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Structure

Editorial 0.3

1 About the Origin and the Significance of theUSTER® STATISTICS 0.4

1.1 Introduction 0.4

1.2 USTER® STATISTICS as Benchmarks 0.5

1.3 USTER® STATISTICS for Yarn Contracts and Product Specifications 0.5

1.4 USTER® STATISTICS for Textile Machinery Manufacturers 0.6

1.5 Users’ Contributions Towards Improving the USTER® STATISTICS 0.6

2 Quality Characteristics of the USTER® STATISTICS 2001and Their Significance 0.7

3 Restrictions 0.14

3.1 Restrictions Imposed by the Raw Material 0.14

3.2 Restrictions Imposed by the Final Product 0.15

3.3 Restrictions Imposed by the Yarn Design 0.15

3.4 Missing Correlation Between Different Quality Characteristics 0.15

3.5 Outliers and Frequent Defects in a Spinning Mill 0.16

3.6 Restrictions in Guarantee Agreements 0.16

3.7 Reproducibility and Variability of Measurements 0.16

4 The Making of the USTER® STATISTICS 0.18

5 Interpreting and Applying the USTER® STATISTICS 0.19

6 Changes to the USTER® STATISTICS 1997 0.21

6.1 New Fiber Quality Characteristics 0.21

6.2 Distinction Between Knitting and Weaving Yarns 0.21

6.3 New Yarn Quality Characteristics 0.21

7 Validity 0.22

8 Disclaimer 0.23

9 Testing Conditions and Sample Sizes 0.24

10 Nomograms of the USTER® STATISTICS 2001 1.1 – 27.xx

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11 Appendix 11.1

11.1 Fiber Properties 11.1

11.1.1 Fiber Bundle Testing 11.1

11.1.2 Single Fiber Testing 11.3

11.1.3 Ambient Laboratory Conditions for Fiber Testing 11.4

11.2 Sliver Testing 11.5

11.3 Roving Testing 11.5

11.4 Yarn Testing 11.5

11.4.1 Count Variation Testing 11.7

11.4.2 Mass Variation Testing 11.7

11.4.3 Yarn Hairiness Testing 11.8

11.4.4 Imperfections Testing 11.9

11.4.5 Yarn Diameter, Cross-section Shape and Density Testing 11.10

11.4.6 Yarn Trash and Yarn Dust Testing 11.10

11.4.7 Tensile Properties Testing 11.11

11.4.8 HV Tensile Properties Testing 11.13

11.4.9 Ambient Laboratory Conditions for Yarn Testing 11.14

11.5 Useful Conversions 11.15

11.5.1 English/Metric Conversions 11.15

11.5.2 Count Conversions 11.16

11.5.3 Staple Conversion Chart 11.16

11.5.4 Special Conversions 11.16

11.6 References 11.17

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Editorial

We are pleased to be able to present to you this compact disk with thenew USTER® STATISTICS 2001. They represent a long series of cotton fiber, yarnand roving tests. The assessments for the USTER® STATISTICS 2001 were be-gun in 1997 and concluded in 2001. They include the most comprehensive rangeof reference figures which have ever been made available to the textile industryand encompass more than 700 graphs.

The reference figures of the new sensors of the USTER® AFIS and the USTER®

TESTER 4 are a novelty in the USTER® STATISTICS 2001. Moreover, a distinctionbetween knitting yarns and weaving yarns was made for the first time in re-sponse to frequently voiced requests from the textile industry. Following theintroduction of compact spinning machines, compact yarns were tested inten-sively which enabled us to include reference figures for compact yarns, too.

The samples were collected from all major textile industry segments. Since com-pact spinning was an absolute novelty, we would like to point out that the com-pact yarns tested were mainly spun in Europe. The USTER® STATISTICS indicatethe origin of each yarn type. For the first time, we succeeded in obtaining asufficient number of samples from China for these reference figures.

Reference figures are important for every industrial process. Since the introduc-tion of ISO 9000, they gained in significance in the textile industry as bench-marks in the spinning process over the last few years. In this respect, theUSTER® STATISTICS can make a major contribution, because the modernUSTER® laboratory testing instruments can automatically rate the tested qualityaccording to the USTER® STATISTICS. Reference figures are also a useful toolwhen determining yarn quality profiles in negotiations with business partners.

The USTER® STATISTICS 2001 will contribute to turning the use of raw materialsand the production of yarns into an increasingly professional process duringwhich nothing will be left to chance. As a result, disastrous economic and finan-cial consequences for textile manufacturers can be reduced to a minimum.

We thank all customers who contributed to this collection of benchmarks bysupplying samples and the laboratory operators for their enormous efforts tocarry out all the tests. In addition, we thank Ms. Gabriela Peters for coordinatingand conducting the tests and analyzing the huge amount of data. We are gratefulto Ms. Anja Schleth, Zellweger Uster, Knoxville, for reviewing the manuscriptand to Mr. Lin Ting-Kun, Zellweger Uster, Shanghai, for the Chinese test results.

Richard Furter

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1 About the Origin and theSignificance of the USTER® STATISTICS

1.1 IntroductionThe USTER® STATISTICS are quality reference figures which permit a classifica-tion of fibers, slivers, rovings and yarns with regard to world production. The lastUSTER® STATISTICS for cotton fibers and yarns were published in 1997. In 1999,the USTER® STATISTICS for slivers followed, but were determined on-line usingthe USTER® SLIVERDATA system. The USTER® STATISTICS 2001 again addresscotton fibers, rovings and yarns. We will later turn to the restrictions regardingthe use of the USTER® STATISTICS. We recommend to read these restrictionscarefully and adhere to them. When used properly the USTER® STATISTICS willcontinue to be appreciated as reference figures by all groups of interested peo-ple.

The USTER® STATISTICS are first and foremost a practical guide to ‘good textilepractices’ in the field of yarn manufacturing. The evidence of specific defects orshortcomings in overall yarn quality, which may become apparent through usingthe STATISTICS as a comparative standard, can be translated into immediatecorrective action in the manufacturing process. Reliable and unequivocal cause/effect relationships have been established over the years and documented in theapplication literature. Legions of textile technologists and USTER® instrumentusers in mills around the world put that experience into action in their daily rou-tine. In the previous edition of the USTER® STATISTICS, we introduced a graphwhich illustrated the improvement in yarn evenness between 1949 and 1997.Now, four years later, we publish the same diagram again (fig. 1). Four additionaldata points were added to the curves, i.e. the evenness values of the 50% line ofthe USTER® STATISTICS 2001. This graph records the mass unevenness CVm. Afurther improvement in yarn evenness is discernible in fig. 1.

Improvement in Yarn Evenness between 1957 – 2001

12

22

20

18

16

14

1955 19651960 1970 1975 1980 1985 1990 1995 2000 2005

Year Année Jahr

Co

effi

cien

t o

f va

riat

ion

Co

effi

cien

t d

e va

riat

ion

Vari

atio

nsk

oef

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ent

CV

m [%

]

CVm [%]

Ne 20 (Nm 34, 29.5 tex)100% Cotton, carded100% Coton, cardé100% Baumwolle, kardiert

Ne 60 (Nm 100, 10 tex)100% Cotton, combed100% Coton, peigné100% Baumwolle, gekämmt Knitting yarn

Fil à tricoterStrickgarn

Weaving yarnFil à tisserWebgarn

Fig. 1

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For the first time, the USTER® STATISTICS 2001 distinguish between knittingyarns and weaving yarns.

Of course, quality is multi-faceted, and while evenness has improved, other pa-rameters have deteriorated to some degree. However, more than other qualityparameters, yarn evenness is closely associated with both the design and man-agement of the entire manufacturing process. Thus, besides being a result oftechnological advancements, evenness has also improved as a result of moreelaborate quality control and quality management practices. It is of paramountimportance for the spinning industry to closely monitor these trends and to pre-pare for a timely and appropriate response. Once lagging behind, a mill will haveto invest heavily to move on and catch up and to eventually keep pace with theglobal development of yarn quality.

1.2 USTER® STATISTICS as BenchmarksThe USTER® STATISTICS have been made for quality benchmarking on the cor-porate level. Benchmarking is a total quality management tool and denotes theprocedure of identifying and quantifying topnotch or world-class performance(benchmarks) in a particular business or product category and comparing thedata with the performance of the own company or product. Established bench-marks and quality standards substantiate the feasibility of attaining greater profi-ciency and of narrowing the performance gap. They legitimize the implementa-tion of strategies to enhance the manufacturing process as a result of hard factsrather than management intuition [1, 2]. In other industries, the availability ofreliable competitor information for comparative analyses in benchmarking is amajor obstacle. Thanks to the USTER® STATISTICS, data on the quality levelsachieved by the top manufacturers in the textile industry are public domain andeasily accessible.

1.3 USTER® STATISTICS for Yarn Contracts andProduct Specifications

The USTER® STATISTICS regularly serve as the platform for yarn contracts andproduct specifications in the framework of commercial transactions. This prac-tice is commonly accepted by the manufacturers, merchants, and processors ofyarns. Many sales yarn spinners, weavers, and knitters have formulated qualityrequirements based on the USTER® STATISTICS. By experience they have deter-mined what quality levels are appropriate for what application. As a more generalguideline to the prevailing quality requirements, literature is available which ad-dresses the subject of yarn specifications for an array of applications and enduses in both knitting and weaving [3, 4, 5, 6]. Much of the experience disclosedthrough these publications emanated from applying the USTER® STATISTICS.

Buyers and salesmen involved in the traditional commodity type trade or in directpurchasing and sales are certainly among the most enthusiastic users of theUSTER® STATISTICS. They appreciate the STATISTICS as a means of categoriz-ing many different qualities by face value. An indistinct yet popular belief prevailsin the international markets for reasonably priced yarns that largely correspondto the 25th percentile of the USTER® STATISTICS to be in high demand. Everynow and then, such a belief manifests an utter quality overkill with regard to theactual processing and end use requirements; in other cases, such specificationsmay well be justified.

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In the long run, however, the market as a whole is and will continue to be drivenby the rule of supply and demand, irrespective of where, when, and by whomthe STATISTICS are referred to in order to advertise or bargain. Good grades onthe overall quality, though, will always serve as a passport to both the domesticand international markets.

1.4 USTER® STATISTICS for Textile MachineryManufacturers

Textile machinery manufacturers as well as manufacturers of accessories fortextile machines have frequently been using the USTER® STATISTICS to appraisethe impact on quality of their new developments in the field of machine technol-ogy or monitoring and control systems. While machine performance in terms ofproductivity or efficiency is easily expressed in absolute numbers, the STATIS-TICS are frequently referred to when it comes to quality aspects. The other sideof the coin is that the machinery manufacturers have also been forced into theroutine of giving performance guarantees based on the USTER® STATISTICS.Again, this particular issue falls into the category of restrictive uses and will beaddressed later.

