Friction Spinning-A Critical Review

Indian Journal of Fibre & Textile Research Vol. 17, December 1992, pp. 246-251

Friction spinning-A critical review

N Balasubramanian The Bombay Textile Resea rch Association. L B S Marg, Ghatkopar(West), Bombay 400 088 Received 13 April 1992

The ability to achieve high twisting rates without the need to rotate the heavier mechanical elements and the low yarn tensions enable very high delivery rates with friction spinning. The soft handle of the yarn, versatility to handle all types of fibres and the core spinning facility are the other meri.ts of this system. However, the low yarn strength. high twist variability, higher hairiness and the restriction to coarser counts are the major drawbacks to be overcome before friction spinning can become commercially viable. The yarn formation is very complex as the angle of deposition of the fibres. suction level inside the drums, surface friction on the yarn tai l a nd the air turbulence have considerable influence on fibre arrangement. Fibres are highly disoriented in the yarn with loops and folds which lead to very low utilization offibre length in yarn strength. The system becomes unstable when the number of fibres in the cross-section falls below a certain level.

Keywords : Core-spun yarn, Dref-2, Dref-3, Friction spinning, Master Spinner, Open-end spinning, Spinning tension

I Introduction number of turns to the yarn. So, very high rates of The need to rotate the package at the twist insertion twisting can be obtained without the need to rotate rate coupled with rapid increase in spinning tension the drum at excessively high speeds. Normall y, the with spinning speed sets a limit to the spindle speeds yarn is twisted 100 times per turn of the drum I . achievable in ring spinning. Open-end spinning Another advantage of friction spinning is that only methods where the open end of the yarn alone needs to the yarn end is required to rotate with angular velocity be rotated for imparting twist were, therefore, req uired for twist insertion while in ring spinning the developed to achieve high delivery rates. Rotor package with the spindle and in rotor spinning the spinning which is one of the first methods developed rotors are also required to rotate with yarn angular on this principle has well-established itself as an ve locity2. As a result, the limitation to speed from alternate to ring spinning in coarse count range for technological considerations is of much lower order certain end uses. Friction spi!1ning represents_'!...n than in rotor spinning and there is a good scope for alternate open-end spinning - method to - rotor achieving much higher production rates. spinning which holds promise of still higher delivery­ The spinning speed in friction spinning in relation rates. to that by other competitive methods of spinning is discussed by Brockmanns3 as illustrated in Fig. I. It is 2 Outline of Friction Spinning observed that friction spinning (Dref-3tJl1J~E In this system, the fibres from the sliver after f~ction spinningnave a higher prOductivity than both pre-opening and individualization are deposited in a rOto r spinning and air-jet spinning. Friction suitable form by an air current into the gap between spinning is, however, restricted to coarse count two cylindrical drums rotating in the same direction. range. Either one or both the drums are perforated and have Another import tnt advantage of friction spinning is 2 a suction arrangement inside them to restrain the the low spinning tension • The low tension accrues fibres while they are rolled and twisted. The yarn is from the absence of centrifugal forces in spinning formed by the frictional forces between then'bresand' which are present in ring and rotor spinning. The yarn the rotating cyfinaricafSu-~fa ces and is withdrawn at­ tension values in friction, rotor and ri ng spinning are right ang e to-the direction of moving surface. Since compared2 in Fig. 2. It is observed that the spinning the drum diameter is many times higher than the yarn tension in friction spinning is only 20% of that diameter, each revolution of drum imparts a large obtained in ring spinning and 14 % of that in rotor BALASUBRAMANIAN: FRICIlON SPINNING 247

