Definition and Classification of Textile Neps | Count of Neps

Any small entanglement of textile fibers that can not be unraveled, formed during carding or ginning.

Classification of Neps
For cotton fiber; there are five types of Neps. These are –

Process Neps: Commonly produced by faulty carding or up to spinning yarn.

Mixed Neps: Fibres tangle around a foreign materials. For instance – Grit.

Immature Neps: Generally form by processing immature fibre.

Homogeneous Dead Neps: A tangle of nearly all dead fibres.

Fuzz Neps: A fault of short fuzz fibers .

Count of Neps
Nep count is the no. of neps per 100 square inches of card web forming ( a standerd hank of sliver of 12 NE on a 40 inch wide card).

How To Measure the Count of Neps?
At first a web is collected from the card placed on a 10 inch × 10 inch black board. Then the neps are counted and the no. of neps found is corrected fro any difference in hank or card width.
Mathematically, Nep Count, n = m × 100 [ m = no. of neps per inch square card web].

Yarn Count/Linear Density | Determination of Yarn Count

The thickness or diameter of a yarn is one of its most fundamental properties. However, it is not possible to measure the diameter of a yarn in any meaningful way. This is because the diameter of a yarn changes quite markedly as it is compressed. Most methods of measuring the diameter of yarn, apart from optical ones, involve compressing the yarn as part of the measurement process. Therefore the measured diameter changes with the pressure used so that there is a need for agreement on the value of pressure at which the yarn diameter is to be defined. On the other hand optical systems of measuring yarn diameter have the problem of defining where the outer edge of the yarn lies as the surface can be rather fuzzy, having many hairs sticking out from it.

Therefore the positioning of the yarn boundaries is subject to operator interpretation. Because of these problems a system of denoting the fineness of a yarn by weighing a known length of it has evolved. This quantity is known as the linear density and it can be measured with a high degree of accuracy if a sufficient length of yarn is used. There are two systems of linear density designation in use: the direct and the indirect.

Direct System
The direct system of denoting linear density is based on measuring the weight per unit length of a yarn. The main systems in use are:

• Tex - weight in grams of 1000 metres
• Decitex - weight in grams of 10,000 metres
• Denier - weight in grams of 9000 metres
1 tex = 10 decitex.

Tex is the preferred SI unit for linear density but it is not yet in common use throughout the textile industry. Other direct systems can be converted into tex by multiplying by the appropriate factor. In the direct system the finer the yarn, the lower is the linear density.

Indirect System
The indirect system is based upon the length per unit weight of a yarn and is usually known as count because it is based on the number of hanks of a certain length which are needed to make up a fixed weight. This is the traditional system of yarn linear density measurement and each branch of the industry has its own system based on the traditional length of hank associated with the locality and the type of yarn manufactured.

The main English ones which are still used every day in the relevant parts of the industry are:

• Yorkshire Skeins Woollen Ny

Count = number of hanks all 256 yards long in 1 pound

• Worsted Count New

Count = number of hanks all 560 yards long in 1 pound

• Cotton Count Nec

Count = number of hanks all 840 yards long in 1 pound

• Metric count Nm

Count = number of kilometre lengths per kilogram

In the indirect systems the finer the yarn, the higher the count. One way of measuring count is to measure the linear density using the tex system in the first instance and then to convert the result to theappropriate count system using the appropriate conversion factor K .

Count =K/Tex

Calculation of Yarn Spinning

Count:

Count is the measure of fineness or coarseness of yarn.

Systems of Count Measurement
There are two systems for the measurement of count.
1) Direct System
2) Indirect System

1) Direct System
It is used for the measurement of weight per unit length of yarn. 

When count increases, fineness decreases. ( count↑ fineness↓ )

Commonly used units in this system of measurement are:-
1) Tex ( 1 Tex = 1g/ 1000m )
2) Grex ( 1 Grex = 1g/ 10,000m )
3) Denier ( 1 Denier = 1g/ 9000m )

2) Indirect System
It is used for the measurement of length per unit weight of yarn.
When count increases, fineness increases. ( count↑ fineness↑ )
 

Commonly used subsystems of indirect system are:-
1) English System ( 1 Ne = 1 Hank/ lb )
2) Metric System ( 1 Nm = 1 Km/ kg )

For cotton yarn, length of 1 Hank = 840 yards. Whenever the type of count is not mentioned with the count, it is understood that it is the English count.

Count Conversion Table

1) Calculate the length of a package of 80/1 and cone weight 2.083 lb.

(Note:- English count is represented as C/N i-e, yarn count/ no. of yarn plies)
Yarn type = 80/1
Cone wt. = 2.083 lb
Cone length = ?

Solution:
Length = Ne x lb x 840 yards

= 80 x 2.083 x 840 yards

= (139977.6÷ 1.0936 )m

= 127997.07 m ——————Ans.

2) Calculate the length of yarn with Ne (80/2) and weight 4.166 lb.
Yarn type = 80/2
Cone weight = 4.166 lb
Cone length = ?

Solution:
 Length = Ne x lb x 840 yards

= (80÷2)x 4.166 x 840 yards

= (139977.6÷1.0936)m

= 127997.07 m ———————-Ans. 


3) Calculate the draft at drawing frame if the feeding sliver is 68 grains/yard, delivered sliver is 48 grains/ yard and the number of doublings is 8 :-

Count of feeding sliver = 68 gr/ yd
Count of delivered sliver = 48 gr/ yd
Doubling = 8 (8 sliver cans used)
Draft = ?

Solution:
Actual draft = (count fed x doubling) ÷ (count delivered)                (direct system)

= (68 x 8)÷ 48

= 11.33——————-Ans.

4) Calculate the grains/ yard of delivered sliver if feeding sliver is 68, doubling is 6 and the draft is 7 :-
Count of F.S = 68
Count of D.S = ?
Doubling = 6
Draft = 7

Solution :
A.D = (F.S x D)÷ D.S

=> 7 = (68 x 6)÷D.S

=>D.S = 68 x 6 = 58.28 grains/ yard —————Ans.

5) Calculate the TPI on simplex if the diameter of back roller is 15/16”, rpm of B.R is 10, rpm of flyer is 1000 and draft is 6 :
TPI on simplex = ?
Dia. of B.R = 15/16”
Dia. of F.R = ?
Rpm of B.R = 10
Rpm of flyer = 1000 rpm
Draft, D = 6

Solution :
S.S of B.R =  πDN  =  π x 15/16” x 10 = 29.45”/ min

D = (S.S of F.R) ÷ (S.S of B.R)

=> 6 = (S.S of F.R)÷29.45

=> S.S of F.R = 6 x 29.45 = 176.71”/ min

TPI = rpm of flyer ÷ S.S of F.R   = 1000 ÷ 176.71 = 5.66 ————————-Ans.

6) Calculate the TPI (twists per inch) produced on a simplex with diameter of front roller 28 mm and its rpm be 30. The rpm of flyer is 1000.
TPI on simplex = ?
Dia. of F.R = 28 mm = 2.8 cm
Rpm of F.R = 30
Rpm of flyer = 1000

Solution :
Dia. of Front roller = 2.8 cm / 2.54             (1 in= 2.54 cm)
 

= 1.1023 inch

Surface speed of F.R, ^DN = π x dia. of F.R x rpm of F.R

= π x 1.1023 x 30

= 103.88 “/ min.

TPI = rpm of flyer ÷ S.S of F.R = 1000 ÷ 103.88
 

= 9.63 ————————-Ans.