1.5 Users’ Contributions Towards Improvingthe USTER® STATISTICS

Because of the constructive criticism that we received from among the industry,the USTER® STATISTICS for fiber and yarn quality have substantially improvedover the years. We are invariably grateful for constructive contributions.

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2 Quality Characteristics of the USTER®

STATISTICS 2001 and Their Significance

In addition to the well-known quality characteristics, the USTER® STATISTICS2001 introduce new quality parameters which were generated using the newsensors of the USTER® AFIS single fiber testing system and of the USTER®

TESTER 4.

The following list encompasses all quality characteristics featured in the USTER®

STATISTICS 2001. It is subdivided into tables for fibers and tables for yarns.

All definitions of fiber quality characteristics which require an explanation aredescribed in detail in fig. 2 through 5.

Description of cotton fiber quality characteristics (USTER® HVI SPECTRUM)

Quality char- Abbrevia- Description Unitacteristics tion

Micronaire Mic Indicates fiber fineness —-

Upper Half UHML Corresponds to the mmMean Length classer's staple.

Definition according to Fig. 2

Uniformity UI Measure for variations of %Index fiber length, length uniformity

Bundle Strength Breaking tenacity g/textenacity measured on fiber bundle

Reflexion Rd Degree of reflexion of %the cotton. The higherthis value, the better thecotton is rated.

Yellowness +b Assessment of color, %degree of yellowness

Trash CNT Number of trash particles —-per defined area

Trash Area Percentage of trash %per defined area

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Description of cotton fiber quality characteristics (USTER® AFIS)

Quality char- Abbrevia- Description Unitacteristics tion

Neps Neps/g Number of neps 1/gper gram

Seed-coat SCN/g Number of seed-coat neps 1/gneps per gram

Short fiber SFC(n) Short fiber content %content SFC(w) by number (n)

and by weight (w).Definition according to Fig. 3

Upper Quartile UQL(w) Corresponds to the mmLength classer's staple.

Definition according to Fig. 3

Fiber fineness Fine Fineness of fibers mtex

Immature IFC Immature fiber content. %fibers Percentage of immature fibers.

Definition according to Fig. 4, Fig. 5

Maturity Mat Ratio of mature to —-immature fibers.Definition according to Fig. 5

Trash particles Trash/g Number of trash particles 1/gper gram

Dust particles Dust/g Number of dust particles 1/gper gram

Visible foreign VFM Visible foreign matter %matter

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The fiber length diagram determined by means of the USTER® HVI instrument isnot an end-aligned staple diagram and is called fibrogram. Fig. 2 is a schematicfibrogram of cotton and shows the determination of the upper half mean length.

Upper HalfMean Length

100%0% 50%

Mean length

Fig. 2 Fibrogram

The USTER® AFIS instrument measures each fiber separately and, therefore, allinformation for an end-aligned staple diagram is available. Fig. 3 illustrates howthe «Upper Quartile Length» (UQL) and the short fiber content are determinedusing the USTER® AFIS. The UQL is the fiber length at 25%. The term «upperquartile» indicates that the value is calculated in the upper quarter of the staplediagram.

Fiber length

Short fiber content SFC

100%

L½"

L(n,w)UQL(w)

L2,5%(n) L5%(n)

0% 25% 50%

Fig. 3 Staple diagram

Fig. 4 and Fig. 5 show the definition of the measured values in relation to thematurity characteristics. The respective parameters can be explained usingFig. 4. Fig. 4 shows the cross-section of a cotton fiber.

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Perimeter P

Area A1

Lumen

Perimeter P

Area A2

Fig. 4

To compute the mean degree of thickening theta, a circular cross-section of themeasured fiber having a perimeter P is calculated, and subsequently area A1 isdivided by area A2.

Fig. 5 shows a maturity measurement using the USTER® AFIS as well as thevalues computed for theta.

Cumulative percent Theta Maturity

Mature fibers (R)

Thinwalled fibers

Immature fibers (IFC)

Mature fibers (R)

Thinwalled fibers

Immaturefibercontent (IFC)

Fig. 5

For this example, the following apply:

Mature fiber content R = 37.6%

Immature fiber content IFC = 10.3%

Maturity (according to Lord): 83.07.0200

3.106.377.0

200=+−=+−= ����

�

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Description of yarn quality characteristics (USTER® TESTER 4)

Quality char- Abbrevia- Description Unitacteristics tion

Count variations CVcb Count variations between %packages

Mass variations CVm Coefficient of variation %of mass

Mass variations CVmb Coefficient of variation %of mass between packages

Imperfections Thin Number of thin places, 1/1000 mThick thick places and nepsNeps

Hairiness H Absolute value of hairiness. —-Measurement of the entirefiber length.

Standard deviation sH Standard deviation of hairiness —-of hairiness within a package

Coefficient of CVHb Variation of hairiness %variation between packagesof hairiness

Trash Dust Dust and trash in yarns. 1/1000 mTrash Counts refer to 1000 m of yarn.

Coefficient of CVd Variation of the %variation yarn diameterof the diameter

Shape Shape Shape of the yarn cross- —-section.Ratio of the axes of an ellipse.

Density D Density of the yarn g/cm3

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Description of yarn quality characteristics (USTER® TENSORAPID 3)

Quality char- Abbrevia- Description Unitacteristics tion

Strength FH Breaking force cN

Tenacity RH Breaking force referred cN/texto the yarn count

Coefficient of CVRH Variation of the individual %variation of values of the tenacitytenacity

Elongation �H Yarn elongation at %breaking force

Coefficient of CV�H Variation of the individual %variation of elongation valueselongation

Work done WH Work performed during cNcmto break tensile testing of yarns

at breaking force

Coefficient of CVWH Variation of the individual %variation of values of work donework done to break

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Description of yarn quality characteristics (USTER® TENSOJET)

Quality Char- Abbrevia- Description Unitacteristics tion

Strength FH Breaking force cN

Tenacity RH Breaking force referred cN/texto the yarn count

Coefficient of CVRH Variation of the individual %variation of values of the tenacitytenacity

Elongation �H Yarn elongation at %breaking force

Coefficient of CV�H Variation of the individual %variation of elongation valueselongation

Work done WH Work performed during cNcmto break tensile testing of yarns at

breaking force

Coefficient of CVWH Variation of the individual %variation of values of work done towork done break

Weak places FHP=0.1 0.1% of all tests cNin the yarn / have a strength belowstrength this value

Weak places �HP=0.1 0.1% of all tests %in the yarn / have an elongation belowelongation this value

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3 Restrictions

This section addresses the restrictions that apply to the use of the USTER® STA-TISTICS and we would like to repeat our advice that this be read carefully andadhered to. Both deliberate and unintentional misuse of the STATISTICS have insome instances in the past resulted in lengthy and costly disputes – all of whichcould have been avoided if all parties involved would have had the same clearunderstanding of the concept underlying the STATISTICS. The reading of thissection is a must for those who are not familiar with that concept, with theSTATISTICS as such, or with the proper interpretation of the data.

3.1 Restrictions Imposed by the Raw MaterialFour primary variables have a decisive impact on corporate success in our textileenvironment as well as in any other industrial venture: man, machine, material,and know-how or information in general. Among these four key elements, theraw material is the crucial component which largely dictates quality but also pro-ductivity and cost in yarn manufacturing. By virtue of their design, the USTER®

STATISTICS for spun yarns do not provide direct access to information about theraw material used for spinning. However, those differences in raw material us-age are indirectly reflected in the data. A high-quality yarn can only be spun fromhigh-quality raw materials and since the raw material frequently accounts formore than 50% of the total manufacturing costs in the medium to fine countrange, the utilization of high-quality, high-priced raw materials will be proportion-ally reflected in the yarn price [7]. Any measures taken in the field of raw mate-rials will not only have a considerable impact on quality but also on a mill’s com-petitiveness and bottom-line profitability.

In those rare cases where the STATISTICS have been corrupted, the motiveshave always been related to what evidently is the single most important drivingforce in the global textile scenario: price. The USTER® STATISTICS, however,provide a dependable indication of quality, exclusively. Although quality is asomewhat elusive term, it is nevertheless a result of tangible assets and thus toa certain degree interrelated with the sales price of a product.

The USTER® STATISTICS should not be interpreted as saying 5% is «good». Incontrary, the 5% line might be indicative of high cost, high price, luxuriousness –even a tendency to price oneself out of the market. By the same token, 95%should not imply «poor» – it might be indicative of a very attractive price and justthe right quality for the target markets. A «good» spinner is actually one who is ina position to achieve an acceptable quality level from a less expensive fiber – thegenuine mastery of spinning. The trouble starts when the USTER® STATISTICSare referred to in order to corroborate complaints about a low rating in certainquality categories. This complaint may be directed at the «good» spinner whoproduces a reasonably priced yarn from a reasonably priced fiber. Yarn price,however, is directly proportional to fiber quality and fiber quality in turn dictatesyarn quality to a great extent. Consequently, pushing yarn quality towards bettervalues would simply cannibalize the price advantage. The USTER® STATISTICSshould be employed as what they really are: a global survey of yarn quality asproduced in every part of the world. Whether or not these qualities are producedeconomically from adequate raw materials and offered at a legitimate price iscertainly beyond the scope of the STATISTICS.

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3.2 Restrictions Imposed by the Final ProductIt lies in the nature of the matter that end uses remain somewhat vague whenyarns are marketed via merchants or importers. It is rare for any merchant tohave firm orders before entering into a contract. Consequently, the focus is onobtaining qualities that are likely to meet the requirements of any potential cus-tomer and which can be successfully marketed in many places and at any givenpoint in time. In the current buyer’s market, merchants have a large number ofalternative sources to choose from. Yet, to minimize risk, commodity type yarnswith high volume of trade are preferred. Under these circumstances, specifiedand actual quality requirements seem to have very little in common.

3.3 Restrictions Imposed by the Yarn DesignWhen properly tailored to the anticipated end use, yarns will exhibit inherentstrengths and weaknesses: As opposed to weaving yarns, for instance, knittingyarns produced from cotton, man-made fibers, or blends thereof are spun at lowtwist multipliers. They will rarely display a high breaking tenacity. If they did, theywould probably result in stiff, harsh fabrics. A somewhat lower breaking tenacitymust also be expected from knitting yarns spun from low-tenacity or pill-resis-tant man-made fibers which are specifically designed for that purpose. Such low-tenacity fibers, however, usually result in excellent yarn elongation. Knittingyarns also possess a higher hairiness. While this would be detrimental to weav-ing yarns, the knitted fabric enjoys a greater cover and a softer hand. To make itclear: It is technically impossible and fatal with respect to the end use to demandthat a yarn be perfect in all categories, say above the 25% line of the USTER®

STATISTICS. The proper way out of this dilemma is for the yarn producer and theyarn processor to jointly develop detailed specifications or requirement profilesfor specific end uses. Many good examples of this partnership approach havebecome known and the USTER® STATISTICS can be of tremendous help in realiz-ing such projects.

