yarn manufacturing I.ppt document for textile

Cotton, Wool, Man made, Fiber grading

WHAT IS COTTON GRADING?
Cotton grading, cotton classification and
cotton classing are the terms used to
express the quality of cotton in terms of its
physical quality parameters.

The term cotton classification or cotton
grading refers to the application of
standardized procedures developed by
USDA for measuring those physical
attributes of raw cotton that affect the
quality of the finished product and/or
manufacturing efficiency

ESSENTIAL QUALITY PARAMETERS
FOR COTTON GRADING
• Fibre length (Upper Half Mean [UHM]
length in inches)
•Length Uniformity Index (UI %)
•Fibre strength (g/tex)
•Micronaire (HVI micronaire)
•Color (HVI color Rd, +b)
•Trash (HVI trash area %)

FIBRE LENGTH PARAMETERS (AS PER FIBROGRAM DIAGRAM)

Upper-half mean length (UHML) and Mean length
(ML)
These definitions are best explained with the following
Fig. These parameters are familiar to High volume
instrument users.

2.5% Span Length (SL):
Distance from the clamp on a fiber
beard to a point up to which only
2.5% of the fibres extend. This is
available from Digital fibrograph as
well as HVI.

50% Span Length (SL):
Distance from the clamp on a fiber beard
to a point up to which only 50 % of the
fibres extend. This is also available from
Digital fibrograph as well as HVI.

Length Uniformity Ratio (UR):
UR = (50%SL/2.5%SL) X 100(This is
often used by digital fibrograph
users).
Length uniformity Index (UI):
UI = (ML/UHML) X 100, this is
commonly referred by HVI users.

Short fiber Index
Although, Fibrogram measurement does not
directly provide information about short fiber
content, empirical relationships can be used to
measure short fiber index from uniformity
parameters. One of such empirical relation
used for American upland cotton is
Short fiber index= 122.56-(12.87UHML)-
(1.22UI)
= 90.34-(37.472.5% SL)-
(0.90UR)
where, UHML and SL are in inch unit

FIBRE STRENGTH
The different measures available
for reporting fiber strength are:
1. breaking strength
2. tenacity or intrinsic strength

Coarse cottons generally
give higher values for fiber
strength than finer ones.

Eliminate the effect of the
difference in cross-sectional
area by dividing the observed
fiber strength by the fiber
weight per unit length.

The value so obtained is known as
"INTRINSIC STRENGTH or
TENACITY". Tenacity is found
to be better related to spinning
than the breaking strength.

• chain length of molecules in the
fiber
•orientation of molecules
•% and size of the crystallites
•distribution of the crystallites

In addition, it is also related to testing
conditions (extrinsic factors) such as:
•gauge length used
•the rate of loading
•type of instrument used and
•atmospheric conditions

Some significant breaking strengths of
fibers:
Polyester 35 – 60 cN/tex
Cotton 15 – 40 cN/tex
Wool 12 – 18 cN/tex

FIBRE FINENESS
Fineness determines how many fibers
are present in the cross-section of a yarn
of given thickness

Fineness influences primarily:
•Spinning limit
•Yarn strength
•Yarn evenness
•Yarn fullness
•Drape of the fabric product
•Luster
•Handle
Productivity (Productivity is influenced
via the end breakage rate, the number of
turns per inch in the yarn and better
spinning conditions).

Color
The color of cotton range from
white to yellowish and is classed
into groups “White”, “Light
spotted”, “Spotted tinged” and
“Yellow stained”, in descending
order of quality

The color of cotton is
measured by the degree of
reflectance (Rd) and
yellowness (+b). Reflectance
indicates how bright or dull
the sample is, and yellowness
indicate the degree of color
pigment.

A three digit color code is
used to indicate the color
grade. This color grade is
determined by locating the
quadrant of the color chart in
which the Rd and +b valued
intersect.

For example, a sample with
an Rd value of 72 and a +b
value of 9.0 would have a
color code of 41-3.

Trash (HVI trash area %)
In addition to useable fibres, cotton stock
contains foreign matter of various kinds
such as vegetable matter; mineral material
(earth, sand, ore or coal dust picked up in
transport); metal fragments, cloth fragments
and packing materials; and fiber fragments

BALE MANAGEMENT :(ENGINEERED
FIBRE SELECTION SYSTEM)
• How many bales will be there in work
area?
•How many bales in each laydown?
•How do we choose properties to define
laydown?
• Do we select by bale or by categories?

Traditional Bale Management
Control: Growth area, Grade, Length
No control: Micronaire, Strength, L.U.

Procedure for Bale Management
Testing of Bales Grouping of Bales Selection of Bales

Concepts of cotton fibre selection
•Selection by group
•Selection by group and
category
•Selection by bale

A + B + C Resultant Laydown
Selection by group

Selection by group and category
Category
Group: A B C
Number of category combinations (k) = xy
X is the number of level for a fibre property
Y is the number of fibre properties considered

Selection by bale:
Selection by bale solves the problem of loss of resolution
of fibre data in category system

Bale management by Spinning Consistency Index (SCI)
Control: Micronaire, Length, L.U., Strength, Color
Number of categories = 15
•Spinning Consistency Index is based on 5 year crop
average for U.S. Upland and Pima cotton
•Three different yarn count from each varieties
Ring and Open End spun yarns
Customization is needed for specific mill

BLOWROOM
Basic operations in the blow-room:
opening
cleaning
mixing or blending
micro-dust removal
uniform feed to the carding machine

Example
Weight of compacted bale =226.8 kg
Bale dimensions 1.4×0.53×0.64 m, and
Bale density is 478 kg/m3
If the individual fibers were, say, 30 mm
in length and 1.7 dtex fineness, then there
would be around 45 billion fibers in each bale

A typical production rate of an average
size plant would be 500 kg/h, which
would mean separating nearly 98 billion
fibers per hour (i.e., 27 million fibers per
second)
? which is not a practical proposition.
Opening is the breaking up of the fiber
mass into tufts.

Cleaning
Light particles such as
dust, are freed and can be removed by air
currents.
Larger particles such as
 leaf, seed, dirt, and sand are loosened, and
some are sufficiently freed to be removed
by beating the tufts against grid bars or
perforated plates.
Cleaning is the removal of unwanted
trash by mechanical means.

