Textile Yarn Count Numbering System and Conversions

TExtile Yarn Count Numbering System and Conversions

Introduction:

The count of yarn is a numerical expression which defines its fineness or size of the yarn. Since yarn is the compressible textile material it is not possible to measure its fineness by any of the testing instrument so it is usually expressed in terms of the linear density or count. The method of calculation of count number is called as yarn numbering system.

Need of yarn numbering system:

The main purpose of manufacturing of the yarn is to convert it in to the fabric form. Usually 90% of the yarn is converted in to the fabric form for making its use and the remaining is used as it is in the yarn form. If the yarn is used as it is then there is no so much need of measuring its dimensions, but if it is to be converted in to the fabric form then in order to manufacture the required fabric, the yarn parameters plays vital role. The fabric parameters are decided from the use of that fabric for which it is to be used, and those fabric parameters are inculcated from the yarn parameters.

The fabric construction is varied with respect to its end use. The main important fabric factors deciding its construction are, yarn spacing and yarn thickness. Out of this the yarn spacing can be measured by counting the number of yarns per inch with use of magnifying glass. The yarn thickness i.e. yarn diameter (assuming that the yarn is almost circular in cross section) is not an easy process even by any of the means due to the following problems.

Direct yarn numbering system (mass/unit length) and Indirect yarn numbering system (length/unit mass):

Each system has its advantage and disadvantage and each has found areas in which, by the custom it is used. It must be noted that, in the first case the number gets larger as the yarn or strand gets coarser. In the second case the number gets smaller as the yarn or strand gets coarser.

The fineness of yarn cannot be expressed easily in terms of diameter as in the case of wires and cords we measure its diameter by using instrument such as micrometer or calipers. But in case of yarn we cannot measure its diameter by using micrometer and caliper because most of the yarns are relatively soft and compressible, also the cross section of the spun yarn is not fully circular and it contains variations in thickness because presence of thick and thin places in the yarn and the continuous filament yarns also suffer from this drawback. Therefore yarn numbering systems like special methods are used to measure the fineness and coarseness of yarn.

DIRECT YARN NUMBERING SYSTEM [MASS/UNIT LENGTH]:

In direct yarn numbering system, the count of yarn is the number of units of weight per unit length of yarn that is the mass per unit length of yarn. The technique name used to describe yarn thickness in the direct system is linear density. In direct yarn numbering system the higher the yarn number or count indicates the coarser or thicker the yarn size and smaller the yarn number or count indicates the finer or lighter the yarn size. This system is generally used for Tex and Denier.

Advantages:

1. The resultant count of the folded yarn can be easy to calculate even component threads are of different counts.
2. The count directly express the size of the yarn and a coarser yarn will have a higher number while a finer yarn will have a lower number.

Disadvantages:

1. We cannot easily calculate the weight of the fabric
2. Calculation of the amount of twist in the yarn and cloth setting are comparative difficult in this system.

The following formula is used to calculate the direct yarn count:

       W x l
N = --------
          L

Where,

N = Yarn count or number system
W = Weight of the sample at the official regain in the units of the system
L = Length of the sample
L = Units of length of sample

Fig: Different yarn number system

1. Tex:
It is defined as the weight of yarn in grams per 1000 meter of yarns or 1 km length.

i.e., wt. in grams per 1000 meters of yarn.

          1000 x Weight in gram’s
Tex = -------------------------------
               Length in meter’s

Example: 30 Tex indicates that 1000 meters of yarn weight 30 grams.

Questions:
A) Calculate the tex-count of nylon yarn, if the length of yarn is 20000 yards & its weight is 400 gram’s.

Answer:

1 yard = 0.9144 meter

          1000 x Weight in gram’s
Tex = -------------------------------
              Length in meter’s

               1000 x 400
Tex = --------------------------
           20000 x 0.9144

Tex = 21.87

2. Denier:
In the direct denier system, the yarn count number indicates the weight in grams of 9000 meters of yarn.

                9000 x Weight in grams
Denier = ------------------------------------
                     Length in meter

Example: 30 Denier indicates that 9000 meters of yarn weight 30 grams.

Questions:
A) The yarn of polyester filament weighing 50 grams in 6000 meter length calculate the Denier of the yarn.

Answer:

                9000 x Weight in grams
Denier = --------------------------------------
                    Length in meter

                9000 x 50
Denier = ----------------------
                   6000

Denier = 75

3. Spyndle Count:
This system is generally used for jute, hemp or dry spun-linen yarn. Spyndle count is defined as weight in pounds per one spindle of 14400 yards.

                  Weight in pound x 14400
Spyndle = ---------------------------------
                      Length in yards

4. Grex Count:
It is defined as weight in grams of 10000 meters of yarn.

                       Weight in gram’s x 10000
Grex count = ----------------------------------------
                           Length in meter’s


INDIRECT YARN NUMBERING SYSTEM [LENGTH/UNIT MASS]

In direct yarn numbering system, the count of yarn is the number of units of length per unit weight of yarn that is the length per unit mass of yarn. The technique name used to describe yarn thickness in the indirect system is linear density. In indirect yarn numbering system higher the yarn number or count indicates the finer or lighter the yarn size and smaller the yarn number or count indicates the coarser or thicker the yarn size. This system is generally used for English cotton count, Worsted count, Linen count, Woolen count, French cotton count and metric count.

Advantages:

1. The amount of twist in the yarn and cloth setting (threads per inch) are directly proportionally to the square root of yarn count and very difficult to calculate.
2. Very easy to calculate weight of the fabric, when the count of warp and weft are expressed in this system.