3.4 Missing Correlation Between DifferentQuality Characteristics

Unfortunately, the USTER® STATISTICS still mislead some people into thinking incausal relationships that do not exist in reality. Several quality parameters dis-played in the STATISTICS are believed to be highly correlated but the fact is thatthey are not. High breaking tenacity, for instance, is not necessarily linked to highbreaking elongation; rather, yarn elongation is determined by spinning speed,spinning geometry, and the resultant specific spinning tension. Likewise, a veryeven yarn may well have a high nep count. End uses calling for a relative free-dom of neps cannot be satisfied by using yarns with a good USTER® CV. Theopposite is sometimes the case: Few neps in a very uniform yarn tend to visuallystick out like a black sheep. Yarns with a little higher CVm or greater hairinesstend to conceal neps in the overall irregularity, much like the often quoted needlein a haystack. If there is a problem with neppy appearance and no way to reducenep counts, try to go a little higher with the CVm.

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3.5 Outliers and Frequent Defects in a SpinningMill

It is a popular illusion that yarns with a high rating according to the USTER® STA-TISTICS are always above and beyond suspicion. A good overall quality does notonly encompass excellent mean values but also low variability of the quality at-tributes as well as unconditional consistency. Only one bad package in the creelof a knitting machine or in warping is bound to ruin several hundred yards ofgreige fabric. We have come a long way in gaining control over sporadic yarndefects by on-line quality monitoring and over scattered weak places by applyingthe USTER® TENSOJET. Every now and then, however, various off-quality situa-tions tend to recur with malicious persistence in spite of the blind faith often putin the USTER® STATISTICS ratings. These include outliers, mix-ups, overlength/underlength or damaged packages, problems with package unwinding behavior,missing transfer tails, improper waxing, shedding and fly, dye streaks (barré),white specks, contamination with foreign fibers – just to name a few. Quality in abroader sense has many dimensions: A truckload of 5% USTER® STATISTICSyarn that arrives too late at the weaver’s loading ramp will not be considered aquality product. Timing is vital due to the seasonal characteristic of the textilebusiness with its frequent peak demands and, of course, due to the increasingpopularity of just-in-time and quick response production.

3.6 Restrictions in Guarantee AgreementsThe issue of performance guarantees negotiated between yarn producers andmachinery manufacturers has already been briefly touched upon. Such perfor-mance guarantees based on the USTER® STATISTICS must be considered a du-bious practice when the effect of raw material, machine settings, maintenance,ambient conditions, and operator proficiency is neglected. A legitimate perfor-mance guarantee should include references to in-depth technological trials con-ducted prior to preparing such a document. It should also embrace technicallysound prohibitive clauses that serve to preclude misunderstandings – or evenworse – litigation between machinery manufacturers and yarn producers. In themajority of all cases, it is not the machine that produces poor quality. If it wouldnot have to process a capricious material like textile fibers, the average textilemachine would probably run uninterruptedly for ten, fifteen years or more with-out any major problems at all. Before making claims against machinery manufac-turers, the potential source of the quality problem as well as its true nature andextent should be investigated thoroughly and objectively.

3.7 Reproducibility and Variability ofMeasurements

Last but not least, a few comments on reproducibility and variability of measure-ments. No matter what measuring instrument is used – from yardstick to atomicclock – there will always be a certain measurement error. This is also true fortextile testing. There are three types of measurement errors: avoidable error,systematic error (bias), and random error. Avoidable error encompasses the fail-ure to choose an appropriate measurement method or to properly operate ameasuring instrument. In the textile laboratory, this is of little significance butselecting instrument settings and sample conditioning present a potential sourceof avoidable error. Systematic error includes calibration error, instrument toler-

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ances, and the fluctuation of ambient conditions. This type of error can be quan-tified fairly accurately. Random error is the most critical component in textiletesting. It is predominantly caused by the variability of the tested material itself.Its magnitude can be approximated by statistical calculations – the confidenceinterval of the mean. The absolute error of a measurement is the total of all threetypes of errors. A measurement should therefore always be reported as x±�x,i.e. the mean value plus/minus the total error to indicate that the true measure-ment value is located somewhere within that interval. All USTER® instrumentscalculate the confidence intervals automatically and they are part of the test re-port. The confidence interval covers the random error component; informationon the systematic error, i.e. instrument tolerances, is provided in our applicationhandbooks.

When comparing actual measurements with the data illustrated in the USTER®

STATISTICS, it is of utmost importance that the total measurement error is keptto an absolute minimum to warrant compatibility. If this is not the case, falseconclusions may be drawn from such a comparison.

There are five things that can be done to minimize the measurement error:

• proper conditioning under constant standard atmospheric conditions• exact calibration of the instrument• correct settings of the instrument• adequate sample size

When actual measurements are then compared with the USTER® STATISTICS,they would appear in the nomogram as a short vertical line – not as a dot. Thetop and bottom ends of that line represent the upper and lower limits of theconfidence interval with the mean exactly in the middle. We cannot eliminate therandom error; however, the confidence interval quickly becomes smaller whenthe sample size is increased. For detailed information on recommended samplesizes and testing conditions, please refer to section 9.

In the context of commercial agreements via yarn contracts and product specifi-cations, it frequently transpires that disputes result from discrepancies betweenmeasurements performed by the purchaser and by the supplier and from thesubsequent comparison of disparate measurements with the USTER® STATIS-TICS. When such incidents are examined more closely, the result often is thatthe basic conditions listed above have been ignored or have simply not beenidentical in both testing locations. In other cases, the problem could be quicklyresolved by applying the t-test procedure. It proved that the differences were notstatistically significant but strictly random due to a pronounced sample variability.The t-test procedure along with further detailed explanations is outlined in ourapplication handbooks. A simplified t-test can be performed by comparing theconfidence intervals: If the confidence intervals of two means overlap, then theobserved difference between the two means is random or statistically insignifi-cant; if they are separated, the difference is considered statistically significant.Applying the concept of the confidence interval can be both very helpful andrevealing. It pinpoints the highly variable characteristic of textile materials whichshould always be taken into consideration.

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4 The Making of the USTER® STATISTICS

The USTER® STATISTICS are not established by merely collecting data. They areestablished by testing actual yarn and fiber samples that we procure on a trulyglobal scale via our agents, overseas partners, or direct contacts with our inter-national clientele. A total of 6140 samples have been tested in our ISO 9001certified textile laboratory in Uster, Switzerland, and the samples from Chinahave been tested in our subsidiary in Shanghai. The geographical distribution ofthe origin of all samples procured for the USTER® STATISTICS is illustrated in Fig.6. The vast majority of samples were processed in Uster. The total volume ofsamples was tested between spring 1997 and spring 2001.

Fig. 6 Geographical distribution of the origin of all samples procured for the USTER®

STATISTICS 2001

All data were entered into a databank and application software specifically devel-oped for this purpose was employed to compute the percentile curves and toplot the nomograms. The lion’s share of the total time spent was definitely de-voted to thoroughly testing the samples in the laboratory. Our databank hasgrown to an enormous size and consists of far more quality parameters thanhave been published in this edition of the USTER® STATISTICS.

North America

Amérique du Nord

Nordamerika

South America

Amérique du Sud

Südamerika

Western Europe

Europe de l'Ouest

Westeuropa

Asia Pacific

Asie Pacifique

Asien-Pazifik

9%

15%

35%

31%

Eastern Europe

Europe de l'Est

Osteuropa

1%

Africa & Middle East

Afrique & Proche Orient

Afrika & Naher Osten

9%

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5 Interpreting and Applying theUSTER® STATISTICS

The USTER® STATISTICS manual consists of several parts, each addressing aspecific quality aspect in the sequence from fiber to yarn. The different sectionsare arranged according to spinning system and raw material composition or yarnstyle. Each section is subdivided into distinct quality attributes (e.g. mass varia-tion, tensile properties, etc.) which are measured with different USTER® instru-ments. A measurement can consist of several individual parameters. Mass vari-ation, for instance, includes CVm and the between-sample variation CVmb. Theseparameters are presented in graphical form. The origin of the samples processedto establish the raw data is illustrated by a pie chart. These pie charts are provid-ed with each quality attribute but not with each parameter because the measure-ments were performed simultaneously on the same samples. A register is pro-vided for quick reference to the sections of interest and after leafing through thepages a couple of times, you will find it easy to work with the USTER® STATIS-TICS.

The most important element of the USTER® STATISTICS are the nomogramswith the percentile curves. The width of the percentile curves intentionally im-poses certain restrictions on accuracy – a subtle reminder of the pronouncedvariability of most textile measurements. Depending on the quality parameterdisplayed on the ordinate (vertical or y-axis), the curves are plotted over staplelength, process stage, yarn count, or defect category and the abscissa (horizon-tal or x-axis) is calibrated accordingly. The x-axis should be the starting point ofany analysis. The percentile curves refer to the percentage of the total worldproduction which equals or exceeds the measurement value given for a particu-lar yarn or fiber description. An example:

The coefficient of yarn mass variation of an Ne 20 (Nm 34, 30 tex) 100% combedcotton ring-spun yarn for knitted fabrics is measured at CVm = 13.6±0.2% by theUSTER® TESTER. A vertical line drawn from the x-axis at Ne 20 intersects withthe two horizontal lines drawn from the y-axis at 13.4% and 13.8% (lower andupper confidence limits) right at the 25th percentile line. Hence, only 25% of allNe 20 combed cotton ring-spun yarns produced worldwide have a CVm of 13.6%or better. Vice versa, 75% of the total world production of comparable Ne 20yarns exhibit a CVm greater than 13.6%.

The 50th percentile curve, commonly referred to as the 50% line, corresponds tothe median. In general terms, the median is the middle number when the mea-surements in a data set are arranged in ascending (or descending) order, i.e.50% of all observations exceed this value and the other 50% lie below. Depend-ing on whether the frequency distribution of a given quality parameter is sym-metric or skewed, the median may or may not be different from the mean.

In some instances, adjacent percentile curves fell very close together. To avoidthe formation of a solid red block, both the 25% line and 75% line were omitted,thus maintaining the clarity of the illustration.

The nomograms in the fiber properties section as well as the ones in the fiber-to-yarn and yarn quality sections for combed cotton ring-spun yarns comprise twoindependent sets of percentile curves. The two sets of curves each characterizea distinct cluster or isolated population within the same graph. We will look at thecotton fiber properties first to explain the reasons for this differentiation: Thehorizontal position of the split point at a staple length of 30...31 mm marks theapproximate center of the transition zone from both short and medium-staplecottons on one hand to long and extra long-staple cottons on the other. With thattransition, several factors change fundamentally. These factors include genetic,botanical, and physiological differences, agricultural methods, environmental in-fluences, harvesting and ginning practices, all of which have a decisive impact onfiber properties. On the yarn side, things are much simpler. Here, the divisionbetween Ne 41 (Nm 70, 14 tex) and Ne 47 (Nm 80, 12.5 tex) indicates the yarncount threshold for using longer staple, high-grade cottons with an overall supe-rior fiber quality, for increasing comber noil extraction, and for modifying the

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overall processing conditions accordingly. Selecting higher quality cotton fibersand adjusting the processing conditions is necessary to raise the spin limit to-wards the finer counts. Naturally, in the fiber-to-yarn nomograms for combedroving, the two clusters occur as well. The curves had to be split at exactly thesame position on the yarn count axis. The graphs provide an opportunity to studythese effects of raw material selection and processing.

