Indian Journal of Fibre & Textile ResearchVol. 23, December \998, pp. 233-241

Low-stress behaviour and sewability of suiting and shirting fabrics

B K Behera & Suraj SharmaDepartment of Textile Technology, Indian Institute of Technology, New Delhi 110 016, India

Received 20 October 1997; accepted 6 January 1998

Low-stress mechanical properties of various suiting and shirting fabrics have been studied onKawabata fabric evaluation system. Sewability of these fabrics has also been studied. The correlationsbetween low-stress mechanical properties and various sewability parameters have been determined fordifferent types of suiting and shirting fabrics. Formability as one of the indicators of fabric making-upprocess is estimated. A high dependence of seam efficiency on fabric weight and thickness has beenobserved whereas these two properties have a high negative correlation with seam pucker. Bending has anegative correlation with both seam efficiency and seam pucker.

Keywords: Formability, Low-stress mechanical properties, Sewability, Shirting fabrics, Suiting fabrics

1 IntroductionThe sewn products industry is one of the most

labour intensive industries to be automated and theextent of automation varies among countries. Whilethere are other methods of shaping fabrics into usableproducts, stitch seaming is by far the most commonmethod used worldover. In this process, the skill andexperience of the operator is still often fundamentalto the quality of the final product, mainly due to thecomplex nature of the manipulations required in theseaming process. The appearance and durability ofthe seams form an important component of thequality of the finished article.

Despite the importance of the seam, from botheconomic and aesthetic points of view, studies onseamed materials are relatively few. Seamed articlesare more complex than fibres and fabrics, and it isapparent that an integrated approach incorporatingcharacteristics of all these material variables isnecessary.

Fundamentally, in garment manufacturing, a two-dimensional structure (fabric) is converted into athree-dimensional structure(garment). During thisprocess, the fabric is subjected to various types ofmechanical stresses. Under close examination, it canbe observed that most of the stresses imposed onfabric during the sewing process are low-stress innature!". Therefore, it is expected that with the helpof low-stress mechanical properties, the sewabilityof the fabric can be assessed and the results can beused to select a particular fabric for the given enduse, depending on its sewing performances. As a

result, research has been directed towards thedevelopment of objective measurement of fabricmechanical and handle properties relevant totailorability. Fabric mechanical properties importantin the determination of stress incurred in the making-up process include load-extension characteristics,buckling, shearing and compression. Other factorsaffecting the appearance of the seamed garmentinclude the effect of garment fit, body movement andgravity", Keeping in view the above objectives, thepresent work aims at determining inter-relationshipbetween low-stress mechanical properties and seamperformance parameters, viz. seam strength, seampucker and seam slippage, of some selected suitingand shirting fabrics.

2 Materials and Methods2.1 Materials2.Ll Fabric Samples

Five suiting fabrics and five shirting fabricscovering a wide range of areal density were chosenfor this work. The details of these fabrics are given inTable 1. .

2.1.2 Sewing ThreadA sewing thread having the following

specifications was used:

Sewing threadTicket no.CSPSingle thread strengthExtension at break

: Spun polyester: 50: 5605: 845g: 17%

234 INDIAN J. FIBRE TEXT. RES., DECEMBER 1998

Weave

Table I-Fabric constructional parameters and dimensional properties

Fabrictype

Code Weightg1m2

Thick-nessmm

Warp Weft Ends Picks Warpcount count lin lin crimp

%

Weftcrimp

%

Relativecover

Suiting fabrics65:35PN .Matty PVI 278 0.95 2115 2115 40 38 \0 7 0.7665:35PN Twill PV2 228 0.79 2140 2140 84 72 6 5 0.8667:33P/C Plain PC3 194 0.89 2130 2130 60 50 II 6 0.7548:52PN Plain PV4 180 0.66 2140 2140 70 62 II 9 0.7848:52PN Plain PV5 145 0.64 2140 2140 56 52 6 5 0.67

