Comparison between HVI and AFIS

Uster HVI Uster AFIS

Measurement Bundle Fibre Single Fibre
Principle
Material Application Bales Bale –Roving
Length : Length
UHML – upper Half Mean Length ,UI UQL – Upper Quartile Length
–Length Uniformity ,SFI-Short Fibre Fibre Length Distribution
Index SFC-Short Fibre Content
“Fineness” “ Fineness”
Micronaire , Maturity Index Fineness , maturity
Fibre Measurement Tenacity IFC – Immature Fibre Content
Strength , Elongation Neps
Colour Neps & Seed Coat Nep count
Colour ( Rd and +b , Colour Grade ) and Size distribution
Contamination Contamination
Trash ( % Area , Count , Trash Grade ) Trash & Dust count and size
distribution

Application Cotton Cleaning & Fibre Selection Process Control

AFIS ( Advance Fibre Information System )

 AFIS is based on –
 aeromechanical fibre processing , similar to opening and carding

 followed by electroptical sensing

 and than followed by high speed microprocessor based computing

and data reporting

 In AFIS , a fibre sample is introduced into the system and is
processed through a fibre individualiser.

 Fibre Individualizers aero mechanically separates into cleaned fibres

, microdust , and trash .

 Each of these components is transported in a pneumatic path and may

be analysed electro-optically .

 The data processing and reporting are handled by a PC .

 AFIS provides basic single fibre information and the distribution of

basic fibre properties .

 These distribution measurements provide more accurate , precise , and

basic information about fibre.
 Fibre Individualiser

A specimen of fibre is hand-teased into a sliver like strand and is inserted into the feed assembly .
It passes between a spring loaded feed roll/ feed plate assembly and is engaged by the pinned and
perforated cylinder .
The fibres are combed and carded ; dust is released and removed through the perforations in the
cylinder .
A secondary stationary flat is used to further clean and comb the fibres . They are then directly
transferred to a secondary cylinder .
A second ‘ counter flow’ slot removes additional trash . Its counter flow air is used to transport
fibres out of the system after a final combing from a third stationary carding flat.
The separated components ( cleaned fibre , microdust , and trash ) are transported along three different
pneumatic paths.
Measuring Principle
Major Components and their Function
1. Motor / Blower :
 Equipped with a separate brushless DC motor for the vaccum blower

 It has internal thermal shutdown circuitry for motor protection.

 A built –in potentiometer allows for vacuum adjustment.

2. Lint/ Waste box :

 The lint /Waste box serves as an air plenum for the distribution and

control of the vacuum system of the unit.

 It is divided into two chambers , lint and waste.
 Airflow is controlled via fixed orifice, flow control valve and direct
blower control.
3. Control System / Control board :
 The control system governs AFIS operations.
 It provides the link between software and the mechanical and
pneumatic hardware.

 The control system through the control board , initiates the sampling
sequence ,polls and monitors system parameters and functions, and
ends the sampling sequence.
 The AFIS software initiates input for the control board.
 Once it has received a ‘start’ signal from the software ,it is in
complete control of the system allowing the host computer to
concentrate on collecting and analysing the data.

 The control system and control board monitor , control and connect
the AFIS system components.
 3a. Monitoring :
 The control board polls and monitors the following components

and indicates their status to the software

 Sliver Detection
 Fibre Individualizer on/off switch
 Feed motor on/off switch

 3b. Controlling :
The control board has real time control over the state and function of
the following components and signals the host regarding any changes
that would affect system performance.
 Feed motor speed and direction
 Fibre individualiser speed
 Flow through fibre and /or trash sensors
 Presence / Absence of sample
 Internal temperature
 Current to motor / blower
 Line Voltage and Frequencty
 Operating time and number of samples
 3c. Connecting :
 The control system is device through which the
following connections are made and governed
 Input Power and compressed air

 AC to DC convertor

 Differential Pressure readings

 230V to 110 V step-down


4. Fibre Individualizer :
 The fibre individualizer uses unique cleaning and separating

techniques to present the fibres pneumatically to the electro-optical

sensors .
 The fibres are opened and cleaned using specially designed pinned
and perforated cylinders.
 Airflow into the perforations of the cylinder allows for thorough
engagement and efficient dust and trash removal.
5. Fibre individualiser motor/ Motor controller :
 There is a separate drive motor for the fibre individualizer.
 The brushless DC motor has its own motor controller board which
monitors and controls the motor speed .
 The motor speed can be adjusted by a potentiometer located on the
board .
6. Feed Motor / Motor controller :
 The feed belts and feed rollers are driven via worm gear with a
stepper motor.
 The motor speed is variable from 140 to 1116 steps per sec.

7. Sliver Detector :
 The sliver detector is located between the feed tray and feed plate.

 Its gives signal to control system when sliver is being presented to the
individualizer / when sliver is no longer present .

 The sliver detector consists of an infrared LED source and detector .

8. Electro-optical sensors :
 The EO sensors consists of three basic elements ; tapered entrance
and exit nozzles , beam forming and collection optics , the detection
circuitry .

 Individualized fibres ( and neps ) are transported pneumatically from

the fibre individualizer by an air stream .

 They enter the E-O sensor through an accelerating nozzle which

straightens ,separates , and align the fibres in proper orientation to the
source detector .

 The fibres penetrate a collimated beam of light and scatter and block
that light in proportion to their optical diameter and in direct relation
to their time of flight through the sampling volume.

 Rectangular waveforms are produced by the light scattered by
individual fibres . Nep signals are much greater in magnitude and
duration and generate a characteristic nep “spike” .

 Trash particles produce smaller spiked waveforms which are

distinguishable from neps in magnitude and duration.

 From these waveforms , which are microseconds in duration , the

pertinent data are acquired ,analysed , and stored in the host
computer . Distributions based on size , length , or diameter can be
generated .
9. Host Computer :
 The AFIS computer system includes an industrialized computer
chassis. A microprocessor based CPU , a serial I/O card , drive
controller card , graphics card and hard drive . It supports the Wenger
1/1 and Okidata 530 printers and mettler balance.
 The AFIS computer contains and supports up to four data Acquisition
boards (DABs) . Each AFIS information module ( e.g. Nep , Length &
Diameter and Trash ) requires its own DAB.

9a. Data acquisition boards ( DAB) :

 The AFIS data acquisition boards are printed circuit board( PCB) that

occupy a bus slot in the backplane of the host computer. The purpose
of these boards is to receive the incoming signal from the AFIS sensor
and translate it to the digital information that is used by the software
to develop that board’s particular fibre information.
10. Software :
 AFIS software performs serve fulfill following purpose.
 Performing data calculation and storage / retrieval
 Initiate and then monitor the control system for interrupts

 Operator / AFIS interface through which testing is

performed .

11. AFIS service Utilities :

 The AFIS utility software is a set of service related programs
that are designed to allow the technicians to
troubleshoot ,diagnose ,test ,and calibrate the AFIS system.
 Information provided by the AFIS
 Nep Classification
 Fibre Neps and Seed coat Neps
 Count and size distribution

 Length and Maturity

 Length by weight and number
 Short Fibre Content

 Maturity Ratio

 Immature Fibre Content

 Trash
 Dust
 Trash

 Total Foreign matter

Nep Module
 Nep Module
 Measures
 Fibre Neps & Sead Coat Neps
 Count and Size distribution
 Fibre Neps :
 Entanglements of the several fibres
 Generated under mechanical treatment of the cotton fibres during harvesting ,
ginning , opening , and cleaning in the spinning mill
 Amount depends on the cotton origin /variety and harvesting method
 Neps are mainly reduced in carding and combing
 Amount of reduction depends on the machinery performance and the quality the
spinning mill wants to achieve
 Sead Coat Neps :
 Fragments of the cotton seed that still some fibre attached
 Created mainly in ginning when the fibres are separated from the seed
 Amount depends on the quality and the aggresiveness of the ginning process
 Removal in carding is very difficult since the attached fibres tend to stick with
the process .
 AFIS Nep data analysis
 Nep : Fibre entanglements
 Causes imperfections in yarn and fabric
 Nep count : Number of neps per gm of material
 analysis of processing equipment
 Nep Size : Nep “average diameter” in microns
 Determines impact on yarn and fabric
 Count /gm CV % : Coefficient of variation between
sample repetitions
 Determines the number of repetitions necessary for good
statistics
 Nep Removal Efficiency : {( in-Out )/ in }x100 %
 Machine performance and comparisons
 Ranges of Neps and Seed Coat Neps in Raw
Cotton ( Short / Medium Staple )

Neps / gm Seed Coat Neps / gm Description

˂100 ˂10 Very Low

101-200 11-20 Low

201-300 21-30 Medium

301-450 31-45 High

˃451 ˃46 Very High

Length and Maturity Module
 Length Module – Measurement
 Length Distribution “by Weight”
 L(w) -Mean length by weight ( comparable to HVI 50 % Span Length )
 L(w) {CV % }-Coefficient of variation for length by weight distribution
 SFC% (w) -Short Fibre content % by weight less than ½ inch ( Comparable to
HVI SFI )
 UQL(w) -Upper Quartile length by weight ; longest 25 % of the fibres
( Comparable to HVI UHML and 2.5 % Span length )
 Length Distribution “by Number”
 L(n) -Mean length by number ( For monitoring fibre length in spinning)
 L(n) {CV % } - Coefficient of variation for length distribution (Control of
Fibre variation in carding , drawing)
 SFC(n) -Short Fibre Content % by number less than ½ inch (Control of fibre
damage in opening ,carding and combing )
 5 % (n) and 1%(n) -Longest 5% of the fibre lengths and Longest 1 % of the
fibre lengths ( Machine Setting )
 D(n) -Average diameter of the fibres by number ( Micronaire estimate ; man
made fibre diameter)
 D(n) {CV % }-Coefficient of variation for fibre diameter
Difference between “By number” and “By Weight”
 By number – more accurate results
when optimizing the spinning
processes.

 By weight – Used by the Mills using

results of the comb sorter array
methods such as Suter –Webb-Array

 The Upper Quartile Length “ by

weight” Close to classer’s staple
Length “by weight” always higher than
length by Number
l(n) =20mm
l(w) =28.3 mm

Upper Quartile Length only calculated “by

weight”
UQL(w) = 34.6 mm

Short Fibre Content “by weight” always

significantly smaller than short fibre content
“by number”
SFC(n) = 31.7 %
SFC(w) =10.1 %
 Length Module – Short Fibre Content
 Cotton Length is determined by variety
 First length development , than development of
the walls
 Initially , the fibres have more or less same length
 Length is reduced with any mechanically treatment

( harvesting , ginning ,opening , cleaning )

 Mainly reduced at combing
 Control of the SFC is very important for the
spinning performance and the yarn quality
 Ranges of Short Fibre Content (w) and
(n) in raw cotton (short / medium staple )

Short Fibre Content Short Fibre Content Description

( number ) ( Weight )
˂18 ˂5 Very Low
19-23 6-8 Low
24-28 9-11 Medium
29-33 12-14 High
˃34 ˃15 Very High
Ranges of maturity , IFC in Raw
Cotton ( Short / medium Staple )

Maturity Ratio Description Immature Fibre Description

Content (%)
˂0.75 Very Immature ˂6.0 Very Low

0.76-0.85 Immature 6.1-.8.0 Low

0.86-0.90 Mature 8.1-11.0 Medium

0.91-0.95 Mature 11.1-14.1 High

˃0.96 Very Mature ˃14.1 Very High

 AFIS Trash Data Measurement
 Total count
 All particles counted ( over trash levels by the optical sensor )
 Trash Count
 All particles larger than 500 microns ( Cleaning an analysis
and efficiencies )
 Dust Count
 All particles less than 500 microns ( dust removal analysis )
 Total Foreign Matter (TFM)
 Calculation of total foreign matter ( comparison to
gravimetric methods )
 Size
 Average size of all particles in microns ( trash and cleaning
classification )
Ranges of trash , Dust content and visible Foreign
matter in Raw Cotton ( Short / Medium Staple )
Trash Count /g Dust count /g V.F.M % Description ˂

˂ 25 ˂200 ˂0.60 Very Low

26-75 201-350 0.61-1.20 Low

76-110 351-600 1.21-2.30 Medium

111-150 601-1000 2.31-3.00 High

˃150 ˃1001 ˃3.01 Very High

 Napping Potential
 The Nepping Potential is tendency of a cotton to form neps
during processing .

