The application of air-jet nozzle in ring spinning system has been turned up in the last decade, and the greatest advantage reported is the reducing of hairiness. In this paper, an attempt has been made to optimize the utility of a single air-jet nozzle in ring spinning system. Some parameters, such as air pressure, the distance between front roller nip line and air-jet nozzle inlet, and the number of orifices were adjusted to get a better quality yarn. In order to confirm the role of these parameters, the properties of ring and jet-ring spun yarns were compared. All the samples were characterized in terms of count, twist, irregularity, hairiness and strength. The results showed that the air pressure and the distance have a significant influence on irregularity; all the experimental parameters have a significant influence on hairiness. By multi-objective programming method, a set of optimal experimental parameters was found, and the properties of jet-ring spun yam were improved significantly

Ibrahim, Sayed M.

Křemenáková, Dana

Zhu, Guocheng

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TextiIné materiá|y Textile MaterialsTHE OPTIMIZATION OF EXPERIMENTAL PARAMETERS FORJET.RING SPINNINGGuocheng Zhu, Sayed lbrahim and Dana KremenakovaDepartment of Textile Technologies, Faculty of Textite Engineering, Technical lJniversity ofLiberec, Liberec, Czech Republic, 46117Abstract: The application of air-jet nozzle in ring spinning system has been turned up in the lastdecade, and the greatest advantage reported is the reducing of hairiness. /n this paper, an attempthas been made to optimize the utility of a single air-jet nozzle in ing spinning sysÍem' Someparameters, such as air pressure, the distance between front roller nip line and air-jet nozzle inlet,and the number of orifices were adjusted to get a better qualiý yarn, ln order to confirm the role ofthese parameters, the properties of ring and jet-ring spun yarns were compared. All the sampteswere characterized in terms of count, twist, irregularity, hairiness and strength. The results showedthat the air pressure and the distance have a significant influence -on irregularity; ail theexperimental parameters have a significant influence on hairiness. By mutti-objectiie programmingmethod, a set of optimal experimental parameters was found, and the propěrties oi iet-ring spu-nyarn were improved significanily.Key words: Ring spinning;Air-jet nozzle; lnegularity; Hairiness; optimization1 INTRODUCTIONRing spinning has been a widely usedmethod of yarn production, but isdisadvantaged due to several limitations, oneof which is the poor integration of manyfibers that protrude from the yarn surfacecausing yarn hairiness [1-2]. Yarn hairinesshas been shown to negatively affect theproperties of the resultant fabric, particularlyin terms of pilling propensity t3-51. Generally,the hairiness of yarn can be reduced eitherby sizing or singeing in the short staple fieldand by Solo-spun or two-folding in the longstaple field [6], but either higher costs or timeconsumption. Another method for reducingyarn hairiness is jet-ring spinning system thatapplied air-jet nozzle into ring spinningsystem, which was proved to be an effectivemethod 17-111.Jet-ring spinning was first reported by Wanget al [7]. ln their work, an upward swirlingflow of air against the yarn movement wasintroduced, and the result showed that theyarn haíriness Was significant|y reduced [7]'Subsequently, Cheng et al [B] studied theeffect of some experimental parameters onyarn hairiness, and stated the relationshipsbetween yarn hairiness and twist level,V|ákna a texti| (1) 2012spindle speed and air pressure. But theirwork showed that the evenness andimperfection of jet-ring spun yarns are worsethan ring spun yarn, and they thought thedistance between front roller nip line and air-jet nozzle inlet hardly affects the yarnhairiness t8l. Ramachandralu et al [g-11]presented that the air vortex in the directionsame as the yarn twist gives better hairinessreduction. And he introduced twin air-jetnozzle into ring spinning system. The resultsdemonstrated that the qualities of yarns wereimproved in 0.25 bar air pressure of first 