Current and Future Trends in Yarn Production1

Volume 2, Issue 2, Spring 2002

CURRENT AND FUTURE TRENDS IN YARN PRODUCTION1

William Oxenham, Ph.D. College of Textiles, North Carolina State University

ABSTRACT

While developments in yarn manufacturing continue to be promoted by machinery makers, spinners are challenged to produce the best quality yarn at an acceptable price. This often results in a compromise, since improved yarn quality can usually only be achieved at a higher processing cost (including raw material selection). An additional difficulty is that the significance of the various attributes of quality change for different yarn’s end uses. While the solution to lowering yarn costs, that has been adopted in recent years has been to create large, almost fully automated spinning mills, this philosophy is presently being questioned, since this significantly reduces flexibility with respect to the fiber and yarn type that can be processed. This is obviously at odds with the current paradigm of customer driven, quick response manufacturing, since this demands inherent flexibility in the successful supplier. This paper reviews the current state of technological innovation in yarn production and examines the relative merits and disadvantages of each system. Some insight will also be given concerning those factors that limit further development of some of these systems. Historical trends in US yarn production have also been surveyed, and the combined information obtained is used as an indicator of the future directions in this key industry.

KEYWORDS: Yarn Production, Spinning, Vortex Spinning, Centrifugal Spinning

1. INTRODUCTION shortcomings in certain aspects of yarn and fabric quality (Figure 2). This aspect Research into new technology for yarn cannot be over stressed since while ring formation peaked in the 60’s & 70’s. Since that spun yarns may not be the best when time some systems have gained significant considered from certain quality aspects, commercial acceptance, whereas other but they do provide an overall balance of proposed systems have met with little (or zero) quality aspects, which still make them success. When viewed in terms of their the yarns of choice for most applications. potential for spinning a range of fiber types (as Thus caution should be exercised when show in Figure 1), it is apparent that real assessing a new system since good success is only evident for rotor (open end) strength and regularity are meaningless if spinning and ring spinning. While other the fabric has a harsh handle or if the systems have promised significant benefits, system is restricted in fiber type that can these have met with limited success due to be successfully spun, etc.

1Plenary Paper presented to The Textile Institute 82nd World Conference, Cairo (Egypt), 2002 Article Designation: Scholarly 1 JTATM Volume 2, Issue 2, Spring 2002

Figure 1 Figure 2

The following is a review of potential be used and thus higher spindle speeds and systems for cotton (or short staple) spinning, higher productivity. indicating their current status and likely prospects for the future. It should be There is still debate over which is emphasized that while the current report is the best format of supply to the ring frame focused exclusively on the spinning and the alternatives of "light weight sliver" machine, preparation for spinning is also or "heavy weight roving". Both have major critical and in particular the ability of these machinery makers as proponents. The earlier processes to feed clean, nep free, well advantage of the light weight sliver is the blended fibers with low variations in elimination of the roving frame, but there is properties. the penalty of much greater space requirements for creeling at the spinning 2. RING SPINNING frame. The use of heavy weight rovings (obviously still requires the use of a roving Ring spun yarns are still regarded by frame) gives much greater productivity on most yarn technologists as having the ideal the roving frame and offers the advantage of blend of properties. This preference for ring easily applied package transfer to the spun yarns is also demonstrated by many spinning frame. The benefits of either feed fabric producers and apparel manufacturers format can only be realized if the spinning and retailers. In terms of technological machine is capable of higher than normal breakthroughs the ring frame lags behind drafts. The benefits afforded by such a high other newer systems, but there have been draft system (offered by Howa) are shown in significant changes in the system that have Figure 3, from which it should be realized enabled spinning speeds to be almost that the benefits in productivity extend back doubled in recent years. The changes have to the finisher drawframe. interacted and it is likely that many of them The current limitation on ring would not have succeeded in isolation. The spinning is maximum traveler speed (about use of automatic doffing and link winding 40 m/s) and it is unlikely there will be any only became an attractive proposition with major increase in this speed in the near the introduction of much longer ring frames future. Different approaches to improving and improvements in splicing technology. the performance (i.e. speed) of the ring & These in turn meant that package size could traveler combination have been tried but be reduced, which enabled smaller rings to these have met with limited or no success.