Disadvantages:

1. It is difficult to calculate the resultant count of the folded yarn in this system, when the component threads are different counts.
2. The count does not express the size of the yarn directly. And a coarser or bulky yarn will have a small count number than a finer or less bulky yarn.

The following formula is used to calculate the indirect yarn count:

N = (L × w)/ W ×l

Where,
N = Yarn count or number system
W = Weight of the sample at the official regain in the units of the system
L = Length of the sample
L = Units of length of sample
W = Units of weight of sample

Numbering system	Units of length(l)	Units of weight(W)
English cotton count (Ne)	840 yards	1 pound (lb.)
Metric count (Nm)	1000 meters / 1km	1 kg
Woolen count  (YSM)	256 yards	1 pound (lb.)
Worsted count (Nek)	560 yards	1 pound (lb.)
Linen count (NeL)	300 yards	1 pound (lb.)
French cotton count	1000 meters	500 grams

1. English cotton count (Ne):
This also known as British count or English count. This defined as the number of hanks each of 840 yards weighing in one pound of the yarn.

                                                   Length in yards
English cotton count (Ne) = ---------------------------------
                                                840 x Weight in lbs

Example:

A. 30/1 cotton (1 means single yarn) indices that 30 840 yards of yarn weight 1 pound.

B. 40/2 cotton (2 means ply yarn) indicates that 20(Resultant count) 840 yards of yarn weight 1 pound.

Questions:
A). A yarn having length of 90,000 yards and its weight in 2 pounds calculate its English count.

Answer:

                                                   Length in yards
English cotton count (Ne) = -----------------------------------
                                                840 x Weight in lbs

          90,000
Ne = -------------------
         840 x 2

English cotton count (Ne) = 53.57

2. Worsted count (Nm):
It is defined as the no. of hanks each of 560 yards weighing in one pound of the yarn.

                                          Length in yards
Worsted count (Nm) = ---------------------------------
                                       560 x Weight in lbs

Example:

A. 1/20 worsted cotton indicates that 20 × 560 yards of yarn 1 pound.

B. 3/40 worsted cotton indicates that 13.33(Resultant count) × 560 yards of yarn.

Questions:

A) If 80 yards worsted yarn weighing 50 grains what is count of yarns.

Answer:

                                         Length in yards
Worsted count (Nm) = ---------------------------------
                                       560 x Weight in lbs

                    80
Nm = ------------------------
          560 x (50/7000)

Nm = 20.0s

3. Linen count (Wet – spun):
Linen count is the number denoting numbers of hank’s each of 300 yards weighing in pound.

                            Length in yards
Linen count = -----------------------------
                         300 x Weight in lbs

Questions:

A) If 240 yards of linen yarn weight 1 oz., what is the count of the yarn.

Answer:

1 lbs. = 16 oz.

                           Length in yards
Linen count = -------------------------------
                         300 x Weight in lbs

                               240
Linen count = ----------------------
                         300 x (1/16)

Linen count = 12.8

4. Woolen Count (Yorkshire count):
Woolen count (Yorkshire count) is the number denoting number of hanks each of 256 yards weighing in one pound (lbs.).

                            No. of hanks of 256 yards
Woolen count = ---------------------------------------
                               Weight in pound (lbs)

                              Length in yards
Woolen count = ----------------------------------
                            256 x Weight in lbs

Questions:

A) The weight of 786 yards of woolen yarn is ¼ lb., what is the count of yarn.

                               Length in yards
Woolen count = ----------------------------------
                            256 x Weight in lbs

                                 768
Woolen count = ------------------
                            256 x (1/4)

Woolen count = 12s

5. French Cotton Count:
It is defined as number of hanks each of 1000 meters weighing in ½ kg.

                                      Length in meter x 2
French count (NF) = --------------------------------------
                                     1000 x Weight in kg

6. Metric count (Nm):
It is defined as number of hank’s each of 1000 m weighing in 1 kg.

                                       Length in meters
Metric count (Nm) = -----------------------------------
                                    1000 x Weight in kg

Example:
A. 30 Nm indicates that 30 Kilometers or 30,000 meters of yarn weight 1 kilogram.

Questions:

A) Calculate Metric cotton count of 60000 yards weighing 1.2 pound (lbs.)

Answer:

1 yard = 0.9144 meter
1 kg = 2.202 pounds

                                        Length in meters
Metric count (Nm) = -----------------------------------
                                     1000 x Weight in kg

                                       60000 x 0.9144
Metric count (Nm) = -----------------------------------
                                     1000 x (1.2/2.202)

                                          54864
Metric count (Nm) = -----------------------------------
                                    1000 x 0.5449

Metric count (Nm) = 100.68







UNIVERSAL YARN NUMBERING SYSTEM:

Tex system of yarn numbering system is called as universal yarn numbering system. This system comes under direct yarn numbering system and it is introduced by International standard organization (ISO) and textile scientists of various organization, manufactures and technologists. This system is applicable to yarn made from both natural fibers as well as synthetic fibers. Hence this system is useful for replacing the several different systems which are being used in the various sectors of the textile industry all over the world.

Tex system can be used from fiber to yarn process. For fineness of cord, wire, ropes and sliver etc. are expressed in terms of kilotex that is the weight of the material in kg in one km length but for the fineness of fiber it can be expressed in terms of millitex that is weight of fiber in mg (milligrams) in one km (kilometer) length. The advantages and drawbacks of direct system of yarn numbering are also applicable to universal system.