Sbirting fabricslOO%L Plain Ll 220 0.76 9 9 49 41 8.6 8.5 0.79100%L Plain L2 185 0.77 14 15 67 49 7.6 4.6 0.8080:20UC Plain LC3 169 0.70 9 9 38 24 4.1 13 0.6155:45UC Plain LC4 144 0.68 16 16 57 45 9 II 0.5962:38UC Plain LC5 128 0.68 25 25 39 40 12.3 3 0.50

P~olyester ; V-Viscose; ~tton: and L-Linen

Diameter at 20gf/cm2: O.IOmm

2.2 Methods2.2.1 Sewing

Sewing was carried out on a Singer (industrial)sewing machine with following conditions:

Machine speed : 3200 stitches/minSeam geometry : plain lock stitch seamStitch length : 2.5 mmLinear stitch density : 8 stitches/inNeedle size : 16Needle thread tension : 60 gBobbin thread tension : 25 gSeam allowance : 1 in

2.3 Evaluation of Fabric Dimensional PropertiesFabric dimensional properties such as areal

density, .fabric set, crimp and cover factor weremeasured using the standard procedures

2.4 Measurement of Fabric Low-Stress MechanicalPropertiesLow-stress mechanical properties including

tensile, shear, bending, compression, roughness andfriction were measured on Kawabata fabricevaluation tester.

2.4.1 Tensile and Shear PropertiesTensile and shear testings were carried out on

KES-FB 1 using the following test parameters:

Sample size : 20 em X 20 emMaximum tensile strain : 100%Maximum shear angle : ±8 deg

: 0.2mm1s(OAO/oIs): 0.00843mm1s(Speed: 1%)

Shear deformation was applied in the widthdirection. The readings were taken in the warp andweft directions for each sample.

Tensile strain rateShear strain rate

2.4.2 Bending PropertiesBending properties were studied on KES-

FB2(pure bending tester) using the following testparameters:

Sample sizeClamp intervalRate of curvatureMax. curvature

: 20cmx 20cm: lcm: O.5/cm.s: ±2.5/cm

2.4.3 Compression PropertiesCompression test was carried out on KES-FB3

using the following test parameters:

Sample sizeArea of plungerRate of compressionMax.compression load

: 20cmx 20cm:2cm2

: 20m1s:50gf/cm2

2.4.4 Surface PropertiesContactor for friction measurement: Ten parallel

steel wires of O.5mm diam. and 5mm lengthsimulating finger-skin geometry (Contact force:50gf).Contactor for geometrical roughness: A steel piano wireofO.5mm diarn. and Smm length placed on fabric surfacewith contact force of 10gf.

BEHERA & SHARMA: LOW-STRESS BEHAVIOUR AND SEW ABILITY OF FABRICS

\

Measured distance : 2cmVelocity : O.1cm/sTension on specimen : 20gf/cm

The signal of wavelength less than lmm wasallowed to pass by a highpass filter of 2nd order.

The low-stress fabric attributes obtained fromabove tests and their notations are given in Table 2.

2.5 EvaluatioD of Sewing Thread Properties2.5.1 Stmlgtb and EIoDgation

Strength and elongation of sewing threads weremeasured as per ASlM-D2256 on an Instron tensiletester.

2.5.2 Loop StreDgthLoop strength was also measured on Instron

tensile tester. In this case, the specimen consists ofthe pieces of yam taken from one package. Both theends of one piece are secured in one clamp of thetesting machine so that the length of the loop is aboutone half of the gauge length.

2.5.3 DiameterDiameter was measured on Prolific thickness

tester(ESSDIEL) at 20gf/cm2 pressure.