400 Ring Rotor 3 Air Jet I. or.I-2 c 300 5 oref -3 E "- 6 DE Friction (Master Spinner I E w a:~ 200 a:>- w :'! w-' o 100

-=:==~=~3.~::I:=:;r;=:r:::~:;=~~-,l Fig. 3- Front and side view or Drel~2 [I - Drarting unit : 0 20 40 60 80 100 0L 2- 0pening roller: 3- Perrorated drums; 4---Take up roller: 5- Winding unit; and 6- Suction system] YARN COUNT, Ne Fig. I- Delivery rates and yarn counts or various spinning systems restraining influence over the fibres as they get twisted by the rol1ing action caused by the rotation of drum to form the yarn. The suction inside the drum also helps to remove dust and trash, thereby contributing to production of a cleaner yarn 7. Twist is determined by >­ u the ratio of suction drum speed to delivery rates. z w => Considerable slippage (60-85%), however, takes a 3 w place between the yarn and the drum as a result of a: l.L which actual twist is much lower than mechanical twist. The extent of slippage increases as the yarn count becomes finer. The machine can also be used for producing core yarns. Tht: core filament is fed axially 100 into the spinning zone and the staple fibres delivered YARN TENSION,eN from the opening rol1er are tied in or wrapped over the Fig. 2- Yarn tension in rriction. rotor and ring spinning filament by the false twist generated by the rotating action of the drums. All kinds of filaments, tapes and 7 spinning. Further, tension variations are also of a elastomers can be used as core . lower order. Because of the low tension, end breaks A 'Parallelistor' or 'Paradisc' was later are low in spinning and higher delivery rates are incorporated into the spinning unit to improve fibre achievable. The low spinning tension has, however, alignment4 in the direction of yarn axis7.9. This the disadvantage that some of the weak places in the consists of a fan like unit located in the flowline of the yarn may escape breakage during spinning process opened fibres as they descend onto the yarn forming and can be a potential source of break during zone. The unit deflects the fibres and parallelizes them subsequent working. in the direction of yarn axis. As a result, yarn strength 9 is improved while twist factor can be lowered . The ~Velopments in Friction Spinning speed of the paradisc can be varied from 1500 to 3500 Dref-2 is one of the earliest friction spinning rpm. The power requirements of the machine are 1.2 4 6 machines introduced in the market - somewhere kW per hour per spinning positionlO, the major around 1977 primarily for long staple fibres. The fraction of power is for creating the vacuum in the machine consists essentially of a drafting unit which spinning drums. Dref-2 is suitable for spinning I s-6s drafts a number of slivers and feeds the drafted strand Ne at around 150 m/min delivery rate. to a sawtooth wire covered opening roller. The Dref-3 is a development over Dref-2 for improving delivered strand from the opening roller is the quality of yarn, productivity and count range. transported by an air stream into the nip between two Unlike Dref-2. Dref-3 is not an open-end spinning perforated drums (Fig. 3). During passage the machine but is a core type friction spinning impurities in the material, because of their weight, arrangement. Here, an attempt is made to improve take a difrerent flight path and are removed. The the quality of yarn by laying part of the fibres in an suction inside the drums provides the necessary aligned fashion a long the direction of yarn axis in 248 INDiAN J. FmRE TEXT. RES., DECEMBER 1992