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6 Changes to theUSTER® STATISTICS 1997

6.1 New Fiber Quality CharacteristicsThree new measurement values have been included in the tests using the AFISsingle fiber testing instrument. These are the maturity and the immature fibercontent as well as the fiber fineness.

6.2 Distinction Between Knitting and WeavingYarns

For the first time, the USTER® STATISTICS 2001 distinguish between weavingand knitting yarns. The borderline between weaving yarn and knitting yarn hasbeen determined to be the following twist multiplier:

• Combed cotton yarn �e = 3.7 (�m = 112)• Carded cotton yarn �e = 3.9 (�m = 119)

Yarns with twist multipliers below these values have been classified as knittingyarns.

6.3 New Yarn Quality CharacteristicsThe two optical sensors OM and OI were used in the tests using the USTER®

TESTER 4. They record the following quality characteristics: Variation of the yarndiameter, shape of the yarn cross-section, yarn density and the number of dustand trash particles in the yarn.

When the first USTER® STATISTICS for imperfections were published in 1957, adecision was taken after prolonged testing to define the following thresholds:thins –50%, thicks +50%, neps +200%. These values refer to the mean numberof fibers in a cross-section of a yarn.

As explained in Fig. 1, the mass unevenness improved to such an extent in thepast 40 years that often no counts can be found in combed cotton yarns in themiddle and coarse range. Therefore, a decision was taken to include the nextlower thresholds in the USTER® STATISTICS 2001, i.e. the settings: thins –40%,thicks +35%, neps +140% and for rotor yarns and airjet yarns +200%.

In addition, not only the tenacity but also the strength of yarns were determinedduring the tensile tests for the USTER® STATISTICS.

Nowadays, variations of quality characteristics are increasingly determined usingthe coefficient of variation CV. Therefore, the unevenness U was not published inthe USTER® STATISTICS 2001 anymore. The conversion factor CV = 1.25 U canbe used here for mass variations with normal distribution.

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7 Validity

The information provided with this edition supersedes all the descriptions per-taining to yarn quality published in previous editions of the USTER® STATISTICS.The quality of industrially manufactured goods is a moving target. It depends ona multitude of factors, most of which are an intrinsic function of time. The depen-dence on time is predominantly related to the state of technology of the produc-tive assets and the technological know-how prevalent in the industry. Time isalso a factor in determining the overall economic environment, the supply anddemand situation, as well as general consumer attitudes and behavior. All of theabove, acting jointly or separately, may have an effect on the quality of raw ma-terials, semi-processed, or finished textile goods. Consequently, the validity ofthe information provided in the USTER® STATISTICS 2001 is confined to the peri-od of time actually covered by the data. The data are essentially of historicalnature by the time this document is published. Naturally, such information willnot sustain its initial significance as time progresses and eventually become ob-solete unless it is updated at some point in the future. Therefore, the informationpresented in this document in either verbal, numerical, or graphical form is sub-ject to change at any time without prior or public notice. Conventional wisdomproves, however, that the USTER® STATISTICS maintain their significance overan extended period of five years or more.

With no exceptions, all the information provided in the USTER® STATISTICS 2001relates to data which have been established using USTER® products. USTER®

products are designed, manufactured, and distributed by Zellweger Uster, Swit-zerland, and Zellweger Uster Inc., USA, or authorized licensees, exclusively. Anyattempt to utilize the information provided in this document in conjunction withdata originating from sources other than USTER® instruments may result insome form of failure or damage. The USTER® STATISTICS are intended for useas a manual of comparative statistics complementing the operational installa-tions of USTER® products at the customer site. For technical details on how toensure proper agreement between the data presented in this document and dataestablished with other USTER® instruments, please refer to the appendix.

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8 Disclaimer

This publication and the information provided therein is for intended use only andsubject to change at any time without prior or public notice. Zellweger Uster willnot assume liability for any direct or indirect damage resulting from unintendeduse of this publication or the information provided therein. The use of this infor-mation for product specifications in commercial contracts is discouraged unlessclear reference is made to this publication or parts thereof and clear numericalspecifications and tolerances are provided in the contract. The use of this infor-mation for arbitration purposes is discouraged unless clear reference is made tothis publication or specified parts thereof and clear numerical specifications andtolerances are provided in legally valid contractual documents pertaining to thecharacteristics of the goods in question. The use of this information for perfor-mance guarantees relating to textile plants, textile machines, or parts or acces-sories thereof is discouraged unless clear reference is made to this publication orparts thereof and clear numerical specifications, tolerances, and restrictiveclauses pertaining to other known influences on the specified performance areprovided in the guarantee documents.

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9 Testing Conditions and Sample Sizes

All tests in relation to the USTER® STATISTICS 2001 were carried out under con-stant climatic conditions. The temperature was 20 °C, the relative humidity65%. The following table lists the testing conditions and the sample sizes.

Parameter Abbrevia- Unit Instrument No. of Teststion samples within

Micronaire Mic --- USTER® HVI 1 10

Upper Half UHML mm USTER® HVI 1 10Mean Length UI % 1 10

Bundle tenacity Strength g/tex USTER® HVI 1 10

Color Rd % USTER® HVI 1 10+b --- 1 10

Trash CNT --- USTER® HVI 1 10Area % 1 10

Neps Neps/g 1/g USTER® AFIS 1 10SCN/g 1/g 1 10

Length SFC(n) % USTER® AFIS 1 10SFC(w) % 1 10UQL(w) mm 1 10

Maturity Fine mtex USTER® AFIS 1 10IFC % 1 10Mat --- 1 10

Trash Trash/g 1/g USTER® AFIS 1 10Dust/g 1/g 1 10VFM % 1 10

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Parameter Abbrevia- Unit Instrument No. of Teststion samples within

Count CVcb % USTER® 10 1variations TESTER 4 FA Sensor

Mass CVm % USTER® 10 1variations CVmb % TESTER 4 10 1

CS Sensor

Testing speed: 400 m/minDuration of test: 2.5 min

Hairiness H --- USTER® 10 1sH --- TESTER 4 10 1CVHb % OH Sensor 10 1

Testing speed: 400 m/minDuration of test: 2.5 min

Imper- Thin places 1/1000 m USTER® 10 1fections Thick places 1/1000 m TESTER 4 10 1

Neps 1/1000 m CS Sensor 10 1

Testing speed: 400 m/minDuration of test: 2.5 min

Trash Dust 1/1000 m USTER® 10 1Trash 1/1000 m TESTER 4 10 1

OI Sensor

Testing speed: 400 m/minDuration of test: 2.5 min

Diameter CVd % USTER® 10 1variation Shape --- TESTER 4 10 1

Density g/cm3 OM Sensor 10 1

Testing speed: 400 m/minDuration of test: 2.5 min

Tensile FH cN USTER® 10 20properties RH cN/tex TENSORAPID 3 10 20

CVRH % 10 20�H % 10 20CV�H % 10 20WH cNcm 10 20CVWH % 10 20

Testing speed: 5 m/min

HV tensile FH cN USTER® 10 1000properties RH cN/tex TENSOJET 10 1000

CVRH % 10 1000�H % 10 1000CV�H % 10 1000WH cNcm 10 1000CVWH % 10 1000FHP=0,1 cN 10 1000�HP=0,1 % 10 1000

Testing speed: 400 m/min

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11 Appendix

The following paragraphs provide useful background information on the differentmeasurements introduced in the USTER® STATISTICS 2001. It is not our inten-tion to give detailed explanations of the instruments, measurement methods, orthe technological significance of each measurement, since they have been de-scribed in chapter 2. Many instrument users are well acquainted with these as-pects to begin with and specialized literature which focuses on these topics isreadily available. This appendix primarily serves to clarify certain questions thatmay arise when studying the USTER® STATISTICS and it gives valuable, practicalhints as to the origin, interpretation, and use of certain data. Needless to say thatif you have any specific needs, please do not hesitate to contact us or your near-est Zellweger Uster representative office.

11.1 Fiber PropertiesThe USTER® STATISTICS on raw cotton fiber properties have been establishedwith USTER® HVI and USTER® AFIS instruments. The corresponding nomogramshave been developed from a representative cross-section of nearly 1,200 differ-ent international cottons. All percentile curves are plotted over staple length.Staple length is the fundamental characteristic of cotton as a textile fiber. In theUSTER® STATISTICS nomograms, HVI and AFIS parameters or the percentilesindicating a certain share of the world cotton production can be determined for agiven staple length. Staple length is usually specified in the contract as classer’sor trade staple. Upper half mean length (UHML) describes the equivalent staplelength of cottons classified by HVI. An alternative is to use the 25% staple lengthby weight (UQL(w)) measured with AFIS. This measurement also closely corre-sponds to the classer's staple.

The pie charts indicating the distribution of sample origins are missing in the fiberproperties section. The reason for that is very simple: The source of each sampleis known to us, of course, but in many cases, the true geographic origin of thecottons was not. A sample may have been furnished by a German mill, for in-stance, but the respective cotton bale may have come from Central Asia orsomewhere else and these details have not always been disclosed to us.

Please note that the data in the USTER® STATISTICS cover several crop years.The average fiber quality of cottons from a certain growing region changes fromone year to another as a result of the prevalent environmental conditions duringthe growing season. With the consideration of more than one crop year, howev-er, these differences are leveled out.

11.1.1 Fiber Bundle Testing

The USTER® HVI (High-Volume Instrument) system is designed to measure largequantities of bale cotton samples within a minimum time frame. This exclusivefeature offers the possibility of classing entire cotton crops on an annual basis,the activities of the US Department of Agriculture (USDA) being an outstandingexample for such an immense project. HVI systems are also utilized to classcomplete warehouse inventories or commercial bale shipments at either the cot-ton producer’s, merchant’s, or spinner’s end of the business. Determining cottonfiber properties on a per-bale basis is a necessary prerequisite for computerizedbale management in the spinning mill. Some 1,300 HVI systems are installed inover 65 countries worldwide, serving the purposes outlined above. Typical HVImeasurements include Micronaire, fibrogram length and length uniformity, 1/8inch gauge length bundle tenacity, reflectance and yellowness on Hunter’s scaleas well as optical trash particle counts and trash area.