Table 2-fabric Mechanical attributes

Test Low-stress property Notation

Extensibility EMLinearity LTTensile energy WTTensile resilience RT

Shear stiffness GHysteresis at 0.50 shear 2HGangleHysteresis at 50 shear 2HG5angle

Bending rigidity BHysteresis of bending 2HBmoment

Linearity of compression LCthickness curve

Compressional energy WCCompressional resilience RC

Coefficient of friction MIU

Mean deviation ofMIU MMDGeometrical roughness SMD

Weight/unit area W

Fabric thickness T

Tensile test

Shear test

Bending test

Compression test

Surfacecharacteristics

Fabric construction

235

2.6 Evaluatioa of SewabiIity2.6.1 Seam Streagth

The test was done as per ASlM-D1683 for failurein sewn seams of woven fabrics on an Instron tensiletester

Load cellCrosshead speedGauge lengthJaw width

: lOOkg: lOOmm/min: 7.5 in: 2 in

The specimens were placed centrally between theclamp faces and the seam perpendicular to pullingforce. Vertical alignment guidelines were alsomarked to aid proper placement in the clamps. Sewnseam strength was calculated. The efficiency of theseam was calculated by using the following formula:

Seam effici (0/) Seam tensilestregthiciency /0 = x 100Fabric tensile strength

2.6.2 Seam PuckerThis test was carried out on an Instron tensile

tester. Seam pucker is expressed as the percentagedifference between the thickness of seamed fabric totwice the thickness of the fabric.

Thickness strain 7

or seam puckerS -2F xlOO

2F

where S is the thickness of seamed fabric; andF, the thickness of fabric.

2.6.3 Seam SlippageThis test was carried out according to ASTM-

D434. The load-elongation curve of the fabric wassuperimposed over a load-elongation curve of thesame fabric with a standard seam sewn parallel to theyams being tested. The force at which the load -elongation curve of the fabric with the seam is apredetermined distance greater than the load-elongation curve of the fabric without a seam isreported as the newtons per meter resistance to yamslippage. Generally, a 114 in.(6.4mm) separation isused, but for some fabrics, a smaller opening ispreferred. A 1 lb (4.4SN) compensation is deductedto allow for elongation of the seam.

3 Results and Discussion3.1 Fabric Properties and Making-up Process

Fabrics are more extensible in the low load regionthan in the high load region. The property in low

236 INDIAN 1. FffiRE TEXT. RES., DECEMBER 1998 Iload region is closely related to the making-up oftailoring process and comfort of the wearer. Inmaking-up process, an initially flat fabric is formedinto a stable complex 3-D garment, Theconformation of the flat fabric to any 3-dimensionalstructure requires a certain amount of deformationsuch as bending, extension, longitudinalcompressionand shearing in the fabric plane at very low loads.Fabric extensibility in the small region causesdifficulty in the handling of fabrics during cuttingand sewing processes. Thus, the tensile, longitudinalcompression, bending and shearing are the mainmechanical properties relevant to the sewing ortailoringprocess.

In principle, investigations were made bycomparing KESF and conventional parameters(mechanicaland dimensional) for suiting and shirtingfabrics with the sewability parameters, viz. seamefficiency, seam pucker and seam slippage. Thecorrelations between low-stress properties andsewability parameters were established. Sewabilityparameters are dependent not only on the fabricproperties but also on the type of seam and stitch,sewing thread properties, sewing machineparameters, and the skill of the operator.Thus, all thesewn samples were prepared using different fabricsunder identical conditionsof sewing. Since th~ fabricundergoes deformation due to the application ofstress in the making-up process, both fabricdimensional and mechanical properties play animportantrole in the study of sewability.

3.2 Fabric Dimensional PropertiesThe dimensionalproperties of various suiting and

shirting fabrics are shown in Table 1. It may be seenfrom the results that with the increase in fabricweight the thickness invariably increases,irrespective of the fabric composition. Increase inmass has been obtained by incorporating coarseryam and interlacement with longer floats. Therelative cover of the fabric also increases with theincrease in fabric areal density.

3.3 Low-stress Mecbanical PropertiesLow-stress mechanical properties of suiting and

shirting fabrics are given in Tables 3 and 4respectively.