core. The remaining fibres are wrapped round the Wrapper core fibre. The sheath fibres are attached to the core Sliver fibres by the false twist generated by the rotating action of the drums. Two drafting units are, therefore, used in the system, one for the core fibres and other for the sheath material. After drafting in the first unit, the core fibres are laid in the nip between the spinning drurr.s in a direction parallel to the axis of the drums. The sheath fibres after passage through the second drafting unit and a sawtooth wire covered roller are deposited over the core fibres by an air stream and wrapped over the core by the rotating ~-8-8-~&1~Core ,,~! action of the drums (Fig. 4). The yarn delivery rate Sliver Perforated Drums ranges from 150 to 200 m/min and the count spun ranges from 4s to 18s Ne. While Dref-2 is meant for long staple material, Dref-3 can handle shorter Fig. 4-Outline of Dref-3 ll fibres . The sheath fibres being fed nearly in a vertical direction over the core fibres get buckled. If an oblique fibre feed could be employed 12, core/sheath yarns can be made in Dref-3 using only a single sliver instead of a number of slivers for sheath. But the conventional vertical feed is found to give a higher yarn strength than oblique feed. A good amount of fibre breakage occurs in the opening roller in the Dref machine which shortens the long fibres; very short ,.--... fi bres are also removed as waste 13. Staple length is P~rforat~d Orum reduced by 20-30% as a result of breakages. ~ F~~ing Unit ' Master Spinner' by Hollingsworth is on the other Friction !)rum t -- Sliv~r {3 (Without P~r'oralions) hand a true open-end friction spinning machine. A ~ single sliver is fed to the machine as in the case of rotor spinning. After being opened and individualized, the Fig. 5-- 0utline of OE friction spinning (Master Spinner) fibres are fed in an oblique direction to the axis of the drums2 as against vertical feed in Drefspinning (Fig. 5). The angle of feed is between 10° and 45°. The 4 Yarn Formation and Structure oblique feed helps to reduce buckling of fibres and The main drawback of the friction spinning is the enables finer counts to be spun. Further doubling of extremely poor fibre orientation and consequently fibres in the different sub-slivers takes place during the low utilization of fibre length in developing yarn formation leading to better yarn uniformity. A strength for the yarn. As the fibres transported by an suction current is superimposed on the fibre stream to air current at high speed from the opening roller have improve orientation of fibres in the collection zone. to land on relatively slow moving drums, the fibres get Though the twist is imparted by two rotating drums, buckled and form loops before they are incorporated only one of them is perforated and has a suction into the yarn 1.15. The mode of landing does not arrangement inside. The other friction drum has a provide much scope for improving fibre orientation. special surface to provide effective frictional grip. The extent of buckling and disorientation is more Yarn counts in the range of IOs-24s Ne can be spun with longer and finer fibres. The unfavourable with delivery rates between ISO and 300 m/min, attachment conditions of the fibres to the yarn result depending upon the raw material. The machine is in lower strength than that found even in rotor further equipped with an automatic piecing carriage spinning. The drop in strength with increase in gauge and cleaning system 14. The second carriage doffs the length is more marked in friction-spun yarns than in full package and puts in its place an empty tube with ring-spun yarns because oflow fibre orientation and starter material. The starter material is also prepared presence of fibre loops. and kept ready on the doffing carriage. A 10-spindle The torque required to form the yarn in friction laboratory version of friction spinning machine is spinning is provided by the friction drums that rotate also offered by Hollingsworth. in opposite directions in the vicinity of the yarn and BALASUBRAMANIAN : FRICTION SPINNING 249