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There is still some confusion about the use of calibration cottons. However,since 1998 only HVI Calibration Cotton is available from the US Department ofAgriculture, Agriculture Marketing Services (USDA-AMS) in Memphis, Tennes-see, USA. The USDA discontinued the provision of ICC. Using HVI-CC and ICCfor calibration results in different test results which are not comparable witheach other and do not correlate with each other in any way. If the system iscalibrated using HVI-CC, the upper half mean length (UHML), the mean length(ML) and the uniformity index (UI) are obtained. Strength results with this calibra-tion are on a higher level than with ICC calibration cotton. Nowadays, ZellwegerUster recommends to use only HVI-CC for calibration, and all tests within theframework of the USTER® STATISTICS were conducted using an HVI-CC calibrat-ed system.

The USDA supplies special cottons for Micronaire calibration, since the Micron-aire range provided by HVI-CC cottons is not nearly large enough. Special calibra-tion tiles are available to calibrate the colorimeter and the grade boxes along witha dot matrix tile are used for trash meter calibration (USTER® HVI SPECTRUMonly dot matrix tile and self-defined cottons). The calibration tiles mentioned arepart of a USTER® HVI SPECTRUM shipment.

Both the United States Department of Agriculture, Agricultural Marketing Servic-es in Memphis, Tennessee, and the Fiber Institute in Bremen, Germany, conductregular HVI round tests on an international basis. Participation in such programsis highly recommended for the monitoring of service personnel and instrumentperformance, i.e. the consistency of the measurements and the compatibilitywith other laboratories.

Cotton fiber testing with USTER® HVI systems is a standardized procedure and isdescribed in detail in ASTM D-4605. Further explanations of the individual func-tional elements of the system, the significance of the measurements, and theproper calibration and operation of the instrument are given in the operating in-structions. Adequate sample conditioning and maintaining constant standard at-mospheric conditions in the laboratory during testing is of extreme importancebecause of the hygroscopic nature of cotton fibers. Please refer to section11.1.3 of this appendix for more information on ambient laboratory conditions forfiber testing.

References to fiber testing standards:

ISO 2403, ASTM D-1448: Micronaire reading of cotton fibersASTM D-1447: Fibrograph measurement of length and length uni-

formityASTM D-1445: Breaking strength and elongation (flat bundle method)ASTM D-2253: Nickerson/Hunter colorimeterASTM D-2812: Non-lint content of cottonASTM D-4605: High-volume instrument testing (SPINLAB system)

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11.1.2 Single Fiber Testing

The USTER® AFIS (Advanced Fiber Information System) is a sophisticated andversatile laboratory instrument for single fiber testing. A pair of pin-type openingrollers, partially surrounded by carding segments, individualize the fibers andseparate non-fibrous components. The fiber individualizer unit utilizes the princi-ple of aero-mechanical separation to extract trash particles, large seed coat frag-ments, and other types of foreign matter from the original fiber specimen. Theseobjects are conveyed through the trash channel. ndividual fibers, neps, and smallseed coat fragments (seed coat neps) pass through the fiber channel. Electro-optical sensors are installed in both the trash and the fiber channel and advancedsignal processing technology is applied to identify and characterize several thou-sand individual cotton fibers, fiber entanglements, and foreign matter. The mod-ular concept of the USTER® AFIS system provides comprehensive informationon the frequency distribution of pertinent dimensional parameters: single fiberlength and the size of neps, trash, and dust particles. The novel features of theAFIS instrument comprise the assessment of single fiber fineness and maturitydistributions as well as the discriminative detection of seed coat fragments. TheUSTER® AFIS has gained international recognition as the most sensible answerto process control and quality monitoring needs in yarn manufacturing. Some560 USTER® AFIS units are installed in 50 countries.

The abundance of information provided by the USTER® AFIS is a result of deter-mining the complete frequency distribution of each measurement. Such distribu-tions include information on the mean values, standard deviations, the numberof observations, and several other parameters that can be calculated using thesefew basic characteristics of a frequency distribution. However, in the USTER®

STATISTICS on fiber quality of cotton in bale form, only the mean values of thefollowing measurements are considered: The number of neps and of seed coatneps per gram of cotton, the percentage of fibers shorter than ½ inch (12.7 mm)by number and by weight (short fiber content, SFC(n),(w)), trash and dust parti-cle counts per gram, visible foreign matter (VFM), the number of immature fi-bers, fiber count and maturity.

Proper calibration of the instrument is a necessary prerequisite to make correctcomparisons between the actual USTER® AFIS measurements and the USTER®

STATISTICS. The calibration of an USTER® AFIS should be left to authorized Zell-weger Uster service personnel. We recommend that reference samples, e.g.round test samples, be used to monitor the consistency of the measurementsand to contact the nearest Zellweger Uster service station if unexpected chang-es or long-term drift should occur. The Fiber Institute in Bremen, Germany, con-ducts AFIS round tests on an international basis. Participation in such programsis highly recommended for closely monitoring the performance of service per-sonnel and of the instrument, i.e. the consistency of the measurements and thecompatibility with other laboratories. This, of course, includes compatibility withthe USTER® STATISTICS as well.

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Nep testing with the USTER® AFIS system is a standardized procedure and isdescribed in detail in ASTM D-5866. Further explanations of the individual func-tional elements of the system, the significance of the measurements, and theproper calibration and operation of the instrument are given in the operating in-structions. Adequate sample conditioning and maintaining constant standard at-mospheric conditions in the laboratory during testing is important. Please refer tosection 11.1.3 of this appendix for more information on ambient laboratory condi-tions for fiber testing.

References to fiber testing standards:

ASTM D-5866: AFIS nep testing

11.1.3 Ambient Laboratory Conditions for Fiber Testing

Cotton fibers are highly hygroscopic and their properties change notably as afunction of the moisture content. This is particularly critical in the case of dyna-mometric properties, e.g. cotton fiber strength. As a result, conditioning andtesting must be carried out under constant standard atmospheric conditions. Thestandard temperate atmosphere for textile testing involves a temperature of20±2 °C (68±4 °F) and 65±2% relative humidity. In tropical regions, maintaininga temperature of 27±2 °C (81±4 °F) at 65±2% relative humidity is legitimate, butthen the absolute moisture content of the conditioned air is different. Modern airconditioning systems, however, are capable of achieving 20±2 °C (68±4 °F) and65±2 % relative humidity in most any location in the world and in the interest ofinternational harmonization, these ambient conditions should be realized when-ever possible. Prior to testing, the samples must be conditioned under constantstandard atmospheric conditions until in moisture equilibrium with the surround-ing air. To attain the moisture equilibrium, a conditioning time of at least 24 hoursis required, 48 hours is preferred. For samples with a high moisture content,conditioning time should be at least 48 hours unless the samples are precondi-tioned, so that the moisture equilibrium is later approached from the dry side.During conditioning, samples should be arranged in single layers in perforatedtrays to allow conditioned air to circulate freely. The moisture content of thesamples to be tested should not differ from that of the cottons used for calibrat-ing the measuring instrument. Therefore, calibration cottons should be subjectedto the same conditioning procedures or, alternatively, stored permanently insidethe conditioned laboratory. Laboratory conditions should be monitored by appro-priate devices that record both short-term fluctuation and long-term drift.

References to fiber testing standards:

ISO 139, EN 20 139, DIN 53 802: Standard atmosphere for conditioning andtesting

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11.2 Sliver TestingThe USTER® STATISTICS for slivers based on measurements determined on-linewere completed in 1999 and may be accessed via the Internet underhttp://www.uster.com. Therefore, they have not been included in the USTER®

STATISTICS 2001.

11.3 Roving TestingThe USTER® STATISTICS 2001 again include measurements of rovings from cot-ton and worsted mills which were made in our textile laboratory using theUSTER® TESTER 4.

11.4 Yarn TestingA new aspect which frequently led to disagreements and uncertainties concernsdifferent quality requirements in relation to subsequent use of yarns in process-ing, which are manufactured and traded world wide. Hitherto, no distinction hasbeen made in the USTER® STATISTICS. This deficiency has been remedied in theUSTER® STATISTICS 2001 edition. For the first time, yarns are shown in differentnomograms according to their subsequent processing purpose, i.e. weavingyarn or knitting yarn.

As in the USTER® STATISTICS 1997 edition, a distinction has been made be-tween cotton qualities on bobbins and on packages. Again, reference measure-ments of yarn mass variations, hairiness and imperfections on bobbins and oncross-wound packages are available for 100% carded and combed ring-spun cot-ton yarns. Hereinafter, you will find the considerations at that time that led to thisdistinction particularly in the cotton segment.

Practical experience has proven time and time again that winding alters the yarnsurface structure. The impact on yarn evenness (CVm) is very limited but chang-es in imperfection counts (thin places, thick places, and neps), hairiness (H), andstandard deviation of hairiness (sH) are much more pronounced. Under normalcircumstances, the tensile properties, i.e. tenacity, elongation, and work-to-break are not affected unless yarns are subjected to excessive winding tension,which is very rarely the case and certainly not a prudent practice. A clear state-ment must be made concerning the role of the winding machine: Changes in theyarn surface structure due to winding cannot be avoided. Nobody would honest-ly expect a yarn to become better after it has been accelerated from zero to 1200m/min or more in a few milliseconds while being pulled off the bobbin, draggedacross several deflection bars and eyelets, forced into a traverse motion atspeeds that make it invisible, and finally rolled up into a firm construction calledpackage or cone. The factors that affect the yarn structure during winding in-clude the frictional properties of the yarn itself, the bobbin geometry and thebobbin unwinding behavior, winding speed, winding geometry as well as thenumber and design of the yarn/machine contact points. However, much as thebobbin unwinding behavior today is the limiting factor for winding speed, it isalso the main reason for these changes in yarn structure. Most of the damageoccurs at the moment when the end is detached and removed from the tightassembly of yarn layers on the bobbin and dragged along the tube at very highspeeds.

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High-speed, automatic winders have frequently been blamed for causing highernep counts but this is not a correct statement. Typical nep-type imperfections,i.e. short mass defects, can be identified as tight fiber entanglements, clumps ofimmature or dead cotton fibers, or seed coat fragments. Naturally, such defectsare not produced by the winding machine. The increase in nep counts after wind-ing is related to the formation of loose fiber accumulations. These fiber accumu-lations represent a true mass defect, yet their appearance in the yarn and in thefinal fabric is clearly different from that of typical fiber entanglements or seedcoat fragments.

When testing 100% cotton yarns in package form for evenness, imperfections,and hairiness with the USTER® TESTER, some very fine and delicate yarns willagain respond with marginal structural changes. This is not a result of mechani-cal stress like in winding but a natural reaction caused by the reversal of the yarnrunning direction. Directional influences are omnipresent; they become apparentin all subsequent processing stages. The evidence of changes in the yarn surfacestructure due to the winding process or as a result of reversing the yarn runningdirection is confined to a few very delicate 100% man-made fiber yarns, coreyarns, and 100% cotton yarns finer than Ne 60 (Nm 100, 10 tex). We recom-mend, however, that the USTER® STATISTICS on 100% carded and combed cot-ton ring-spun yarns on cross-wound packages be referred to whenever massvariation, hairiness, and imperfections of cotton yarns in package form are ofinterest. Since the tensile properties are not affected by the phenomena de-scribed above, the USTER® STATISTICS on ring-spun bobbins should be used forpackages as well. The STATISTICS on count variation and the between-samplecoefficients of variation of evenness and hairiness are only useful when testingbobbins. Testing packages of ring-spun yarns always involves the risk of catchingthe top end of one bobbin and the bottom end of another (plus the splice inbetween), which may distort the measurements.