 Micronaire value of cotton gives an indication of the nepping

potential of the raw cotton .

 Coarse fibre is more resisting to nep formation than a fine fibre.

 A mature fibre with a rounder cross section is more resistant to

nepping than an immature fibre with its flat ribbon like cross
section.
 The napotometer is used to grade raw cotton with respect to
nepping potential .

 The Instrument is basically a miniature card with three rollers

clothed with metallic wire.

 Investigations of causes of neps in general showed that:

 • 60% due to immature fibres

 • 35% due to normal fibres

 • 5% due to seed coat fragments

 A sample of 25gr is first hand carded into a 5inchx 5 inch pad
and then fed to the nepotometer .
 After 4 min treatment the web is removed and collected on to
a black velveteen –covered board ,4 inch x 9 inch .
 Its nepppiness is graded against a set of photographic
standards .
 As in the case of shirley test it is preferable to have a standard
web weight for judgment.
 Tests showed that the sample weight fed to the nepotometer
could be calculated from a knowledge of either the micronaire
value or the upper half mean fibre length as determined by
the fibrograph.
 Sample Weight in Grains = 30 – ( 2 x micronaire readings)
or 10x( 1+ Upper Half Mean length )


 Nep Count
 Nep Count ( a small knot like aggregate of tightly
entangled cotton fibres, usually not larger than a
common pin-head ,about 2 mm in diameter ) , is
number of neps per unit weight of material, usually
expressed in terms of number of neps per gram.

 Alternately , Nep count is the number of neps per

100 sq inch of card web , forming a standard hank
of sliver of 0.120 on a card 40 inch wide .
 At a first inspection it would seem necessary to collect a web from card , on a black
board 10 in X 10 in , count the neps and correct the number obtained to account for
any difference in hank and card width .

 It is often difficult for observer to decide whether a spec in the web is a nep or not .
Repeated counts by the same observer may result in different nep counts.

 Investigation of the problem by the Shirley Instt led to the development of a

simplified technique of nep counting . A fuller treatment of the test is described by
Linnert from whose article the present notes are largely derived .

 From Each side and the middle of the card samples of web are collected on black
boards ( 11.5 inch X 5 inch ) , and over the top of each web sample a counting
tempelate is placed
 The card web is taken up Black Plate ( 11.5X 5 in ) with 34 round
holes , each hole or cell being 1 sq. inch area. During the collection of
samples the card continues to run .

 The number of neps in each cell is not counted , we do not therefore ,

obtain the mean number of neps per Square inch in that way . Instead ,
we employ a method based on the statistical characteristic of the
poission distribution.

 In each cell there may be none , one , two , three … etc . neps. The
frequency distribution of these “events” or success is of the Poission
form, the neps being randomly occurring events .

 Therefore , if N cells are observed , the number of cells in which no

neps occurred i.e. no success , will be given by the first term of the
series , N exp ( -m) .

 If the number of cells containing one or more neps is counted , thus
giving the value , x , then
N-x =N exp (-m)

 In the test , the number of cells containing one or more neps is

counted , thus giving the value , x .

 We can determine , m , the mean number of Neps per cell

m = { log10N –log10(N-x)} / log 10e

 The Shirley tempelates has 34 cells in it , hence N is 34 ,

So we have , m = { log1034 –log10(34-x)} / log 10e

therefore , m=1.531-log 10 (34-x) / 0.434

 Having derived the mean number of neps per square inch , i.e per
cell , multiplying by 100 provides the nep count , n , for the card web
sample .

 The Nep count , N , has been defined as the number of neps per 100
sq inch of card web forming a standard hank sliver of 0.12 on a card
40 inch wide .

 If the sample web does web does not conform to this standard the nep
count is given by :

N = n X {hank /0.12 } x {card width in inches /40 }

or
N= {21x n x hank sliver x card width in inches } /100
Question : 4 kilotex is produced from a web of card width 38” after
testing 5 cells web formed to contain nep. Calculate nep count.
 Solution:
Sliver hank = 4 Ktex = 590.6/ 4000 Ne = 0.14765 Ne
Given :
 Card width = 38”

 No. of cells = x = 5

m = {log10N – log10 (N-x)} / log10 e

= {log 10 34 – log 10 (34-5) } / log 10 e

= 0.159

Nep count, n = m X 100 = 0.159 X 100 = 15.90
 Actual Nep Count = {0.14765x 38}/ 0.12x 40 =18.58
 Rating of the Neps
 Over the Years Yarn Imperfections have increased ,specifically yarn
neps ( +200 %) have increased in carded and combed yarn .

 Cotton Fibre Neps are created by the mechanical handling and

cleaning of the cotton

 The Neps are increased throughout the ginning , opening and cleaning
process .

 Carding and Combing process help in alignment of the fibres and

reduction of imperfections specifically Neps
Range of Neps and Seed Coat Neps in Raw Cotton
( Short / Medium Staple Cotton )

Neps per gram Seed Coat Neps per gram Description

˂100 ˂10 Very Low

101-200 11-20 Low

201-300 21-30 Medium

301-450 31-45 High

˃ 451 ˃46 Very High

Range of Neps and Seed Coat Neps in Raw Cotton
( Long Staple Cotton )
Neps per gram Seed Coat Neps per gram Description

˂100 ˂7 Very Low

101-150 8-12 Low

151-200 13-20 Medium

201-250 21-25 High

˃ 251 ˃26 Very High

Seed Coat Neps and Fibre Neps at Different
Stages of processing
Increase of Neps V/s Trash Reduction
Increase of Neps in opening and Cleaning
Nep Removal Efficiency
 In the spinning mills the process of opening and cleaning increases
neps in cotton and trash is reduced.

 Increase in neps levels in the spinning mills from bale to card

material vary depending on the aggressiveness of the cleaning
equipment .

 Nep removal efficiency is a good tool to use for analyzing the

carding and combing process.

 The increase in neps should be in progressive manner ( straight line

when plotted on graph ) . Any sudden increase or decrease means
that cleaning equipment should be immediately analysed.

 Cleaning equiment can also cause fibre damage if adjusted too

aggressively. Nep and short fibre content can be analysed at the same
time to determine the extent of any fibre damage.
 Effect of Noil removal on Neps
 There is a correlation between neps in sliver and
neps in yarn

 Increase in Noil % at comber results in reduction in

neps in the combed sliver and yarn made out of it .
 Nep and Trash
 Nep and Trash levels should both be monitored in
card sliver
 Nep count , trash amount and efficiency are
independent , The design of the card is such that
different elements affect removal of trash and nep
differently.
 Neps are greatly affected by the card flats and
throughput speeds.
 Trash is greatly affected by the licker-in , feed plate
and cylinder wire. There is some interaction of these
elements on both neps and trash but they are small .
 Uses
 Reducing yarn Imperfections
 Improving Spinning Efficiency
 Reducing Fabric Dyeing Defects
 Card Maintenance
 Waste optimisation / Cleaning Efficiency
 Optimisation of the Noil at Comber
 Optimisation of the machine setting .
Maturity Coefficient Measurement By
NaOH Method
 Maturing of Cotton Fibres
• Cotton fibres begin (after the flower dies) as thin-
walled hollow cylinders
• They first lengthen without changing in diameter;
takes around 20 days
• They then mature; takes about another 30 days
• In maturation, cellulose is deposited on the inside of
the cylinder – the ‘secondary wall’
• The hole down the centre (the ‘lumen’) becomes
progressively smaller
• The outer diameter of the fibre remains virtually
unchanged
 A cotton fibre consists of a primary layer and secondary
layers of cellulose surrounding the lumen or central canal.
 In the case of mature fibres, the secondary thickening is
very high, and in some cases, the lumen is not visible.
 In the case of immature fibres, 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
fibre. Hence to a cotton breeder, the presence of excessive
immature fibres in a sample would indicate some defect in
the plant growth.
 To a technologist, the presence of excessive percentage of
immature fibres in a sample is undesirable as this causes
lowering of the fabric appearance due to formation of neps,
uneven dyeing, etc.
· Mature/Over-mature

· Immature

· “Dead”
Maturity-Circularity
 Circularity θ, is given by the ratio of fibre wall
thickness by the area of the circle of same perimeter.
 Circularity θ = 4ΠA/ P²
 Where A = cross sectional area of wall thickness , P = Perimeter
 θ = 0.577 when maturity factor is unity.
 Empirical relation between % mature and dead fibres and θ is

θ = .00309(N-D) + 0.403
 A value of N-D = 60 is taken as standard, θ , standard circularity is
s
given by θ s = 0.59
 Maturity ratio can be estimated by the following equation
 Maturity Ratio = θ / θ s = { (N-D) /200 } + 0.7
Where - N = % of fibres with θ >0.5 and
D = % of fibres with θ <0.25
 Degree of Thickening is given by 2ΠT / P ( T isWall
thickness and P is Perimeter )
Maturity of the Cotton
 Thickness of the secondary wall has close
relationship with circularity of the fibre
which is closely related to the maturity of the Fibre.
 Degree of Secondary cell wall thicknening
 It is the ratio of the solid cross section area of the
(A) to that of a circle ( A0) bound by its perimeter .
 The Optimum level of the Ɵ lies between 0.8-0.9
 Ɵ= A/ A˳ = 4ΠA/P²
 Where P = Πd ; P² = Π²d²
 A˳ = Πd²/4=P²/4Π

 A – Fibre Cross section Area

 A˳- Area of the Circle
Other Parameters to express the maturity
 Maturity Ratio ( M) = H/Hs
 H = Average mass per cm
 Hs = Standard mass per cm

 Maturity Count = N- D
 N= Normal Fibres %
 D = Dead Fibres %
 Fibre Maturity

Calculation of Fibre Maturity :

After length development , cellulose

is deposited inside the hollow fibre
→ Fibre Maturing .

→Maturity = Degree of Cell wall

thickening
=Amount of cellulose inside the fibre

Measurements :
-Fineness
-Immature Fibre Content
-Maturity Ratio
 Calculation of the Fibre Maturity
 Maturity (according to Lord )
 M = [{ R-IFC }/ 200 ] + 0.7
 Where
 R- Mature Fibre Content (%)
 IFC – Immature Fibre Content ( %)

e.g.
 Mature Fibre Content = 37.6 %

 Immature Fibre Content =10.3

 Maturity Coefficient = {(37.6-10.3 )/ 200 }+0.7 = 0.83

Cotton Fibre Maturity
 Fibre maturity is the extent of development of the fibres.
 As is the case with other fibre properties, the maturity of
cotton fibres varies not only between fibres of different
samples but also between fibres 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 fibre.
 An immature fibre will show a lower weight per unit length
than a mature fibre of the same cotton, as the former will
have less deposition of cellulose inside the fibre.
 Depending upon thickness of wall , the fibres can be
characterized as mature , Immature and Half mature
fibres.
 In order to determine maturity , 500-600 fibres are examined under
microscope after treating in 18 % caustic soda soln .
The presence or absence of convolutions is observed and fibres are
classified as:
1) Mature or Normal fibres ( Appears as rod like )
2) Immature or dead fibres (Appears like ribbon)
3) Half mature or Thin walled fibres (Lying between above
two classes)
 Maturity Ratio(M) : M=(N-D)/200 +0.7
 Maturity Co-efficient :
Mc = ( N+0.6H+0.4I)/100
 N= Percentage of mature fibres
 H= Percentage of half mature fibres
 I= Percentage of Immature fibres

 If 100 fibres are examined from the cotton crop grown under the best
conditions , the normal fibres(N) expected would be 67 % and dead
fibres to be 7%.
 Other methods
 Differential Dyeing method :
Mature & Immature fibres differ in their behaviour towards various
dyes .This difference between the dyeing properties of mature and
immature fibres is employed to give the visual indication.

 Polarised light method :

Appearance of fibres are observed under a micrscope with suitable
polarizing equipment which gives a numerical estimate of fibre
maturity.
A sample of fibre is prepared on a small black pad and fad into the
instrument . The fibres are scanned by an electrical system and the
observations are translated into a meter reading by an electronic
circuit.
 If maturity coefficient is

 less than 0.7, it is called as immature cotton

 between 0.7 to 0.8, it is called as medium mature

cotton

 above 0.8, it is called as mature cotton

Significance
 Affects the quality of yarn
 Causes Nepping Tendency and processing trouble
specially in case of fine cotton .