the frictional drag on the ya rn by the drums. The ya rn Feild Duct is held in contact with the drums with a fo rce - dependent upon the air sucti on created inside one or both drums. The applied fo rce va ri es alo ng the yarn forma tion zone because of the coni cal shape o f the yarn tail. Lord el al. 16 showed that the incoming fibres a re subjectcd to shear fi elds set up between the ya rn and torque generating surface and sna rl s and buckles while being entra pped into the yarn. Varying amounts of air turbulence in the system also ca use disorientation o ffibres. Johnson a nd Lo rd 17.tri ed to simulate fri cti on spinning by using a la rge-scale a nalogue of the same tha t operated with wa ter as fluid. They showed that leakage fl ows in the contact point between the rota ting fri cti on drums a nd the stationary inner suction cylinder has considera ble influence on the mode of ya rn forma ti on. C ross fl ows ca rry the fibres from ingoing to outgoin g roller a nd contribute to wra pping o f fibre on the tail. There a re basicall y two types of fi bres in the Fi&. 6-M ode of ya rn format ion fri ction-spun yarns 18. One is. extended in the axial direction of yarn with or without hooks a nd the other As the yarn count becomes fin er, the number of is repeatedly folded back over itself. Such fibres have a fibres in the sleeve reduces a nd the incidence o f holes very low fibre length utilizati on and do not contribute in the sleeve increases23 . The cha nces o f yarn ta il much to the strength o f the yarn a nd it is, therefo re, losing contact. with sleeve therefore increase, important to reduce the proporti on o f such fibres. leading to end breaks. Thus, end breakage rate There is also a third type offibre sometimes fo und. It increases steeply when the number o f fibres in the belongs to fibres esca ping the yarn tail aft er initial cross-section drops below a certain level. The contact with it. Such fibres rota te in the nip of the instability in yarn forma ti on as the number offibres in fricti on drums fo r sometime and afterwards get the cross-secti on reduce is the main reason why incorporated into the yarn. friction spinning is restricted to coarse counts. The Stalder and Solima n 19 - 21 concluded, on the basis minimum number o f fibres required in ya rn of ob serva ti ons with hi gh-speed cinema togra ph, cross-section to form a yarn is of a hi gher o rder in that the yarn does not emerge in coni cal form as is friction spinning tha n even in ro to r spinning. normall y visua li zed but is sun ounded by a rotating The examina ti on o f the ya rn at the formation zone sleeve of fibres of a pproxima tely cylindrical fo rm. with the help of proto graphs with short duration fl ash The rotating sleeve is fo rmed by the fibres a rriving techniques showed tha t ya rn forma ti o n in fri cti on 24 25 from feeding unit. Subsequently, the fibres a re spinning is much more complex . . While the fibres tra nsferred from the rota ting sleeve o nto the near the tip are loosely wrapped around the yarn tail , non-rotating yarn core which is axiall y withdrawn. those away from the tip are progressively more tightly 24 Twist is impa rted to the yarn by the rota ti on o ffibre wrapped . Ya rn tail is tapered with a highly unstable sleeve while fibres a re being peeled from it. The fi bre tip. The tail also has an appendage consisting of a soft sleeve a nd the mode o f ya rn fo rmati on a re illustrated infla ted mass which rota tes a ro und the a xi s. The core in Fig. 6. Because of the varying ya rn diameter, twist is a ppea rs to be projecting into the mass. Twist greater in the core than in the surface of the yarn. Lord distribution in the ta il is hi ghl y vari a ble with criss el al. 16 found that the helix angle increases from outer cross fibres having varying helix angle. There is a n to inner layers in core fricti on yarns (like Dref-3). But intermittent slippage of twist from the tail which adds on open-end fri cti on-spun yarns, helix angle to instability26. decreases from o uter to inner layers. The twi st Another drawback in friction spinning is the va ri ation across the cross-secti on of the ya rn is a bsence o f ' back do ublings' fo und in rotor spinning 2 another reason for the lower strength of which even o ut vari a ti ons in the input material • fricti on-spun yarn as all the fibres do no t sha re the Periodic air stream variations tha t a re introduced by load equa ll y. Another problem is the vari a bility in virtue o f the fact tha t the opening roller is spirally twist from one spinning position to a nother22. clothed with wire introduce mass vari ations which do 250 INDIAN J. FIBRE TEXT. RES., DECEMBE R 19'12