Mixing or Blending
Through random variations, fibers from
differing parts of the same bale, as well as
between bales of the same batch of raw
material, will differ in properties
Tuft blending is the mixing of fibrous tufts
from opened bales to produce a
homogenous mass for consistent yarn
properties.

Feeding to the Card
• At the end of the cleaning line, 40 to 50%
of impurities are removed (largely heavy
particles), and the opened material is then
fed into the carding process

Methods of opening, cleaning,
mixing and blending
Opening and cleaning machines employ one
or more of the following actions:
The action of opposing spikes, which is
principally an opening action
The action of beater and grid bar, which
gives both opening and cleaning
The action of air currents, which gives
only cleaning

Five common zones of modern
blow room
• Bale opening (Pre opening)- Zone-1
• Coarse Cleaning(Pre cleaning) Zone-2
• Mixing or blending Zone-3
• Fine opening and cleaning Zone-4
• Chute Feeding or in some
cases lap formation in scutcher Zone-5

Mixing bale opener
For short staple processing, the production
rates can be up to 600 kg/h, and up to 3,500
kg/h for longer staples.

Automatic bale opener
(1) Control unit, (2) fiber bales, (3), working
head with tooth discs, (4) swivel tower, and
(5) air duct for material transport.

Various opening devices used in
blow-room

Cleaning by grids
Two part Grid
a: closed b: open
c: aggressive angle

Slotted Sheet and
perforated Sheets
Triangular Sectional bars
Angle bars Blades

Calculation of machine production and
number of beaters of blow room
Intensity of Opening
To assess the opening action of a beater, we
refer to its intensity of opening. This
can be defined as the amount of fibrous
mass in milligrams per one striker of a
beater for a preset production rate and
beater speed, thus

where I = intensity of opening (mg)
P = production rate (kg/h)
nb = beater speed (rpm)
N = number of strikers
The following table gives examples of I values for
commonly used beaters. The intensity
of opening is an estimate of the tuft size produced by a
given beater.

Cleaning Efficiency of blow room machinery
This is the percentage of the impurities
removed from the fiber mass. Hence,

where WIN and WO = respective mass
values of the impurities in the fiber at the
input and output to a machine or a
sequence of machines
CE = cleaning efficiency
Some unavoidable fiber loss occurs during
mechanical cleaning. The settings of grid
spacing will evidently control the fiber
content of the waste. When considering
this fiber loss, we can refer to the effective
cleaning (EC) of a machine or a sequence
of machines as

where WT = mass of waste
WF = mass fiber in the waste

Cotton Transportation and
Distribution
• Having passed the first stage of opening
process, cotton is delivered by air flow to
the condenser
Condenser
• There are several types of condensers, high
speed condenser being one of the most
widely used.

• Object of the pedal feed motion is to
maintain the weight of cotton fed to the
beater from feed roller as constant per unit
time.
• The sheet of cotton is fed to the beater
through pedal and pedal roller and pair of
heavily weighted feed rollers.
Piano Feed Regulating Motion in Blow Room

• 16 pedals are provided below the pedal
roller.
• They are swinging depending upon the
thickness of the cotton sheet.
• If thick layer of cotton is going through
pedal roller, the speed of the feed roller is
reduced and increased in the case of thin
layers of cotton is fed in order to keep the
feed constant per unit time.

b
h
v
V 


V= the volume of cotton fed into the
machine in unit of times
V= is the rate of feeding the sheet of cotton
to the next machine
h= is the thickness of the sheet and
b= is its width

As the width of the sheet does not change
the formula given above can be written
simpler
v  h = constant,
i.e. the .rate of feed must be inversely
proportional to the thickness of the sheet
fed.
• According to this the pedal evener motion
varies the rate of feeding in inverse ratio to
the thickness of the mass entering as a way
of bringing about a constant/ quality fed.

Speed calculation
• To calculate the rotary speed of an organ of
a machine, the rotary speed of, the organ
which speed is known is to be multiplied
by the gear ratio from this organ to the
organ which rotary speed is to be found:

nx = ni…………………(1)
Where nx = the rotary speed of the working organ to be calculated
n= the rotary speed of the working organ known
i= the gear ratio from the organ that rotary speed is known to the
organ that rotary speed is to be calculated
 To calculate the surface speed of a working organ, its rotary
speed is to be multiplied by  and by its diameter
1000
x
x
x
n
d
V



Gearing diagram of blending feeder
with evener roller

Gearing diagram of cage condenser

TERMS, DEFINITIONS AND RELATIONS
FIBERS
Fiber length (mean)…l
Fiber mass… m
Fiber volume… V
Fiber surface
area… A
Fiber cross section
(green) area… s
Fiber perimeter… p
Fiber density… 
Fiber fineness… t
unit (SI):
usually:
1
m
V
 
m
t
l

1kg 1m 1Mtex

6
1tex 10 Mtex


Staple fibers are the fundamental
units of yarn. So, the structural
theory of yarn must include the
required parameters of fibers and
their relationships. Some of them
are introduced here.
One of most frequently used fiber
parameters is the fiber fineness –
the ratio between fiber mass and
fiber length. The main physical
unit of fiber fineness is 1Mtex,
which is equal to 1kg/1m. But this
unit is not very practical. A more
useful unit is one-millionth of
1Mtex, i. e. 1tex and especially for
fibers, 10 times smaller value, so-
called “decitex” – dtex, is used.
Let us introduce the convention:
All derived equations correspond
to the international standard unit
system.
l
A
m
V
s
.
p

Bohuslav Neckář, TU Liberec, Dept. of Textile Structures
Example: We consider a cotton fiber of 1.7 dtex fineness and 28
mm length. The fiber mass is 0.00476 mg. 1 kg of these cotton
fibers has a total length of 5882 km. An ordi-nary shirt of 200 g
contains fibers of total length 1176 km.
2
Fineness of different types of fibers
Fibrous material Fineness
Micro-fibers < 1 dtex
Cotton and compatible chemical fibers about 1,6 dtex
Wool and compatible chemical fibers about 3,5 dtex
Coarse (carpet) fibers > 7 dtex