 Neps may be seen as specks in the dyed cloth

 May cause shade variation after dyeing .
 Nowadays the above properties are measured by
‘HVI’ which is an automated version of the above
facilities. Advantage with this instrument is that a
large no. of samples can be tested in a relatively
short time. Therefore , it is possible to test each &
every bale in a modern textile mill with this
instrument. This instrument can also give ‘Colour
Index’ of cotton.
 The determination of fineness of a cotton is
affected by maturity of sample as immature fibre
will show a lower weight per unit length than a
mature fibre of the same cotton as immature fibre
will have less deposition of cellulose inside the
fibre.
 Differential Dyeing Method

 Fibres dyed in boiling dye bath containing 0.36g Diphenyl Fast red ;
5 BL and 0.84 g Chloarantine Fast green BLL in 120 g of water.

 Red dye has specific affinity for thick walled mature fbres and green
dye has affinity for thin walled immature fbres.

 As a result Mature fibre is dyed to red Immature fibre is dyed to green

 By visual comparison of the dyed samples against standards, maturity

of the sample is estimated.
 Micromat Fineness and Maturity Tester by SDL or WIRA Fibre
Fineness tester

The instrument provides independent estimates of fineness and
maturity of cotton from measurements of pressure drop through a
plug of cotton at 2 levels of compression.
 Arealometer :
 The instrument determines specific surface area, fineness and maturity of
fibres. Resistance to air flow through a plug of fbres is measured at two pressure
levels. The increase in resistance to air flow at low porosity (high compression )
over that at high porosity is correlated to immaturity of cotton.
 It is proposed that immature fibres get flattened at high compression and
therefore offer higher resistance to air flow.


While the instrument is useful for measuring of fineness and maturity
on raw cotton, it does not give accurate results on mechanically
processed material
Fibre Fineness by Air Flowmeter &
Sheffield micronaire
 Fibre Fineness
 The term "fibre fineness" can be defined in various
ways. There are five measures that may be used:
perimeter, diameter, area of cross-section, mass per
unit length and specific fibre surface.

 Commonly used Fibre Finenees Unit : mm / micron

for fibre diameter , Micrograms per inch , denier /
dtex etc
 Fibre Fineness- Significance
 Finer the Fibre more the numbers in yarn cross section

 More the Fibers in the cross section more will be uniformity

in yarn , better strength , less number of imperfections .

 Limiting Irregularity improves as the fibre are more in yarn

cross section
 Vr 2 = [{1002/N} + Vm2/N ]
 N = Number of the Fibres in the Cross section
 Vm = Irregularity of the Fibre

 Finer the Fibre can be spun into finer count , can spun the
same yarn with less twist
 As the Fibre Diameter increases bending rigidity
(Resistance to bending ) increases . A stiff fibre will affect
the ability of the fabric to drape and hang gracefully.
 As the fibre diameter increases , torsional rigidity
( Resistance to twisting ) increases , it is easier to spin with
fine fibres

 Light reflectance increases as the with finer fibres due to

more reflecting surface and therefore will be more lustrous

 Dye uptake is more in coarser fibres .

 Finer Fibre absorbency is more , wicking property will also

be better
 Fibre to Fibre cohesion is more in case when finer
fibres are used .

 Most of the cotton fineness determinations are likely

to be affected by fibre maturity, which is an another
important characteristic of cotton fibres.
Isuues related to the measurement of the
Fibre Fineness:
 Irregular shape of the Fibre ( Cross Section )

 Fibre to Fibre variation in fineness (In case of natural fibres)

 Variation in diameter along the length ( In case of natural

Fibres )

 Mass per Unit Length is directly related to cross Sectional

area ( In case of the fibre of circular Cross section , we can
calculate the linear density if fibre density is known )
 Selection of Methods for
measurement of fibre Fineness :
 Depends upon the form the fibre ( From Raw
Fibre ,Sliver , Roving or Yarn )

 Type of the Fibre

Method of determination- Gravimetric Method
 By measuring mass and the length of the fibre

and than linear density is determined .

 With the help of Comb Sorter Diagram

 Measure the total length and mass selected

from the Comb sorter Diagram
Method of determination- Diameter Measurement
 Applicable in case of wool and fibre having circular cross
section by Microscopic Measurement

 Procedure :
 Condition the Fibre

 Cut the Fibres in small length

 Mounting material on the glass slide ( Mounting agent with

suitable refractive Index– Liquid Paraffin with very thin layer)

 Examine the Fibre on microscope and measure the diameter with

the help of scale on microscope
Method of determination- Air Flow Method
 Fineness measurement by Gravimetric method or by measuring the
diameter on microscope is very time consuming , therefore, now a days
fineness is measured by indirect method based on “Air flow” principle
 As there is considerable variation in the linear density from fibre to
fibre, even amongst fibres of the same seed, single fibre methods are
time-consuming and laborious as a large number of fibres have to be
tested to get a fairly reliable average value.
 The measuring instrument is called “Fineness Meter”

 Some of the instruments based on this principle are –

 Sheffiled micronaire tester
 ATIRA fineness tester
 WIRA Fibre Fineness Tester
 Port-ar
 Arealometer
AIR FLOW
Principle

A sample of known weight is compressed in a cylinder to a known

volume and subjected to an air current at a known pressure .

The rate of air flow measures surface area i.e. “specific Surface Area ”
which is ratio of the surface area to the volume which is indirectly
proportional to the fibre diameter .

 Therefore, by measuring the rate of air flow under controlled

condition , the specific surface of the fibre can be determined and
consequently the fibre diameter/ fibre fineness.
 Volume = Cross Section area(A) x Length(L )
= Π (d/2)2 L
 Where d= diameter

The surface area ( ignoring ends ) = ΠdL

Specific Surface area is defined as Total Surface
area per unit mass i.e (ΠdL)/{Π (d/2)2 L }x density
= 4/d x density
The ratio also equals the ratio
Perimeter of cross section / Area of Cross Section =
Πd/Π(d)2 = 4/d

Thus , Specific Surface area α 1/d

 Fibre fineness by Air Flow Method
 By This method Fibre Fineness is measured in
micronaire Value which is the linear density in
micrograms per inch.

 This method gives average Fibre Fineness

measurement by Indirect method for mass of the
fibre using Flow meter .

 Finer Fibre will have more surface area with respect

to coarser fibre ( For same mass of the fibre bulk
which is constant for particular Instrument )
 At a constant pressure air will pass through the chamber ,
finer fibre will have more resistance to air flow i.e. Air Flow
rate is directly proportional to diameter

 Air Flow meter are Pre-calibrated to give the Fibre fineness.

 Fibre Should be well opened before Testing , Mass should

be as per the instrument’s specification and should be
preferably cleaned to remove impurities .

 Alternately, the measurement can also be done by measuring

the pressure drop at a constant air flow .
Sheffield Micronaire Tester
 Measures the fibre fineness in
terms of micrograms per inch
(micronaire value) for cotton
by air flow method.
 The measuring principle is
based on permeability-to-air
also known as Air Flow
Principle .

 For wool , scale of the

instrument is graduated in
microns

 The Sheffield measures the resistance to the flow of air
offered by a quantity of cotton fibers of a given mass
(3.240 ± 0.001 g) placed in a constant volume ( 1 cubic
inch) with the help of flow meter being calibrated in
terms of fineness instead of volume per unit time.
 The Sheffield apparatus consists of three parts:
 A cylindrical chamber in which the fibers are
placed and compressed (Airflow in the chamber is
regulated by the operator and the volume of chamber is
equal to 1 Cubic inch)
 A gauge to measure pressure at the entry of the apparatus
 A gauge that displays volume of air going through the
fiber plug and leaving the chamber (this gauge has a
scale calibrated in µg/inch or in micron .
 An Air compressor supplies air to the instrument
via the foot operated valve, the air filter , the shut
off valve , and the air regulator .
 Air regulator controls the air pressure difference
across the plug of fibre reducing the input pressure
of over 40lb/ sq inch to 4.75 lb/ sq inch which is
measured by a manometer built into the instrument.
 Rating of Micronaire Value
 Below 3 –Very Fine
 3 to 3.9 –Fine
 4 to 4.9- Avg Finee
 5 to 5.9- Coarse
 6 and above- Very coarse

 While mixing different varieties of cotton , it is

advisable to mix cotton of same micronaire
value ,otherwise the yarn becomes uneven with
more number of neps.

 The result of the difference of the micronaire value

of the cotton taken for mixing is more than the
difference in the fibre length.
Procedure :
 A special master plug is pushed home into the fibre compression
chamber.

 The instrument is then adjusted so that the float in the flowmeter tube
rises to an upper limit , with air flowing through the plug , and to a
lower limit , when the flow of air is restricted by placing the thumb
over a hole in top face of the plug . The adjustment is made by the
float positioning knob and calibration screw .

 When the initial adjustment is completed the master plug is removed

and the instrument is ready to test the samples.

 Weight the sample of 50grains( 3.24 gm)

 Open the sample into a fluffy mass with the fingers to randomize the
fibres removing all knotty balls and stringy section of fibres.
 Place the sample in fibre compression chamber .
 Insert the fibre compression plunger and lock into place by
twisting. This compresses the sample into a porous fibre
plug of 1 inch diameter and 1 inch length .
 Step on the foot pedal to turn on the air and take the scale
reading to the nearest 0.1 scale unit at the point level with
the top of the float.
 Step on the foot pedal to shut off the air , remove the fibre
compression plunger and again step on the foot pedal . The
sample will be blown out of the compression chamber.
 Before inserting another sample , operate the foot pedal to
shut off the air supply.
The micron test for wool :
 Micron test for wool fineness is similar to that of cotton , the

difference arise in regard to size of sample (5.9 g). Before Testing ,

the wool must be degreased and than conditioned. The fibre diameter
is read from the scale .
 There are some possible source of error as given below-

 The degree of random orientation of the fibres in the plug .

 Regain : although the sample is conditioned before being

compressed into the compression chamber , the r.h of the
compressed air supply may differ from the laboratory air .
 Medullation : The medulla , or hollow canal , which is present in

some wool fibres will affect the reading. Where high medullation
is present , there will be more fibres in a given weight. There will
thus be greater resistance to air flow and the float will not rise as
high as it would for a sample of the same mean diameter but free
from medullation . Hence , the mean diameter readings for heavy
medullated wools will give too low a figure for the mean diameter.
 Fibre Bundle Strength
by
Pressley and Stelometer
 Fibre Strength and Elongation
 Fibre strength denotes the maximum tension the fibre is
able to sustain before breaking.
 The strength can be tested by testing single fibre or bundle
of fibres.
 Manmade fibres are usually tested for their individual
strength as there is very less variation in length and fineness
of the fibres.
 Natural fibres are tested for their bundle strength due to
high variation in terms of length and fineness.
 It can be expressed as breaking strength or load (g) ,
tenacity (gm /Tex)
 If the individual fibre strength of fine and coarse fibres are
tested, then the coarse fibres will show more strength.
 Cosider two yarns A and B , of same count , Yarn A spun
from fine fibres and yarn B spun from coarse fibres.

 The breaking length of fine fibres is generally higher than

that of coarse fibres. Hence , Yarn “A” will show more
strength than yarn B.
Therefore, in the selection of raw
materials ,knowledge of comparative strength of available
fibres is extremely useful. This can be done either by
single fibre testing or by group fibre testing.
 Bundle Strength of cotton is measured by stelometer and
Pressley Fibre strength tester .
 Elastic recovery is the ability of the material to try and return from
elongation towards its original length.
 If a fibre returns to its original length from a specified amount of
deformation (x), then it is said to have 100% elastic recovery at x-
percent elongation. Elastic recovery is always expressed as %age.
 The elasticity or elastic recovery of a fibre is determined by several
aspects such as the type of load applied, how many times it is held in
the stretched position (cyclic loading) and the time duration of the
application of such loads.
 When a fibre is subjected to a force, it will stretch to a certain degree
after some initial resistance. The extent of such stretching is described
as the elongation or extension.
 It can be measured either as an elongation under certain load or an
elongation reached under which the fibre breaks.
Single Fibre strength V/s Bundle strength
 The fibre strength testing can be done in two ways :

 Single Fibre Strength Testing

 Bundle (group ) fibre strength testing

 The strength of fibre is expressed in terms of either tenacity

(gms/ denier or gms /tex ) or breaking length (in Km) .

