FIBERS TESTINGIMPORTANCE OF RAW MATERIAL IN YARN MANUFACTURING

Raw material represents about 50 to 70% of the production cost of a short-staple yarn. This fact is sufficient to indicate the significance of the raw material for the yarn producer. It is not possible to use a problem-free raw material always, because cotton is a natural fibers and there are many properties which will affect the performance. If all the properties have to be good for the cotton, the raw material would be too expensive. To produce a good yarn with this difficulties, an intimate knowledge of the raw material and its behaviour in processing is a must.

Fibers characteristics must be classified according to a certain sequence of importance with respect to the end product and the spinning process. Moreover, such quantified characteristics must also be assessed with reference to the following

What is the ideal value? What amount of variation is acceptable in the bale material? What amount of variation is acceptable in the final blend

Such valuable experience, which allows one to determine the most suitable use for the raw material, can only be obtained by means of a long, intensified and direct association with the raw material, the spinning process and the end product.

Low cost yarn manufacture, fulfilling of all quality requirements and a controlled fibers feed with known fibers properties are necessary in order to compete on the world's textile markets. Yarn production begins with the raw material in bales, whereby success or failure is determined by the fibers quality, its price and availability. Successful yarn producers optimize profits by a process oriented selection and mixing of the raw material, followed by optimization of the machine settings, production rates, operating elements, etc. Simultaneously, quality is ensured by means of a closed loop control system, which requires the application of supervisory system at spinning and spinning preparation, as well as a means of selecting the most suitable bale mix.

BASIC FIBERS CHARACTERISTICS

A textile fibers is a peculiar object. It has not truly fixed length, width, thickness, shape and cross-section. Growth of natural fibers or production factors of manmade fibers are responsible for this situation. An individual fibers, if examined carefully, will be seen to vary in cross-sectional area along it length. This may be the result of variations in growth rate, caused by dietary, metabolic, nutrient-supply, seasonal, weather, or other factors influencing the rate of cell development in natural fibers. Surface characteristics also play some part in increasing the variability of fibers shape. The scales of wool, the twisted arrangement of cotton, the nodes appearing at intervals along the cellulosic natural fibers etc.

Following are the basic characteristics of cotton fibers :

Fibers length Fineness Strength

Maturity Rigidity Fibers friction Structural features

STANDARD ATMOSPHERE FOR TESTING

The atmosphere in which physical tests on textile materials are performed. It has a relative humidity of 65 + 2 per cent and a temperature of 20 + 2° C. In tropical and sub-tropical countries, an alternative standard atmosphere for testing with a relative humidity of 65 + 2 per cent and a temperature of 27 + 2° C, may be used. FIBERS LENGTH

The "length" of cotton fibers is a property of commercial value as the price is generally based on this character. To some extent it is true, as other factors being equal, longer cottons give better spinning performance than shorter ones. But the length of a cotton is an indefinite quantity, as the fibers, even in a small random bunch of a cotton, vary enormously in length. Following are the various measures of length in use in different countries

mean length upper quartile effective length Modal length 2.5% span length 50% span length

Mean Length

It is the estimated quantity, which theoretically signifies the arithmetic mean of the length of all the fibers present in a small but representative sample of the cotton. This quantity can be an average according to either number or weight.

Upper Quartile LengthIt is that value of length for which 75% of all the observed values are lower, and 25% higher.

Effective LengthIt is difficult to give a clear scientific definition. It may be defined as the upper quartile of a numerical length distribution eliminated by an arbitrary construction. The fibers eliminated are shorter than half the effective length.

Modal lengthIt is the most frequently occurring length of the fibers in the sample and it is related to mean and median for skew distributions, as exhibited by fibers length, in the following way.

(Mode-Mean) = 3(Median-Mean)

where,Median is the particular value of length above and below which exactly 50% of the fibers lie.

2.5% Span Length:

It is defined as the distance spanned by 2.5% of fibers in the specimen being tested when the fibers are parallelized and randomly distributed and where the initial starting point of the scanning in the test is considered 100%. This length is measured using "DIGITAL FIBROGRAPH".

50% Span Length:

It is defined as the distance spanned by 50% of fibers in the specimen being tested when the fibers are parallelized and randomly distributed and where the initial starting point of the scanning in the test is considered 100%. This length is measured using "DIGITAL FIBROGRAPH".

The South India Textile Research Association (SITRA) gives the following empirical relationships to estimate the Effective Length and Mean Length from the Span Lengths.