'S'nozzle and 0.5 bar air pressure of second 'Z'nozzle. Zeng et al [10] presented their reportabout the properties of jet-ring spun yarns byadjusting air pressure and orifice angle of theair-jet nozzle, the results showed thathairiness will be reduced in a higher airpressure and a smaller orifice angle, butunfortunately, the evenness of yarndeteriorated.In this work, our objectives are:1. to assess the effect of some experimentalparameters, which are air pressure, thedistance between front roller nip line andair-jet nozzle inlet, and the number oforifices, on the jet-ring spun yarnproperties,60TTextilné materiály2. to find the optimal experimentalconditions by mulii_objectiveprogramming method.We use Box-Behnken experimental design toexamine the effects of different spiňningparameters on yarn properties. |n order tóevaluate the performance of Jet_ring spinning,we tested both conventional ring aňd;et-rini,spun yarns and compared with them iňevenness, imperfection, hairiness, andtensile properties.2 MATERIALS AND METHODSA cotton roving was provided by VelvetaCompany. The yarns were produced in aspinning system which combined rinjspinning with a single air-jet nozz|e. |n ordeřto determine the role of air pressure, thedistance between the front roller nip line andnozzle inlet, and the number of orifices inobtaining optimum yarn characteristics, threelevels. of air pressure, 0.25, O.S, 0.75 bar,three kinds of distance, 1,2,3 cm, and alsothree different orífice's num.ber, 2, 3 and 4were selected. The nozzle schematicdiagram was showed as Figure 1, thedirection of nozz|e inlet face toňrd the frontroller..And the parameters of jet nozzlewere:chamber diameter is 3.5 mm, orifice diameteris 0.7 mm, orifices angle is 4S0.After prepared the lamples, we put thesamples into the conditions of 65% humidity:l.d ?5'C temperature for 24 hours for theTorowtng testing. These samples were testedIn terms of count, twist, evenness, hairiness(Zweig|e G567), imperfection rÚ.te' tester 4)"nq tensile property (tňstron 4411,,pretension was 0.125 N, gauge was 50 cm,tensile speed was 100 mm7miň)'Figure I The schematic of air_jet nozzle. (A) theinlet of compressed,air; (Bi) th-e orifices; (bj tnenozzle inlet of air; (D) the nozzle ouflet of air 'Box-Behnken designA three-level three factorial Box_Behnkenexperimental design (constructed usingMinitab 16) was used to evaluate the effectšof the selected independent variables on theresponse. The number of experimentsrequired to investigate the previously notedthree factors at three |eve|s woutd be,27 (3á).However, this was reduced to 15 using áBox-Behnken experimentaI design. Ťneresults from this limited number ofexperiments provided a statistical model,which. can help us find the optimumexperimental conditions and the relationshipsbetween experimental results andparameters. The significant variables like airpressure, the distance between front rollernip line and air-jet nozzle inlet, and thenumber of orifices were chosen as the criticalvariables and designated as X1, X2 and X3,respectively. The low, middle and high levelsof each variable were designated as _1, 0?nd +1, respectively, and given in Table .1.And the actual design of tňis experiment isgiven in Table 2.Textile MaterialsTab|e í Factors and factor |evels investigated in Box-Behnken experimenta| designš?:rneoX3: The numbGiď ormces (nV|ákna a texti| (1) 2012 61TextiIné materiályTable 2 The design of this experimentfn a system involving three significantindependent variables X1, X2 and X3 themathematical relationship of the response onthese variables can be approximated by thequadratic polynomial equation:Y=ao+ atXt + azXz+ dsXs! a12X1X2+ atsXtXs + azsXzXs * a11X1'* azzXz2 + afiXs2 (1)where Y is estimate response, cr6 is constant,o"1, Cx2 oř.