvantageous, as they prevent the pile from opening uniformly. 

Inspection of the fabric attribute dimensions for all location points revealed that certain attributes were either absent or unrecognizable. These attributes are fiber bundle, fiber single, fiber crimp, fiber surface, fiber pattern, yarn type, and yarn twist direction. Therefore, these attributes were deleted from the statistical analysis. The remaining attributes were either present at all location points or exhibited variation. These attributes included the three (layers, 1/1, and float) whose interactive effects had direct relevance to the research hypothesis, and the following fiber and yarn attributes paired fibers, 0 twist, combined yarns, yarn system A, yarn systems A + B, yarn systems A + B + C + D, fabric distortion, red, green, and black. 

Object Yarn System Fiber Twist Yam Unit1 Direction of Twist0 Degree of Twist... 

Figure 13. Re-plied yam two-ply, Z-twisted yarns plied with another of the same in an S-twist direction, No. 1156, Mound C, Etowah, 1.5 mm diameter of single yam, 12X.

The Etowah people, like the Spiro people, incorporated feathers into yams with structural permutations beyond what might have been used by the earlier Tunacunnhee-Hopewell people. Unlike the Spiro people, the Etowah people may not have spun down as described by King and Gardner (8), but rather they may have used the perhaps older tradition of core-feather-binder yam to achieve their purposes. The feathers found in the yarns of No. 1145 show no twist or twist direction. 

As a form of direct fabric evidence, the physical shapes of textile fabric pseudomorphs have been studied to identify fiber type and yam and fabric construction. Pseudomorphs of paired filaments in mineralized fabric formations found on Shang-period bronze weapons were determined to be replaced silk (I, 2) S-and Z-twisted silk staple yarn pseudomorphs were identified as well as fabric constructions, including float yams and a ribbed weave. 

Twist in the yarn Most yams have filaments that are twisted. The main reason for this is that an untwisted yam is difficult to weave or knit. Two types of twists can be given to the yam, a counterclockwise twist or S twist and a clockwise twist or a Z twist. Figure 2.1 shows these twists. We can also make a ply yam by using reverse twist directions. This serves to balance out residual stresses. We can also twist together two or more plies to make a cord. Commonly, yam designation on a fiber spool provides information such as name, linear density, number of fibers and fiber type. 

Twist Number of turns per unit length in a cord or yarn direction of twist can be either clockwise ( S twist) or counterclockwise ( Z twist) twist imparts durability and fatigue resistance to the cord, though tensile strength can be reduced. 

To use the range of fibers for tire applications, the yarns must be twisted and processed into cords. First, yarn is twisted on itself to give a defined number of turns per inch (i.e., ply twisting). Two or more spools of twisted yam are then twisted into a cord. Generally the direction of twist is opposite that of the yarn this is termed a balanced twist. There are a number of reasons for twist in a tire cord ... 

Based on the yam volume description, the fibrous stmcture of the yarn, or, more generally, the fibrous stmcture of the unit cell, is described as follows. Consider a point P and the fibres in the vicinity of this point. The fibrous assembly can be characterised by physical and mechanical parameters of the fibres near the point (which are not necessarily the same in all points of the fabric), fibre volume fraction Vf and direction /of them. If the point does not lie inside a yam, then Ff = 0 and/is not defined. For a point inside a yam, fibrous properties are easily calculated, providing that the fibrous stmcture of the yam/ply in the virgin state is known and its dependency of local compression of the yarn/ply, bending and twisting of the yam are given. Searching the cross-sections of the yams, cross-sections S, = S(si) and S,+i =5 (s,+i) (s is a... 

Twist Number of turns per unit length in a cord or yarn direction of twist can be either... 

A filament yarn (or a flat yarn) is a continuous tow that has been twisted to aid future processing. The direction of twist in a yarn is designated as Z or 5 twist—Z twist if the spirals around the axis slope in the same direction as the middle portion of the letter Z and S if the spirals slope in the same direction as the middle portion of the letter S (Twist in Appendix 1). A Z twist is normally applied to a single tow, whereas plied yarns tend to have S twist. A twisted tow can give improved composite mechanical properties, such as flexural strength. 

Twist Measure of spiral turns per unit length given to yarn or strand hold constituent filaments together—S twist if spirals slope in same direction as middle portion of letter S, Z twist if spirals slope in same direction as middle portion of letter Z. 

Twist direction n. The direction of twist in yarns and other textile strands is indicated by the capital letters S and Z. Yarn has S-twist if when it is held vertically, the spirals around its central axis slope in the same direction as the middle portion of the letter S, and Z-twist if they slope in the same direction as the middle portion of the letter Z. When two or more yams, either single or plied, are twisted together, the letters S and Z are used in a similar manner to indicate the direction of the last twist inserted. 

Figure 3.26 presents a comparison of three yarn types with regard to yarn uniformity, twist level, and yarn structure. Table 3.2 shows a comparison of the three most important spinning principles in various characteristics both direct (tenacity, elongation, uniformity, and so on) and indirect (tensile force) parameters were chosen. 

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