Effective length = 1.013 x 2.5% Span length + 4.39 Mean length = 1.242 x 50% Span length + 9.78

Fibers Length Variation

Even though, the long and short fibers both contribute towards the length irregularity of cotton, the short fibers are particularly responsible for increasing the waste losses, and cause unevenness and reduction in strength in the yarn spun. The relative proportions of short fibers are usually different in cottons having different mean lengths; they may even differ in two cottons having nearly the same mean fibers length, rendering one cotton more irregular than the other.It is therefore important that in addition to the fibers length of a cotton, the degree of irregularity of its length should also be known. Variability is denoted by any one of the following attributes

1. Co-efficient of variation of length (by weight or number) 2. irregularity percentage 3. Dispersion percentage and percentage of short fibers 4. Uniformity ratio

Uniformity ratio is defined as the ratio of 50% span length to 2.5% span length expressed as a percentage. Several instruments and methods are available for determination of length. Following are some

Shirley comb sorter Baer sorter A.N. Stapling apparatus Fibrograph

uniformity ration = (50% span length / 2.5% span length) x 100uniformity index = (mean length / upper half mean length) x 100

SHORT FIBERS

The negative effects of the presence of a high proportion of short fibers is well known. A high percentage of short fibers is usually associated with,

Increased yarn irregularity and ends down which reduce quality and increase processing costs

Increased number of neps and slubs which is detrimental to the yarn appearance

Higher fly liberation and machine contamination in spinning, weaving and knitting operations.

Higher wastage in combing and other operations. While the detrimental effects of short fibers have been well established, there is still considerable debate on what constitutes a 'short fibers'. In the simplest way, short fibers are defined as those fibers which are less than 12 mm long. Initially, an estimate of the short fibers was made from the staple diagram obtained in the Baer Sorter method

 Short fibers content = (UB/OB) x 100

While such a simple definition of short fibers is perhaps adequate for characterizing raw cotton samples, it is too simple a definition to use with regard to the spinning process. The setting of all spinning machines is based on either the staple length of fibers or its equivalent which does not take into account the effect of short fibers. In this regard, the concept of 'Floating Fibers Index' defined by Hertel (1962) can be considered to be a better parameter to consider the effect of short fibers on spinning performance. Floating fibers are defined as those fibers which are not clamped by either pair of rollers in a drafting zone.

Floating Fibers Index (FFI) was defined as

FFI = ((2.5% span length/mean length)-1)x(100)

The proportion of short fibers has an extremely great impact on yarn quality and production. The proportion of short fibers has increased substantially in recent years due to mechanical picking and

hard ginning. In most of the cases the absolute short fibers proportion is specified today as the percentage of fibers shorter than 12mm. Fibrograph is the most widely used instrument in the textile industry , some information regarding fibrograph is given below. Fibrograph:

Fibrograph measurements provide a relatively fast method for determining the length uniformity of the fibers in a sample of cotton in a reproducible manner.

Results of fibrograph length test do not necessarily agree with those obtained by other methods for measuring lengths of cotton fibers because of the effect of fibers crimp and other factors.

Fibrograph tests are more objective than commercial staple length classifications and also provide additional information on fibers length uniformity of cotton fibers. The cotton quality information provided by these results is used in research studies and quality surveys, in checking commercial staple length classifications, in assembling bales of cotton into uniform lots, and for other purposes.

Fibrograph measurements are based on the assumptions that a fibers is caught on the comb in proportion to its length as compared to total length of all fibers in the sample and that the point of catch for a fibers is at random along its length.

 

FIBERS FINENESS

Fibers fineness is another important quality characteristic, which plays a prominent part in determining the spinning value of cottons. If the same count of yarn is spun from two varieties of cotton, the yarn spun from the variety having finer fibers will have a larger number of fibers in its cross-section and hence it will be more even and strong than that spun from the sample with coarser fibers. Fineness denotes the size of the cross-section dimensions of the fibers. AS the cross-sectional features of cotton fibers are irregular, direct determination of the area of cross-section is difficult and laborious. The Index of fineness which is more commonly used is the linear density or weight per unit length of the fibers. The unit in which this quantity is expressed varies in different parts of the world. The common unit used by many countries for cotton is microgrammes per inch and the various air-flow instruments developed for measuring fibers fineness are calibrated in this unit. 

Following are some methods of determining fibers fineness.