|d crg are linear coefficientS, Ct.12, Ct13and ozg are interaction coefficients betweenthe three factors, &11, o.22 and cr33 arequadratic coefficients.Textile MaterialsIn this model given in equation (1),interactions higher than second-order havebeen neglected. A multiple regressionanalysis is done to obtain the coefficientsand the equation can be used to predict theresponse.3 RESULT AND DISCUSSIONThe yarn counts and twists were close toeach other, the ring yarns count and twistswere 23t0.33 tex and 730x26 tpmrespectively. And the value was 23+0.39 texand 716115.89 respectively when the nozzledirection was down. The properties of ringspun yarn were showed in Table 3.Table 3 Properties of ring spun yarn*CV represents the mass unevenness of yarns; H represents the total length of fibers protruding the yarn bodyper centimeter yarn |ength; 51+2 repÍeS€nts the tota| number of fibers within one mi||imeter and two mi||imetersprotruding from yarn body; Sa represents the total number of fibers which equals and more than threemillimeters; -50% TP, +50% TP and +140o/o TP represent -50% thin places, +50% and +140% thick placesrespectively; Te represents the tenacity of yarns; El represents the elongation of the yarns."at the 0.05 level, each group data was significantly drawn from a normally distributed population.TrialNo. Air pressureíbar)The distanceícm)orifices number(n)1 +1 +l 02 +1 -1 03 -1 +1 04 -1 -1 05 0 +1 +16 0 +1 -17 0 -1 +18 0 -1 -19 +1 0 +110 -1 0 +111 +1 0 -112 -1 0 -113 0 0 014 0 0 015 0 0 0CV(o/o\-50%TP(/km)+50o/oTP(/km)+140%TPí/km) Sr.z (/m) 53 (/m)Te(cN/tex)EI(oÁ\20.3510.19 397x86.2 1 08711 30 337x41.6 '160.09t6.270 '16.05011 .560 17.98r1.63 5.15r0.49V|ákna a texti| (1) 2012 62Textilné materiá|yř*5s^->;s(!1g.st*,tormeo nrsnn*sr3'í Effect of experimenta| parameters onGV of jet-ring spun yarnJh" analysis of data according to Box-Behnken method demonstrated that the airpressure and the distance between frontroller nip line and air-jet nozzle inlet have aninfluence on the yarn's CV. A mathematicalmodel was built to express the relationshipbetween them. And in order to clearlydescribe this mathematical model a 3Dsurface plots was presented (Figure 2). Theminimum value of CV is 19.32i2% Whenxr=-0.5203 ánd x.=1 by optimization method.Textile Materialsthat in some conditions the evenness of jet-ring spun yarns were worse than ring spunyarn, but after optimization, we can find areasonable experimental condition toimprove the CV.3.2 Effect of experimentat parameters onimperfection of jet-ring spun yarnThe air pressure and orifice number have anobvious influence on impeďection, themathematical models and images are shownin Figure 3. And the minimum value of -50%TP is 295/km when X3=1, of +SgoToyt ,.813/km when Xl=-1 áfld 4=] , of +140oÁTP is198/km When Xt=-1 ánd x3=1.Compared ring system with jet-ring system,the difference is the air flow. Therefore, thedifference of thin places and thick placesbetween ring and jet-ring spun yarn are thelosing of fibers and the warping fibers causedby the air flow. We can find an interestingtrend among these properties from themathematical models, the higher the airpressure, the worse the imperfection, themore orifices, the better the imperfection.Suitable and uniform air flow field isbeneficial to produce uniform yarn, othenruise,the losing of fibers make the thin places, anddisorderly warping fibers make the thickplaces. And the more orifices, the better theuniform of air flow field.3.3 Effect of experimenta! parameters onhairiness of jet-ring spun yarnThe hairiness of yarn is influenced by airpressure, distance and orifice number baseon our work. Figure 4 shows themathematical model and slice image ofhairiness with the length less than 3 mm, andequation (2) expressed the relationship ofhairiness with the length more than 3 mmcorresponding to the experimentalparameters. By the optimum method, we gotthe minimum value of St*z and Sg áre112.47331m and 2.4941lm respectively whenXt=-1 , X2=-1, X3=1.'l 'l AjÍPÍ€ssuÍg{btr]A řg * Žs'33ř! **.i ss'!4 -9'3ř}sš} +$'3*:t*f * *'*r**x;é$'x*s,* $$ř; p"r!&}*i}Figure 2 The mathematical model and image ofcV corresponding to the experiménta|parametersAlthough the influence of the air pressureand the distance between front roller nip lineand air-jet nozzle inlet on CV is notconspicuous from the mathematical model,there are some interesting phenomena. Thelower air pressure gives the lower CV value,and the CV value decrease as the increaseof orifice number. The lower air pressuremeans that less energy and cost was needed,and the more orifice number means thatuniform f|ow was needed. Ear|íer researchersreported that there was a slight deteriorationin CV with jet-ring spinning, and theyattributed this phenomenon to theconcentration of mass in very short lengthsbecause the surface fibers wrap around theyarn body. In our work, the results showeddV|ákna a texti| (1) 2012 63TextiIné materiá|y*js**řč * }*€*;í4 * **"6x5 : tss'*{s,Í**'$*35 ; s4'&s43}Textile MaterialsIiiIIijB.