It is valid
Cross-sectional area… s
- from geometry:
Equivalent fiber
diameter… d
3
The shown equations are valid for
fiber fineness.
From geometrical standpoint, the
fiber “fineness” is characterized by
the ratio V/l, but the standard
fineness is moreover influenced by
fiber density. Therefore, it is not
correct to compare the fine-nesses
of fibers having different densities
by the standard fine-ness; it is
better to use the ratio t/. Fineness
and density define the cross-
sectional area. Cross-sectional area
enables to evaluate the equivalent
fiber diameter. For cylindrical
fibers, the derivation is trivial. For
non-cylindrical fibers, the same
equation represents the diameter of
a ring having the same cross-
sectional area.
,
m
V
t
l


s V l t
  
2
4,
s d
 
 
4
4
d s
t
  
 
V t
l


t s
 
V
t
l
 
 
 
 
, ,
tl
V 

s
d


p d
d
s s

DE-DUSTING
• Apart from opening
and cleaning of raw-
material, de-dusting is
the very important
process in blow room.
Cleanomat CVT-1 of Trutzchler
Cleanomat CVT-3 of Trutzchler
trash removal concept in CVT cleaners

De-dusting keeps the atmospheric air clean
Hergeth Hollingsworth dust remover
Rieter Dust Extractor
Trutzchler dustex DX

• When cotton travels through the blow
room it is cleaned of dust on almost every
machine.
• Modern blow room line is equipped with
fans, their capacity being 800 m3/hr for
feeders and 5000 m3/hr every high speed
condenser
• General amount of dust laden air drawn
from blow room with two opening and
picking line is about 25,800 m3/hr

• Dust content of air sucked is 25-35 mg/m3,
• Whereas the dust content of the air in the
room is not allowed to exceed 3 mg/m3
• The dust laden air is exhausted into special
filters by means of piping
• The recirculation of the air free of dust into
the room allows constant temperature and
humidity to be maintained

Flow diagram of waste removal plant

• As we can see in the above figure in new
installations in new buildings a central
filter (part of the air-conditioning plant)
will probably be chosen
• The dust-laden air flows against a slowly
rotating filter drum (1).
• A layer of dust and fly forms, is removed
by rollers and falls into a carriage located
beneath the drum.

• Before the air returns into the room, it is
passed through the fine filter in the form of
a filter drum (2).

RECOMMENDED PROCESS CONDITIONS IN BLOW-ROOM
• Higher fan speeds will increase the material
velocity and will create turbulence in the bends.
This will result in curly fibres which will lead to
entanglements.
• If the production rate per line is high, the reserve
chamber for the feeding machine should be big
enough to avoid long term feed variations.

• It is advisable to reduce the number of
fans in the line
• Fan speeds, layout of machines should be
selected in such a way that material
choking in the pipe line, beater jamming
etc will not happen.
• The feed roller speeds should be selected
in such a way that it works at least 90% of
the running time of the next machine.

• Heavy particles like metal particles, stones
should be removed using heavy particle
removers , double magnets etc, before they
damage the opening rollers and other
machine parts
• Number of cleaning points are decided
based on type of ginning (whether roller
ginned or saw-ginned), the amount of
trash, and the number of trash particles and
the type of trash particles.

• Machinery selection should be based on
the type of cotton and production
requirement
• Material level in the storage
chambers should be full and it should
never be less than 1/4 th level.
• Grid bars should be inspected periodically,
damaged grid bars should be replaced.
Grid bars in the front rows can be replaced
earlier

• If the cotton is too sticky, the deposits on
the machine parts should be cleaned at
least once in a week, before it obstruct the
movement of the fibre
• Fibre rupture should be checked for each
opening point. 2.5 % span length should
not drop by more than 3%. If the
uniformity ratio drops by more than 3%,
then it is considered that there is fibre
rupture.

• High fan speed, which will result in high
velocity of air will increase neps in cotton
• Nep increase in the blow-room should not
be more than 100%.
• The nep increase in each opening machine
should be checked with different beater
speeds and settings, and the
optimum parameters should be selected.

• Blow room machinery lay out should be
designed in such a way that there should be
minimum number of bends, and there
should not be sharp bends to avoid fibre
entanglements.
• Some of modern blow room line from a
few companies are shown in the following
Fig. However, sometime it may be
desirable to go for combination of
machines from different manufacturers

Rieter Blow Room Line
LMW Blow Room Line

Control Feed of the Card
1 Cage condenser B44
2 Fine opener B38
3 Cage condenser B44
4 Fan B151
5 Pressure transducer
6 Control unit
7 Control feed duct
8 Chute feed B139

• The B139 chute feed operates on the two
trunk system with continuous regulation of
the web of tufts. In the feed duct the
material passes over the chute feeds where
the tufts are separated by purely
aerodynamic means to fill the upper
material reserve trunk.

• The movable feed roll transfers the
material from the upper trunk via a feed
pan to the opening roll. The material is
conveyed to the lower trunk and condensed
by an airstream generated by the fan. A
pressure transducer adjusts the speed of the
feed roll in accordance with the varying
pressure of the bottom reserve trunk.

The exhaust air from the upper trunk is
conveyed into a dust extraction duct
whereas the exhaust air from the lower
trunk is retrieved and recycled by the fan.

Cotton carding
Objectives and working principle
• Fibre opening/individualising
• Fibre cleaning
• Elimination of Dust
• Reduction in Neps
• Fibre mixing/blending
• Fibre aligning
• Sliver forming

Basic Design of Revolving Flat Card

Tandem card
• Two individual cards are joined together to
make up a unit

Additional Objective of woolen card
• Woolen card delivers the full width web of
fibres into narrow round twist-less threads
ready for direct spinning in ring frame.
Conventional woolen cards usually have two to three
tambours, a working width of 3.5m, a working length
of about 15.8m and a line production rate of up to
1,000 kg/h

Additional objective of Jute Card
• In bast fibres, such as jute, fibres are not
completely separated but arrive in spinning
mills in the form of bundles. Cards split
fibre bundles into finer forms, so that the
drafting is easy and finer yarn can be
produced

Main Parts of Breaker Card:
D = Delivery roller
Do = Doffer
W = Worker roller
S = Stripper roller
T = Tin cylinder
S = Shell
P = Pin roller
F = Feed roller