Gravimetric or dimensional measurements Air-flow method Vibrating string method

Some of the above methods are applicable to single fibers while the majority of them deal with a mass of fibers. As there is considerable variation in the linear density from fibers to fibers, even amongst fibers of the same seed, single fibers methods are time-consuming and laborious as a large number of fibers have to be tested to get a fairly reliable average value.

It should be pointed out here that most of the fineness determinations are likely to be affected by fibers maturity, which is an another important characteristic of cotton fibers.

Air-flow Method (Micronaire Instrument)

The resistance offered to the flow of air through a plug of fibers is dependent upon the specific surface area of the fibers. Fineness testers have been evolved on this principle for determining fineness of cotton. The specific surface area which determines the flow of air through a cotton plug, is dependent not only upon the linear density of the fibers in the sample but also upon their maturity. Hence the

micronaire readings have to be treated with caution particularly when testing samples varying widely in maturity.

In the micronaire instrument, a weighed quantity of 3.24 gms of well opened cotton sample is compressed into a cylindrical container of fixed dimensions. Compressed air is forced through the sample, at a definite pressure and the volume-rate of flow of air is measured by a rotometer type flowmeter. The sample for Micronaire test should be well opened cleaned and thoroughly mixed( by hand fluffing and opening method). Out of the various air-flow instruments, the Micronaire is robust in construction, easy to operate and presents little difficulty as regards its maintenance.

FIBERS MATURITY   Fibers maturity is another important characteristic of cotton and is an index of the extent of development of the fibers. As is the case with other fibers properties, the maturity of cotton fibers varies not only between fibers of different samples but also between fibers of the same seed. The causes for the differences observed in maturity, is due to variations in the degree of the secondary thickening or deposition of cellulose in a fibers.

A cotton fibers consists of a cuticle, a primary layer and secondary layers of cellulose surrounding the lumen or central canal. In the case of mature fibers, the secondary thickening is very high, and in some cases, the lumen is not visible. In the case of immature fibers, due to some physiological causes, the secondary deposition of cellulose has not taken sufficiently and in extreme cases the secondary thickening is practically absent, leaving a wide lumen throughout the fibers. Hence to a cotton breeder, the presence of excessive immaturefibers in a sample would indicate some defect in the plant growth. To a technologist, the presence of excessive percentage of immature fibers in a sample is undesirable as this causes excessive waste losses in processing lowering of the yarn appearance grade due to formation of neps, uneven dyeing, etc.

An immature fibers will show a lower weight per unit length than a mature fibers of the same cotton, as the former will have less deposition of cellulose inside the fibers. This analogy can be extended in some cases to fibers belonging to different samples of cotton also. Hence it is essential to measure the maturity of a cotton sample in addition to determining its fineness, to check whether the observed fineness is an inherent characteristic or is a result of the maturity.

DIFFERENT METHODS OF TESTING MATURITY

Maturity Ratio

The fibers after being swollen with 18% caustic soda are examined under the microscope with suitable magnification. The fibers are classified into different maturity groups depending upon the relative dimensions of wall-thickness and lumen. However the procedures followed in different countries for sampling and classification differ in certain respects. The swollen fibers are classed into three groups as follows :

1. Normal : rod like fibers with no convolution and no continuous lumen are classed as "normal" 2. Dead : convoluted fibers with wall thickness one-fifth or less of the maximum ribbon width are

classed as "Dead" 3. Thin-walled: The intermediate ones are classed as "thin-walled"

A combined index known as maturity ratio is used to express the results.

Maturity ratio = ((Normal - Dead)/200) + 0.70 where,N - %age of Normal fibersD - %age of Dead fibers

Maturity Co-Efficient

Around 100 fibers from Baer sorter combs are spread across the glass slide(maturity slide) and the overlapping fibers are again separated with the help of a teasing needle. The free ends of the fibers are then held in the clamp on the second strip of the maturity slide which is adjustable to keep the fibers stretched to the desired extent. The fibers are then irrigated with 18% caustic soda solution and covered with a suitable slip. The slide is then placed on the microscope and examined. Fibers are classed into the following three categories

1. Mature : (Lumen width "L")/(wall thickness"W") is less than 1 2. Half mature : (Lumen width "L")/(wall thickness "W") is less than 2 and more than 1 3. Immature : (Lumen width "L")/(wall thickness "W") is more than 2 4. About four to eight slides are prepared from each sample and examined. The results are

presented as percentage of mature, half-mature and immature fibers in a sample. The results are also expressed in terms of "Maturity Coefficient"

Maturity Coefficient = (M + 0.6H + 0.4 I)/100

Where,M is percentage of Mature fibersH is percentage of Half mature fibersI is percentage of Immature fibers

If maturity coefficient is

Less than 0.7, it is called as immature cotton Between 0.7 to 0.9, it is called as medium mature cotton Above 0.9, it is called as mature cotton

Air-flow Method for Measuring Maturity

There are other techniques for measuring maturity using Micronaire instrument. As the fineness value determined by the Micronaire is dependent both on the intrinsic fineness(perimeter of the fibers) and the maturity, it may be assumed that if the intrinsic fineness is constant then the Micronaire value is a measure of the maturity.