not get evened out because of the absence of back Padmanabha n and Rama krishnan 2 9 found that doublings. Periodic strength variations are, the filament core Dref-3 spun yarn is stronger than therefore, found in the yarn. 100% cotton yarn and cotton core yarn by about 13 % Unlike in ring-spun yarns, fibres in friction-spun and 20% respectively. The hi gher hairiness in Dref-3 yarns exhibit migration from outside to inside of the yarns was confirmed by these a uthors. 100% cotton yarn with very little reversal in the direction of yarns could not be spun to 18s Ne from 134 and H4 I R 27 migration • • But the migra tion is stronger in cottons on Dref-3 . friction-spun yarns than in ring-spun ya rns. The Padmanabhan30 compared the properties of 100% difference in migrational behaviour may also be viscose and 100% polyester yarns made on Dref-3 partly responsible fo r the lower strength of with ring-spun a nd rotor-spun yarns made from the friction-spun yarns. same raw materi a l. Maximum yarn strength was found in ring spinning followed by Dref-3 and then 5 Yam Properties rotor spinning. Lower yarn strength found in rotor The properties of fri ction-spun yarns, ring-spun spinning compared to fricti on spinning is at variance yarns and other yarns spun on modern spinning with the results of other workers and thi s may be systems have been compared by several authors and partly because low drafts were used in rotor spinning. the findings have been at times di vergent because of The U % and imperfections were lower in ring-spun the differences in raw materia l and processing yams than in Dref and rotor spinning which is also at conditions. For 20s Ne yarn made from 65/35 variance with the results of other workers. polyester-cotton blend. Brockmann3 found Polyester/cotton blend yarns made on Dref-3 are maximum strength in wrap spinning followed by superior to ring-spun yarns in strength by 25% but ring, air-jet, rotor and friction spinning in that inferior in U%, imperfections, strength uniformity order. Thus, the lowest yarn strength is found in a nd hairiness. Dref-3 ya rns made out of friction spinning. Mass regularity is comparable in polyester/cotton blends give a lower resistance to air-jet, ring- and wra p-spun yarns but friction-spun abrasion and repeated extensions compared to ring 31 yarn has a higher irregularity while rotor-spun yarn and rotor yarns . Wi th decrease in polyester has a still higher irregularity. The imperfections in component, the abrasion resistance increases while friction-spun yarn are lower tha n in rotor but higher the resistance to repeated extension decreases. In than in ring and air-jet yarns. Further, the another study on 40 and 60 tex polyester/cotton 32 friction-spun yarns are more hairy than a ll other blends , friction-spun yarns are found to be more yarns. The yarn is also susceptible to strip back and irregular than rotor- and ring-spun yarns in terms of di sintegra tion upon abrasion. Friction-spun yarns twist a nd linear density variability. Coarser counts have a low hot air shrinkage a nd comparable are more regular in terms of mass irregulari ty but have shrinkage in boiling water to ring- a nd wrap-spun a higher twist variability. yarns. 2 8 6 End Use Louis el al. . compared the strength of 74,45 and 33 tex cotton yarns produced on ring, BD-200 rotor and The soft handle of the yarn a nd the absence of Dref-3 systems from cottons varying in one case in wrapper fibres give friction-spun yarns an staple length and bundle strength and in another case advantage in weft and pile yarns, velvets, blankets, in micro naire a nd found that the strongest yarns a re terry towels and knit-goods. Other application areas produced by ring spinning followed by rotor spinning are cleaning clothes and mops, furnishings, filters and a nd then Dref-3. Rotor spinhing results in the most technical fabrics, and secondary carpet backings regular yarn followed by Dref-3 a nd then ring made of polypropylene. Dref-spun yarns have better spinning. Further, the best yarn appearance grade is dimensional stability and bonding strength with 7 obtained in Dref-3 followed by ring spinning and adhesive • Recycled textile wastes and trimmed then rotor spinning. But Dref-3 ya rns are more hairy. selvedges from shuttleless weaving can be directly Cotton ya rns fin er than 54 tex could no t be spun on processed into yarn 7 , thus reducing the raw material Dref-3 at 200m/ min. Spinning performance is better cost. Interlinings can be made at lower cost if yarns 33 with 70% core and 30%) wrap than 50% core and 50(10 made in Dref-3 are used . The advantages are in wrap in Dref-3. But y ... m strengt h is better with the terms oflower labour costs, reduced waste , lower raw latter. The ai r suction pressure has considerable material cost a nd improved loom shed eflkiency. influence on strength or yarns in Dref-3 with yarn Being ideally suited for preparing core sp un ya rns, strength showing ma rked deterioration when suction friction spinning can be employed for manufacture of pressure drops below 70 cm of water. industrial textil es like conveyor beltings, tarpaulins, BALASUBRAMANIAN: FRICTION SPINNING 251 awnings, roof coverings34 , etc. where the core 13 Gruoner S, The dref spinning system, Tex t Asia. 8 (3) (1977) filament will give the strength while the staple fibre 44. covering will provide the adhesion required for the 14 TetzloffG. Unconventional spinning methods, Int Text Bull. Yarn Forming . (4) (1987) 73 . coating. Some attachments are also available for 15 Lunenschloss J & Brockmanns K J, Theoretical and practical fitting on friction spinning machine to produce slub description of fibre moving and twist insertion during OE or fancy yarns14. friction spinning. Int Text BIIII. Yarn Forming. (I) (1987) 55. 