Worsted carding set
In worsted yarn spinning, virgin wool and
long staple synthetic fibers, especially
polyester and polyacrylnitrile, are processed

Card clothing arrangements and fibre transfer
Analysis of Disposition
Carding Disposition( Point to Point )
Doffing or Stripping Disposition( Point to
Back )

Forces on Fibre during interaction
between wires In Caring Disposition
( Point to Point)
Forces on Fibre during interaction
between wires In Doffing Disposition
( Point to Back)

• E is the component trying to retain the
fibre in to the clothing and K is transfer (or
carding) component which helps the fibres
to pass to the other wire. (Point to Point)
• D presses the fibre into the clothing and A
helps in stripping (Point to Back)

• Carding is the action of reducing tufts of entangled
fibers into a filmy web of individual fibers by
working the tufts between closely spaced surfaces
clothed with opposing sharp points.
• Machines used to carry out this work are called
cards, and we shall consider three types that are of
importance in the processing of cotton, wool and
man-made fibers:
1.revolving flat card
2.worsted card
3.woolen card
Carding Theory

• From the definition, it can be easily reasoned that
carding is most effective with very small, well
opened tufts, i.e., containing only a few tens of
fibers. Although the opening and cleaning stage
produces tufts on the order of a few milligrams,
further opening is required to obtain a uniform
feed of suitably small tufts for carding.

Interaction and fibre transfer
• Fibres are transferred to the main cylinder
from Licker-in by point to back (stripping)
action and the draft between licker-in and
cylinder is around 2
• The metallic wire of the licker-in must be
coarser and less dense than that of cylinder.
• The surface speed of the cylinder must be
faster than that of licker-in
• Gap between the licker-in and the cylinder
should be close

• Guide surface length (a) &
• Nose (d) play important roles in opening
• A sharp nose holds the fibre strongly,
thereby helps intensive but less gentle
opening
• Round nose results poor retention and so
bad opening; licker-in may tear out lumps
of fibres.
FEEDING DEVICE:

• Short guide surface leads to more waste
removal by mote knife
• Long surface results in fibre pressed
against the licker-in and results in low
waste (also, low separation of trash).
• The length is therefore dependent on fibre
length (within a broad range)

New Developments
• Feed cylinder is located below the spring
loaded plate
• The feed batt runs downwards without any
diversion, thereby helps gentle opening in
licker-in.

• In conventional system, feed plate to
licker-in setting is adjusted, whereas, in the
new system, setting point is b/a. "a" and
"b" are shown in the figure
LICKER-IN
• Licker-in is a cast roller with saw toothed
clothing fixed on it
• Beneath the licker-in there is an enclosure
of grid elements or carding segment. Mote
knifes are also fixed to help separation of
trash

The major functions of licker-in are:
1. Open material into very small flocks
2. To clean fibres by separating trash particles
• In modern carding machines, almost 50-70
% of material is transferred into cylinder by
licker-in in the form of very small flocks and
rest 50-30 % as individual fibres.
• Diameter: 250 mm
• RPM: 1000

• For conventional cards with cylinder speed
of 168 RPM, the best licker-in speed is
between 420-600 RPM.
• The circumferential speed of licker-in is
around 13-15 m/sec and draft between feed
roller and licker-in is more than 1000
The degree of cleaning, opening and fibre
damage depend on:

• Thickness of batt
• Density of batt (which depends on pre
opening)
• Degree of orientation of feed fibres.
• Material throughput speed
• Speed of the licker-in
• Licker-in clothing
• Type of feed
• Settings

Separation of Trash
• The conventional cleaning system in
licker-in region consists of 1-2 mote knives
and a grid.

• One half of grid is made of slotted sheet
(b) and other half of perforated sheet (c).
• Most of the foreign matters get eliminated
exclusively by scrapping off on the mote
knives.
• In high performance cards, no grid bars are
provided. Instead, carding segments are
used.
Rieter Card

Multiple Lickers-in
• The clothing arrangement is point to back,
relative to each other and speeds are
progressively increased
600 RPM (1st licker-in)
via 1200 RPM to 1800
RPM (3rd licker-in)

• Since, modern high production cards
process large quantity of material (up to
100 kg/hr), thorough opening in licker-in is
very essential in order to avoid uncarded
material passing to the sliver

CARDING CYLINDER
• Cylinder is mostly made of cast iron or
steel and covered with card clothing.
Diameter is usually 1280-1300 mm and
speeds vary from 250-600 RPM
• Some manufacturers claim reaching
cylinder speed up to 750 RPM in their
recent models

• Beneath the cylinder, either there is a grid
with traverse slots or a closed sheet
• Above the licker-in and also above the
doffer, there are protective casing
• One of these protective sheets near the flats
(known as front plate) is specially formed
as a knife blade
• Flat strip can be regulated by adjusting the
distance between the cylinder and the front
plate

• A closer setting results in a reduction of
flat strips
• The reason for decrease in the amount of
flat strip as the lip of the front plate is
moved nearer the surface of the cylinder is
that this intensifies the current of air being
carried under the plate by the quickly
moving cylinder
• It helps fibre transfer from flats to cylinder.
Air current does not remove the fibres, but
assists the cylinder to rob fibres from the
flats.

FLATS
• Flat bars are made of cast iron. But recently
developed cards have aluminum bar flats.
Each bar is approximately 32-35 mm wide.
Bars are given ribbed form (T shape) in
order to prevent longitudinal bending

• The arrangement of wire points towards
the material flow direction is narrower as
shown in the following Fig.
• This is required so that fibres are not
pushed along, but can pass underneath the
wires points and have progressive opening

Additional carding segments
• Number of wire points per fibre (number
of points presented in a unit time / number
of fibre feed in the same time)
• In licker-in, this ratio is approximately 0.3
(three fibres per point) and in the main
cylinder, it is about 10-15.

• The best way to increase throughput
without sacrificing carding effect is to have
additional carding points.
• Additional carding plates and also multiple
licker-in thereby make closer settings and
high speeds possible without much fibre
damage.