 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.
 Testing of bundles of fibres takes less time and involves less
strain .
 The fibres are not used individually , the strength of yarn
also depends on other factors such as fineness of the
material ,number of fibres in cross section ,surface
character of fibre , inter fibre friction , cohesion ,
variability and also twist factor adopted during spinning .
Hence bundle strength has better correlation with spinning
performance in comparison to intrinsic strength
determined by testing of individual fibres.
 The bundle strength measured at 1/8 inch (3 mm ) gauge
length has better correlation with yarn strength than the
strength measured at other gauge length.
 The behavior of fibre and its several properties viz.
Extension, elastic recovery, yield point etc. under
different condition of loading can be studied on single fibre
strength test which is not possible for the group of fibres.
 Significance
 Strength of fibre is important as yarn strength and fabric
strength depend upon the fibre strength.

 Higher elongation of fibers resist breakage during

processing for yarn manufacturing.

 Fibers with a higher degree of elongation tend to spin more

efficiently as they deform more easily during spinning .

 Higher degree of cotton fiber elongation significantly

improve open-end spun yarn qualities.


 Important Terms & Definition
 Stress = Force Applied / Cross Sectional Area

 The cross section of many fibres are irregular in shape and difficult to
measure . To simplify, the linear density of the specimen, a dimension
related to cross section is used, the linear density may be expressed in
denier or tex count. Therefore , it is convenient to use a quantity
based on the mass of the specimen.

 This is termed as the mass stress or specific stress and is defined as

the ratio between the force applied and the linear density. i.e.

Mass Stress = Force Applied /Mass per unit length

= Force Applied / Linear density

 Strain – Elongation / Initial Length

 Tenacity :
The tenacity of a material is the mass stress at break, the units
being gm per denier or gm per tex.
 Stress Strain Curve V/s Force Elongation Curve
 Stress – Strain Curve
 Stress – Force / Cross Sectional
Area
 Strain – Elongation / Initial Length
 Force - Elongation Curve
( N- cm )
 The use of F-E curve gives a better comparison of
different material and their behavior under stress .

 General shape of the Curve remains the same but

the relative position is changes

 Stress – Strain Curve of the fibre depends upon the

molecular structure of the material

 Stress- Strain Curve of the yarn and fabric are

modified according to the construction parameters
such as twist , weave , mechanical and chemical
finishes etc.
 External Force is balanced by the molecular structure of the material

 Molecular Structure :
 Crystalline regions ( structure chain of the molecules )

 Amorphous regions ( structures in haphazard manner)

 In early stage of stretching the material , elongation is mainly
concerned with deformation of amorphous regions in which primary
and secondary bonds are stretched and sheared. If the stress is
removed at this stage extension would be recovered and material
would exhibit elastic properties.

 By increasing the stress further , stress strain curve bends sharply and
large strains or extensions are produced by small increase in stress. A
sort of plastic “flow” of the material occurs. The long –chain
molecules rearrange themselves with further breaking of secondary
bonds .

 This rearrangement of the molecules puts the material in a better

position to withstand further stresses and the rate of extension
decreases. The stress strain begins to bend towards the stress axis until
finally the breaking point is reached .
 Yield Point is a point where marked
decrease in slope occurs , Before yield
point the extension is considered to be
elastic. Above the yield point some of the
extension is not recoverable.
 Modulus - The slope of the first part of
the curve up to the yield point is known a
the Initial modulus (Young’s modulus)
 Modulus as general term is a measure of
the stiffness of the material .i.e. resistance
to extension.
 Chord Modulus – Slope of the straight
line between two specified points on the
curve. The value can be derived from
measurements of the difference in force
between two given values of extension or
the difference in extension between two
given values of the force.
 Secant modulus – This value is slope of the
straight line drawn between zero and a specified
point on the curve. It is often measured simply
as the value of extension at a given force or
alternatively as the value of force at a given
extension.
The recorded secant modulus of elasticity is
mostly that corresponding to strain at the first
application of stress in creep tests so that likely
sources of variability are rate of loading or time
to apply the load, the level of stress

 Tangent Modulus – This value is the slope at a

specified point as shown in figure .
 The tangent modulus is useful in describing the
behavior of materials that have been stressed
beyond the elastic region. When a material is
plastically deformed there is no longer a linear
relationship between stress and strain as there is
for elastic deformations.
 Initial modulus:

 The tangent of angle between initial curve and horizontal

axis is equal to the ratio of stress and strain. In textile
science it is known as initial young’s modulus.

 Initial modulus of textile materials depends on chemical

structure, crystallinity, orientation of fibre etc.

Initial modulus, tanα = Stress

Strain

Tan α ↑↓ → extension ↓↑
 Work of rupture:
The energy required to break a specimen or total work
done for breaking a specimen is termed as work of rupture and
is expressed by the units of joule, calorie etc. If applied force
‘F’ increases the length of a specimen in small amount by ‘dl’
then we have-
Work done = Force X Displacement
= F X dl
 Work factor :

Work factor can be defined as the ratio between

work of rupture and the product of breaking load and breaking
elongation.
So, Work factor = Work of rupture
Breaking load x Breaking Elongation
A yarn specimen length of 250 mm has extension of 5 % , the
length of the specimen after removal of load was found to be
252 mm . What will the elastic recovery percentage
 If the fibre obeys hook’s law, then the load-elongation curve would be
a straight line and the work of rupture = ½ x Breaking load x
Breaking elongation
 So, in an ideal case, the work factor, Wf = 1/2, whereas, Wf >1
for top curve and Wf <1 for bottom curve.
 Work recovery:
The ratio between work returned during recovery and total work
done in total extension is known as work recovery.

Work recovery = Work returned during recovery

Total work done in total extension

Total extension = Elastic extension + Plastic extension

Total work done in total extension = (Work done in elastic extension +

Work done in plastic extension)
 Elastic recovery:

 The power of recovery from an immediate extension is called as

elastic recovery.

 Elastic recovery of fibres depends on type of fibres, fibre structure,

type of molecular bonds and crystallinity of fibres.

 Elastic recovery can also be defined as the elastic extension against

total extension and expressed as the percentage.

So, Elastic recovery (%) = Elastic extension x 100

Total extension
 Bundle Strength
 Instruments used to determine the bundle strength of fibres.
1) Pressley Tester 2 ) Stelometer
 Pressley Tester: Balance type tester ,works on principle of moments.
 “ O” Gauge Test :
-The pressley tester tests a small flat bundle of fibres gripped
between special clamps known as pressley clamps. A small tuft of
fibres are selected at random and manipulated into a parallel ribbon
about 1/4 inch wide . The top jaws of the clamps are then pressed
over the fibres and tightened to a predetermined limit using a wrench.
Now a fringe of fibres will protrude from each side of the clamp.
These fibres are trimmed-off using a knife.
 3 mm Gauge Test: A plate of 3 mm is placed between the clamps.

STELOMETER : The instrument works on the pendulum lever
principle with a constant rate of loading of the fibres. The force
acting on the fibre is proportional to the sine of the angle through
which the pendulum has moved from the vertical position.
Measuring principle of Tensile Testing instruments
 The tensile testing instruments can be classified in to three
groups depending on their working principle.

 Constant Rate of Load

 Constant Rate of Extension

 Constant Rate of Traverse

 Constant rate of loading (CRL):

 The rate of increase of the load is uniform with time and

the specimen is free to elongate . The elongation being

dependent on the extension characteristics of the
specimen at any applied load .
 Constant rate of traverse (CRT ):
 The pulling clamp is moves at a uniform rate and load is

applied through the other clamp which moves

appreciably to actuate a load measuring mechanism so
that the rate of increase of load or elongation is usually
not constant and is dependent on the extension
characteristics of the specimen.

 Constant rate of elongation (CRE):

 The pulling clamp is moves at a the rate of increase of

specimen length is uniform with time and the load

measuring mechanism moves a negligible distance with
increasing load .
Stelometer
 The “Stelo” meter – the name coined
from strength and elongation which
functions on pendulum lever principle.
 Pendulum Lever Principle
 Clockwise moment of F about the
pendulum pivot O = F x OQ
 This moment is balanced by the

anticlockwise moment of W , The

weight of the pendulum , about O , = W
x OG sin Ɵ
 Hence, F x OQ =W x OG Sin Ɵ

Therefore , F= W x (OG/OQ) x Sin Ɵ

i.e. F = K Sin Ɵ or F α Sin Ɵ
Thus, Load on the fibre bundle is directly
proportional to the sin of the angle
through which pendulum is moved .
Therefore , if the rotation of the beam can
be so controlled that SinƟ varies at a
constant rate , the rate of loading will
be constant .
 A bunch of fibres are put into two jaws
having separation of 3.2 mm.

The loading of the specimen is carried

out by a pendulum system, which is
mounted in such a way that it rotates
about its C.G.

The Pendulum is pivoted from the beam

but the pivot of the beam is at the CG of the Pendulum .

The Sample is held b/w the clamp attached to the beam and one attached
to the pendulum.

The beam and pendulum start in a vertical position but the C.G. of beam
is such that when it is released the whole assembly rotates.
 As the Beam rotates the pendulum moves from
vertical so that it exerts a force on the sample .
 The speed of rotation is controlled by adjusting the
dashpot so that rate of loading is 1Kgf/sec .
 When The sample breaks the pendulum falls away
leaving a maximum reading .
 The breaking load and elongation at break are noted
from the scales .
 Tenacity ( g/ tex ) =
breaking force in kgf x15 /sample mass in mg
Procedural Details
 One Part of the pressley clamp are held in the adjustable holder carried by the beam
while other is held in a slot on the top end of the pendulum .
 The Clamps after removal of the protruding fibres are loaded in the slots on top of
the stelometer .
 A special deshpot device controls the rotation of the pendulum axis or beam .
 Dashpot is arranged and moves in such a way that the rate of loading is app.
constant and adjusted to 1 Kg/ sec by special arrangement.
 The movement of the beam applies the tension to the bundle by pulling apart the
two parts of the clamp .
 A Pointer, freely mounted on the axis and driven by a sensing pin that is mounted
on the pendulum , moves over a scale graduated from 2 to 7 kg , small pointer is
dedicated for the elongation on a secondary scale .
 The Indicators can be read to the nearest 0.01 Kg for breaking load and 0.1 % for
elongation of specimen.
 The Breaking Load can be read on the scale , the broken fibres are collected from
the clamps and weight in mg is determined accurately
 Pendulum weight remains stable while the axis moves round the arc of numbering
which shows the final result .
 Tenacity is determined on dividing breaking load by weight of the sample .
Pressley Fibre Bundle Strength Tester
 Pressley fibre strength tester -
functions on pivoted beam balance
principle.
 The beam AB is pivoted at O.
 When B rises, clamp C1 moves
upwards.
 Initially the beam have a slight
inclination of few degree to the
horizontal.
 Heavy rolling weight (W) when
released from the catch, it rolls
down the beam.
 A'O increases until the fibres break.
 As soon as break occurs, the arm
AO drops and brake arrangement
stops the carriage instantly.
 The distance A'O is the measure of breaking force. The scale is
directly graduated on the beam AB.

