link no. 59 customer magazine spun yarn systems - Rieter

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26 LINK 59 . 1 /2012 TECHNOLOGY Fig. 11 Rotor carded, Single Jersey 100 %, Cotton, 1 1/16", Ne 30, Navel KS-NX, 110 000 U/min, αm 109. Fig. 12 Rotor combed, Single Jersey 100 %, Cotton, 1 1/16", Ne 30, Navel KS-NX, 110 000 U/min, αm 109. Fig. 13 Ring carded, Single Jersey 100 %, Cotton, 1 1/16", Ne 30, 12 200 U/min, αm 109. Fig. 14 Ring combed, Single Jersey 100 %, Cotton, 1 1/16", Ne 30, 15 000 U/min, αm 109. hairiness values of a rotor yarn. Thus, with rotor yarn the yarn hairiness is not primarily determined by the fiber length for but rather by the yarn structure. Clear advantages concerning yarn abrasion are obvious with rotor yarns. Abrasion with a ring yarn is higher by more than factor 5 compared to that of a rotor yarn. It can be ascertained that the combing process has a positive impact on the yarn abrasion of a rotor yarn. The advantages of the rotor spinning technology when processing Shankar 6 cotton with a relatively high level of short fibers are impressive. Micrographs show the typical rotor yarn structure with wrapper fibers in comparison to the ring yarn structure. The greater hairiness and the associated volume increase of the ring yarn are clearly visible on the micrographs. Normally, a rotor yarn is characterized by a greater yarn diameter than a ring yarn, at an equal yarn count. This results in higher opacity in knits. However, as is shown by these results, this effect can also be reversed by a shortening staple length with ring yarn due to inferior yarn orientation and bonding in the yarn strand (Fig. 10). Knitted fabric properties In this specific case, the following commonly practised and typical criteria for assessment of the knits were applied: • Fabric touch • Opacity • Evenness • Pilling Touch, opacity and evenness As to be expected, ring yarn is softer to the touch than rotor yarn. The greater opacity of the carded ring yarn compared to rotor yarn is in this case due to the higher hairiness. This influence is also apparent in the diminished opacity of combed ring yarn. Carded ring yarn shows a clearly inferior fabric appearance to that of rotor yarns. Only the combing process can improve the appearance in comparison to carded ring yarns to lie within the same range as rotor yarn. The use of the combing process with rotor yarn cannot achieve improvements in the knits. Pilling Most of the physical properties of an end article are the result of the structure of the processed yarn. The pilling characteristics of the textile surface, especially in knits, are one of the most important quality criteria. End articles that form surface fiber pills after only a short period of wear cause an extreme devaluation of quality and are undesirable. Pilling is therefore a constant theme and can be substantially influenced and improved by lower hairiness and the fiber bonding structure of the end spinning process.
The higher the grade, the better 6 5 4 3 2 1 0 Fig. 15 PILLING VS. TYPE OF YARN Knitted fabric, Ne 20, acc. to Martindale, Yarn count Ne 20, Martindale 500 1 000 1 500 2 000 2 500 3 000 3 500 4 000 4 500 5 000 5 500 6 000 6 500 7 000 7 500 Rotor carded, αm = 109 Rotor combed, αm = 109 Cycles Ring combed, αm = 98 Ring carded, αm = 109 With all the knits examined, the ring yarn showed the worst pilling values. The carded rotor yarn achieved the lowest pilling values resp. the best marks (Figs. 11-14). The greater randomization of fibers and the wrapper fibers produce resistance to the formation of fiber pills. It can be clearly seen that the combed rotor yarns show inferior values to those of the carded rotor yarns. This fact can also be explained by the reducing randomization of the fibers due to the different staple compositions (Fig. 15). Summary By means of the combing process, the trash content is reduced in a range from 60 – 85 %. With a low combing level, the combing process can certainly represent a technologically suitable solution for the rotor spinning process. The additional short fiber extraction shows no benefit in the question of yarn evenness with rotor yarn. That means with the rotor spinning process, short fibers can be far better guided through the fiber guide channel than is possible with ring spinning by means of the drafting arrangement. In contrast, with the production of ring yarn the combing process is indispensible to improve quality when a higher short fiber percentage, a lower mean staple or a higher trash content exist in the cotton. LINK 59 . 1 /2012 TECHNOLOGY Such prerequisites have a far less negative effect on the rotor spinning process than on the ring spinning process. According to the raw material constellation and the type of downstream processing, the rotor spinning process can be considered as more economical. The evenness of the rotor yarns is superior to that of ring yarn in the case of processing carded Shankar 6 cotton at a yarn count of Ne 20. By means of the combing process, the ring yarn quality can be considerably improved and is only then superior to the carded rotor yarn in the case examined, with the exception of the hairiness and abrasion resistance and the pilling values. The greater hairiness and the associated volume increase in the ring yarn resulted in a better opacity in the knitted fabric. Normally, a rotor yarn is characterized by a greater yarn diameter at equal yarn fineness than with a ring yarn. This results in a higher opacity in the knitted fabric. This effect can be reversed by a shortening staple length due to the inferior fiber orientation and bonding in the yarn strand. Ring yarn has a softer touch compared to rotor yarn. By means of the combing process with rotor yarn, no improvement in the knitted fabric can be achieved. The reduction of the twist coefficient with combed rotor yarn also does not lead to any improvement, neither in the touch nor in the other assessment criteria. With all the knits examined, the ring yarn exhibited the worst pilling values. The rotor yarn achieved the best pilling values. 12-111 • Harald Schwippl Head Technology Winterthur harald.schwippl@rieter.com 27
Page 1 and 2: The customer magazine of Rieter Spu
Page 3 and 4: Ready for the Future Recent months
Page 5 and 6: On the one hand, we are able to mor
Page 7 and 8: WASTE COMPOSITION IN THE BLOWROOM,
Page 9 and 10: Economy Quality Flexibility 1 2 Hig
Page 11 and 12: Automation in Combing More than 50
Page 13 and 14: Fig. 6 Lap change on the E 76 combe
Page 15 and 16: R 60 - Nm 28 / Ne 17, 100 % COTTON
Page 17 and 18: Fig. 2 With SERVOtrail the roving f
Page 19 and 20: NE 30, 100 % COTTON, KNITTING YARN
Page 21 and 22: 4 spinning systems in the Rieter Sp
Page 23 and 24: Installed rotors [1 000] Fig. 3 Fig
Page 25: Number of particles/1 000 m Fig 9 F
Page 29 and 30: Innovative Retrofits for Draw Frame
Page 31 and 32: Presentation of the Rieter Award in

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