*.fi €.& 4E4 *3 s *ž *4 &.* *8sťspqa{'Íťs$*$**ďř* {?*;}**}* ?3.33$*g*t$?'*$*?x f&:=0.?c8é;p={.ffiffi}Cr E*S&**w@ěffiBáé€ffi&* ?G**t&1n *l4€4'é*P*358.*&? *8ésŤ5ď: *Ť4.:Ťš4ĚgsTÍřtá;p'*,{s#*}Figure 3 The mathematical models and images of yarn properties corresponding to the experimentalparameters, (B) -50%TP corresponding to orifice number; (C) *SO"U"TP corresponding to air pressureand orifice number; (D) +140oÁTP corresponding to air pressure and orifice numberffiř*&ffi&&&!s!{$tl$$x *11*,t$+lj'*&É\ *$3.él44x,.43s$?$4 **5"5ffi?{{R*4.fl62:p*.$tr$}and image of yarn hairiness correspondingEFigure 4 The mathematicalparameters64č&Bs&h{$*Ís*úecÚ6Ír${*V|ákna a texti| (1) 2012model to the experimentalTexti|né materiá|yS s : 2| .4948 + 5.1096 x, _ 7 .592x, _ t .7 893 x,x, _ I.57 65 x,x. _ 3 .9967 i, _ 2.089 5 ú(R2=0.9918; p=O.O0OO)The yarns hairiness are significantly reducedwhen air-jet nozzle was applied, and lowerair pressure, less distance and more orificenumber are beneficial to reduce yarnhairiness. As to the cause of yarn hairiness,which has been attributed to the escape offibers form the twisting action from within thespinning triangle 11, 121. And Pillay's studydemonstrated that the yarn hairiness issignificantly correlated with fiber length,fineness and torsional and flexural rigiditiesof fibers [13]. With respect to the efíect of airpressure on yarn hairiness, someresearchers stated that may be moreprotruding fibers were wrapped into the yarnbody causing by swirling air flow [7, 8]. As airpressure increases, the tangential velocity,which is responsible for wrapping theprotruding surÍace hairs around the yarnbody, increases. This leads to morewrapping fiber ends and so less hairiness.However, with increasing nozle pressure,the recirculation zone that occurs betweenthe inlet and the jet orifices increases. Thisincrease is a potential source for fibercurving, so it impedes the wrapping of theprotruding fiber ends [í0].The distance between front roller nip line andair-jet nozzle inlet also played a significantrole in yarn hairiness, the results showed thatthe yarn hairiness decreases as the distancedecreases. This phenomenon could beexplained from several aspects, (1) theformation of yarn and hairiness wereoccurred in triangle zone, therefore, the yarnproperties and hairiness were easy to beinfluenced by outer conditions; (2) the closerto the triangle zone, the more fibers warpedinto the yarn body; (3) some floating fiberscould be blowing away.The more orifice number, the more uniformof the air flow [14], therefore, it is important toprovide the uniform air flow for improving theyarn hairiness.Textile Materials3.4 Effect of experimental parameters onYarn tensile propertiesDuring this work, the strength and elongationproperties were slightly influenced, and didnot discussed because they did not to benegative effects on yarns' usage.3.5 The optimal experimental conditionsfor jet-ring spun yarnf n order to get a set of reasonableexperimental parameters for all of theproperties of jet-ring spun yarn, we took all ofthe equations into account by multi-objectiveprogramming method. The best values are19.3212, 112.4729, 2.4941, 295,812.9 and197.6367 corresponding to CV, S1*2, 53, -50%TP, +50%TP and +140oÁTP respective|y.And the optimal experimental parametersfrom Matlab arext = -1, xz = -I, xs =Iln our previous work, we applied the nozzlewhich produced the upward air flow into ringspinning system and built somemathematical models [15], but we did notgive a set of reasonable experimentalparameters for producing yarns. Therefore,in this work, we replenish this part by multi-objective programming. The minimum valuesfrom each mathematical model are 19.1, i15,6.09, 186.5, 118.3 and 197.3 correspondingto CV, 51*2, Ss, -50%TP, +50%TP