Incorrect comparisons with the USTER® STATISTICS may also result from test-ing actively conditioned yarns. Active thermal conditioning is performed at thevery end of the manufacturing process to suppress the twist liveliness or theyarn torque. This is normally accomplished by treating bobbins or packages withhigh-temperature water vapor in a conditioning chamber or in a vacuum environ-ment with low-temperature saturated steam in the gaseous phase. In any case,the moisture regain of the fibers may alter their physical properties and affectcapacitive yarn testing. In addition, the moisture is not always homogeneouslydistributed within a thermally conditioned bobbin or package. Therefore, changesin tenacity, elongation, and work-to-break as well as evenness, imperfections,and defect levels must be expected. The bobbin and package samples testedwithin the framework of the USTER® STATISTICS have been cleared of all pack-ing material upon receipt, preconditioned in a dry atmosphere for several days orweeks, and conditioned to moisture equilibrium under constant standard atmo-spheric conditions. By doing so, any adverse effects on testing caused by ther-mal conditioning are completely eliminated. Please refer to section 11.4.9 of thisappendix for more information on proper sample conditioning and ambient labo-ratory conditions for yarn testing.

The influence of the raw material on the quality of spun yarns has been exten-sively covered on the first pages of these USTER® STATISTICS. It is a true fact oflife that nobody can spin a world-class yarn from coarse wool or short and weakcotton fibers even if the latest and best machinery is employed. The quality sta-tus achieved by a spinner always represents the compound effect of the skills ofthe work force and the management, the performance of the machines, thequality of the raw material, and the know-how in processing technology.

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11.4.1 Count Variation Testing

The term count variation (CVcb) denotes the between-sample coefficient of vari-ation of yarn count in percent. Count variation can be determined semi-automat-ically with the USTER® AUTOSORTER by reeling 100 m or 120 yards of yarn offeach bobbin or package and placing each skein on the balance. The calculation isperformed by the instrument. The F/A module of the USTER® TESTER 4 providesa fully automatic determination of the yarn count and count variation.

Count variation is no longer as critical as it used to be some years ago. It is awell-documented fact that a count variation of CVcb>3.0% can impair fabric ap-pearance, primarily in knitting. However, the application of feed control systemsfrom the bale opener to the card, short-term and long-term card autoleveling,and drawframe autoleveling at ever shorter lengths, in particular, has improvedthe situation appreciably.

Proper calibration of the instrument is a necessary prerequisite to make correctcomparisons between the actual AUTOSORTER or USTER® TESTER 4 measure-ments and the USTER® STATISTICS on count variation. The calibration of an AU-TOSORTER or USTER® TESTER should be left to authorized Zellweger Uster ser-vice personnel. Please contact the nearest Zellweger Uster service station if un-expected changes or long-term drift should occur. TESTEX AG in Zurich, Switzer-land, conducts yarn quality round tests on an international basis. Participation insuch a program is highly recommended for closely monitoring the performanceof the serivce personnel and of the instrument, i.e. the consistency of the mea-surements and the compatibility with other laboratories. This, of course, includescompatibility with the USTER® STATISTICS as well.

The determination of the yarn count is a standardized procedure and is describedin detail in ISO 2060. Further explanations of the individual functional elements ofthe USTER® AUTOSORTER or the USTER® TESTER 4, the significance of themeasurements, and the proper calibration and operation of the instruments aregiven in the operating instructions. Adequate sample conditioning and maintain-ing constant standard atmospheric conditions in the laboratory during testing isimportant. Please refer to section 11.4.9 of this appendix for more informationon ambient laboratory conditions for yarn testing.

References to count variation testing

ISO 2060, DIN 53 830: Determination of yarn count

11.4.2 Mass Variation Testing

The assessment of mass variation with the USTER® TESTER needs no introduc-tion. The USTER® STATISTICS on mass variation include nomograms on the co-efficient of variation of yarn mass (CVm) and the between-sample coefficient ofvariation of the CVm (CVmb). A USTER® TESTER 4 has been used for testing of allyarn samples that have been procured for the USTER® STATISTICS 2001. How-ever, the STATISTICS on mass variation are fully compatible with the data provid-ed by the preceding product generations, i.e. USTER® TESTER 1, USTER®

TESTER 2, and USTER® TESTER 3.

Proper calibration of the instrument is a necessary prerequisite to make correctcomparisons between the actual USTER® TESTER measurements and theUSTER® STATISTICS on mass variation. The calibration of a USTER® TESTERshould be left to authorized Zellweger Uster service personnel. Please contact

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the nearest Zellweger Uster service station if unexpected changes or long-termdrift should occur. TESTEX AG in Zurich, Switzerland, conducts yarn quality roundtests on an international basis. Participation in such a program is highly recom-mended for closely monitoring the performance of the service personnel and ofthe instrument, i.e. the consistency of the measurements and the compatibilitywith other laboratories. This, of course, includes compatibility with the USTER®

STATISTICS as well.

The determination of yarn unevenness by electronic yarn testing instrumentswith capacitive sensors is a standardized procedure and is described in detail inISO 2649. Further explanations of the individual functional elements of theUSTER® TESTER, the significance of the measurements, and the proper calibra-tion and operation of the instrument are given in the operating instructions and inthe application handbook on evenness testing. Adequate sample conditioningand maintaining constant standard atmospheric conditions in the laboratory dur-ing testing is important. Please refer to section 11.4.9 of this appendix for moreinformation on ambient laboratory conditions for yarn testing.

References to yarn mass variation standards:

ISO 2649, DIN 53 817: Determination of yarn evenness

11.4.3 Yarn Hairiness Testing

The first statistical information on yarn hairiness was presented in the 1989 edi-tion of the USTER® STATISTICS. In the following years, the hairiness measure-ment has become firmly established in the industry. The hairiness module of theUSTER® TESTER 4 consists of an electro-optical sensor which converts the scat-tered light reflections of the peripheral fibers into a corresponding electrical sig-nal while the solid yarn body is eclipsed. The hairiness measurement is per-formed simultaneously with the measurement of yarn evenness and imperfec-tions. Yarn hairiness is expressed in the form of the hairiness value H, which isan indirect measure for the number and the cumulative length of all fibers pro-truding from the yarn surface. This value, along with the within-sample standarddeviation of hairiness (sH) and the between-sample coefficient of variation ofhairiness (CVHb), is covered by the USTER® STATISTICS.

High or low hairiness, even when going to the extremes, is not necessarily aquality deficiency. The yarn hairiness requirements are strictly governed by theend use. Yarns with higher hairiness are usually produced for end uses in knit-ting, such as underwear, knitted outerwear, and sportswear. Most weaving ap-plications call for a smooth yarn surface, especially with warp yarns. A typicalexception are pile yarns for terry fabrics, which often exhibit a high hairiness.Greater hairiness can also improve the filling insertion behavior (air friendliness)of certain yarns processed on high-speed air-jet weaving machines.

One aspect that is not reflected in the USTER® STATISTICS on yarn hairiness isthe occurrence of periodic hairiness defects. While modern yarn monitoring sys-tems detect mass periodicities with a high degree of accuracy and reliability,there is no on-line monitoring system for hairiness. Consequently, knowledge ofthe average hairiness of a yarn does not preclude the existence of periodic hairi-ness defects, which adversely affect fabric appearance. In some cases, a highstandard deviation of hairiness is at least an indication of the presence of hairi-ness periodicities.

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Proper calibration of the instrument is a necessary prerequisite to make correctcomparisons between the actual USTER® TESTER 4 measurements and theUSTER® STATISTICS on yarn hairiness. The calibration of a USTER® TESTER 4hairiness module should be left to authorized Zellweger Uster service personnel.Please contact the nearest Zellweger Uster service station if unexpected chang-es or long-term drift should occur. TESTEX AG in Zurich, Switzerland, conductsyarn quality round tests on an international basis. Participation in such a programis highly recommended for closely monitoring the performance of the servicepersonnel and of the instrument, i.e. the consistency of the measurements andthe compatibility with other laboratories. This, of course, includes compatibilitywith the USTER® STATISTICS as well.

Further explanations of the individual functional elements of the hairiness mod-ule of the USTER® TESTER 4, the significance of the measurements, and theproper calibration and operation of the module are given in the operating instruc-tions and in the application handbook on hairiness testing. Adequate sample con-ditioning and maintaining constant standard atmospheric conditions in the labora-tory during testing is important. Please refer to section 11.4.9 of this appendixfor more information on ambient laboratory conditions for yarn testing.

11.4.4 Imperfections Testing

The USTER® STATISTICS on imperfections include nomograms on the number ofthick places, thin places, and neps per 1,000 m of yarn as determined with theUSTER® TESTER. The sensitivity settings for the detection of imperfections are –50% for thin places, +50% for thick places, and +200% for neps. As mentionedunder 6.3, the next lower thresholds –40%, +35% and +140% have been includ-ed in USTER® STATISTICS for the first time. These settings are commonly usedfor all yarn types except rotor-spun yarns. The structure of rotor-spun yarns isintrinsically different from that of conventional ring-spun yarns. Neps in rotor-spun yarns tend to be spun into the solid yarn body rather than remaining on theyarn surface, which is typical for ring-spun yarns. Although embedded in the yarncore, these neps still represent a short mass defect and they will therefore trig-ger the imperfection counter upon exceeding the preset threshold value. Howev-er, compared to neps that are attached to the yarn surface, fully embedded nepsare barely perceptible for the human eye. In order to balance the typical visualappearance of rotor-spun yarns with the imperfection counts of the USTER®

TESTER, the +280% sensitivity setting for neps has become a common conven-tion for the testing of rotor-spun yarns. In addition to the 280 % neps, nep class+200% has been included for the first time as an additional nomogram for OErotor-spun yarns and airjet yarns.

A USTER® TESTER 4 has been used for the testing of all yarn samples that havebeen procured for the USTER® STATISTICS 2001. However, the STATISTICSon yarn imperfections are compatible with the data provided by the precedingproduct generations, i.e. USTER® TESTER 1, USTER® TESTER 2, and USTER®

TESTER 3.