Carding bars at feed and at delivery

Doffer
• The doffer is mostly made of cast iron and
fitted with metallic clothing. Diameter is
500-700 mm. Doffer runs at a speed of 40-
100 RPM. Surface speed is 500-700 m/min
• The cylinder-doffer area is called the
transfer zone, since the objective is for
fibers to be transferred from the cylinder to
the doffer.

Basic features of a revolving flat card

Detaching and sliver formation
• On conventional cards, web is doffed from
the doffer by an oscillating comb. It
oscillates up to 2500 strokes per minutes.
In all high production cards, it is replaced
by a roller.
D = doffer, S = stripping/doffing roller,
P = pressure/crushing rollers, W = doffer
web, SL = sliver.

COILING IN CANS
• The slivers are coiled in cans for storage
and transportation.
Most of the modern high production cards
have automatic can changing mechanism.

Recycling Layer and Transfer Coefficient
• The presence of a fiber layer on the cylinder
clothing in the bottom transfer zone, observed by
Lauber and Dehghani, indicates that not all the
fiber mass on the cylinder leaving the carding zone
becomes part of the doffer web on first contact
with the doffer clothing.
• Using the tracer fiber technique of different-
colored fiber ends, Ghosh and Bhaduri found that
fibers generally went around with the cylinder for
several revolutions before being incorporated in
the doffer web.

• Important to an understanding of fiber transfer are
the following fiber mass values per revolution of
the cylinder:
Qo, the operational layer, i.e., the fiber mass leaving
the carding zone
Q1, the mass transferred from cylinder to doffer
Q2, the mass of the recycling layer
The ratio of Q1 to Qo is termed the transfer
coefficient, K, and can be measured as described
below.

• After the card has reached a steady running state, the feed, doffer, and
flats (or workers and strippers) are stopped while the cylinder continues
running. The doffer is then restarted with the feed and flats (workers and
strippers) out of action.
• Initially, the doffer will present the part of the web that was on it when it
was stopped. This is easily detached along a visible dividing line formed
when the feed roller was stopped. The mass of the remaining part of the
web will be Qo.
Representation of the fiber mass distribution
within a revolving-flats card

• Within a single revolution of the cylinder, a point
on the doffer would travel a distance of
where Rc = the cylinder radius (m)
Vc = cylinder surface speed (m/min)
Vd = doffer surface speed (m/min)
• If T is the sliver count in ktex, and P is the card
production rate in kg/h, then
P = 0.06VdT
c
d
c
d
V
V
R
L

2


And
• Hence, from the measurement of Qo, K can be
calculated for known production parameters.
• Reported values for K are within the range of
0.02–0.18, This means that, with each cylinder
rotation, 82 to 98% of the fiber mass (Qo) remains
on the cylinder as the recycling layer, Q2.
)
(
2 3
10
3
.
33
1 grams
in
V
TV
R
TL
Q c
c
V
P
R
c
d
c
d

 



)
(
3
10
3
.
33
grams
in
Q c
c
KV
P
R
o




• From the above figure, if QL is the fiber mass on
the taker-in, then this will be drafted to give the
mass QLC fed to the cylinder with each cylinder
revolution,
• where Vt and Vc = the taker-in and cylinder
surface speeds, respectively
• The mass going into the carding zone with each
revolution of the cylinder is QLC + Q2 and is
called the cylinder load; that leaving the zone is
Qo = QLC + Q2 – Qf
where Qf = the fiber mass per cylinder revolution
contributing to the flat waste
c
t
L
LC
V
V
Q
Q 

• An equation for the roller-clearer card would not
include Qf . Although an important parameter, Qf
is much smaller than QLC + Q2. Therefore,
Qo may be taken as a practical estimation of the
cylinder load for the card. Hence, from the start
of carding, the buildup of cylinder load, Qo, the
doffer web, Q1, and the recycling layer, Q2, will
follow the geometric progression given in the
following table.
• When n is very large, there is continuity of fiber
mass and, ignoring the flatstrap waste, the mass
from the taker-in onto the cylinder, per revolution
of the cylinder, equals the mass transferred to the
doffer, i.e., Q1 = QLC.

Factors that Determine the Transfer Coefficient,
K
There are two actions that form the recycling layer:
1) retaining power of the cylinder
2) cylinder clothing taking back, from the doffer
web, previously transferred fibers

• Based on the mechanism for fiber transfer,
particularly in the top zone, the transfer coefficient
is governed by the tooth angle, tooth density, and
the circular motion and diameters of the cylinder
and the doffer.
• These factors influence the effectiveness of the
two rollers to hold fibers onto their respective
clothing, i.e., their retaining powers and thereby
determine the transfer coefficient K.

Various types of card clothing
• Flexible clothing
• Semi flexible clothing
• Metallic clothing

The type of card clothing required depends
on many factors such as:
• Design of cylinder and rollers
• Speed of cylinder and rollers
• Material throughput
• Fibre type and characteristics
• Quality requirements and price of clothing

Flexible clothing
• Mostly found in woolen cards.
• In high production short staple cards, this
type of clothing is found only in flats
• The cross-section of wires used is shown in
the following figure:
Round wore Sectoral wire Ovoid wire
Flat wire
(seven gauges)
(four gauges)
(for fancy roller)

Fillet foundation
• Made by gluing together layers of cotton
cloth
• Number of layers may vary from four to ten
• To increase the strength of the fillet, middle
layer is normally made of linen
• Vulcanized rubber, wool felt etc. are also
used on the top layer in many fillets

Wire Geometry
• The flexible wire with a knee is shown in
the following figure

Semi rigid clothing
• These are similar in structure to flexible
type; however, the backings are less elastic
than flexible clothing
• They do not choke with fibres like flexible
clothing
• They are less capable of yielding when
subjected to a bending load

Rigid metallic clothing
• Inserted pin and rigid metallic wire
Inserted Pin
• set in a rigid foundation such as metal or
wood
• Are found in Jute and Flax cards and also
may be on early rollers of a woolen card

pin/sq cm
• Jute breaker card: 0.3 - 1.25
• Jute finisher card: 0.8 - 1.4
• Flax breaker card: 5.6 - 9
• Flax finisher card: 5.6 – 9
Rigid metallic wire
• used in licker-in and cylinder of cotton
cards and is increasingly becoming popular
for worsted and semi-worsted cards