Article Designation: Scholarly 2 JTATM Volume 2, Issue 2, Spring 2002

Figure 3 Figure 4

Examples of these approaches are: "Compact Spinning" they renamed their • Use of high tech materials for the commercial application of this technology ring and traveler – such as ceramic. Comfort Spinning then subsequently Com4, • The use of rotating rings – a system since this implies a better fabric hand (as tried and subsequently discounted in opposed to "compact"). The system relies on the 70’s – has more recently been condensing the strand, which emerges from demonstrated by Howa. the drafting system and promotes a better • Replacement of the traveler with a yarn structure with lower yarn hairiness. rolling (rather than sliding) element This is achieved by utilizing suction to has been recently suggested, consolidate the strand prior to twisting as however there is no reported shown in Figure 4. The resultant effect on experience of this device in an yarn structure is clearly apparent from the industrial environment. comparison of Com4 and conventional ring- spun shown in Figure 5. The consolidated Other ways of increasing production have structure yields better yarn properties. The been sought and the current vogue is benefits that can be achieved over towards systems that will permit spinning at conventional ring spun yarns can be realized lower twist levels while maintaining as stronger yarns (for the same twist) or adequate yarn properties for subsequent similar yarn strength can be obtained at processing (and satisfactory fabric twenty per cent lower twist (Figure 6). properties). This can be achieved by various Alternative approaches to this approaches to "Compact Spinning", which technology are typified by the EliTe system relies on modifications to the machinery to of Suessen, which uses a perforated system facilitate improvement in yarn formation after the normal drafting system (Figure 7). and structure, resulting in improved tensile In addition Suessen also apply a slight draft characteristics and surface properties in the to enhance consolidation and reduce the resultant yarn. While the idea is not new width of the strand during yarn formation (originally proposed by Fehrer as part of the (Figure 8). While it is agreed that this DrefRing concept) several machinery technique can produce higher quality ring makers have shown ring frames equipped to spun yarn, there is no doubt that the systems spin yarns with compact structure. are complex and usually require roving stop motions, which inevitably increase the costs The company with the greatest per spindle. experience with this technology is Rieter. While they introduced the terminology

Article Designation: Scholarly 3 JTATM Volume 2, Issue 2, Spring 2002

Figure 5 Figure 6

Figure 7 Figure 8

There are also concerns about the formation, the system has not been a type of fibers which can be successfully universal success and its acceptance has processed using this approach and many been restricted to certain geographic areas. agree that the system will be more Since the introduction of rotor spinning, successful processing longer (combed ?) there have been major increases in cotton staples. Recent mergers and processing speeds that have necessitated a acquisitions in the textile machinery reduction in rotor size, which in turn has industry (in particular Rieter’s purchase of resulted in deterioration in yarn quality Suessen) seem to indicate that there will be a (Figure 9). Lately there has been concern rationalization of the types of systems that that the differential in price between ring will be offered in the future. spun and rotor spun yarn seems to have increased. An examination of data on yarn 3. ROTOR SPINNING prices over several years indicates that this is indeed not a recent phenomenon but Rotor spinning is the only system to appears to be a systematic trend, which can offer a real challenge to ring spinning for be traced back over 15 years (Figure 10). coarser yarn counts. While it offers There is no doubt that rotor spinning will, successful processing of cotton at for the foreseeable future, hold a place in the significantly higher speeds than ring coarser yarn sector, but in order to gain in spinning, and it is generally agreed that the other sectors some mechanism of improving yarn processes better during fabric certain aspects of yarn quality is essential.

Article Designation: Scholarly 4 JTATM Volume 2, Issue 2, Spring 2002

Figure 9 Figure 10

4. FRICTION SPINNING 5. JET SPINNING

The considerable hype concerning The status of jet spinning is friction spinning as a potential replacement summarized in Figure 12. The major issue for rotor spinning was never realized. There with this system is that, despite repeated are several reasons behind this failure, but promises, it was not possible to produce the major shortcoming of the system is 100% cotton yarns of acceptable quality. In shown in Figure 11. It is clearly evident addition there are some restrictions on yarn from this chart that there is a distinct drop in count, which precluded the spinning of yarn tenacity at higher processing speeds, coarse yarns. Jet spinning has also had even though a constant twist may be limited success in producing knitting yarns. maintained by using higher friction roller The system has, however, proven to be speeds. It appears that this technology will successful in niche markets for the be restricted in end-use to certain processing of polyester rich blends. The “technical” applications, such as those areas future of Jet spinning must however be which are currently being successfully questionable with the introduction of Vortex covered by use of DREF spinning machines. spinning which is viewed to be technically superior.

Figure 11 Figure 12

Article Designation: Scholarly 5 JTATM Volume 2, Issue 2, Spring 2002

6. VORTEX SPINNING is still underway on this system and in particular refinements in nozzle (jet) design A summary of the status of Vortex will be an ongoing feature. Initial spinning is given in Figure 13. It must be information indicates that the system is emphasized that this system should not be easily applicable to polyester/cotton blends confused with vortex open-end spinning, and that acceptable yarns can be produced which was developed in Poland during the with greater cotton content than was early 70's. While there must be a significant achieved with Jet spinning (Figure 14). This amount of data on this system, most of this is no doubt due to the improvement in the is regarded as proprietary, since much of the number of wrapper fibers that are available early work on the system has been carried in vortex spinning and it can be seen from out in selected spinning mills in the USA. Figure 15 that, when locally untwisted, the The system has been exhibited as a cotton two part structure of the yarn is clearly spinning machine and much has been made visible. There is limited commercial about the ability to spin carded (and drawn) production of 100% cotton yarns and there cotton, as distinct from the requirement of are concerns over the amount of waste combed cotton for jet spinning. It is generated during spinning (> 5%). believed that significant development work