3.3.1 Tensile Properties3.3.1.1 TeosUe Stram at SOOgfIcm(EM)

EM indicates low-stress extensibility. Thisextensibility is related to ease of crimp removal,which, in turn, determines the mobility of threadswithin the fabric. Mobility of thread under low loadis expected to influence seam slippage. EM is veryimportant for fabric tailorability. A larger value ofEM causes problem during tailoring; especially, itresults in distortion of fabric during sewing andsteam processing. On the other hand, higher EMprovides wearing comfort. While comparing the EMvalues of plain woven polyester-viscose (48:52)fabric with twill woven polyester-viscose (65:35)fabric, it may be seen that the difference is not

Table 3-Low-stress mechanical properties of suiting fabrics

Property Fabric samplePVI PV2 PC3 PV4 PV5

EM 5.52 4.57 5.59 4.37 3.69B 0.235 0.105 0.115 0.132 0.06HB 0.299 0.148 0.167 0.176 0.066LT 0.751 0.737 0.783 0.762 0.679WT 10.81 8.41 10.93 8.31 6.26RT 46.04 50.93 51.53 55.17 58.45LC 0.344 0.315 0.295 0.322 0.308WC 0.192 0.168 0.239 0.161 0.162RC 56.39 56.09 48.551 54.033 58.436G 1.957 1.573 1.84 2.8 0.7452HG 5.71 4.48 5.23 8.02 22HG5 8.56 7.47 6.52 10.23 3MIU 0.195 0.184 0.179 0.174 0.206MMD 0.021 0.129 0.0862 0.0211 0.0927SMD 17.001 4.172 12.377 8.506 11.236W 25.83 21.28 18.64 16.67 13.13T 0.95 0.79 0.89 0.66 0.64Formability 1.297 0.48 0.643 0.517 0.221

BEHERA & SHARMA: LOW-STRESS BEHAVIOUR AND SEWABILITY OF FABRICS 237

Table 4--Low-stress nlechanicaI properties of shirting fabrics

Property Fabric sampleLI L2 LC3 LC4 LV5

EM 1.4 2.52 1.39 1.96 1.51B 0.315 0.2 0.267 0.108 0.145HB 0.128 0.067 0.127 0.064 0.112LT 1 0.9 0.92 1.03 0.92WT 0.35 0.57 0.32 0.5 0.35RT 81.44 82.69 63.85 60.48 58.87LC 0.639 0.654 0.538 0.665 0.748WC 0.059 0.057 0.086 0.048 0.044RC 58.3 52.68 52.66 51.08 56.39G 0.353 0.253 0.278 0.513 0.2422HG 0.234 0.114 0.281 0.645 0.6262HG5 1.083 0.39 0.477 1.571 0.299MIU 0.168 0.186 0.201 0.167 0.171MMD 0.0234 0.0419 0.027 0.025 0.0216SMD 13.86 9.44 11.24 10.97 19.31W 21.86 18.49 16.91 14.46 12.54T 0.76 0.77 0.70 0.68 0.68Formability 0.441 0.504 0.371 0.211 0.219

significant. In fact, a twill weave provides moremobility to the yam because of less crossover points.Therefore, it should provide higher EM value.However, the twill woven polyester-viscose (65:35)fabric used here, because of its higher polyestercontent, produces more bulk to the component yamwhich has resulted more surface to surface frictionand less EM value. Among all the fabrics, heavyweight polyester suiting fabrics give higherextensibility than linen fabrics. Extensibility almostincreases with weight, which is mainly due to highercrimp. With the increase of polyester content, EMvalue increases. This may be due to the higherextensibility of polyester fabric in low load region. Inlinen-cotton blended fabrics, the extensibilitydecreases with the increase of linen content. It maybe mentioned here that a larger value of EM in warpcauses problems in tailoring due to distortion offabric during sewing. Thetrigher the value ofextensibility, the more the difficulty in laying up,cutting and sewing.

3.3.1.2 Linearity of Tensile Curve(L T)The linearity of tensile property affects the fabric

extensibility in the initial strain range. Low values ofLT give high fabric extensibility in the initial strainregion but fabric dimensional stability is reducedwhich may cause seam puckering. From the results,it may be observed that polyester-based suitingfabrics are more extensible than linen-based shirting

fabrics in low-load region. This is due to the highextensible polyester component.

