Transcript Lecture 4: Yarn count - Chemical Engineering Resources

By
Dr. Abu Yousuf
Department of Chemical Engineering & Polymer Science
Shahjalal University of Science & Technology
Sylhet-3114, Bangladesh
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Yarn formation
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Definition of Count: According to the Textile Institute “Count is a number
of indicating the mass per unit length or length per unit mass of yarn”.
There are several count system of yarn. These count systems have
been divided in two ways. One is Direct System where length is fixed
and another is Indirect system where weight is fixed.
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•Also called the 'direct system' or the 'direct number system‘
•This system is based on the weight of a given length of yarn
•So the numbers you see refer to this weight
•It is a metric system which involves much simpler methods
of calculation
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Direct System (Length Fixed):
A). Tex: Weight of yarn in gm present in 1000 meter length. It is a
universal system of counting the yarn.
B). Denier: Weight of yarn in gm present in 9000 meter length. It is
basically used for man made fiber.
C) Pounds Per Spindle: Weight of yarn in lbs present in 1440 yards
length.
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Fixed weight system
• This is based on the length of yarn that makes up a given weight
• The weight is fixed and the length is variable, so the numbers you see relate
to length
• This is the original and traditional method used for calculating the thickness of
a yarn
• The method is also known as the 'indirect system' or count
• The count or indirect system is very complex
• Each fibre, (wool, cotton, worsted, silk, etc.) uses a slightly different method of
calculation
• To further complicate matters, some countries and locations have developed
their own variations of the system
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Indirect System ( Weight Fixed):
A). English Cotton Count: No. of hanks of 840 yds
present in 1 lb of yarn.
B) Metric Count: No. of hanks of 1000 meters present in
1 kg of yarn.
C) Worsted count: No. of hanks of 560 yds present in 1
lb of Yarn. It is basically used for Wool.
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International System
In 1956, The International Organisation for Standardisation (ISO) ,
decided that it would make more sense if there was only one universal
system.
It
was
suggested
that
the
TEX
system,
which is a fixed length, direct system, should be adopted world wide.
Many spinners and manufactures have adopted this method as their
standard but large sections of the industry have not, and still continue to
use the traditional methods.
However, over the last few years support for the idea has grown,
and the Standardisation Organisation is confident that in the not too
distant future, the Tex system will be accepted as the world wide
standard.
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Tex
• Tex is a unit of measure for the linear mass density of fibers and is
defined as the mass in grams per 1000 meters.
• Tex is more likely to be used in Canada and Continental Europe, while
denier remains more common in the United States and United Kingdom.
• The unit code is "tex". The most commonly used unit is actually the
decitex, abbreviated dtex, which is the mass in grams per 10,000 meters.
• dtex is used for very thin threads like machine sewing threads
• With these very thin threads a Tex value could be misleading
• Tex is used for measuring fiber size in many products, including cigarette
filters, optical cable, yarn, and fabric.
One can calculate the diameter of a filament given its weight in dtex with
the following formula:
where ρ represents the material's density in grams per cubic centimeter and the
diameter is in cm.
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Cotton count
• Cotton Counts: The number of hanks of 840 yds in one pound of weight i.e.
10 count cotton means that 10x840 yds weighs = 1 lb.
•
40 count cotton = 40x840 yards yarn.
•
In the United Kingdom, one to 40s are coarse counts (Oldham Counts), 40
to 80s are medium counts and above 80 is a fine count. In the United States
ones to 20s are coarse counts.
Hank: A length of 7 leas or 840 yards.
One Lea - 120 yds (yarn is strength tested in lea strength) Cotton yarn may be
spun is S twist (recverse or Z twist (normal) twist is imparted to produce the
strength.
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YARN COUNT CALCULATION

Example:







No of yarn sample taken=12
Length of each yarn sample=6 cm
Total yarn length=(12x6)÷100 m =0.72m
Weight of these samples =0.060gm
Weight of 1 km in length=(1000 x 0.06)÷0.72 =83.3gm
Therefore, yarn count =83.3 tex
Conversion to other systems:
1.
2.
3.
Cotton Count =590.5/83=7’s
Denier =83.3 X 9=749 denier
Metric Count (Nm)=1000/83.3 =12 Nm
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Worsted Yarn Count
Take the number of yards of spun yarn; let's say 450 yards
divide that by the weight of the yarn, say 8 ounces.
That’s 56.25 yards per ounce.
Multiply the 56.25 by 16 (1 lb). This comes to 900 yards per pound.
*Now take the 900 YPP times the number of plies in the yarn, let's say 2....
900x2 = 1800 yards.
Now divide the 1800 by the factor for the fixed weight system, which in this
case is worsted so the factor is 560 and you have 1800 yards divided by 560
for a worsted count of: 3.2.
To figure the count for a singles worsted, simply omit the step marked with the
*. So in our example, the final step would be: 900 yards divided by the
worsted factor of 560 = 1.6. The worsted count of the singles is 1.6.
Or: Number of yards divided by weight of yarn times 1 lb (16 oz or 454 grams)12
times the number of plies divided by 560 equals Worsted Count.
This chart shows how to convert any count
system into Tex.
÷
cotton count
(nec)
= Tex
÷
worsted
count(New)
= Tex
1938.00
÷
woollen
count(Ny)
= Tex
1000.00
÷
metric Nm
= Tex
0.1111
×
denier
=Tex
590.50
885.80
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Denier
1 denier = 1 gram per 9 000 meters
= 0.05 grams per 450 meters (1/20 of above)
= 0.111 milligrams per meter
In practice measuring 9,000 meters is both time-consuming
and wasteful. Usually a sample of 900 meters is weighed
and the result multiplied by 10 to obtain the denier weight.
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Also remember:
fixed weight/indirect/count value - the higher the number the thinner the yarn,
fixed length/direct/tex value - the higher the number the thicker the yarn.
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example
CALCULATI WEIGHT
ON
per 1000mts
1000 ÷ 15 = 66
1 ply, Nm 30/2
66 grams
tex
1 ply, 2/24's (Ne 885.80 ÷ 12 =
73 grams
w)
73 tex
1 ply, 64 Tex
64grams
VALUE
yarn A
yarn B
yarn C
METRES
in 1 kilo
15,000
13,700
15,600
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Although all the above yarns are called 1 ply,
we can see that yarn B is thicker than the other two,
and yarn C is the thinnest
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