 As the distance from the pivot is proportional to the force on the fibre
bundle , the arm can be directly calibrated in units of force (lbf)

 At the end of the test the two halves of the bundle are weighted , and
as the total length of the bundle is fixed a figure of merit known as the
Pressley Index can be calculated . PI = Force ( lbf) / mass ( mg )

 As the Gauge Length in this test is zero , the Elongation of the Fibre is
not calculated.
 The Balance Principle
 The Balance type of
testers are based on
upon the “ Principle of
moments”
Factors affecting tensile properties of Textiles and the
results obtained from testing instruments

 Rate of loading / Rate of traverse / Time taken

to break the specimen
 Length of the test specimen / Gauge Length
 Conditioning of the samples
 Machine Capacity
 Jaw holding the fibres
 Jaw pressure
 Test Specimen length

 The graph shows the strength or breaking load of the

specimen at very small increments of length along the
complete length AB .
 If we test the specimen at a gauge length AB the strength
recorded would be that of the weakest point and value will
be S1. If we have tested the same in two halves , we would
have obtained two breaking load S1 and S2 the mean of
which will be higher than S1.
 Testing the yarn at shorter gauge length will give higher
strength .
 The Rate of Loading and the
time to break the specimen
 A rapid test produces a higher breaking load than a slow
test.
 Let FT= the Breaking Load for a time to break of T Sec
 F10 = the Breaking load for a time to break in 10 Sec
Then , Ft= F10 ( 1.09-0.09 log T)
i.e . ( FT-F10 )/F10 = 0.1 log (10/T)
 Example : A yarn gave a strength of 200g when the time taken to
break was 10 sec . Estimate the breaking load if the rate of loading
was increased to cause the yarn break in 1 sec
 Ans :
 F1=F10 (1.1-0.1 log 1.0) = 200(1.1-0.1x0.0) =200x1.1=220 g
 The load elongation Curves obtained at two rates of extension is
shown in graph .
The Capacity of the Machine
 If a weak specimen is tested on a high capacity
machine , the time to break will be short , therefore
an optimistic strength result will be produced due to
break in very short time .

 The capacity of the machine should be chosen so

that time required to break the specimen is close to
the recommendation.
 The Effect of humidity and temperature
 The mechanical behavior of textile fibres and fibre
structures is influenced by the amount moisture in the
specimen.

 The stress strain curve of hydrophobic fibre at dry and wet

will be similar while in case of hydrophilic fibres the curve
at dry and wet will be significant different.

 For Routine testing it is essential that a standard testing

atmosphere is maintained in the lab and sufficient time is
allowed to reach equilibrium conditions before tests are
made. The time required will very and mainly depend on the
form in which material is available .
 The Previous history of the specimen
 Differential behavior of a specimen after it has been
strained beyond its yield point ( already strained )
w.r.t its behavior in unstrained condition.

 Chemical treatment / damage due to chemical attack

may affect the tensile strength
 The form of the test specimen
 The complexity of the structure may range from a
relatively simple flat fibre bundle through the more
complicated structures of single and plied yarn to
woven and knitted fabrics and other forms of
manufacture.
 The man who carries out the testing of the specimen
must be ware of the interrelated factors such as
changes due to twist , changes in the thread count,
crimp and other related factors and should be
curious to know the reason of unexpected results.
 Clamping ( Grips)
 Jaw Slip / Jaw damage
 Time dependent effect
 Due to visco elastic nature of textile material
they require certain time to respond to applied
load
 On increasing rate of extension or rate of
loading , breaking strength increases and
reduces the extension at break for most of the
textile material.
 Fibre Quality Index
 In order to decide quality characteristics of the cotton
required for spinning of different count of desired CSP
values , a single measure of overall quality of cotton has
been established by SITRA. This measure is known as “
Fibre Quality Index’ and can be given by –
FQI = lusm / f
Where –
 lu – product of 2.5 % Span length (mm) and uniformity ratio
(% ) measured on digital fibrograph divided by 100
 s- Bundle Strength in g/ tex at 3 mm gauge ( Stelometer )

 m - maturity coefficient

 f-Fibre Fineness as determined on micronaire and expressed

in micrograms per inch

 Some other quality Indices
 Fiber quality index (FQI )
 Fibre Quality Index = {UHM x UI xSTR } / Mic

 Spinning Consistence Index ( SCI )

 Spinning Consistence Index ( SCI) =

- 414.67 +2.9 x strength +49.1xUHM +4.74 xUI -9.32

xMic +0.95 xRd+0.35xb
 Linear Density of man made fibres and strength
 In case of man made fibres , fineness is commonly
expressed as denier i.e. weight of 9000 meter of
length in gms .

 This can be done by measuring -

 the length and weight of no. of fibres directly ( Cut &
Weigh Method )
 by using resonance principle on vibroscope instrument.

 Cut & Weight Method
 With individual complete fibres the length of each fibre is measured
with the help of a scale on a velvet ped. Two pairs of tweezers are
used to remove the crimp. Each fibre is weighted on a micro balance
and results are used to calculate the weight per unit length.

 Alternatively ,
 Make up a bundle of 50 fibres already cut to length and weigh the

bundle
 Measure the length of the bundle

 Denier = Weight of the bundle of the 50 fibres in mg X 9000 / 50 x

length of the bundle (mm)

Fineness by Vibroscope
 When a violinist tunes his instrument he adjusts the
tension in each string until the pitch of the note produced
by blowing or plucking the string is correct.
 In other words , the string is vibrating at right frequency.
 The violin has four strings tuned to E ,A, D and G .
 The string “E” being the highest in pitch. The count or
denier of the string varies too , the finest being the E and
coarsest the G.
 From this preamble it may be inferred that frequency ,
tension and the fineness are related quantities.
Weighted specimen is clamped to the vibrator at A and passes over the
knife edge K.
Clamp and knife edge are connected to a 150 V source so that the
specimen is electrically charged.
Transverse vibrations of the specimen will therefore induce a charge in
a brass screw S situated midway between the clamp and the knife edge
and spaced 1 mm from the specimen.
Screw thus acts as a transducer , if the signals from it is amplified
suitably and fed back to the vibrator , an oscillatory loop is formed ,
thus causing the specimen to vibrate at its resonance frequency.
Voltage across the vibrator can then be fed into the frequency
measuring circuit and the frequency of the oscillation indicated on the
Measurement of single Fibre Strength
 Single-fiber specimens are broken on a constant-rate-of extension
(CRE) type tensile testing machine at a predetermined gauge
length and rate of extension equipped with :

 electronic force measuring device .

 A device giving force –elongation curve ( to indicate

whether fibre slippage is occurring in the clamps.

 A digital display or a data collecting system .

 Clamps suitable for gripping the test specimen at the

required initial length .

 Provision for precise calibration

 Using the force extension curve, the breaking force and elongation at
break are determined.
 Fibre elongation (extensibility) is an important cotton fibre property
that directly affects yarn and fabric strength and extensibility.
 Fibre with low elongation is brittle and breaks easily in processing,
which leads to reduced fibre length and increased short fibre content.
These effects in turn become negative factors affecting yarn evenness
and strength.
 The force-elongation curve and linear density are used to calculate
breaking tenacity, initial modulus, chord modulus, tangent modulus,
tensile stress at specified elongation, and breaking toughness.
 The breaking load and the extension at break shall be measured on
individual fibres using 10 or 20 mm test length.
 The time to Break from the commencement of loading shall be 20 ±2
Seconds
 Testing is carried by using a suitable tensile testing instruments.
 The mounting of the specimen shall be under standard Pre-Tension.
TERMINOLOGY AND DEFINITIONS:
 Load:
 Application of a load to a specimen in its axial direction causes a
tension to be developed in the specimen. It is measured in grams
or pounds, newtons etc.
 Breaking Load/Breaking Strength:
 This is the load at which the specimen breaks. It is usually
expressed in grams or pounds.
 Stress:
 It is the ratio between the force and the area of cross-sectional of
the specimen.
i.e., Stress = Force applied / Area of cross section

But in case of textile material, only for circular materials, it can be measured.
Cross section of yarns and fabrics, due to unknown packing characteristics the
exact cross-sectional area is very difficult to measure. Also the cross-section of
yarns, fibers or fabrics are irregular.
 Specific/Mass Stress :
In case of textile material the linear density is used instead of the
cross sectional area. It also allows the strength of yarns of different
linear densities to be compared.
Specific stress = Force / Linear density (initial)
The preferred units are N/tex or mN/tex, other units which are found in
the industry are gf/denier and cN/dtex.
 Tenacity or Specific Strength :
The tenacity of material is the mass stress at break. It is defined as
the specific stress corresponding with the maximum force on a
force/extension curve. Units are grams/denier or grams/tex.
 Strain:
When a load is applied to a specimen, a certain amount of stretching
takes place. The elongation that a specimen undergoes is
proportional to its initial length. Strain expresses the elongation as a
fraction of the original length.
i.e., Strain = Elongation / Initial length
 Extension percentage :
This measure is the strain expressed as a percentage rather than a
fraction.
i.e., Extension % = Elongation / Initial length
 Breaking extension :
Breaking extension is the extension in % at the breaking point.
 Gauge length :
The gauge length is the original length of that portion of the
specimen over which the strain or change of length is determined.
 Breaking Length:
Breaking length is an older measure of tenacity. It is the theoretical
length (in Km) of a specimen of yarn whose weight would exert a
force sufficient to break the specimen. It is usually measured in
kilometres. e.g. 10 tex yarn breaks at a load of 150grams
Breaking length would be = 15km (RKm)
The numerical value is equal to tenacity in g/tex (150/10)
 CRIMP
 Crimp is the waviness, or succession of bend, curls, or waves in the
strand induced either naturally, mechanically, or chemically.

 Crimp in man-made fibers is produced by the application of heat and

pressure or by rolling the fibers between fluted rolls.

 Crimp in fiber affects the carding and subsequent processing of the

fiber into either a yarn or a nonwoven fabric.

 Staple crimp in fiber will also affect the bulk or openness of a yarn
and therefore the hand and visual appearance of the finished textile
product.
 Fibre Crimp also plays level and that fibre crimp plays an important
role in yarn extensibility, compressibility, and fabric extensibility
and improves fabric quality
 Crimp is expressed numerically as the number of waves
(crimps) per unit length or as the difference between the
distance between two points on the fibre when it is relaxed
and when it is straightened under suitable tension,
expressed as a percentage of the relaxed distance.

 Crimp of the fibres is important for converting into yarn &

is expressed as crimp % or crimp recovery %.

 Crimp % expresses extent of crimpiness in fibre where as

crimp recovery refers to recovery of crimp after an
application of stress %.

Crimp % , C = (L-P)/P x 100

 Crimp of yarn in fabric
 When warp and weft yarns interlace in fabric they follow a wavy or
corrugated path . Crimp % is a measure of this waviness in yarns i.e.
it is % excess length of yarn over the cloth length.

Crimp % = {(l-p)/p} 100

 Crimp normally varies ranging from 1% to 14%.
 It affects the cover, thickness, softness and hand of the fabric.

 When it is not balanced it affects the wear behaviour and balance

of the fabric, because the exposed portions tend to wear at a more
rapid rate than the fabric.

 The crimp balance is affected by the tensions in the fabric during

and after weaving. If the weft is kept at low tension while the
tension in warp directions is high, then there will be considerable
crimp in the weft and very little in the warp.
 Working Procedure for crimp Measurement

1) At first we have to select the warp or weft way of the fabric. Then we
should select the test length of the yarn.
2) According to test length we will cut the flap of fabric.
3) Now a single yarn is removed from the flap of fabric carefully.
4) One end of the yarn is gripped in the fixed gripper of the m/c and the
other end is gripped in the other setting the test length.
5) Tension for the yarn is found out from count & set on the m/c.
6) After that we will apply tension along the yarn length with hand by
taking away the other end of yarn far from the first end.
 TRASH
 The raw cotton consists of foreign fibres matter such as broken leafs ,
pods , seed coats , seed fragments , sand and dirt etc known as
“trash”
 These impurities i.e . ‘trash” needs to be determined from
commercial as well as quality point of view. The Shirley trash
analyser is used for determination of trash and lint content in the
cotton / cotton waste .
 The Shirley trash Analyzer is useful for following –
 To give definite figures of Trash and clean cotton to purchaser and seller .
 To provide an idea to cotton spinners / Waste spinners of his existing
machinery capabilities on any particularly class or mark of cotton / cotton
waste .
 To determine the state of cleanliness of the product at any stage upto and
including carding .
 To Ascertain the quantity of spinnable fibre in the waste from any
production machine .
Shirley Trash Analyser
 works on the principle of buoyancy
separation principle by use of air currents .
 Consists of a feed roller, licker- in, the
cylinder and a blower to open the fibers and
separate lint and trash.
 The cotton is fed slowly to the lickerin and,
as it is broken up, the air blast carries the
lint around the bottom of the flow plate and
up to the condenser.
 Air stream is so adjusted that it carries only
the cotton fibres and dust, leaving the trash
to fall in the lower portion of the machine.
 The dust passes through the cage to the
exhaust and the fibres are collected in the
delivery box .
 Trash and heavy particles drop into the
waste chamber.
 The working is similar that of a miniature
carding machine.
 Measurement
 Normally, 100-200 gm. cotton is tested for determining the
trash %. The care is taken so that no trash is lost in
handling.
 Lint Content :
The portion consisting of cotton fibres separated
from the specimen and free from trash.
 Trash Content:
The amount of material other than fibres
collected from the specimen in test.
 Invisible Waste ( Cage Loss ) :
The part of specimen not accounted for by adding together
the lint and trash contents.
 Spin Finish
 Artificial fibres require spin finishes for conversion into textile
materials for various applications and efficient operation. Although a
spin finish on a fibre surface might be only a few molecules thick, it is
one of the most important parameters affecting the quality and
performance of the processing

 A spin finish is a preparation applied by the manufacturer of MMF

to staple fibers .

