Yarn occupies the intermediate position in the production of fabric from raw material.
Yarn results are very essential, both for estimating the quality of raw material and for controlling the quality of fabric produced. The important characteristics of yarn being tested are:
- Yarn Count
- Yarn Twist
- Yarn Strength & Elongation
- Yarn Evenness
- Yarn Hairiness etc.

Table Of Contents:
1.0 Yarn Count
1.1 Yarn Count Variation
1.2 Conversion Table For Yarn Counts

2.0 Yarn Twist
2.1 Twist Standards

3.0 Yarn Strength And Elongation
3.1 Tensile Strength of Single Yarn
3.2 Skein Strength Or Lea Strength

4.0 Yarn Evenness
4.1 Unevenness/Irregularity
4.2 Imperfections
4.3 Relative Count

5.0 Yarn Hairiness
5.1 Uster Hairiness Index
5.2 Zweigle Hairiness Index

6.0 Standard
6.1 Standard Cotton Yarn
6.2 Testing Equipments

Once the cartons are ready for shipment, the packing lists are ready, our representative visit the mill, make a random selection of cartons. He will take one cones each from the selected cartons for the test. If the quality will be acceptable the tested cones must be shipped marking tested cone.

1.0 Yarn Count
The fineness of the yarn is usually expressed in terms of its linear density or count.
There are a number of systems and units for expressing yarn fineness. But they are Classified as follows :-

DIRECT SYSTEM:
1. English count (Ne)
2. Metric count (Nm)
INDIRECT SYSTEM:
1. Tex
2. Denier

1. Ne: No of 840 yards yarn weighing in One pound
2. Nm: No of one-kilometer yarn weighing in One Kilogram
3. Tex: Weight in grams of 1000-meter (1 kilometer) yarn
4. Denier: Weight in grams of 9000-meter (9 kilometer) yarn

For the determination of the count of yarn, it is necessary to determine the weight of a known length of the yarn. For taking out known lengths of yarns, a wrap-reel is used.
The length of yarn reeled off depends upon the count system used. One of the most important requirements for a spinner is to maintain the average count and count variation within control.

1.1 Yarn Count Variation
The term count variation is generally used to express variation in the weight of a lea and this is expressed as C.V.%. The number of samples and the length being considered for count checking affects this. While assessing count variation, it is very important to test adequate number of leas. After reeling the appropriate length of yarn, the yarn is conditioned in the standard atmosphere for testing before it's weight is determined.

1.2 Conversion Table For Yarn Counts
Tex Ne Den Nm
Tex Den/9 1000/Nm
Ne 590.54/Tex 5314.9/Den Nm x .5905
Den Tex x 9 9000/Nm
Nm 1000/Tex 9000/Den

2.0 Yarn Twist
Twist is defined as the spiral disposition of the components of yarn, which is generally expressed as the number of turns per unit length of yarn, e.g. turns per inch, turns per meter, etc. With increase in twist, the yarn strength increases first, reaches a maximum and then decreases.
Depending on the end use, two or more single yarns are twisted together to form "plied yarns" or "folded yarns" and a number of plied yarns twisted together to form "cabled yarn". Among the plied yarns, the most commonly used are the doubled yarns, wherein two single yarns of identical twist are twisted together in a direction opposite to that of the single yarns. Thus for cabled and plied yarns, the direction of twist and the number of turns per unit length of the resultant yarn as well as of each component have to be determined for a detailed analysis.
Direction of twist is expressed as "S"-Twist or "Z"-Twist. Direction depends upon the Direction of rotation of the twisting element.
Twist take up is defined as, "The decrease in length of yarn on twisting, expressed as a percentage of the length of yarn before twisting.

2.1 Twist Standards
- Cotton combed knitting T.M. = 3.4 to 3.6
- Cotton combed weaving T.M. = 3.7 to 3.8
-Cotton carded knitting T.M. = 3.8 to 4.0
-Cotton carded weaving T.M. = 3.9 to 4.2

3.0 Yarn Strength & Elongation
Breaking strength, elongation, elastic modulus, resistance abrasion etc are some important factors, which will represent the performance of the yarn during actual use or further processing. Strength testing is broadly classified into two methods
1. Single End Strength Testing
2. Lea Strength

3.1.Tensile strength of single yarn
During routine testing, both the breaking load and extension of yarn at break are usually recorded for assessing the yarn quality. Most of the instruments record the load-elongation diagram also. Various parameters such as initial elastic modulus, the yield point, the tenacity or elongation at any stress or strain, breaking load, breaking extension etc can be obtained from the load-extension diagram.