• Wool regain should not be more than 25%
and fat content should be less than 0.6 %
• Key to success of high speed high
production cards, as flexible wires can not
withstand high strain imposed when the
machine runs faster along with high
throughput rate
• Rectangular cross-sectional base from the
base of which, project the hardened teeth

• Wire is hardened during manufacturing by
passing through flame and a quenching
bath
• A high degree of uniformity in hardening
is required
• Since the base has to be wound on a roller,
this portion has to remain relatively soft
and pliable. The wire is wound on the
roller or cylinder in spiral form

• High carbon alloy steel is used to
manufacture a cylinder wire.
Profiles for licker-in and cylinder
Licker-in
Cylinder
Arrangements used
without groove

Specifications and geometry of
the teeth
a1: Base width; a2: Tooth thickness at the root; a3: Tooth
thickness at the tip; h1: Overall height of the tooth; h2:
Height of the base; h3: Depth of the tooth; T: Tooth
pitch (when the wire is stretched out)
: Carding angle (or face angle); : Tooth apex angle; : Trailing angle

Some important parameters in card clothing
Point Density
• This is the number of points per square
area
• High point density gives a better carding
effect
• However, if point density is above the
optimum, then loading of clothing would
take place and carding effect would be
deteriorated

Point density depends on:
• Fibre fineness
(Coarse fibres require low density)
• Roller speed
• Material throughput
Number of points presented to the number of
fibres in a given time is a very important
factor that determines the efficiency of
carding

• Point density also depends on the total
available carding surface in the machine
Height of Clothing
• If angles were to remain the same, then a
shorter tooth gives a low pitch, thereby
density can be increased
Points /sq. cm =
)
(
)
(
100
mm
Pitch
mm
BaseWidth 

• A short tooth reduces choking and thereby
better carding over the total surface can be
achieved.
• On the cylinder, tooth height is kept short,
usually, 2mm-3.8 mm.
• If height is too short, then fibre control will
be less; at the same time, if height is more,
then fibre transfer to doffer will be less and
recycling will take place resulting in neps.

Angle
• Carding angle () is
the most important
angle of the tooth
The normal range is usually
kept as follows:
Licker-in + 50 to -100
Cylinder +120 to +270
Doffer +200 to +400
Negative angle is used in licker-in for processing
man-made fibres, since cleaning is not the
objective. Even in cylinder, for man made fibres,
low angle is used.

Trailing angle
• A lower trailing angle reduces the fibre
loading, but higher angle helps better
penetration.
The tooth point
• For optimum operation, the point should
not have a needle form but, should have a
land as shown
• In order to provide retaining power, the
land should terminate in a sharp edge.

Cut to point tooth
• Most of the recent cylinder wires have the
smallest land or cut-to-point tooth.
• Sharp point penetrates better, thus reduces
friction, which in turn reduces the wear on
the wire and increases working life
• However, flat top wire is used in wool
carding where burr removal is required. It
improves the action of burr beating roller
provided in the woolen card.

Mechanics of fibre hooks formation in carding and
influence of hooks
Morton with Summers and Yen revealed
that fibres after carding form hooks of five
groups:
• It was found that majority of fibres were
hooked as in group 2. Group 2 hooks are
also larger in size than group 1.

The actual mechanism of hook formation
Before transfer, fibres remain caught at
the cylinder teeth. During transfer,
projecting ends are caught by doffer
clothing. As a result of higher surface speed
of cylinder compared to doffer, it sweeps
the rest part of the projected fibre (tail)
caught by doffer. The tail of the fibre
emerges first and so it comes out as a
trailing hook.

Increased production rates can result:
• In a decrease in the number of majority
hooks and increase in the number of
minority hooks.
• With medium and short staple cotton, the
later effect (increase in minority hooks) is
not significant. Thus, increase in doffer
speed can be beneficial in decreasing the
total number of hooks. But above an
optimum speed, cylinder loading will be
high (due to high throughput rate) and
quality of carding is reduced.

Influence of hooks
• The presence of hooked fibres in the sliver
reduces the effective length of fibre and
properties that benefit from length of
constituent fibres thereby suffer
• If hooks persist into the yarn, the yarn will
be weaker and thereby more ends down
will be observed in spinning.

• If a hook is presented as trailing hook, then
it gets straightened out.
• If fibre is presented to the nip of the front
roller, it is suddenly accelerated, but
trailing end is caught by more number of
slowly moving fibres controlled by the
back roller.
• This results in straightening of hooks

• This is more likely to happen when draft is
more
• Number of passages between carding and
ring frame is so adjusted that majority
hooks are introduced to the ring frame as
trailing hooks
• Odd number of passages are therefore used
between carding and ring frame.

• If a hook is presented to the combing
machine as leading hook, it is straightened
out by the revolving comb
• However, if the hook is presented as a
trailing hook, it does not happen and the
fibre may be removed as a short fibre; waste
in combing will be reasonably high

Process parameters in carding
Important factors to be decided while processing
fibres of different types in a card:
• Settings between different points
•wire clothing specifications
• speeds of different parts, (such as licker-in,
cylinder, doffer, flats etc.)
•Draft
•linear density of sliver and feed material
• production rate etc.

Technical Details
Machine /Model Max
Production
(kg/hr)
Width
(mm)
Sliver Licker-in
RPM
Cylinder
RPM
Doffer
RPM
No of Flats
Rieter C 51 120 1000 3.5 - 8.0 300 - 600 104 revolving
40 working
Crosrol MK5D 965 3.5 -7.0 660 - 1500 425 - 770 40-120 89 rev
36 working
8 stationary (cotton)
12 stationary (synthetic)
Crosrol
CST(Tandem
card)
100 965 3.5 - 7.0 660 - 1500
(breaker)
120 finisher
425 - 770
(breaker &
finisher)
89 rev
36 working
5 stationary (cotton)
Marzoli C501 100 3.3 - 6
Textima
1453/3
53 1000 740 - 930 320 - 400 6 - 36 102 revolving
42 working
SACM HP800 1020 820 - 1300 320 - 600 30 - 100 106 revolving
42 stationary

Online monitoring and adjustment system
• Online measurement of neps: for example,
Nep control NTC of Trutzschler
• Readjusting setting between cylinder and
flat while machine is running; for example,
Flat control FTC of Trutzschler
• Grinding while machine is running;
example, IGS (Integrated Grinding
System) of Rieter