3.3.1.3 Tensile Resilience(RT) .RT indicates recovery from tensile deformation.

From the results, it may be seen that in the suitingfabrics as the polyester content increases, the RTvalue decreases. This is because polyester has lowinitial modulus. LC and LV fabrics are less resilientas compared to 100% linen fabric because linen hasvery high initial modulus as compared to cotton andviscose. Also, it may be seen from the results that thelinen-based fabrics are more resilient than polyester-based fabrics.

3.3.2 Bending Properties3.3.2.1 Bending Stiffness (B)

Fabrics with higher bending stiffuess showstronger resistance when bent by the external forceencountered during fabric manipulation in spreadingand sewing. Linen and linen-based fabrics have morebending stiffness than polyester-based fabrics in lowload region. This is due to the high stiffness of linenfibre compared to polyester and viscose fibres.

3.3.3 Shearing Properties3.3.3.1 Shear Rigidity(G)

Polyester-based suiting fabrics have more shearrigidity than linen-based fabrics. Also, it is found toincrease with the increase in areal density. The

238 INDIAN 1. FIBRE TEXT. RES., DECEMBER 1998

reason may be that polyester and viscose have highercoefficient of friction(J.I.=O.58and 0.53) as comparedto linen and cotton(J.I.=O.40and 0.22). Therefore, therotation of threads at crossover points in low loadregion is difficult in polyester-based fabrics ascompared to linen-based fabrics. The higher value ofG causes difficulty in tailoring and discomfort inwearing.

3.3.3.2 Hysteresis of Shear Force at SOSbearAngle (2HGS)The results show that suiting fabrics have more

2HG5 than shirting fabrics. The high value of 2HG5causes trouble in tailoring and wrinkling duringwear.

3.3.4 Frictional PropertiesIt may be seen from the results that both low-

weight suiting and shirting fabrics have high valuesof geometrical roughness because of the greatersurface variation in a unit area due to less threaddensity. PVl is having higher geometrical roughnessyet it is having higher weight. It may be due to the

matty weave of the fabric. However, in the case ofPV2, the surface roughness is lower. This may bedue to the use of twill weave, in which greaternumber of floats cause low surface variation in a unitsurface area. Fabrics with different frictionalproperties fed during sewing may cause unevenfeeding,which may lead to pucker.

3.4 SewabilityThe characteristics of a high quality seam are

strength, elasticity, stability and appearance. Thesequality parameters were measured in terms of seamefficiency,pucker and seam slippage and the resultsare given in Table 5. Other relevant fabricmechanicalproperties are given in Table 6.

3.4.1 Seam EfficiencyThe retention of strength in a seamed fabric after

sewing with respect to the original fabric strength ismeasured in terms of seam efficiency. With theincrease in fabric strength, the seam efficiencydecreases in both suiting and shirting fabrics because

Table 5----Sewability of suiting and shirting fabrics

Sample code Weight Cover Seam pucker Resistance to seam slippage Seam efficiencyglm2 % N/m %

Suiting fabricsPVI 278 0.76 4.38 3795 19.77PV2 228 0.86 II 3668 19.15PV3 194 0.75 14.56 1550 20.84PV4 180 0.78 27 1300 32.39PV5 145 0.67 27.26 1492 38.61

Sblrting fabricsL1 220 0.79 1.36 3046 26.56L2 185 0.80 5.78 2286 41.25

LC3 169 0.61 11.41 1829 52.03LC4 144 0.59 23.89 1326 65.97LV5 125 0.50 53.16 642 106.81

Table 6-Fabric mechanical properties

Sample Fabric strength Fabric elong. at break Flexural rigidity (Go) Cohesive couple (Co) Co/Gocode N/m % dynes cm2/cm dynescmlcm

PV1 28327 25 190 120 0.63PV2 28602 25 120 110 0.92PV3 24902 26 138 84 0.6PV4 18724 3Q 180 44 0.24PV5 14667 34 44 44 1.0

L1 13785 15 83 23 0.30L2 11198 16 60 21 0.35LC3 10852 18 48 12 0.25LC4 8657 15 43 13 0.30LV5 4073 24 38 10 0.26

BEHERA & SHARMA: LOW-STRESS BEHAVIOUR AND SEWABILITY OF FABRICS 2.39

the seam efficiency is inversely proportional to thefabric strength for a given sewing thread. With theincrease in flexural rigidity( Go}and cohesive couple(Co), the seam efficiency decreases in both suitingand shirting fabrics because increase in both Go·andCocauses increase in fabric strength.