Two types of strengths can be determined for a yarn
1. Tensile strength -load is applied gradually
2. Ballistic strength - applying load under rapid impact conditions

3.2. Skein strength or lea strength
The skein breaking strength was the most widely used measure of yarn quality in the cotton textile industry. The measurement of yarn quality by this method has certain drawbacks. Firstly, in most of the subsequent processing, such as winding, warping or weaving, yarn is used as single stranding not in the form of a skein except occasionally when sizing, bleaching, mercerizing or dyeing treatments are carried out on hanks. Secondly, in the method used for testing skein strength, the rupture of a single strand at a weak place affects the result for the whole skein. Further, this method of test does not give an indication of the extensibility and elastic properties of a yarn, the characters which play and important role during the weaving operations. However, since a large size sample is used in a skein test as against that in a single strand test, the sampling error is less. The skein used for strength test can be used for determination of the linear density of the yarn as well.
After finding out skein strength, broken skeins are also weighed to determine the linear density. The most common skein used is the lea and the results of lea strength tests are expressed as C.S.P., which is the product of the linear density (count) of the yarn in the English system (Ne) and the lea breaking strength expressed in lbs. In view of the fact that C.S.P. is much less dependent on yarn count than on strength, especially when count differences are small, C.S.P. is the most widely used measure of yarn quality.

4.0 Yarn Evenness
Non-uniformity in variety of properties exists in yarns. There can be variation twist, bulk, strength, elongation, fineness etc. Yarn evenness deals with the variation in yarn fineness. This is the property, commonly measured, as the variation in mass per unit length along the yarn, is a basic and important one, since it can influence so many other properties of the yarn and of fabric made from it. Such variations are inevitable, because they arise from the fundamental nature of textile fibres and from their resulting arrangement. Accordingly, there are limits to the achievable yarn evenness.

4.1 Unevenness / Irregularity
The mass per unit length variation due to variation in fiber assembly is generally known as "IRREGULARITY" or "UNEVENNESS". It is true that the diagram can represent a true reflection of the mass or weight per unit length variation in a fiber assembly. For a complete analysis of the quality, however, the diagram alone is not enough. It is also necessary to have a numerical value that represents the mass variation. The mathematical statistics offer 2 methods
1. The irregularity U%: It is the percentage mass deviation of unit length of material and is caused by uneven fiber distribution along the length of the strand.
2. The coefficient of variation C.V.%

4.2 Imperfections
Yarns spun from staple fibers contain "IMPERFECTIONS". They are also referred to as frequently occurring yarn faults. They can be subdivided into three groups
1. Think places
2. Thick places
3. Neps
The reasons for these different types of faults are due to raw material or improper preparation process. A reliable analysis of these imperfections will provide some reference to the quality of the raw material used.

The standard sensitive levels are as follows
- Thin place: -50%
- Thick place: +50%
- Neps: +200%

Thin places and thick places in a yarn can, on the one hand, quite considerably affect the appearance of a woven or knitted fabric. Furthermore, an increase in the number of thin places and thick places refer to a particularly valuable indication that the raw material or the method of processing has become worse.
On the other hand, it cannot be concluded from the increased number of thin place faults that this yarn, the downtime of weaving or knitting machines will be increased to a similar degree. Thin places usually exhibit a higher yarn twist, because of fewer fibres in the cross-section resulting in less resistance to torsion. The yarn tension does not become smaller proportionally with reduced number of fibres. With thick place faults the contrary is the case. More fibres in the cross-section result in a higher resistance to torsion. Thick places have therefore, in many cases, a yarn twist which is lower than the average. The yarn tension in the yarn at the position of the thick place is only in very few cases proportional to the number of fibres. These considerations are valid primarily for ring-spun yarns. Neps can influence the appearance of woven or knitted fabrics quite considerably. Furthermore neps of a certain size can lead to processing difficulties, particularly in the Knitting machines. Therefore the avoidance of neps in the production of spun yarns is a fundamental textile technological problem.
Neps can be divided, fundamentally, into two categories:
-Raw material neps
-Processing neps
The raw material neps in cotton yarn are primarily the result of vegetable matter and immature fibres in the raw material. The influence of the raw material with wool and Synthetic fibres in terms of neps production is negligible. Processing neps are produced at ginning and also in cotton, woolen and worsted carding. Their fabrication is influenced by the type of card clothing, the setting of the card flats, workers and strippers, and by the production speeds used.