and+140%TP respectively. But for holisticoptimization, the optimal values are 19.2399,134_4354, 6.17, 196.562, 126.944 and200.0375 in turn. The optimal experimentalparameters from Matlab arexr =I, xz = -I, xz = -0,1693.6 Gomparison of properties of ring andjet-ring spun yarnsThe optimum experimental conditions for jet-ring spun yarn are 0.25 bar air pressure, 1cm distance and 4 orifices when the nozzleproduce the downward air flow, 0.75 bar airpressure, 1 cm distance and 3 orifices when(2)V|ákna a texti| (1) 2012 65TextiIné materiá|ythe nozzle produce the upward air flow. InTable 4, we give the optimum values of jet_ring spun yarn. ln Figure 5, we comparedthese three kinds of yarns.Textile MaterialsTable 4 Properties of jet-ring spun yarn in optimum experimental conditionsUV(%l-sOVoTP(/km)+50o/oTP(/km)+140%TPí/km) Sr*z (/m) 53 (/m)Te(cN/tex)EI(%l19.3219.24295 813 198 112.47 2.49 18.5 5.82186 127 200 134.43 6.17 17.75 5.55Figure 5 Comparison of ring and jet-ring spun yarns4 CONCLUSIONS 5A .single air-jet nozzle is applied into ring 1.spinning system, and a king of jet-ring spuňyarn with improved quality is obtained bV .adjusting the air pressure, the distancó z.between front roller and the nozzle inlet, andthe orifice number of nozzle. The air 3.pressure and the orifice number have a slighteffect on yarn CV, but have a sionificánteffect on yarn imperfection. All of the 4'experimental parameters played important 5.roles in yarn hairiness. And the optimalexperimental conditions should be adiustedwhen the direction of nozz|e was chánged. 6.The optimal experimental parameters are0.25 bar air pressure, 1 cm distance and 4 T.orifices when the nozzle produce thedownward air flow, O.TS bar air pressure, 1cm distance and 3 orifices when the nozzle B.produce the upward air flow.REFERENCESlvang X, Huang W., Huang X.B.: A Study on theFormation of Yarn Hairiness, J. Textile lnst. 90Part 1, No 4, 1999, 555-569Za .K.: Investigation of post-spinning yarnEngineering, PhD Thesis, Deakin UŇersity,Australia.2003Baird M.E., Hatfield p., Morris G.J.: pilling ofFabrics a Study of Nylon and Nylon BlendedFabrics. J. Textile Inst.47(4), 1956, 181_201Timmis J.B.: How to Live with pilling, Knittiing Int.83(e), 1976, 82-S6Barella A., Bardi X., Castro L.: HairinessModification by yarnA/arn and yarn/MetalFriction, Melliand Textilber. T2(1), 1991, 3_4lhang L., Wang X.: Comparing the Hairiness of!:I"^-slyl and Ring Spun, Texlite Res. J. T3(7),2003.640-644Wang X.G., Miao M.H., How y.L.: Studies oflglling spinning - partl: Reducing yarnHairiness with The JetRing, Texti|e RósearchJournal 67 (4), 1997, 253-2SBCheng K.P.S., Li C.H.L.: JetRing Spinning andIts Inf|uence on Yarn Hairiness,1eitite Rés. .t.72,2002, 1079_1087Vlákna a texti| (1) 2012 6613.9.14.TextiIné materiá|yRamachandralu K., Dasaradan B.S.: Designand Fabrication of Air Jet Nozzles for Air VortexRing Spinning System to reduce the Hairinessof Yarn, The Journal of The Institution ofEngineers (lndia) 84, 2003, 6-9Zeng. Y.C., Yu C.W.: Numerical andExperimental Study on Reducing YarnHairiness with the JetRing and JetWind, Text.Res. J. 74(3),2004,1-5Ramachandralu K., Ramesh V.: Design andDevelopment of Twin Air-jet Nozzle System forRing Spinning, The Journal of The Institution ofEngineers (lndia) 86, 2005, 1-5Najar S.S.: An Analysis of Twist Triangle in RingSpinning, PhD Thesis, The University of NewSouth Wales, 1996Textile MaterialsPillay K.P.R.: A Study of the Hairiness of CottonYarns, Part 1: Effect of Fiber and Yarn Factors,Textile Res. J. 34,1964,663-674Wang S., Yu X.: New Textile Yarns, ed. 1,Pub|ishing Company of Donghua Universiý:Shanghai, 2A07, 121Zhu GC, |brahim S.' Křemenaková D.: Theoptimization application of air-jet nozzle in ringspinning system, In 1B'n InternationalConference STRUTEX Structure and StructuralMechanics of Textiles. 7-8th December 2011,Technica| Universiý of Liberec, Liberec, CezchRepublic15.10.'t1.12.i Vlákna a textil (1) 2012;i67

The optimization of experimental parameters for jet-ring spinning

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The optimization of experimental parameters for jet-ring spinning

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