Basic routine maintenance of a card
• Stripping is required for flexible card
clothing in order to clean the wires from
the knee
• If the cylinder gets loaded, then problems
appear in the running of the card and then,
cylinder should be cleaned
• This is often done by a hand scrapper/
brush while cylinder is rotated slowly

Grinding and maintenance of clothing
• Fibre - metal friction results in wearing out
of teeth over a period of time. Wire points
become round at the top and loose
aggressiveness
• In order to re-sharpen the teeth, grinding is
therefore necessary
Cylinder Flats (for regrindable flats)
First grinding: 80 - 150,000kg 120 - 150,000 kg
Each additional grinding: 80 - 120,000kg. 80 - 120,000 kg.
For doffer, the grinding frequency is half of cylinder grinding frequency. Grinding is not
done for licker-in clothing and it is replaced after 100,000-200,000 kg of fibre processing.
This is because there is no land in licker-in wires.

Autoleveling
• Essentially, the basis of an autoleveling
system is to control the consistency of
output from a process by deliberately
altering the input so that a measured value
of a parameter characterizing the output has
minimum deviation from a preset value.

• Alternatively, a measured value
characterizing the input may be monitored
and, when deviating from a preset value,
the input is deliberately changed with the
intention of maintain minimum variation of
the output.
• The first approach is referred to as closed-
loop autoleveling, and the second as open-
loop autoleveling

• S and A represent the locations of the
sensors and actuators, the dotted lines
show the signal path, and the solid lines
illustrated the material flow.

• Most autoleveling systems on cards employ
the closed-loop principle.
• The idea is for the sensor to monitor the
sliver irregularity and the control unit to
interpret the electronic data in terms of
variations in the sliver count from the
preset count required.

• Then, according to the size of any
unacceptable differences and whether they
are greater or less than the preset value, the
control unit automatically modifies the
draft of the card by slowing or increasing
the feed roller speed.

• The time elapsed between changing the
feed roller speed and its effect detected in
the output sliver is the response time of the
carding process or the lag time resulting
from the process.

• Carding has a slow response time, so, when
closed-loop systems are used to adjust feed
roller speed, only long-term sliver
irregularity can be controlled, and the
system is called a long-term autoleveler.

• Various types of sensors may be used to
monitor the sliver irregularity, but the
tongue-and-groove device is probably the
most popular and is considered to be very
simple and reliable.

Tongue-and-groove device fitted for short-
term closed-loop autoleveling at the card

• This basically consists of a grooved bottom
roller through which the sliver passes while
under compression by a top roller that fits
the groove
• Variation in the sliver thickness causes the
top roller to rise and fall, thereby
monitoring the sliver irregularity

• The movement of the top roller is
converted into an electronic signal, which
is fed to the control unit.
• Open-loop systems, as indicated earlier,
are fitted to the feed device to the card. The
sensor either monitors thickness of the batt
or mass per unit area.

Open-loop autoleveler on short-staple card
• This is done prior to the measured portion
of the batt being fed forward by the feed
roller, and the necessary change to the feed
roller speed is regulated to increase or
reduce the feed rate.

• The pressure senor is fitted at the front of
feed plate, where the plate and feed roller
forms a wedge to progressively compress
and nip the batt; changes in the batt
thickness are readily detected.

Draw frame
• Draw frames are used after carding in yarn
manufacturing process. In the case of
combed yarn manufacturing, draw frames
are used before as well as after combing

Objectives
The draw frame has the following
objectives to attain:
• Improvement in material evenness
• Parallelizing fibres
• Mixing and Blending
• Dust removal

Elements of the draw frame
• Creel (sliver feed)
• The drafting system
• Suction systems for the drafting arrangement
• Delivery and coiling

The drafting system
• Bottom rollers
• Top rollers and
• Fiber guiding devices

Bottom rollers
• Axial flutes
• Spiral (inclined) flutes
• Knurled flutes
• The diameter of the bottom rollers in draw
frames lies in the range 20-90 mm, but
normally diameters between 25 and 50 mm
are used

Top rollers
• Top rollers can be one-piece rollers (draw
frames) or twin rollers (roving and ring
frames)
• Hardness is specified in terms of degree
shore
Soft: 600-700 shore
Medium: 700-900 shore
Hard: Above 900 shore

• A soft coating is used where good
guidance is necessary
The pressure on top roller can be applied by:
• Dead weights ( now obsolete)
• By Spring weighting (more common)
• Pneumatic weighting (Rieter) – mostly
used in modern draw frames.
• Magnetic weighting (Saco Lowell)
• Hydraulic systems (hardly used)

Fiber guidance in the drafting zone
1. Aprons
• Aprons have been introduced in the main
drafting zones of the speed frame and the
ring frame to achieve better fibre control
The cradle opening (the gap
between the two aprons near the
front roller nip) is adjustable, and
there is an optimum setting for
yarn regularity and spinning
performance.

2.Pin Control
• Pin Control is used only in the case of long
fibres where a suitable device can be fitted
between two pairs of rollers.
• Such draw frames are known as gill boxes
and used in long fibre spinning process
(worsted and semi-worsted)

The amount of inter-fibre and fibre-metal
pressure depends on
• pin length,
• thickness,
• population density and depth of penetration
as well as on the
• fibre density of the sliver processed

3.Pressure bar
• Stationary pressure bar “A” deflects the
sliver as it approaches the front roller nip
and thereby applies lateral pressure which
helps to control the floating fibres by
preventing them running fast until nipped
by front pair of rollers
This is one of the most widely
used arrangements in modern
draw frames and is found in
Rieter, Schubert & Salzer and
Toyoda draw frames.

Staggered roller arrangement
• 3-over-4 roller drafting arrangement (Marzoli draw frame)
4-over-3 roller drafting
arrangement with pressure
bar (Zinser draw frame)

5-over-4 roller drafting arrangement (Rieter)
• 'B' is the break draft zone
and 'A' is the main draft
zone.
• The nip spacing can be
adjusted by radial shifting of
rollers 2 and 4.
• In the main drafting field, a
pressure bar ensures firm
guidance of floating fibres.