 It is used in the form of a water- based emulsion and contains anti-

static agents, emulsifiers and lubricants.

 Advantages of spin finish :

 To lubricate the fiber surface

 To protect against electrical charge generated due to high
friction and low electrical-conductivity of synthetic fibers.
 To assist opening achieved by optimal interplay with the set
crimp of fibers.
 To impart coherence to a fiber strand ( fiber adherence in the
card web, D/F sliver and yarn).
 To assist in avoiding the formation of laps caused by building
up of spin finish on the thread guide. Lap formation can also arise
from electrostatic attraction in absence of adequate spin finish.
 To reduce fly generated due to inadequate fiber adherence.
 To lubricate properly so that fiber shortening does not occur.
 Yarn Count
The term count or yarn number is commonly used to define
fineness of yarn. Several systems and units are used for
expressing the yarn count.

Indirect System
In this system count is number of units of length per unit of
weight. In this case higher the count, finer the yarn.

Direct System
In this system count of yarn is the number of units of weight per
unit length of yarn.

Universal System
Tex system of yarn numbering is called universal system. This is
a direct system & introduced by ISO (International Organization
for Standardization).
Weight/Unit Unit of mass Unit of length
length
Indirect
System 1 Lb Hank of 840 yd.
a) New English 1kg Hank of 1000
b) Metric ½ Lb mts.
c) French Hank of 1000
mts.
Direct System
1) Tex (T) 1 gm. 1000 mt.
2) Denier (D) 1 gm. 9000 mt.
 CONVERSIONS
 From Indirect to Indirect :

Count in Unknown System X( length Unit / Weight Unit)

= Count in known System X (Length unit /Weigt Unit )

 From Indirect System to Direct System :

Count in Indirect System X (Length Unit / Weight Unit)

=1/(Count in Direct system X Weight Unit /Length Unit )

 From Direct System to Direct System :

Count in Unknown System X( weight Unit / Length Unit)

= Count in Known system X (Weight Unit /Length Unit)
 Formula for yarn count – Direct System :

N = Wx l / L
Where N =The yarn number
W = The weight of the sample in the unit of the system
L = The length of the sample
l= The unit of length of the sample
Example : If a skin of 100m of filament yarn weighs 1.67 g . Calculate
the denier .
Soln : W = 1.67 g
L= 100 m
l= 9000 m
Denier = 150.3 Den
 Formula for count -In Direct system

 N=Lxw÷lxW

Where :
N = Yarn Number
W = Weight of the sample in the unit of the system
w = Unit of weight of the system
L = length of the sample
l = The unit of length of the system
Example : A lea of cotton ( 120 yards ) of cotton yarn weighs 25
grains . Cal its count in the cotton system .

Soln : 120 x 1 ÷ 840 x (25 / 7000 ) = 40s

 Measurement
Basic requirements of yarn count determination are -
-An accurate length measurement
-An accurate weight measurement

Instruments Used for count determination -

 The Wrap reel
 Wrap Block

 The Balance :
-Analytical balance
- Knowles Balance
-Quadrant Balance
-Beesley Balance
- Digital Balance
Knowles Balance:
 A type of beam balance with a hexagonal section rod.

 On this rod A,B,C,D and E are the 5 individual faces

calibrating in count scale up to a certain range.

 These faces can be brought to the viewer by truing a screw

placed one side of the rod.

 Again for every face A to E there is a separate wt calibrating

A,B,C,D and E.

 On the beam there is an moveable ride which can move on

the scale to make the beam balanced.
Procedure:
 120 yds of yarn is placed on the right hand pan of the
balance and any of the of the 5 (A-E) are placed on the left
hand pan.
 Then the truing screw is turned and the corresponding is
kept on pan then the scale is brought in front. e.g. , if weight
B, is kept of pan then then the scale B will brought in front.
 At this stage, the balance will be unbalanced.
 Now by sliding the rider on the scale the beam is balanced.
 Now the position of rider on scale will indicate the yarn
count.
Quadrant Balance
 A given length of sample (4 yds of cotton) is measured by
measuring scale.

 Adjusting the quadrant balance the sample is hung in its

hook and from the respective scale, count is directly
measured.

 Three types of scale are present in quadrant balance

i) 4 yds for sliver(hank)
ii) 20yds for roving (hank)
iii) 840yds for yarn (count)

 The operation is repeated 16 times and mean is calculated.

The mean will be the count.
 BEESLEY
BALANCE :
 BEESLEY BALANCE helps to determine yarn count of
fabrics.
 It comprises of a balance in which it is provided with a
pointer which on one side corresponds to a datum line and
the other side is provided with a hook/hanger where the
specimen is hanged.
 In the middle of the pointer there is a small notch provided
where either small or large hook-weight is to be placed.
 On the placement of the hook-weight in the notch, the
pointer would fall in a downward position from the datum
line.
 Place the yarn one by one after cutting it according to the
template provided till it corresponds to the datum line and
the No. of yarns would give the Yarn Count.
 Yarn Count
 In the traditional count systems a folded yarn is denoted by the count
of the singles yarn preceded by a number giving the number of single
yarns that make up the folded yarn.
For example, 2/24s cotton count system implies a yarn made from two 24s count
cotton yarns twisted together; 1/12s cotton count means a single 12s count
cotton yarn.
 In the tex system there are two possible ways of referring to folded
yarns: one is based on the linear density of the constituent yarns and
the other is based on the resultant linear density of the whole yarn.
In the first way the tex value of the single yarns is followed be a
multiplication sign and then the number of single yarns which go to
make up the folded yarn, e.g. 80 tex X 2 . This indicates a yarn made
from twisting together two 80 tex yarns.
 In the second way of numbering folded yarns is R 74 tex / 2 .It
means R = resultant, 74 tex is the final yarn count and 2 is denoting
no. of plies twisted together.
 Twist :
 It is spiral turns given to a yarn in order to hold the constituent fibres
or threads together. It is expressed as TPI (Twist per Inch) or TPM
(Twist per Meter).
 It gives strength to yarn & feel in the fabric.
 The direction of twist becomes important because it influences the
character and the appearance of the finished materials .

 S twist-anticlockwise ; Z twist-clock wise.

 Effect of twist characteristics
As the twist increases, the lateral force holding the fibres together is increased so that
more of the fibres are contributed to the overall strength of the yarn.
 As the twist increases further , the angle that the fibres make with the yarn axis

increases, so prevents them from developing their maximum strength which occurs
when they are oriented in the direction of the applied force. As a result, at certain
point the yarn strength reaches a maximum value after which the strength is reduced
as the twist is increased still further .
 The amount of “twist” in the yarn produces different characteristics:

 Low twist – make bulky, soft and fuzzy fabrics

 Average twist – most common

 High twist – make a very smooth, shiny fabric

Twist Multiplier :
-The value of TM is decided by the spinner on the basis of type of yarn to be
produced
-Using the same TM , cotton yarns spun to different count will posses the same
characteristics such as same degree of hardness and twist character.
 TPI = TM count
Level of Twist:
 Twist is expressed as the number of turns per unit length, e.g. TPM or TPI.
 However the ideal amount of twist varies with the yarn thickness i.e., the thinner the
yarn, the greater is the amount of twist that has to be inserted to give the same
effect. The factor that determines the effectiveness of the twist is the angle that the
fibers make with the yarn axis.

 Fig shows diagrammatically a fibre taking one full turn of twist in a length of yarn
L. the fibre makes an angle with the yarn axis. For a given length of yarn, the angle
is governed by the yarn diameter D:
tan θ = п D/L
 The greater the diameter of the yarn, the greater the angle of twist (for same twist
level). As 1/L is equivalent to turns per unit length then:
tan θ ∝ D x turns/unit length
 In the indirect system for measuring linear density the diameter is
proportional to 1/√count. Therefore
tan θ ∝ (turns / unit length ) / √ count
Twist factor is defined using this relationship:
K= (turns / unit length ) / √count
(K is the twist factor)
 Value of K differs with each count system.

 (a) In case of Tex (direct system):

K= TPM x √count

 (b) For indirect:

K= TPI (or TPM or TCM)/ √count

 (Value of K ranges 3.0—8.0 from softer to harder)

 Twist effects on yarn and fabric properties:
(a) Handle :
 As the twist level in a yarn is increased it becomes more compact because the fibres
are held more tightly together, so giving a harder feel to the yarn.
 A fabric made from a high-twist yarn will therefore feel harder and will also be
thinner. A fabric produced from a low-twist yarn will have a soft handle but at the
same time weaker yarn thus resulting in pilling and low abrasion resistance of
fabric.
(b) Moisture absorption :

High twist holds the fibres tight thus restricting water to enter. Such a high
twist yarn is used where a high degree of water repellency is required, e.g. in
gabardine fabric. Low twist yarn is used where absorbency is required.
(c) Wearing properties :

With an increase in twist level wearing properties (abrasion and pilling) are
improved. High level of twist helps to resist abrasion as the fibres can’t easily
pulled out of the yarn. The same effect also helps to prevent pilling (which result
from the entanglement of protruding fibres).
(d) Aesthetic effects :

The level of twist in yarn alters its appearance both by changing the thickness
and light reflecting properties.
 Different patterns can be produced in a fabric by using similar yarns but with

different twist levels; a shadow stripe can be produced by weaving alternate bands
of S and Z twist yarns.
 Level of twist can also be used to enhance or subdue a twill effect : a Z-twill

fabric produced by weaving Z-twist yarns will have enhanced Z-twill effect. Same
is the case for S-twill.
(e) Faults :
 Because of level of twist in a yarn can change its diameter and other properties such

as absorption; same yarn can change the appearance of a fabric, so giving rise to
complaints.

Twist Applications :
 Georgette is made of highly twisted yarn (upto 1000 TPM) by weaving S and Z
twisted yarns alternately both in warp and weft direction.
 Chiffon is made in the same way but yarn is more twisted (up to 2000 TPM) and
finer than that used in georgette-Cupramonium rayon is used.
 Herringbone is made by using yarns of different types and levels of twists.
 Effect of twist factor on physical properties:
 A cotton yarn having twist factor of 3 will feel soft and docile,
whereas one with twist factor 8 will feel hard and lively.(A lively yarn
is one that twists itself together when it is allowed to hang freely in a
loop) .
 Crepe yarns use high twist factors (5.5-8.0) to give characteristic
decorative effects. A fabric made from such yarns is first wetted and
then dried without any constraint to produce characteristic uneven
crepe effect.
 The twist in yarn is not usually distributed uniformly along its length,
such that :Twist x mass per unit length = constant
i.e. twist tends to run into the thin places in a yarn; twist level will
vary along the yarn inversely with the linear density.
 So it is suggested that twist level should be determined at fixed
intervals along a yarn such as every meter.
 Measurement of yarn Twist :
 Twist is measured by untwisting the yarn in case of plied yarn and by
twist-re-twist method in case of single yarn.

I) Direct counting method :

 This is the simplest method of twist measurement.
 The method is to unwind the twist in a yarn and to count how many
turns are required to do this.
 A suitable instrument has two jaws at a set distance apart. One of the
jaws is fixed and the other is capable of being rotated.
 A counter is attached to the rotating jaw to count the turns.
 Testing is started at least one meter from the open end of yarn. A
standard tension (tex/2) is used when yarn is being clamped.
 Twist is removed by turning the rotatable clamp until it is possible to
insert a needle between the individual fibres at the non-rotatable
clamp end and to traverse it across the rotatable clamp.
 A magnifying glass is needed to test the fine yarns.
II) Untwist-twist method or Twist contraction method :
 This method is based on the fact that yarns contract in length as the

level of twist is increased and it increases in length on twist

removing, at last reaching a maximum length when all the twist is
removed.
 The yarn is first gripped in the left-hand clamp which is mounted on a

pivot and carries a pointer.