Dyeing Methods

Mature and immature fibers differ in their behaviour towards various dyes. Certain dyes are preferentially taken up by the mature fibers while some dyes are preferentially absorbed by the

immature fibers. Based on this observation, a differential dyeing technique was developed in the United States of America for estimating the maturity of cotton. In this technique, the sample is dyed in a bath containing a mixture of two dyes, namely Diphenyl Fast Red 5 BL and Chlorantine Fast Green BLL. The mature fibers take up the red dye preferentially, while the thin walled immature fibers take up the green dye. An estimate of the average of the sample can be visually assessed by the amount of red and green fibers.

FIBERS STRENGTH

The different measures available for reporting fibers strength are

1. breaking strength 2. tensile strength and 3. tenacity or intrinsic strength

Coarse cottons generally give higher values for fibers strength than finer ones. In order, to compare strength of two cottons differing in fineness, it is necessary to eliminate the effect of the difference in cross-sectional area by dividing the observed fibers strength by the fibers weight per unit length. The value so obtained is known as "INTRINSIC STRENGTH or TENACITY". Tenacity is found to be better related to spinning than the breaking strength. The strength characteristics can be determined either on individual fibers or on bundle of fibers. 

Single Fibers Strength

The tenacity of fibers is dependent upon the following factors:

Chain length of molecules in the fibers orientation of molecules size of the crystallites distribution of the crystallites gauge length used the rate of loading type of instrument used and atmospheric conditions

The mean single fibers strength determined is expressed in units of "grams/tex". As it is seen the unit for tenacity has the dimension of length only, and hence this property is also expressed as the "BREAKING LENGTH", which can be considered as the length of the specimen equivalent in weight to the breaking load. Since tex is the mass in grams of one kilometer of the specimen, the tenacity values expressed in grams/tex will correspond to the breaking length in kilometers.

Bundle Fibers Strength

In practice, fibers are not used individually but in groups, such as in yarns or fabrics. Thus, bundles or groups of fibers come into play during the tensile break of yarns or fabrics. Further, the correlation between spinning performance and bundle strength is atleast as high as that between spinning performance and intrinsic strength determined by testing individual fibers. The testing of bundles of fibers takes less time and involves less strain than testing individual fibers. In view of these  considerations, determination of breaking strength  of fibers bundles has assumed greater importance than single fibers strength tests.

 FIBERS ELONGATION:

There are three types of elongation

Permanent elongation: the length which extended during loading did not recover during relaxation

Elastic elongation : The extensions through which the fibers does return Breaking elongation: the maximum extension at which the yarn breaks i.e. permanent and

elastic elongation together Elongation is specified as a percentage of the starting length. The elastic elongation is of decisive importance, since textile products without elasticity would hardly be usable. They must be able to deformed, In order to withstand high loading, but they must also return to shape. The greater resistance to creasefor wool compared to cotton arises, from the difference in their elongation. For cotton it is 6 -10% and for wool it is around 25 - 45%. For normal textile goods, higher elongation are neither necessary nor desirable. They make processing in the spinning mill more difficult, especially in drawing operations.

FIBERS RIGIDITY

The Torsional rigidity of a fibers may be defined as the torque or twisting force required to twist 1 cm length of the fibers through 360 degrees and is proportional to the product of the modulus of rigidity and square of the area of cross-section, the constant of proportionality being dependent upon the shape of the cross-section of the fibers. The torsional rigidity of cotton has therefore been found to be very much dependent upon the gravimetric fineness of the fibers. As the rigidity of fibers is sensitive to the relative humidity of the surrounding atmosphere, it is essential that the tests are carried out in a conditional room where the relative humidity is kept constant.