Draft and attenuation
• A carded sliver contains 20,000-40,000
fibres in cross-section. In a yarn, the
number of fibres in the cross section is
approximately 100
• Gradual reduction of the cross section is
called “attenuation”
• Extension of the length is called drawing
• The amount of extension of length is called
draft.

• If there is wastage, then attenuation will be
more than expected due to draft. So,
Attenuation = Draft  100/ (100-P) where,
P is the percentage waste.
• Attenuation is the “actual draft” and it can
be calculated by determining the ratio of
input linear density to output linear density
(tex system).
• The ratio between the speeds of the
delivery and feed of the drafting device is
called “mechanical draft”.

Roller drafting principle
3
2
V
V
Draft (DB) =
2
1
V
V
Draft (DM) =
2
1
3
2
V
V
V
V

Total Draft (DT) =

Suction systems for the drafting arrangement
• Helps to remove dust laden air
• It also tries to suck any of the fibres that
tend to wrap around the rollers and thus
helps in preventing roller lapping

Delivery and coiling
• Usually d=kktex; where k=1.6-1.9. For synthetic fibres,
bigger coiler tubes are used. This will help to avoid
coiler choking and kinks in the slivers while coiling in
the can.
• The sliver is deposited in the form of a cycloidal coil in
the can
• Material coming out of
the drawing frame does
not have much cohesion
• The diameter of trumpet
(d) depends on the sliver
linear density

Number of Draw Frame Deliveries
• Many modern draw frames fitted with
autolevellers have a single delivery.
• Autolevellers adjust the draft depending on
the thickness variation of slivers.

Monitoring and autolevelling
• Monitoring systems can be classified
according to whether they monitor:
1.The machine
2.Production or
3. Quality
Quality monitors are of three different types:
displays, self-compensation and
autolevelling.

Monitoring devices with autolevelling systems
• The objective of an autoleveller is to
measure the volume of fibers passing
through (sliver thickness variations) and
then continuously alter the draft
accordingly so that more draft is applied to
thick places and less to thin places to
deliver less irregular sliver than it otherwise
would have been.

• Autolevellers may be classified in to three
main groups according to the basic
principle of operation: Open-loop, closed-
loop and combined-loop autolevellers.
Open-loop autolevellers
• They compensate variations of short (to
medium) wave length

• If the direction of the arrows in the above
figure is followed from any starting point,
it always leads ‘out into the open’ at a
place marked delivered material.
• Since measurement is made on the input
material, the correction may either be
applied to the back or front rollers

Closed-loop autolevelers
• It is designed to correct medium-and long-
term variations
If the direction of the arrows is followed from any starting
point, except the delivery, it always leads to a never-ending
circuit of the loop which links the process and the control
unit, hence the name ‘closed-loop’.

• Thus, if measurement is made on the
output, the correction may be applied to
either the back (usually) or front rollers of
the main drafting zone as shown in Fig.

Combined-loop auto levelers
• Designed to correct short, medium and
long-term variations.
Various loop arrangements are used:
• open-loop and closed-loop devices are
combined into an integrated autolevelling
system
Capacitive sensing is generally used
in the in-feed and mechanical or
pneumatic sensing in the delivery

• Combination of two separate closed-loops
• Measurement on the material of
intermediate thickness between
back and front rollers of a
drafting zone (fig. g)
•Use of drafting force to measure of sliver
thickness within a drafting zone

Adjustment points
• Altering feed roller speed is usually used to
change the draft
• Change of delivery speed would lead to
continuous changing of production and
change of speed of large masses, such as
coiler cans and their associate drives.
• More acceleration and deceleration will be
required
• If integrated draw frames are used delivery
roller speed needs to be changed.

Fibre guidance in the drafting zone
• Fibre a will either break or if, it can resist the
stress, it will be pulled out of the nip line of back
rollers.
• Type d fibres are called floating fibres,
since they float in the drafting region

Floating fibre distribution in the drafting zone
• A merino worsted sliver with a mean fibre
length (MFL) of 68 mm and a maximum
fibre length of 150 mm may have about
60% of floating fibres when processed with
a ratch (nip to nip distance) of 150 mm.

• There may be 33% - 80% floating fibres in
cotton drawing and 75% in conventional
worsted drawing process
• The floating fibres are the cause of
unevenness in the drafted strand
Drafting wave •"A" fibres are held by the
back roller that move slowly
•'B' fibres are held by the front
rollers and being withdrawn
relatively quickly
•"C" fibres not held by either set of rollers but
supported by other fibres (floating fibre)

Amplitude and wave length
Factor that affect the drafting wave are:
• Variation in twist or fibre entanglement
• Differences in fibre length distribution and
fibre arrangements
It has been observed in the processing of cotton that
the range of wavelengths is from about half to twice
the mean wavelength; the mean wavelength is
usually more than twice the maximum fibre length.

The amplitude of drafting wave depends on
the following factors:
• Draft: Amplitude increases with the
increase in draft.
• Setting: A wider setting increases the
amplitude of drafting wave.
If setting is too close, may result short
thick place in the yarn due to momentary
stoppages of delivery rollers due to
slippage, resulting in yarn defects known as
crackers.

• Fibre entanglement: The amplitude of
drafting wave will be high, if fibres are
highly entangled in the drafting zone
• Fibre frictional field: The amplitude of the
drafting wave is highly influenced by the
fibre frictional field.
Fibre frictional field
The rear field extends far in to the
drafting zone and front field should
be short but strong so that only
nipped fibres are drawn out, but not
the floating fibres

Influencing factors of frictional field
• Pressure of top rollers
• Hardness of top rollers
• Roller diameter
• Material characteristics such as cross section of sliver
strand, density of sliver strand, breadth of the strand and
twist etc.
a: hard top roller cot a: small diameter roller
b: medium top roller cot b: big diameter roller
c: soft top roller cot

Combing
Employed to perform
• Elimination of a precisely pre-determined
quantity of short fibres.
• Elimination of remaining impurities after
blow-room and carding.
• Elimination of neps

Combing improves following properties of
yarn :
• Yarn Evenness
• Strength
• Cleanliness
• Smoothness and
• Visual appearance

yarn manufacturing I.ppt document for textile

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