 After being led through the rotating jaw, the yarn is pulled through
until the pointer lies opposite a zero line on a small quadrant scale;
jaw is then closed.
 At this stage the specimen is under a small tension and has a nominal
length of 10''.
 As the twist is removed, the yarn extends and the pointer assumes a
vertical position, so removing the tension.
 Eventually all the twist is taken out but the jaw is kept rotating in the
same direction until sufficient twist has been inserted to bring the
pointer back to the zero mark again.
 Total number of turns recorded on the revolution counter is divided by
20.
 The method is based on the assumption that the amount of twist put in
is equal to the twist that has been removed. However, this is not
necessarily the case.
 For woollen yarns the test may give results up to 20% below the true
value and for worsted it may be 15% higher.

 It may be due to :
 At the point of twist removal the fibres in the yarn are

unsupported so that any tension in the yarn may cause the fibres
to slip past one another, so increasing the length of yarn.
 With same yarns when the twist is removed the amount of twist

to bring it back to the same length is not equal to the twist taken
out.
 Because of these problems the method is not recommended for

determining the actual twist of a yarn but only for use as a

production control method.
 It suggests that 16 samples are tested using a gauge length of

250mm. However , the method is easy to use.

 Twist Contraction

 Take Up or twist contraction % is defined as the difference

in length between the twisted and untwisted threads
expressed as a percentage of untwisted length i.e.

 Take Up % or twist contraction %

= {( Untwisted length-twisted length)/untwisted
length}x100
 Some Definitions
 TWIST ON TWIST :
 In case of Ply Yarn , when twist direction in ply is similar to that of

component yarns, It is called twist on twist. This will produce a

hard twisted strand e.g. Crepe and Voile yarns

 WEFT ON TWIST :
 In case of Ply Yarn , when twist direction in ply is different to that

of component yarns, It is called weft on twist. This will produce a

soft twisted strand .
 BALANCED TWIST :
 A Yarn is said to be in balance if amount of twist is just enough to

keep component yarns or fibres in position. If more twist is put in

the yarn , it will kink & snarl and if less twist is put in the yarn , it
will tend to untwist and again will kink. In case of Hosiery and
Sewing threads , balance of twist in the yarn is very important .
 Spin Finish
 A Spin finish is a liquid or solid composition that is applied to the
surface of man-made fibres in order to improve the processing of
such fibres in short –staple or long staple spinning .

 The following terms are used to define the same thing ; Spin Finish ,
waxing , size , dressing , coating , fibre finish , spinning lubricant ,
agent , textile treating composition / agent and conditioning agent .

 It is used in the form of a water- based emulsion and contains anti-

static agents, emulsifiers and lubricants.
 The primary function of a spin finish is to eliminate the build up of
static electricity charges on fibres during processing.
 This is achieved in two ways .
 The finish makes the the fibre hydrophilic in order to facilitate

charge dissipation ( leakage ) .

 It reduces the static and dynamic friction of the fibres and

subsequently the yarns, while they are moving in contact with

machine parts , diminishing the generation and build up of charge.
 As an example , yarns experience drag as they pass over a ceramic
guide or pass through the traveller during ring spinning , If the drag is
too great , due to the degree of friction between fibres and machinery ,
fibres can be damaged .
 A spin finish can reduce the amount of friction to a level which avoids
problems such as end breaks in fibres .
 Friction can also cause local fusion of fibres especially at points
where the fibres rub guides and other machine parts during winding.
 Components of Spin Finishes
 Spin finishes consists of several components , including
 Lubricants
 Emulsifiers
 Antistatic agents
 Cohering agents
 Antioxidants
 Pigments
 Antifoam agents
 Other additives ( such as bactericides , corrosion inhibitors and
wetting agents )
 Types and Application of Spin Finishes
 The Type of spin finish to be used depends on many factors , these
include –
 The Chemical properties of the fibre

 The Type of spinning process , e.g. Short or long staple spinning

or continuous filament spinning

 The technique used for applying the finish

 Spin finishes are most commonly applied as emulsions , except for

acetate finishes which are deposited as pure blended oils .
 Some finishes are applied by emulsion bath between drawing stage
and the tow going to the top converters as in the case of continuous
filament production .
 They can be added all in one go to the polymer solution during
spinning as happens in melt spinning. Alternatively , can be sprayed
onto the fibres as in case of opening and cleaning lines (blow room )
 Quality Issues in the use of spin Finishes
 The quantity of spin finish applied to staple fibres during the processing is critical
and must be optimized so that neither too much nor too little is used .
 Too little spin finish can generate technical problems such as increased static
electricity charges on the frictional surfaces of the fibres during processing and dry
surfaces on fibres which lead to surface flakes .
 Too much spin finish can lead to a greater amount of smearing . In addition to this ,
it can cause chokeing in the metallic card cloth and the pins ( teeth ) of the opening
cylinder of the rotor spinning M/c. The smearing effect associated with fibre debris
can generate hard cake which can cause damage to machinery as well as affecting
fibre appearance.
 A high degree of fibre to fibre friction can lead to efficient binding and cohesion
between the fibres in the carding web or sliver , lack of excessive bulkiness of the
fibrous tufts and a reasonable yarn strength .
 A low friction between fibres and machine parts prevents choking of the metallic
card cloth and produces less fibre breakages during carding or opening , and less
fibre accumulation in the yarn guides . A low fibre friction can also result in less
fibre disturbances during operations in such operations such as roller drafting , the
opening line , carding and rotor spinning.
 Key Requirement for Spin finishes
 Spin Finishes must meet a range of requirements if they are to be effective and to
add value to the final product . These requirements can be covered under following
 Interaction with fibres
 Spin finishes should not affect fibre morphology and quality .

 must be readily adsorbed and have good adherence to the fibre surface .

 Ability to wet the fibre surface and spread evenly over it to avoid dry friction.

 it must be easily removed before dyeing.

 It must also have no effects on dyeing absorption i.e. the dye affinity of the
fibres or dye fastness . Some spin finishes have been used to block certain dyes
where this is required.
 Does not affect the shelf life of the final yarn. Some finishes use titanium

dioxide to enhance colours in fabric but the additive is abrasive and can weaken
the yarn.
 Interaction with processing conditions and machinery
 Must not cause damage to metallic and non metallic surfaces of machine parts

( e.g. aprons , cots , rotors of spinning machines )

 Must not show gluing effect which might cause fibres to adhere to the

machinery .they must be easy to clean from both fibres and machinery .
 Safety and other issues
 Spin finishes must be able to withstand intensive rubbing, i.e. low
wearability , and resistance to flaking when subjected to friction.
 Thermal stability and reasonable ability to undergo evaporation
( sublimation) with no ill-effects .
 A constant viscosity with increase in temperature
 Lack of Foaming.
 Control of Volatility , smoke potential , and flashpoint of the finish
 They must show low migration into polymer (e.g rubber ) components
which could cause swelling and fracture.
 Spin finishes must be toxicologically and physiologically safe.
 Spin finishes must be safe for storage for longer duration i.e. high
resistance to ageing , bacterial attack and oxidation.
 Testing of Spin Finish
 Several techniques are available to measure the spin finish content of
fibres . Some of them are –
 Automated Infrared ( IR ) analyser method
 A small mass ( 1 g) of the fibre is put into a container .

 A known volume of solvent is added .

 The container is then vibrated to extract the finish . The solvent is

transferred to an IR ( infrared ) cell .

 The infrared absorbance is recoded at a constant wavelength .

The percentage of finish content can be calculated from a

specified calibration curve.
 This manual procedure can be simplified by using an automated

IR analyser , where the fibre sample is put on an integrated

balance for automatic mass calculation .
 The extracted finish automatically fills a cup . The finish

solution is agitated and pumped to an IR analyser for absorption

investigation .
Soxhlet Techniques :
 A mass of 10 g of filament / fibre is placed in a funnel .
 Solvent is added to the mass of the fibre and the funnel is
vibrated for a few minutes ( 3-5 ) to completely remove the
finish from the yarn .
 The solvent is then removed via evaporation .
 The finish content is determined by dividing the mass of the
finish by mass the mass of the sample , and then multiplying
by 100 .
 The finish must be completely soluble in the cold solvent .
Water is a good solvant for polypropylene while petroleum
ether is a suitable solvent for polyamide.
 The solvent must not solubilize the fibre’s oligomers.
 Near Infrared reflectance analysis ( NIRA ) Techniques
 This technique is used for measuring the spin quantity on the

filament / fibre without the use of solvents .

 When the light beam is blocked by a filament or fibre sample ,

some of the light beam is absorbed and rest is reflected .

 The level of the absorbed light varies accrding to the chemical

nature of the fibre and the finishes .

 Through a comparision of the original light and the reflected light ,

it is possible to determine the percentage of finish quantity in the

yarn .
 A group of standard samples of fibres or filamnts with different

known percentages of finish are tested by the apparatus to build a

correlation between the standard samples and the tested samples .
 X-Ray photoelectron spectroscopy :
 X-ray photoelectron spectroscopy (XPS) can be used to give a

picture of the morphology of the finish that is deposited on the

fibre surface

 Radioactive tracer technique :

 When the lubricant ( finish ) is marked with a radioactive tracer , it

is then possible to track the finish deposit on the fibre surface with
the help of a Geiger Counter , or indirectly from contact
photography of the filament .
 A Spin finish is a liquid or solid composition that is applied to the surface of man-made fibres
in order to improve the processing of such fibres in short –staple or long staple spinning .
 The following terms are used to define the same thing ; Spin Finish , waxing , size , dressing ,
coating , fibre finish , spinning lubricant , agent , textile treating composition / agent and
conditioing agent .
 A an electrostatic charge is generated on fibre surfaces during processing due to friction
between the fibres themselves or between them and parts of the spinning machinery with
which they come in contact . This charge can cause major problems in processing . Static
electricity causes fibres to attaract or repel one another , disrupting yarn formation. It can also
cause fibres tostick to other surfaces such as machine parts . In addition , it is important that
synthetic fibres used for producing fabrics, particularly , household or industrial fabrics ,
have optimum antistat friction properties if they are to perform properly in use.
 The primary function of a spin finish is to eliminate the build up of static electricity charges
on fibres during processing. This is achieved in two ways . First , the finish makes the the
fibre hydrophilic in order to facilitate charge dissipation ( leakage ) . Second , it reduces the
static and dynamic friction of the fibres and subsequently the yarns, while they are moving in
contact with machine parts . , diminishing the generation and build up of charge .
 Spin finish can also control the amount of friction during processing . As an example , yarns
experience drag as they pass over a ceramic guide or pass through the traveller during ring
spinning , If the drag is too great , due to the degree of friction between fibres and
machinery , fibres can be damaged . A spin finish can reduce the amount of friction to a level
which avoids problems such as end breaks in fibres . Friction can also cause local fusion of
fibres especially at points where the fibres rub guides and other machine parts during
winding.
 Components of Spin Finishes
 Spin finishes consists of several components , including
 Lubricants
 Emulsifiers
 Antistatic agents
 Cohering agents
 Antioxidants
 Pigments
 Antifoam agents
 Other additives ( such as bactericides , corrosion inhibitors and wetting agents )
 Types and Application of Spin Finishes
 The Type of spin finish to be used depends on many factors , these include –
 The Chemical properties of the fibre
 The Type of spinning process , e.g. Short or long staple spinning or continuous filament spinning
 The technique used for applying the finish