3.4.2 Seam PuckerSeam pucker is a distortion in the surface of a

sewn fabric and appears as a swollen effect along theline of the seam. It is determined by measuring thepercentage increase in the thickness of the seamedfabric over the original fabric under a constant load.

It may be observed from the results that thepuckering consistently decreases with the increase infabric weight, cover and thickness in both suiting andshirting fabrics. This may be due to the increase ininplane compression resistance. As the values offlexural rigidity( Go} and cohesive couple( Co}increase, the seam pucker decreases.

3.4.3 Seam SlippageA partial or complete loss of seam integrity

manifested by yam slippage parallel to stitch line isconsidered as seam slippage. Resistance Of yamslippage increases with the increase in fabric weight,cover and thickness of the fabric in both suiting andshirting fabrics. This may be due to betterinterlooping of sewing thread with fabric in bothsuiting and shirting fabrics, and higher contact areadue to bulkier mass.

3.S FormabilityIt is related to minimum compression sustainable

by a fabric before the onset of buckling". The lowerthe formability the more likelihood of seam pucker,because a fabric is unable to accommodate the smallcompression placed on the fabric by the sewingthread. The maximum and minimum limits of fabricformability also depend on sewing thread, needlesize and thread tension, which were kept constant inthis experiment. The results for formability (fables 3and 4) clearly show that formability is higher forhigher weight fabrics and lower for lower weightfabrics. This may be due to the fact -that heavyweight fabrics have more rigidity which increasesthe enplane compression resistance.

3.6 Correlatlbil between SewabiUtyParameten and Low-stress PropertiesA linear correlation was determined between

sewability parameters and low-stress fabric

mechanical properties. The model for regressionequation was taken as:

y=bx+a

where

b= :E(x-xmean)(y- Ymean}:E(x - xmean}2

a=Ymean-bxmeanSDy SDy

Ypred =--x-r-- Xmean+YmcanSDx SDx

if r=O, then Ypre<F Ymean

The higher the r, the more YptUi may vary from Ymean

and the lower the r, the more the Ypred regressestowards the mean.

:Exy/ N - (xmean) (Ymean)r = -----==-----'='-SDx SDy

where SDx =True standard deviation of the 'x' sampleSDy =True standard deviation of the y sampler = Pearson coefficient of correlationYpred = Sewability parameterX = Low-stress mechanical property

The results for correlation coefficient with varioussewability parameters are given in Table 7 and thecomments on each parameter are given below.

3.6.1 Seam EfficiencyFor suiting fabrics, a high negative correlation is

obtained with bending properties. Increase inbending stiffuess causes increase in fabric strength,which, in turn, decreases the seam efficiency. Thesame reason applies for weight and thickness.Shearing properties do not influence the seamefficiency.

For shirting fabrics, the reasons for thedependence of seam efficiency on bending stiffuess,weight and thickness are same as for suiting fabrics.Shearing properties do not influence the seamefficiency in shirting fabrics also.

3.6.2 Seam PuckerFor suiting fabrics, a very high negative

correlation is obtained between seam pucker andweight/thickness. Increase in weight and thicknessincreases the bending resistance. So, enplanecompression resistance increases and, therefore,seam pucker value decreases.

A high correlation is found with tensileresilience(RT) i.e. recovery from tensile deformation.