The Slenderness Ratio

Fibers stiffness plays a significant role mainly when rolling, revolving, twisting movements are involved. A fibers which is too stiff has difficulty adapting to the movements. It is difficult to get bound into the yarn, which results in higher hairiness. Fibers which are not stiff enough have too little springiness. They do not return to shape after deformation. They have no longitudinal resistance. In most cases this leads to formation of neps. Fibers stiffness is dependent upon fibers substance and also upon the relationship between fibers length and fibers fineness. Fibers having the same structure will be stiffer, the shorter they are. The slenderness ratio can serve as a measure of stiffness,

Slender ratio = Fibers length /Fibers diameter

Since the fibers must wind as they are bound-in during yarn formation in the ring spinning machine, the slenderness ratio also determines to some extent where the fibers will finish up fine and/or long fibers in the middle coarse and/or short fibers at the yarn periphery.

TRASH CONTENT

In addition to usable fibers, cotton stock contains foreign matter of various kinds. This foreign material can lead to extreme disturbances during processing. Trash affects yarn and fabric quality. Cottons with two different trash contents should not be mixed together, as it will lead to processing difficulties. Optimising process parameters will be of great difficulty under this situation, therefore it is a must to know the amount of trash and the type of trash before deciding the mixing. Shirley Trash Anlayser

A popular trash measuring device is the Shirley Analyser, which separates trash and foreign matter from lint by mechanical methods. The result is an expression of trash as a percentage of the combined weight of trash and lint of a sample. This instrument is used

To give the exact value of waste figures and also the proportion of clean cotton and trash in the material

To select the proper processing sequence based upon the trash content To assess the cleaning efficiency of each machine To determine the loss of good fibers in the sequence of opening and cleaning.

Stricter sliver quality requirements led to the gradual evolution of opening and cleaning machinery leading to a situation where blow room and carding machinery were designed to remove exclusively certain specific types of trash particles. This necessitated the segregation of the trash in the cotton sample to different grades determined by their size. This was achieved in the instruments like the Trash Separator and the Micro Dust Trash Analyser which could be considered as modified versions of the Shirley Analyser.

The high volume instruments introduced the concept of optical methods of trash measurement which utilised video scanning trash-meters to identify areas darker than normal on a cotton sample surface. Here, the trash content was expressed as the percentage area covered by the trash particles. However in such methods, comparability with the conventional method could not be established in view of the non-uniform distribution of trash in a given cotton sample and the relatively smaller sample size to determine such a parameter. Consequently, it is yet to establish any significant name in the industry. RAW MATERIAL AS A FACTOR AFFECTING SPINNING

Fineness determines how many fibers are present in the cross-section of a yarn of particular linear density. 30 to 50 fibers are needed minimum to produce a yarn fibers fineness influences

1. Spinning limit 2. Yarn strength 3. Yarn evenness 4. Yarn fullness 5. Drape of the fabric 6. Lustre 7. Handle 8. Productivity

Productivity is influenced by the end breakage rate and twist per inch required in the yarn.

Immature fibers(unripe fibers) have neither adequate strength nor adequate longitudinal stiffness. They therefore lead to the following,

1. Loss of yarn strength 2. Neppiness 3. High proportion of short fibers 4. Varying dyeability 5. Processing difficulties at the card and blowroom

Fibers length is one among the most important characteristics. It influences

1. Spinning limit 2. Yarn strength 3. Handle of the product 4. Luster of the product 5. Yarn hairiness 6. Productivity

It can be assumed that fibers of under 4 - 5 mm will be lost in processing (as waste and fly). fibers upto about 12 - 15 mm do not contribute to strength but only to fullness of the yarn. But fibers above these lengths produce the other positive characteristics in the yarn.

The proportion of short fibers has extremely great influence on the following parameters 1. Spinning limit 2. Yarn strength

3. Handle of the product 4. Lustre of the product 5. Yarn hairiness 6. Productivity

A large proportion of short fibers leads to strong fly contamination, strain on personnel, on the machines, on the work room and on the air-conditioning, and also to extreme drafting difficulties.

A uniform yarn would have the same no of fibers in the cross-section, at all points along it. If the fibers themselves have variations within themselves, then the yarn will be more irregular.

If 2.5% span length of the fibers increases, the yarn strength also increases due to the fact that there is a greater contribution by the fibers strength for the yarn strength in the case of longer fibers.

Neps are small entanglements or knots of fibers. There are two types of neps. They are 1.fibers neps and 2.seed-coat neps.In general fibers neps predominate, the core of the nep consists of unripe and dead fibers. Thus it is clear that there is a relationship between neppiness and maturity index. Neppiness is also dependent on the fibers fineness, because fine fibers have less longitudinal stiffness than coarser fibers.