The fibre producers can often give the best advice for electing the spin finish . It is recommended that
spinning mill applies the fibre manufacturer’s own finish so that it can closely matched with the
fibre.
Spin finishes are most commonly applied as emulsions , except for acetate finishes which are
deposited as pure blended oils .
Some finishes are applied by emulsion bath between drawing stage and the tow going to the top
converters as in the case of continuous filament production . They can be added all in one go to the
polymer solution during spinning as happens in melt spinning. Alternatively , they can be sprayed
onto the fibres as in case of top blending in the gill box frames in the opening and cleaning lines
( blow room )
 Key Requirement for Spin finishes
 Spin Finishes must meet a range of requirements if they are to be effective and to add
value to the final product . These requirements can be covered under following –
 Interaction with fibres
 Interaction with processing conditions and machinery
 Safety and other issues
 It is essential that the application of spin finishes should not affect fibre morphology
and quality . A spin finish must be readily adsorbed and have good adherence to the fibre
surface . It must have the ability to wet the fibre surface and spread evenly over it to
avoid dry friction. On the other hand , it must be easily removed before dyeing. It must
also have no effects on dyeing absorption i.e. the dye affinity of the fibres or dye fastness
. Some spin finishes have been used to block certain dyes where this is required. It is
also important to ensure that the finish does not affect the shelf life of the final yarn.
Some finishes use titanium dioxide to enhance colours in fabric but the additive is
abrasive and can weaken the yarn.
 Spin finishes must be able to withstand intensive rubbing, i.e low wearability , and
resistance to flaking when subjected to friction.
 Thermal stability and reasonable ability to undergo evaporation ( sublimation) with no
ill-effects .
 A constant viscosity with increase in temperature
 Lack of Foaming.
 Control of Volatility , smoke potential , and flashpoint of the finish

 In particular , they must show low migration into polymer ( e.g rubber
) components which could cause swelling and fracture.
 They must not show gluing effect which might cause fibres to adhere
to the machinery .they must be easy to clean from both fibres and
machinery .
 Spin finishes must be toxiocologycally and physiologically safe.
 Spin finishes must be safe for storage for longer duration i.e. high
resistance to ageing , bacterial attack and oxidation.
 Quality Issues in the use of spin Finishes
 The quantity of spin finish applied to the artificial staple fibres of continuous filaments
during their processing is also critical and must be optimized so that neither too much nor too
little is used . Too little spin finish can also generate technical problems such as increased
static electricity charges on the frictional surfaces of the fibres or filaments during processing
, and dry surfaces on fibres which lead to surface flakes .
 The addition of too much spin finish can lead to a greater amount of mearing , e.g. in the
rotor groove ( collecting surface ) of the rotor spinning machine . In addition to this , , it can
cause chokeing in the metallic card cloth and the pins ( teeth ) of the opening cylinder of the
rotor spinning machine. The smearing effect is associated with fibre debris that can generate
what is known as hard cake which can cause significant damage to machinery as well as
affecting fibre appearance.
 It is important that the type and application of spin finish achieves the right balance in the
degree of friction achieved during processing . A high degree of fibre to fibre friction can
lead to efficient binding and cohesion between the fibres in the carding web and carded or
drawn sliver , lack of excessive bulkiness of the fibrous tufts and the ahcievement of a
reasonable yarn strength . It can also increase the false –twist effect during rotor spinning that
helps yarn formation inside the rotor.
 A low friction between fibres and machine parts prevents choking of the metallic card cloth ,
allows easy separation of the fibre wedge from the collecting surface of the rotor’s spinning
machines , and produces less fibre breakages during carding or opening , and less fibre
accumulation in the yarn guides . A low fibre friction can also result in less fibre disturbances
during operations in such operations such as roller drafting , the opening line , carding and
 Potential Spin finish problems in short staple plants include –
 Swelling of the rubber aprons and cots of the top rollers of the roller drafting
system
 Flaking of fibres and an increase in static charge accumulation , caused by an
uneven distribution of spin finish spraying .
 The formation of hard coatings on different machine parts such as teeth of the
licker-in , opening roller pins ( teeth ) of the rotor spinning machines ,
trumpets on card ,or on the draw frame and the speed frames ( flyers ) and the
pressing arm eyelet ; this can lead to an increase in production costs due to the
need for more cleaning and more downtime .
 A decrease in wear in machine parts such as the sliding wall of the rotor
spinning machines’s rotors, the traveller of the ring spinning machines , and
the toothed cylinders of the feeding section of the rotor spinning machines , due
to the fact that the spin finish recipes contain corrosion inhibitors. Whilist ,
overall , this is beneficial , it is well known that degree of wear in machine parts
enhances the quality of yarn spinning .
 Testing of Spin Finish
 Several techniques are available to measure the spin finish content of fibres .
Some of them are –
 Automated Infrared ( IR ) analyser method
 A small mass ( 1 g) of the fibre is put into a container . A known volume of

solvent is added . The container is then vibrated to extract the finish . The
solvent is transferred to an IR ( infrared ) cell . The infrared absorbance is
recoded at a constant wavelength . The percentage of finish content can be
calculated from a specified calibration curve. This manual procedure can be
simplified by using an automated IR analyser , where the fibre sample is put
on an integrated balance for automatic mass calculation . The extracted finish
automatically fills a cup . The finish solution is agitated and pumped to an IR
analyser for absorption investigation .
 Soxhlet Techniques :
 A mass of 10 g of filament / fibre is placed in a funnel . Solvent is added to the

mass of the fibre and the funnel is vibrated for a few minutes ( 3-5 ) to
completely remove the finish from the yarn . The solvent is then removed via
evaporation . The finish content is determined by dividing the mass of the
finish by mass the mass of the sample , and then multiplying by 100 . The
finish must be completely soluble in the cold solvent . Water is a good solvant
for polypropylene while petroleum ether is a suitable solvent for polyamide.
 Near =Infrared reflectance analysis ( NIRA ) Techniques
 This technique is used for measuring the spin quantity on the filament / fibre without the use of
solvents . When the light beam is blocked by a filament or fibre sample , some of the light beam is
absorbed and rest is reflected . The level of the absorbed light varies accrding to the chemical nature
of the fibre and the finishes . Through a comparision of the original light and the reflected light , it is
possible to determine the percentage of finish quantity in the yarn . A group of standard samples of
fibres or filamnts with different known percentages of finish are tested by the appratus to build a
correlation between the standard samples and the tested samples .

 X-Ray photoelectron spectroscopy

 X-ray photoelectron spectroscopy (XPS) can be used to give a picture of the morphology of the
finish that is deposited on the fibre surface
 Radioactive tracer technique
 When the lubricant ( finish ) is marked with a radioactive tracer , it is then possible to track the finish
deposit on the fibre surface with the help of a Geiger Counter , or indirectly from contact
photography of the filament .
 Spin finish
 A spin finish is a preparation applied by the manufacturer of MMF to staple fibers . It is
used in the form of a water- based emulsion and contains anti-static agents, emulsifiers
and lubricants.
 Size:
 Sizes are applied by the spinner of MMF to filament yarns ( smooth and texturized, textile and technical). They
are mostly used in the form of water based emulsion but can also be applied in a solvent free form (neat oil) or
in an organic solvent-base. In absence of water, they have fluid consistency and contain mainly lubricating
products.
 Greases:
 The concept of grease is mostly connected to animal fibers but also in connection with dyed (synthetic) flocks
or sliver. These are considered as secondary finish. They are applied as water based emulsion.
 Spin Finishes , Sizes and Grease Features :
 They have a common characteristics, all of them act as lubricants
in manufacturing and processing of fibers , filament, and resulting
yarn.
 Processing can not be done adequately without the application of
lubricants. The significance is analogues to lubrication oil in motor.
 The only function is not lubricating or influencing frictional
properties but influence other properties such as anti-static, thread
connections, openability and protection of the material.
 It not only provides advantages but also creates some problems such
as sticky smears, cause swelling of fibers or fiber guiding
elements, create fumes, decomposes to heat etc.
 So the best practice is to use optimal range of finishes which will
balance between benefits and problems.

Why spin finishes are required : purpose / necessity ?
 Natural fibers have inherent lubricating compound( natural wax ore
grease) needed for textile processing.
 MMF have smooth surfaces, and contains low moisture content,
and have high frictional coefficient. So it is necessary to apply spin
finish to correct this coefficient of friction, and to eliminate static
electrical charge.
 Necessity during spinning:
 It is used to impart sliding characteristics, give adequate thread joining
properties and prevent building electric charge. A size develops its properties
in the presence of applied moisture. During spinning , the filaments are
coiled into cans, these cans are then grouped and fed to the drawing stage.
 Necessity during drawing:
 In this process filaments pass through many drawing and guiding elements. So
it is necessary to give them some sliding so that they can slide easily over
guiding elements while preventing slippage. Further more adherence of
oligomers must be prevented.

 Why final spin finish is applied
 To lubricate the fiber surface in order to give optimal fiber to fiber, fiber to
foreign body friction characteristics. Foreign bodies are of various kinds and
regarded as surface roughness (metal, ceramic, rubber, plastic).
 To protect against electrical charge. Electric charge arises from high friction and
low electrical-conductivity properties of synthetic fibers.
 To assist opening .This effect, and with it the subsequently mentioned fiber
adherence, is achieved by optimal interplay with the set crimp of fibers.
 To impart coherence to a fiber strand ( fiber adherence in the card web, D/F
sliver and yarn). It is a contradiction to opening mentioned above.
 To assist in avoiding the formation of laps. Lap formation is caused by building
up of spin finish on the thread guide. Lap formation can also arise from
electrostatic attraction in absence of adequate spin finish.
 To reduce fly. Fly is generated due to inadequate fiber adherence.
 To lubricate properly so that fiber shortening does not occur.
 Requirements to be fulfilled by spin finish
 No disadvantageous effect on the yarn or machines.
 Easily washed out.
 No diminution of dye fastness
 No influence on dye affinity
 Even distribution on the fibers.( otherwise non lubricated parts are
subject to friction)
 High adherence to the fiber surface.
 Good storability( resistant to ageing, i.e. resistant to migration or
bacterial attack)
 No gluing effect
 No flaking when rubbed.
 Either resistant to heat. Or sublimated without leaving any
residue.
 Insensitive to rubbing(wear)
 Environmentally friendly and Non-toxic: must be biodegradable
 What are the components of spin finish ?
 Lubricants :
 Lubricants improve sliding properties. They include mineral oils, waxes
and oils of esters. Esters oils have higher resistance to temperature
change and lower reduction in viscosity at higher temperature than
mineral oils, waxes. Mainly polymeric lubricants such as polyalkenylene
oxide, polyalkenylene and silicon oils etc. are used.
 Emulsifiers :
 It improves emulsifying properties but also enable spin finish to be washed
out. These emulsifiers are tensides(surfactants) of anionic or nonionic
substances. They include ethers and soaps of fatty acid, ethers of fatty
alcohol, fatty amino ethers, sulphates, amino acid substance. Cationic
and amphoteric ethers are now used solely on acrylic fibers.
 Antistatic agents :
 The main Antistatic Agents are Ester salts or phosphoric acid , Metal salts
of fatty acid and Anionic and cationic emulsifiers

 In processing due to friction electrostatic charge is generated on fiber surface- this

problem can be reduced by using anti-static components of spin finish.
 Fiber adhering substance :
 These substances ensure lateral coherence of fiber strands and prevents
splitting out of individual fibers. This includes
Sarcosides ,Sulphosuccinates , Sulphated oils and Colloidal silicic acid.
 Additives :
 This includes Antioxidant( steroid inhibited phenols) ,Bactericides ( silver
colloids, Cl- formaldehayde release , Corrosion inhibitors ( Sarcosides,
metal salts of fattyacid) ,wetting agents (emulsifiers)
 Spin-finish composition :
 Lubricant concentration between 20-70%
 Up to 80% proportion of surface active products(emulsifiers, antistatic agents)
 Less then 5% additives.
 Problems arises due to spin finish ?
 Spin finish combines with dust and forms hard coating on machine parts. Which
disturbs processing such as in the card clothing, sliver guide passages ( of card
and D/F), in the flyer( on roving frame), and on the rotor and opener roller ( on
rotor spg.). This adds additional cost as these parts must be cleaned periodically.
 Inadequate distribution of spin finish can cause fiber flaking and lead to increase
in ends breakage and accumulation of static charge.
 If spin finish penetrates into machine components such as rollers and aprons
when the M/C is not running. It can cause swelling or cracking creating drafting
problems.
 Fiber treated with TiO2 as delustrant shows lower drafting resistance but
simultaneously higher wear on fiber guide elements.
 Besides TiO2 other spin finish can also cause wear on m/c components, cationic
substances are suspected in this connection.
 Wear occurs on travellers and on opening rollers of rotor spinning machines
leads to spinning problems and degrading yarn characteristics.