240 INDIAN J. FIBRE TEXT. RES., DECEMBER 1998

Table 7--Coefficient of correlation between sewability parameters and low-stress mechanical properties

Property Seam efficiency Seam pucker Seam slippageSuiting Shirting Suiting Shirting Suiting Shirting

EM 0.5 0.16 -0.8 -0.21 -0.01 -0.06B -0.83 -0.72 0 -0.7 0.77 0.81HB -0.8 -0.05 -0.74 -0.01 0 0.2LT -0.81 -0.2 -0.4 -0.13 0.3 0.16WT -0.03 -0.2 -0.75 -0.22 0.23 0.06RT 0.91 0.81 0.96 0.77 -0.86 -0.88LC -0.19 -0.64 -0.43 -0.71 0.62 0.5WC -0.55 -0.6 -0.44 -0.65 -0.08 -0.46RC 0.41 0.03 0.112 0.08 0.35 0.3G -0.33 -0.14 -0.06 -0.12 -0.01 -0.012HG -0.37 -0.02 -0.08 -0.03 0.06 0.162HGS -0.47 -0.3 -0.3 -0.23 OJ 0.18MIU -0.41 -0.2 0.01 0.32 0.61 0.1MMD 0.423 0.42 0.4 0.5 -0.23 -3JSMD -0.07 -0.7 -0.32 -0.77 0.3 0.5W -0.86 -0.94 -0.95 -0.9 0.86 0.9T -0.88 -0.8 -0.93 -0.76 0.60 0.87

RT helps the fabric to return back from stretching atseam line after sewing.

For shirting fabrics, a high dependence of seampucker with fabric weight, tensile resilience, bendingrigidity and thickness is observed. The reasons aresame as stated in the case of suiting fabrics. In a two-layered fabric, as the geometrical roughnessincreases, the value of the seam pucker decreases dueto less chances of slippage of two fabrics on eachother during sewing. Shearing properties do notinfluence the seam pucker.

3.6.3 Seam SlippageFor suiting fabrics, the resistance to seam slippage

shows high correlation with bending properties. Asthe bending stiffness of fabric increases the contactarea between sewing thread and fabric threadsincreases. It may lead to increase in resistance ofseam slippage i.e. it will resist the bodilydisplacement of the seam line with respect to threadsparallel to seam line. High dependence of seamslippage resistance on weight and thickness is due tothe incorporation of coarser threads. The same reasonas for bending is also applicable here.

For shirting fabrics, high dependence of seamslippage resistance on weight, thickness and bendingstiffness is observed. The reasons are same as in thecase of suiting fabrics. Moderate correlation is foundwith geometrical roughness. Due to geometricalroughness there will be less slippage between sewing

threads and fabric threads and, therefore, theresistance to seam slippage will be higher.

4 ConclusionsFabric thickness and cover factor increase with the

increase in fabric weight for all compositions.Polyester/viscose and polyester/cotton suiting fabricsgive higher breaking strength and elongation ascompared to linen and linen-based fabrics.

Bending stiffness almost increases with theincrease in weight of suiting and shirting fabrics.Polyester-based fabrics give higher. extensibilitycompared to linen-based shirting fabrics, whereaslinen-based fabrics are more. resilient compared topolyester-based fabrics. Linen-based shirting fabricsgive more bending stiffness as compared topolyester-based fabrics. Polyester-based fabrics havemore shear rigidity compared to linen-based fabrics.Low-weight fabrics give higher geometricalroughness.

Seam efficiency decreases with the increase infabric strength, flexural rigidity, cohesive couple,areal density and thickness. Seam pucker decreaseswith the increase in' flexural rigidity and cohesivecouple. It also decreases with the increase in' fabricweight, cover and thickness in both suiting andshirting fabrics. Resistance to yam slippage increaseswith the increase in fabric weight, cover andthickness in both suiting and shirting fabrics.

BEHERA & SHARMA: LOW-STRESS BEHAVIOUR AND SEWABILITY OF FABRlCS 241

A high negative correlation is found betweenseam efficiency and bending properties in bothsuiting and shirting fabrics. High dependence ofseam efficiency on weight and thickness is alsofound in both the cases. Seam pucker has a high 4 Behera B K & Hari P K, Indian J Fibre Text Res, 19negative correlation with bending properties, weight (1994)4.and thickness. However, shearing properties do not 5influence the seam pucker. Seam slippage resistancehas a high correlation with bending pr~perties, fabric 6areal density and thickness. Geometncal roughness . 7

also influencesthe seam slippageresistance. 8

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