Nature produces countless fibers, most of which are not usable for textiles because of inadequate strength.

The minimum strength for a textile fibers is approximately 6gms/tex (about 6 km breaking length).

Since blending of the fibers into the yarn is achieved mainly by twisting, and can exploit 30 to 70% of the strength of the material, a lower limit of about 3 gms/tex is finally obtained for the yarn strength, which varies linearly with the fibers strength. Low micronaire value of cotton results in higher yarn tenacity. In coarser counts the influence of micronaire to increase yarn tenacity is not as significant as fine count.

Fibers strength is moisture dependent. i.e. It depends strongly upon the climatic conditions and upon the time of exposure. Strength of cotton, linen etc. increases with increasing moisture content.

The most important property influencing yarn elongation is fibers elongation. Fibers strength ranks seconds in importance as a contributor to yarn elongation. Fibers fineness influences yarn elongation only after fibers elongation and strength. Other characters such as span length, uniformity ratio, maturity etc, do not contribute significantly to the yarn elongation. Yarn elongation increases with increasing twist. Coarser yarn has higher elongation than finer yarn. Yarn elongation decreases with increasing spinning tension. Yarn elongation is also influenced by traveller weight and high variation in twist insertion.

For ring yarns the number of thin places increases, as the trash content and uniformity ratio increased For rotor yarns 50%span length and bundle strength has an influence on thin places.

Thick places in ring yarn is mainly affected by 50%span length, trash content and short fibers content.

The following expression helps to obtain the yarn CSP achievable at optimum twist multiplier with the available fibers properties.

Lea CSP for carded count = 280 x SQRT(FQI) + 700 - 13CLea CSP for combed count = (280 x SQRT(FQI) + 700 - 13C)x(1+W)/100

where,FQI = LSM/FL = 50% span length(mm)S = bundle strength (g/tex)M = Maturity ratio measured by shirly FMTF = Fibers fineness (micrograms/inch)C = yarn countW = comber waste%

Higher FQI values are associated with higher yarn strength in the case of carded counts but in combed count such a relationship is not noticed due to the effect of combing.

Higher 2.5 % span length, uniformity ratio, maturity ratio and lower trash content results in lower imperfection. FQI does not show any significant influence on the imperfection.

The unevenness of carded hosiery yarn does not show any significant relationships with any of the fibers properties except the micronaire value. As the micronaire value increases, U% also increases. Increase in FQI however shows a reduction in U%.Honey-dew is the best known sticky substance on cotton fibers. This is a secretion of the cotton louse. There are other types of sticky substances also. They are given below.

honey dew - secretions fungus and bacteria - decomposition products vegetable substances - sugars from plant juices, leaf nectar, overproduction of wax, fats, oils - seed oil from ginning pathogens synthetic substances - defoliants, insecticides, fertilizers, oil from harvesting machines

In the great majority of cases, the substance is one of a group of sugars of the most variable composition, primarily but not exclusively, fructose, glucose, saccharose, melezitose, as found, for example on sudan cotton. These saccharides are mostly, but not always, prodced by insects or the plants themselves, depending upon the influence on the plants prior to plucking. Whether or not a fibers will stick depends, not only on the quantity of the sticky coating and it composition, but also on the degree of saturation as a solution. Sugars are broken down by fermentation and by microorganisms during storage of the cotton. This occurs more quickly the higher the moisture content. During spinning of sticky cotton, the R.H.% of the air in the production are should be held as low as possible. The following table  shows the degree of correlation between the various cotton fibers quality characteristics and those of the yarns into which these fibers are spun  -  RING SPUN YARNS. 

Yarn evenness Imperfection and classimat faults Breaking tenacityBreaking

elongation Hairiness

Fibers lengthMicronaire value

Nep, trash, leaf,

microdust, fibers  fragments1/8" breaking strength1/8" elongationColor/reflectance                      

significant correlation       

good correlation  

little or no correlation   The following table shows the degree of correlation between the various cotton fibers quality characteristics and those of the yarns into which these fibers are spun - ROTOR SPUUN YARNS.  

  Yarn evennessImperfections and classimat faults

Breaking tenacity

Breaking elongation Hairiness

Fibers length          Micronaire value          Nep, leaf, trash,microdust, fibers fragments

         

1/8" breaking strength          

1/8" breaking elongation          

Color/ reflectance          

significant correlation       

good correlation  

little or no correlation