16 Lord P R, Joo C W & Ashizaki T, The mechanics of friction 7 Future Outlook spinning. J Text Inst . 78 (4) (1987) 234. 17 Johnson NAG & Lord P R, Fluid-flow phenomena in friction Unlike rotor spinning, friction spinning has still not spinning, J Text Illst. 79 (1988) 526. established itself as a viable method of yarn 18 Rust J P & Lord P R. Variations in yam properties caused by a manufacture. The main drawbacks are the lower yarn series of design changes in friction spinning machine. Text Res strength and the inability to spin medium and fine J . 61 (1991) 645. 19 Stalder H & Soliman H A. Nell' model for yarn formation in counts. These arise to a large extent from the way the friction spinning. paper presented at the 7th Colloquium of fibres get incorporateq into the yarns. Considerable Institute of Textile and Process Technology. Denkendorf. research and development work is needed in this area 1988. before this system becomes commercially viable. 20 Stalder H & Soliman H A. A study of yarn formation process There are, however, certain distinct advantages in during spinning. Melliand Textilber In! (Eng Ed). 70 (2) (1989) E 44. friction spinning which justify further developmental 21 Krause H W. Soliman H A & Stalder H. The yam formation in efforts. The spinning tension is very low and very high friction spinning, Int Text Bull. Yarn Forming. (4) (1989) 31. twisting rates are possible without the need to rotate 22 Neuhaus L. The present situation in various spinning the drum at higher speeds. The yarn is devoid of techniques and tendencies in their development. Melliand wrapper fibres and has a softer handle. The system is Textilber lilt (Eng Ed) . 67 (1986) E 309. 23 Stalder H. Spinning in the nineties. in Textilefashioning the also more versatile in handling all types of natural and future (The Textile Institute. Manchester), 1989. 151. synthetic fibres. 24 Lord P R & Rust J p, The surface of the tail in open-end friction spinning, J Textlnst. 81 (1990) 100. 25 Lord P R & Rust J P, Fibre assembly in friction spinning. J References Text Inst . 82 (1991) 465. I Stalder H. New spinning methods. their application and 26 Lord P R & Rust J P. Twist distribution in open-end friction possibilities fordevelopment.lnt Text Bull. Yarn Forming . (I) spun yarn. J Textlnst. 81 (1990) 211. (1988) 27. 27 Lunenschloss J & Brockmanns K J. Cotton processing by new 2 LunenschlossJ, Mechanism ofOE friction spinning, Int Text spinning technologies- possibilities and limits, Int Text BIIII. Bull. Yarn Forming. (3) (1985) 29. Yarn Forming. (2) (1986) 7. 3 Brockmanns l( J, Friction spinning analysed. Int Text Bull. 28 Louis G L. Salaun H L &- Kimmel L B. Comparison of Yarn Forming. (2) (1984) 5. properties of cotton yarns produced by dref3. ring and open­ 4 Dref friction spinning for coarse and medium count yarns. end spinning methods. Text Res J. 55 (1985) 344. African Text . August/September (1985) 33. 29 Padmanabhan A R & Ramakrishnan N, An assessment oOhe 5 Gruoner S. First experience with dref spinning system. dref 3 spinning system for pracessing Indian COl/ons . paper Melliand Textilber Int (Eng Ed). 57 (5) (1976) 776. presented at the 29th Joint Technological Conference of 6 Lennox-Kerr P, OE spinning without a rotor, Text-Ind. 140 . A TI RA. BTRA. SITRA & NITRA (BTRA, Bombay). 1988. (2) (1976) 55 . I. 7 Gsteu M G. A spinning process makes the grade. Int Text Bull. 30 Padmanabhan A R. Properties of man-made fibre yarns spun Spinning. (I) (1982) 65. on dref 3 spinning sys,lem, Indian J Fihre Text Res. 16 (1991) 8 Gruoner S, Drefspinning system, Text Asia. 8 (3) (1977) 44. 241. 9 LennoxoKerr P, Look for major open-end developments 31 Barella A & Manich A M. Friction spun yams vs ring and rotor from Europe, Tex t World. 127 (8) 1977) 26. spun yarns: Resistance to abrasion and repeated extensions. 10 Gruoner S, Advanced development in dref spinning, Text Res J. 59 (1989) 767. Text-Prax Int . 32 (8) (1977) 36. 32 Manich A M & De castellar M D. Twist and linear density II Lennox-Kerr P, Fehrer develops another concept in coefficient of variance-length curves of polyester/cotton spinning- and it is not open-end, Text World, 128 (8) (1978) yarns spun by different processes, Text Res J . 62 (1992) 115. 29. 33 Gsteu M, Interlining fabric from dref-friction yarns.lnt Text 12 Brockmanns K J &Johnson N, The influenceoffibre feeding Bull. Yarn Forming. (4) (1986) 65 . arrangements on the properties of friction spun yams, Int T~xt 34 Gsteu M, High tech yarns with friction spinning technology. Bull. Yarn Forming. (3) (1986) 27. Int Text Bull. Yarn Forming. (I) (1989) 36.