Proper calibration of the instrument is a necessary prerequisite to make correctcomparisons between the actual USTER® TESTER measurements and theUSTER® STATISTICS on yarn imperfections. The calibration of a USTER® TESTERshould be left to authorized Zellweger Uster service personnel. Please contactthe nearest Zellweger Uster service station if unexpected changes or long-termdrift should occur. TESTEX AG in Zurich, Switzerland, conducts yarn quality roundtests on an international basis. Participation in such a program is highly recom-mended for closely monitoring the performance of the service personnel and ofthe instrument, i.e. the consistency of the measurements and the compatibilitywith other laboratories. This, of course, includes compatibility with the USTER®

STATISTICS as well.

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Further explanations of the individual functional elements of the imperfectioncounter of the USTER® TESTER, the significance of the measurements, and theproper calibration and operation of the instrument are given in the operating in-structions and in the application handbook on evenness testing. Adequate sam-ple conditioning and maintaining constant standard atmospheric conditions in thelaboratory during testing is important. Please refer to section 11.4.9 of this ap-pendix for more information on ambient laboratory conditions for yarn testing.

11.4.5 Yarn Diameter, Cross-sectional Shape and DensityTesting

The USTER® STATISTICS 2001 include the coefficient of variation of the yarndiameter, the cross-sectional shape and density. Increasing experience in usingtextile measuring instruments resulted in ever-growing demands on yarns andthe appearance of woven and knitted fabrics. Time and again it was noticed thattextile measuring sensors which have been known for a long time can explain agreat deal, but there are still defects in textile formations which are difficult tointerpret. Moreover, quality losses occur during process control which are invari-ably difficult to explain. Therefore, Zellweger Uster decided some years ago todevelop two more sensors in addition to the well-known sensors used to deter-mine mass variation and the sensors used to analyze hairiness:

• Optical sensor to measure yarn diameter, cross-sectional shape of yarns, den-sity and surface structure.

• Optical sensor to determine any remaining yarn trash and yarn dust.

The optical sensor to measure the yarn diameter uses two light sources ar-ranged at a 90 degree angle to examine the yarn. This arrangement guarantees ahigh stability of the measurement, and at the same time it is possible to measurethe roundness of the yarns, since the roundness of yarns also influences theappearance of textile fabrics.

11.4.6 Yarn Trash and Yarn Dust Testing

The sensor to determine yarn trash and yarn dust is used to detect remainingtrash and dust in the yarn. It is therefore possible to monitor the reduction of thetrash and dust content during the entire spinning process. Trash and dust con-tained in the yarn is of particular significance for processing yarns on weavinglooms and knitting machines. The two quality characteristics, trash and dust inyarns, have also been included in the USTER® STATISTICS 2001.

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11.4.7 Tensile Properties Testing

The USTER® STATISTICS on tensile properties are valid for measurements per-formed with the USTER® TENSORAPID single-end tensile testing instrument.Nomograms are available for breaking force (FH), breaking tenacity (RH), break-ing elongation (�H) and work-to-break (WH) as well as for the total coefficients ofvariation of each one of these parameters (CVRH, CV�H, CVWH). The total coeffi-cient of variation describes the overall variability of a tested lot, i.e. the within-sample variation plus the between-sample variation. If 20 individual single-endtensile tests are performed on each of ten bobbins or packages in a sample lot,the total coefficient of variation is calculated from the pooled data of the totalnumber of tests (200 in this example) that were carried out.

The terminology used for describing the tensile properties may raise some ques-tions. In the USTER® STATISTICS, we have applied the same terminology that isused in the international standards on textile testing. However, these standard-ized denominations are not always clear. The following must be carefully consid-ered: The breaking tenacity is calculated from the peak force which occurs any-where between the beginning of the test and the final rupture of the specimen.The peak force or maximum force is not identical with the force measured at thevery moment of rupture (force at rupture). The breaking elongation is calculatedfrom the clamp displacement at the point of peak force. The elongation at peakforce is not identical with the elongation at the very moment of rupture (elonga-tion at rupture). The work-to-break is defined as the area below the stress/straincurve drawn to the point of peak force and the corresponding elongation at peakforce. The work at the point of peak force is not identical with the work at thevery moment of rupture (work-to-rupture). In the USTER® STATISTICS on tensileproperties, all parameters are derived from the true peak force measurement.However, as long as the stress/strain curve of a yarn exhibits a linear or progres-sive characteristic, these differences are irrelevant because the maximum forceis very much the same as the force at the point of rupture. This is the case, forinstance, with 100% cotton yarns. But: When the stress/strain curve shows adegressive characteristic, the peak force may be higher than the force at ruptureand the elongation at peak force is lower than the elongation at rupture. This isthe case with worsted yarns or yarns which are spun from certain man-madefibers. When comparing data on tensile yarn properties with the USTER® STATIS-TICS, the true meaning of these measurements must be known. Some numberwhich happens to be declared as yarn strength, for instance, must not necessar-ily be compatible with the USTER® STATISTICS. The application handbook ontensile testing with the USTER® TENSORAPID is highly recommended to thosewho may wish to obtain further information on these topics.

The USTER® TENSORAPID applies the CRE principle of tensile testing. The termCRE serves as an abbreviation for ‹constant rate of extension›. CRE describesthe simple fact that the moving clamp is displaced at a constant velocity. As aresult, the specimen between the stationary and the moving clamp is extendedby a constant distance per unit of time and the force required to do so is mea-sured. The following details are of utmost importance in ensuring compatibilitybetween the data presented in the USTER® STATISTICS and the data on tensileproperties obtained in practice: To be compatible, a measurement must be per-formed according to the CRE principle. The velocity of the moving clamp, alsoreferred to as the testing speed, must be exactly 5 m/min. The gauge length, i.e.the length of the specimen or the distance between the stationary and the mov-ing clamp should be 500 mm and a pretension of 0.5 cN/tex must be applied.Testing conditions that deviate from this description will most certainly result indifferent measurement values.

CRE single-end testing at 5 m/min is the most widely accepted practice in theinternational textile industry and it has therefore been chosen as the testingmode for the USTER® STATISTICS on tensile properties. However, other meth-ods are still being applied but their significance is deteriorating rapidly. These

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methods include CRE single-end testing with 20 s time-to-break. Textile materi-als exhibit a partially viscoelastic behavior and their tensile properties changenotably as a function of the time during which mechanical forces and deforma-tions are acting upon a fiber, yarn, or fabric. Therefore, the tensile properties ofyarns also change with the testing speed. The difference between a time-to-break of 20 s and the 0.2…0.4 s required to break a specimen made of fiber-spun yarns at 5 m/min causes significant differences between the respectivemeasurement values. Similar discrepancies may occur when comparing CRL(constant rate of load) single-end measurements from the USTER® DYNAMATwith the CRE 5 m/min TENSORAPID data provided in the USTER® STATISTICS.In general, there are two fundamental criteria which affect the compatibility be-tween different measurements of tensile yarn properties: Criterion number oneis the testing conditions, i.e. the testing principle (CRE, CRL), testing speed,gauge length, and pretensioning. The second criterion, which also affects themagnitude of the differences, relates to the specific stress/strain characteristicof the yarn itself, which is determined by the fibrous materials, the blend ratio,and the yarn construction. A detailed appraisal of the various tensile testing sys-tems and the reasons for the differences between the measurements is provid-ed in the application handbook on tensile testing with the USTER® TENSORAPID.

Proper calibration of the instrument is a necessary prerequisite to make correctcomparisons between the actual USTER® TENSORAPID measurements and theUSTER® STATISTICS on tensile properties. The calibration of a USTER® TENSO-RAPID should be left to authorized Zellweger Uster service personnel. Pleasecontact the nearest Zellweger Uster service station if unexpected changes orlong-term drift should occur. TESTEX AG in Zurich, Switzerland, conducts yarnquality round tests on an international basis. Participation in such a program ishighly recommended for closely monitoring the performance of the service per-sonnel and of the instrument, i.e. the consistency of the measurements and thecompatibility with other laboratories. This, of course, includes compatibility withthe USTER® STATISTICS as well.

The determination of the CRE tensile properties of yarns by means of electronicyarn testing instruments is a standardized procedure and is described in detail inISO 2062. However: While the basic procedures of automatic CRE single-endtensile testing are outlined in all applicable national and international standards,the testing speed of 5 m/min – much to our regret – has not yet been consid-ered. In spite of this shortcoming, it is definitely the preferred mode of tensiletesting from a global point of view.

Further explanations of the individual functional elements of the USTER® TEN-SORAPID, the significance of the measurements, and the proper calibration andoperation of the instrument are given in the operating instructions and in theapplication handbook on tensile testing. Adequate sample conditioning and main-taining constant standard atmospheric conditions in the laboratory during testingis important. Please refer to section 11.4.9 of this appendix for more informationon ambient laboratory conditions for yarn testing.

References to tensile testing standards:

ISO 2062, ASTM D-1578, DIN 53 834: Single-end tensile testing

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11.4.8 HV Tensile Properties Testing

The term HV tensile properties is used for describing a novel method of tensiletesting. HV stands for high-volume and high-velocity. The USTER® TENSOJET isa laboratory instrument which for the first time provides true high-volume andhigh-velocity features in tensile testing. With the USTER® TENSOJET, the mech-anism which is used for applying a tensile force, to extend, and ultimately breaka specimen consists of two pairs of cam-type rollers, arranged at a distance of500 mm. The top and bottom cam-type rollers are designed to allow an end to beinserted between the rollers, to be clamped at the nip point, and to be extendedjust a fraction of a second later. A force sensor is installed in the yarn channelwhich connects the two pairs of rollers. The curvature of the yarn channel caus-es a flat angle deflection of the yarn at the tip of the sensor so that the radialcomponent of the tensile force can be measured. The entire measurement cycleconsists of four phases: continuous yarn take-up and intermediate storage, in-sertion of the end by a compressed air nozzle, clamping and extension to ruptureby the rollers, and removal of the broken end into the waste bin via an air flow.The USTER® TENSOJET operates according to the CRE principle at a testingspeed of 400 m/min. The actual time-to-break is in the neighborhood of 3 ms fora 100% cotton yarn. As a result, the instrument is capable of performing 30,000individual breaks per hour and offers the possibility of testing an enormousamount of yarn within a very reasonable time frame. Such dramatic increases insample size provide a suitable means for the detection and assessment of spo-radic weak places in the yarn, which dictate the yarn breakage frequency andmachine efficiencies in subsequent processing. High-performance tensile test-ing with the USTER® TENSOJET is also an almost perfect simulation of the dy-namic loads which affect a yarn during filling insertion on high-speed weavingmachines.

In the USTER® STATISTICS on HV tensile properties, nomograms are availablefor breaking force (FH), breaking tenacity (RH), breaking elongation (�H), andwork-to-break (WH) as well as for the total coefficients of variation of these pa-rameters (CVRH, CV�H, CVWH). In general terms, the TENSOJET measurementscorrespond to those provided in the USTER® STATISTICS on tensile properties asdetermined with the USTER® TENSORAPID and the previous paragraph can bereferred to for more detailed explanations. However, due to the significant differ-ence in testing speed, TENSOJET compared to TENSORAPID measurementsshow generally higher force values.