Figure 13 Figure 14

Figure 15 Figure 16

Article Designation: Scholarly 6 JTATM Volume 2, Issue 2, Spring 2002

7. CENTRIFUGAL SPINNING • ability to supply competitively priced smaller lot sizes. The idea of utilizing a centrifugal chamber to twist and collect the yarn is not The factors above inter-relate and it is new and indeed the Topham Box was a apparent that the issue is not simply feature of early Rayon filament spinning associated with lower labor costs because lines. Other incursions into this type of with automated spinning machinery, the spinning included the Greenbank labor forms only a small part of the overall Axispinner, which was designed for yarn costs. International financial exchange producing two-fold worsted yarns. Recently rates have recently been a significant factor there has been renewed interest in this in the overall pricing of yarns and a dollar technology and such a system was shown as which has been strong against other a prototype at ITMA '99 by the Russian currencies has favored the import of yarns. Company Techmaschexport (see Figure 16). In this machine the yarn was spun into a An additional factor contributing to relatively small pot operating at 35,000 the current situation in spinning in the US, is revs/min. When sufficient yarn is produced the past trend to invest in large automated the yarn is withdrawn from the pot and mills. These proved to be extremely wound onto a small (70 g) cylindrical effective in competing on cost and analyses package. The illustrations of a full machine indicated that very few countries could indicate automatic doffing and transport of produce yarns cheaper than the US and even these packages and it is probable that these then the differences were marginal. The would be fed to a rewinding machine to downside of this philosophy is that to produce larger packages for knitting and balance the production lines, the mills lose weaving. While this must be still judged as a flexibility with respect to fiber type (blend developing technology it should offer the composition) and yarn specifications (count benefit of yarns with properties almost and twist factor). Thus the economic identical to ring spun yarns. It is believed benefits previously afforded are lost when that other machinery makers also have an there are greater labor requirements and active interest in this technology. down time due to lot changes. This is a major issue that the US industry has to 8. COMMERCIAL TRENDS address, possibly by creating sub-units within the mills. At the present time there is a decline in yarn production in the USA (Figure 17) When viewed from the processing and this is accompanied by much adverse machinery involved it is clear that there is a publicity about mill closures. The reasons general downward trend in the investment in for this trend are complex and include such ring spinning and a leveling off of the features as: investment in rotor spinning (Figure 18). • relocation of other parts of the The number of positions of jet and vortex textile chain to other countries; spindles is estimated to be around 110,000. • higher speed machinery requires The decline in spinning positions during the less facilities and people to maintain 90’s was not reflected in a sharp decline in the same national production; production (figure 17). This arises because • the availability of lower cost yarns the reduction in ring spindles was from other countries provides direct significantly offset by the switch to rotor competition; spinning and jet spinning, and the upgrading • changes in the driving forces within of older generation rotor spinning machines the textile supply chain; with newer (and faster) machines. Figure 19, which is based on recent data from Schlafhorst (US), clearly indicates the Article Designation: Scholarly 7 JTATM Volume 2, Issue 2, Spring 2002 significant increases in production that has maintaining the same production level. taken place in most spinning systems over Indeed if some of the ring spindles were the ten years up to 2000. Typically over replaced with rotors (as seems evident in 45% increase in productivity was achieved figure 18) then there could be an increase in by most technologies, enabling a reduction production with less “spindles”. of about 30% in “spindles” while

Figure 17 Figure 18

Figure 19 Figure 20

While there has been a decline in the is going, both technologically and spinning capacity it is apparent from figure geographically. While some existing 20 that the US is still a major force in yarn technologies will retain niche markets production. It is also clear that the US has a (composite yarns for sewing threads, jet much greater global share of higher speed spinning for sheeting, etc.), there is no doubt spinning technologies. that ring and rotor will continue to be the dominant spinning technologies for at least 9. CONCLUSIONS the next decade. There is, however, also no doubt that there is significant interest in the Most spinning machinery makers are potential of newer systems such as vortex, cautious about where the spinning industry but at the present time, details are not yet

Article Designation: Scholarly 8 JTATM Volume 2, Issue 2, Spring 2002 generally available about this system. The direction of spinning is thus hard to predict, but a clearer picture will emerge when the following questions can be answered: • Is Vortex spinning good enough? • Will interest in ring spinning continue to dominate? • Will compact spinning succeed? • How fast can rotor spinning go? • Does centrifugal spinning have a future? • Is there another spinning technology being developed?

AUTHOR’S ADDRESS:

William Oxenham, Ph.D. Associate Dean for Academic Programs College of Textiles North Carolina State University P O Box 8301 Raleigh, North Carolina 27695-8301 (919) 515-6573 – Telephone (919) 515-3733 – FAX [email protected]

Article Designation: Scholarly 9 JTATM Volume 2, Issue 2, Spring 2002