4.3 Relative Count
It is a measure used to calculate the count variations using capacitance method of
USTER TESTER. It calculates a value called "Average Value Factor AF". This factor is proportional to the mean count of the tested sample length.
The relative count describes the variation of count between separate measurements within a sample. The single values are calculated such that they are in direct reference to the mean value of the sample that is always considered to be 100%. The relative count is always estimated with reference to a test length of 100m or 100 yards.
From the single-overall report, it is possible to recognize immediately which samples are lying above or below the mean value. The standard deviation provides a reference to the variation in count between samples. As the mean value is always 100%, the standard deviation also provides a reference to the coefficient of variation. If the samples are from the same bobbin this would indicate the "within bobbin" variation and if the samples are from the same bobbin this would indicate the "within bobbin" variation and if the samples are from different bobbins this would indicate "between bobbin" variation.

5.0 Yarn Hairiness
Hairiness is a measure of the amount of fibres protruding from the structure of the yarn.
In the past, hairiness was not considered so important. But with the advent of high-speed looms and knitting machines, the hairiness has become a very important parameter. In general, yarn spun with Indian cotton show high level of hairiness due to the following reasons.
I. High short fiber content in mixing.
II. Low uniformity ratio.
III. High spindle speeds.
Hence most of the Indian yarns have a hairiness index above 50% Uster standards.
Hairiness is measured in two different methods.

5.1 Uster Hairiness Index
This is the common method followed in India. The hairiness index H corresponds to the total length of protruding fibres within the measurement field of 1cm length of the yarn.

5.2 Zweigle Hairiness Index
This zweigle hairiness measurement (S3) gives the number of protruding fibres more than 3mm in length in a measurement length of one meter of the yarn. From the above you can infer that Uster hairiness index give the total length of hairs whereas zweigle hairiness testers give the absolute number of fibres. Though the later measurement is more accurate, most of the Indian spinners are still following Uster Hairiness index only.

6.0 Standards
We have fixed the standards for different yarn characteristics for cotton spun yarns for different end uses. The following table gives the quality requirement.

6.1 Testing Equipments
- Premiere Tester - 4
- Uster Tester - 3
- Uster Tensorapid - 3
- Classmate II
- Coefficient of Friction Meter
- Wrap Reel
- Compusortor
- Electronic Wrap block
- Twist Tester
- Zweigle Hairiness Tester
- Splice strength Tester
- Online testing instruments
- Sliver data on Draw frames
- Ring Data on Ring frames
- On line Classmate on Autoconer

Package Inspection
Package Inspection include the inspection of the followings:

Cone Weight: To Check that the cone weight is ok.

Tail Length: To see that the proper (At least 20 inches) pigtail kept in cones.

Cone Size: To check that the cone size is exactly as required.

Cone Making: To check that there shall be no badly done cones included.

Cone Angle: The cone angle should be as desired by the buyer.

Length of the yarn: To measure the length/cone in meter.

Winding: To see that the winding is ok as per desired by the customer.

Shipping Marks: Cartons/Cones should contain the details as requested by the customer.

Quality of Cones/Cartons/Pallets:To see that materials are of international standards.

Stuffing: Proper stuffing of the material in the container.

Note:-
Each quality (Cotton, Polyester etc.) of yarn must be produced separately from Blow room to winding to avoid contamination of foreign fibres, raw-white, dyed and dirty material etc. Some textile fibres are highly hygroscopic and their properties change notably as a function of the moisture content. Moisture content is particularly critical in the case of properties, i.e yarn tenacity, elongation, yarn evenness, imperfections, count etc. Therefore conditioning and testing must be carried out under constant standard atmospheric conditions. The standard atmosphere for textile testing involves a temperature of 20+-2 degree C, and 65+-2% Rh. In tropical regions, maintaining a temperature of 27+-2 degree C, 65+-2%RH is legitimate. Prior to testing, the samples must be conditioned under constant standard atmospheric to attain the moisture equilibriums. To achieve this it requires at least 24 hours.