The nomograms on the percentile values of breaking force (FP=0.1) and breakingelongation (�P=0.1) relate to the occurrence of weak places in spun yarns. Thepercentile value 0.1% of the breaking force (FP=0.1) signifies that 0.1% of allmeasurements exhibit a breaking force that is equal to or lower than the speci-fied value. For the USTER® STATISTICS, ten samples of each lot have been se-lected and 1,000 individual tensile tests have been performed on each bobbin orpackage. This is a total of 10,000 measurements per lot. The percentile value0.1 % of the breaking force indicates that ten measurements (0.1% of 10,000breaks) lie below that value. An example:

The percentile value 0.1% of the breaking force of an Ne 20 (Nm 34, 29.5 tex),100% carded cotton ring-spun yarn was measured at FP=0.1 = 400 cN, whichcan be converted into RP=0.1 = 13.6 cN/tex. Consequently, 0.1 % of all measure-ments represent weak places with a breaking force of less than 400 cN or abreaking tenacity of less than 13.6 cN/tex. If ten bobbins have been tested, eachwith 1,000 breaks, this equates to a total of ten such weak places. The percen-tile value 0.1% of the breaking force FP=0.1 = 400 cN corresponds to the 50th

percentile of the USTER® STATISTICS.

In this context, it is very important to keep in mind that a comparison with theUSTER® STATISTICS on weak places is only permissible if the total number ofbreaks performed on a sample lot is exactly 10,000. Percentile values of both the

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breaking force and the breaking elongation that have been determined with few-er or more than 10,000 breaks cannot be compared with the data provided in theUSTER® STATISTICS.

Proper calibration of the instrument is a necessary prerequisite to make correctcomparisons between the actual USTER® TENSOJET measurements and theUSTER® STATISTICS on HV tensile properties. The calibration of a USTER® TEN-SOJET should be left to authorized Zellweger Uster service personnel. Pleasecontact the nearest Zellweger Uster service station if unexpected changes orlong-term drift should occur. TESTEX AG in Zurich, Switzerland, conducts yarnquality round tests on an international basis. Participation in such a program ishighly recommended for closely monitoring the performance of the service per-sonnel and of the instrument, i.e. the consistency of the measurements and thecompatibility with other laboratories. This, of course, includes compatibility withthe USTER® STATISTICS as well.

Further explanations of the individual functional elements of the USTER® TENSO-JET, the significance of the measurements, and the proper calibration and opera-tion of the instrument are given in the operating instructions. Adequate sampleconditioning and maintaining constant standard atmospheric conditions in thelaboratory during testing is important. Please refer to section 11.4.9 of this ap-pendix for more information on ambient laboratory conditions for yarn testing.

11.4.9 Ambient Laboratory Conditions for Yarn Testing

Some textile fibers are highly hygroscopic and their properties change notably asa function of the moisture content. Typical hygroscopic fibers are cotton, wool,rayon, silk, flax, etc. Moisture content is particularly critical in the case of dyna-mometric properties, i.e. yarn tenacity, elongation, and work-to-break, but yarnevenness, imperfections, and defect levels are also affected. As a result, condi-tioning and testing must be carried out under constant standard atmosphericconditions. The standard temperate atmosphere for textile testing involves atemperature of 20±2 °C (68±4 °F) and 65±2 % relative humidity. In tropical re-gions, maintaining a temperature of 27±2 °C (81±4 °F) at 65±2% relative humid-ity is legitimate, but then the absolute moisture content of the conditioned air isdifferent. Modern air conditioning systems, however, are capable of achieving20±2 °C (68±4 °F) and 65±2 % relative humidity in most any location in theworld and in the interest of international harmonization, these ambient condi-tions should be realized whenever possible. Prior to testing, the samples mustbe conditioned under constant standard atmospheric conditions until in moistureequilibrium with the surrounding air. To attain the moisture equilibrium, a condi-tioning time of at least 24 hours is required, 48 hours is preferred. For sampleswith a high moisture content (thermally conditioned yarns), conditioning timeshould be at least 48 hours. The best practice is to precondition such samples ina dry atmosphere, so that the moisture equilibrium is later approached from thedry side. During conditioning, the samples must be removed from any boxes orcontainers used for transportation, cleared from all packing material, placed in anupright position to expose the entire bobbin or package surface to the condi-tioned air, and arranged in such a fashion that ample space is left between thesamples to allow conditioned air to circulate freely. Laboratory conditions shouldbe monitored by appropriate devices that record both short-term fluctuation andlong-term drift.

References to standards defining the standard atmosphere for conditioning andtesting:

ISO 139, EN 20 139, DIN 53 802: Standard atmosphere for conditioning andtesting

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11.5 Useful Conversions

11.5.1 English/Metric Conversions

English Unit Abbre- Metric Unit Metric Unit Abbre- English Unit(US) viation viation (US)

Length Lengthinch in 2.54 cm centimeter cm 0.3937 infoot (=12 in) ft 30.48 cm meter m 3.28 ftyard (=3 ft) yd 0.9144 m meter m 1.0936 ydmile mile 1609.344 m kilometer km 0.6241 mile

Area Areasquare inch in2 6.4516 cm2 square centimeter cm2 0.155 in2

square foot ft2 929.030 cm2 square meter m2 10.76 ft2

square yard yd2 0.836 m2 square meter m2 1.196 yd2

acre ac 0.405 ha hectare ha 2.47 acsquare mile mile2 2589.99 m2 square kilometer km2 0.386 mile2

Volume Volumecubic inch in3 16.3871 cm3 cubic centimeter cm3 0.061 in3

cubic foot ft3 0.0283 m3 cubic meter m3 35.288 ft3

cubic yard yd3 0.7646 m3 cubic meter m3 1.308 yd3

fluid ounce fl oz 28.4 ml milliliter ml 0.0352 fl ozpint pt 0.473 l liter l 2.11 ptgallon gal 3.79 l liter l 0.264 gal

Mass Massgrain gr 0.0648 g gram g 15.432 grounce oz 28.3495 g gram g 0.0353 ozpound lb 0.4536 kg kilogram kg 2.205 lb

Force Forcegram-force gf 0.9807 cN centi-Newton cN 1.02 gfpound-force lbf 4.4483 N Newton N 0.2248 lbf

Pressure Pressurepound-force/in2 p.s.i. 6894.76 Pa bar (=105 Pa) bar 14.5 p.s.i.pound-force/ft2 p.s.f. 47.8803 Pa Pascal (N/m2) Pa 0.0209 p.s.f.

Tenacity Tenacitygram-force/den gf/den 8.838 cN/tex centi-Newton/tex cN/tex 0.113 gf/dengram-force/tex gf/tex 0.9807 cN/tex centi-Newton/tex cN/tex 1.02 gf/tex

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tex dtex den Nm NeC NeW NeL grains/yd

dtex den 1000 590.54 885.8 1653.510 9 Nm NeC NeW NeL

den 10000 5905.4 8858 165350.9 Nm NeC NeW NeL

9000 5314.9 7972.3 14882Nm NeC NeW NeL

1000 10000 9000 14.1tex dtex den gr/yd

590.54 5905.4 5314.9 NeW NeL 8.33tex dtex den 1.5 2.8 gr/yd

885.8 8858 7972.3 NeL 12.5tex dtex den 1.87 gr/yd

1653.5 16535 14882 23.33tex dtex den gr/yd

tex tex den 14.1 8.33 12.5 23.3370.86 708.6 637.7 Nm NeC NeW NeL

Nm = metric count NeC = cotton count NeW = worsted count NeL = linen count

Nm · 0.5905

Nm · 0.8858 NeC · 1.5

Nm · 1.6535 NeC · 2.8 NeW · 1.87

NeC · 1.6934 NeW · 1.13 NeL · 0.6048

gr/yd · 70.86

gr/yd · 708.6

gr/yd · 637.7

11.5.2 Count Conversions

11.5.3 Staple Conversion Chart 11.5.4 Special Conversions

Category inches 32nds decimals mm

13 / 16 26 0.81 20.6short 27 / 32 27 0.84 21.4

7 / 8 28 0.88 22.229 / 32 29 0.91 23.015 / 16 30 0.94 23.8

31 / 32 31 0.97 24.6medium 1 32 1.00 25.4

1 1 / 32 33 1.03 26.21 1 / 16 34 1.06 27.01 3 / 32 35 1.09 27.8

1 1 / 8 36 1.13 28.6medium to long 1 5 / 32 37 1.16 29.4

1 3 / 16 38 1.19 30.21 7 / 32 39 1.22 31.01 1 / 4 40 1.25 31.8

long 1 9 / 32 41 1.28 32.51 5 / 16 42 1.31 33.31 11 / 32 43 1.34 34.11 3 / 8 44 1.38 34.91 13 / 32 45 1.41 35.7

extra long 1 7 / 16 46 1.44 36.51 15 / 32 47 1.47 37.31 1 / 2 48 1.50 38.11 17 / 32 49 1.53 38.91 9 / 16 50 1.56 39.7

1 19 / 32 51 1.59 40.51 5 / 8 52 1.63 41.3

tex =

dtex = tex · 10

den = tex · 9 dtex · 0.9

Nm =

NeC =

NeW =

NeL =

grains/yd =

Rkm = 1.0197 · cN/texcN/tex = 0.9807 · Rkm

Twist Multiplier �e = 0.031 ·��mTwist Multiplier �m = 30.25 · �e

Turns per inch t.p.i. = 0.0254 · T/mTurns per meter T/m = 39.37 · t.p.i.

Fahrenheit °F = 1.8 · (°C+32)Centigrade °C = 0.5556 · (°F–32)

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11.6 References

[1] Richert, U.: Benchmarking. Ein Werkzeug des Total QualityManagement – Teil 1: Begriffe, Ziele und Me-thodenQZ Qualität und Zuverlässigkeit 40Germany (March 1995)

[2] Richert, U.: Benchmarking. Ein Werkzeug des Total QualityManagement – Teil 2QZ Qualität und Zuverlässigkeit 40Germany (April 1995)

[3] Anonymous: Textiles and Clothing: An Introduction to QualityRequirements in Selected MarketsInternational Trade Centre UNCTAD/GATTGeneva, Switzerland (1994)

[4] Frey, M.; Douglas, K.: Yarn Quality Characteristics Necessary to Satisfythe Demands of Subsequent Processing and theAppearance of the Finished FabricZellweger Uster Special Print SE 478Uster, Switzerland (1992)

[5] Frey, M.; Douglas, K.: Characteristics of Ring-Spun Yarns for KnittingZellweger Uster Special Print SE 481Uster, Switzerland (1994)

[6] Morris, D. E.: The European Community Market for CottonYarns and Cotton Grey ClothsInternational Trade Centre UNCTAD/WTOGeneva, Switzerland (1996)

[7] Strolz, H.; Munkholt, P.: 1995 International Production Cost ComparisonInternational Textile Manufacturers FederationZürich, Switzerland (1995)