2012
DAFFODIL INTERNATIONAL UNIVERSITY
Department of Textile Engineering
Faculty of Science & Information Technology
TE-407: Project
On
“Various Types of Knitting Mechanism Used in Circular weft Knitting
Machine”
Academic Supervisor:
Md. Azharul Islam
Lecturer
Department of Textile Engineering,
Daffodil International University
Prepared By:
SI No
Name
ID No.
01
Shibli Kaium
091-23-1232
02
Tajuddin
091-23-1208
03
Md. Yusuf Ali
091-23-1235
Department of Textile Engineering
Daffodil International University
Submission Date: 03/01/2013
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DAFFODIL INTERNATIONAL UNIVERSITY
DECLARATION
We hereby declare that, this project has done by Shibli Kaium, Tajuddin, and Md.
Yusuf Ali under the supervision of Md. Azharul Islam, Lecturer, Department of
Textile Engineering, Daffodil International University. We also declare that neither
this project nor any part of this project has been submitted elsewhere for award of any
degree or diploma.
Signature of the Supervisor
Signature of the Departmental Head
Md. Azharul Islam
Dr. Md. Mahbubul Haque
Supervisor & Lecturer
Professor & Head
Department of Textile Engineering
Department of Textile Engineering
Daffodil International University
Daffodil International University
Paper Prepared By
SI No
Name
ID No.
01
Shibli kaium
091-23-1232
02
Tajuddin
091-23-1208
03
Md. Yusuf Ali
091-23-1235
Signature
Department of Textile Engineering
Daffodil International University
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ACKNOWLEDGEMENT
Our university has given us the opportunity to perform our project work. We are
obliged to Prof. Dr. Md. Mahbubul Haque , Head of the Textile Department and
supervising Teacher Md. Azharul Islam of the University for giving us the
opportunity to accomplish of the project work.
Heartfelt thanks goes to Textile engineers of various industries (Karnaphuli Knitting
Industries, Devine composite mill ltd and Squire knit fabrics ltd.) from whom we
collect the sample.
Above all, we would like to acknowledge our deep debt to all teachers of our
University and especially of ‘Fabric Manufacturing Technology’ department for
their kind inspiration and help which remain us the backdrop of our efforts.
Finally, we would like to convey our acknowledgement that we remain responsible
for the inadequacies and errors which doubtless remain.
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ABSTRACT
Now a day’s most of the exported RMG are required knitted fabric. All these knitted
fabrics are produced in different types of knitting machine like single jersey, Rib,
Interlock, Fleece. Lots of derivatives are also ordered by the buyers. On that time it
becomes very necessary to have a vast knowledge about various mechanism used to
produce knitted fabric. We have analyzed the mechanism for producing best knitted
fabric.
During our project work we manage to watch carefully and effectively the knitting
mechanism along with machine specification and the major factors which are
necessary to control for producing better quality fabric without any fault. Our efforts
were to develop a dependable way so that we can easily visualize or can forecast the
resulting knitting mechanism with required configuration.
We have tried our best to emphasize on the adjustable points on which fabric G.S.M,
Stitch length, Fabric width, design development, machine maintenance, various
tension adjustments, Compactness etc directly or indirectly depends.
The theoretical as well as the practical knowledge that we gathered from our classes
and in industries help us to perform our project with credit and for this we specially
convey thanks to our teachers.
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TABLE OF CONTENT
1.
INTRODUCTION ................................................................................................................................................ 7
2.
KNITTING.......................................................................................................................................................... 8
3.
TYPES OF KNITTING ......................................................................................................................................... 8
3.1. WARP KNITTING ...................................................................................................................................... 9
3.2. WEFT KNITTING....................................................................................................................................... 9
4.
CIRCULAR WEFT KNITTING ............................................................................................................................ 10
5.
YARN IN PACKAGE FORM .............................................................................................................................. 11
5.1. THEORETICAL REVIEW ...................................................................................................................................... 11
5.1.1. TYPES OF PACKAGE .................................................................................................................. 11
5.1.1.1. HANK ................................................................................................................................... 11
5.1.1.2. CONE .................................................................................................................................... 11
5.1.1.3. CHEESE ................................................................................................................................ 11
5.1.1.4. COP ....................................................................................................................................... 12
5.1.2. WINDING PROCESS ................................................................................................................... 12
5.1.2.1. THE UNWINDING ZONE ..................................................................................................... 12
5.1.2.2. THE TENSION & CLEARING ZONE ................................................................................... 12
5.1.2.3. THE WINDING ZONE .......................................................................................................... 13
5.2. INDUSTRIAL ASSESSMENT ................................................................................................................. 13
6.
CREELING MECHANISM ................................................................................................................................. 14
6.1. THEORETICAL REVIEW ...................................................................................................................... 14
6.1.1. CREEL.......................................................................................................................................... 14
6.2. INDUSTRIAL ASSESSMENT ................................................................................................................. 15
7.
YARN FEEDING MECHANISM ......................................................................................................................... 16
7.1. THEORETICAL REVIEW ...................................................................................................................................... 16
7.1.1. YARN PATH SEQUENCE FROM CREEL TO NEEDLE .............................................................. 16
7.1.3. NEGATIVE FEED DEVICE.......................................................................................................... 18
7.2. INDUSTRIAL ASSESSMENT ................................................................................................................. 18
7.3. YARN ARRANGEMENT FOR FEEDER STRIPES AND ENGINEERING STRIPES ..................... 19
7.3.1. INDUSTRIAL ASSESSMENT ...................................................................................................... 20
8.
SETTING THE M/C AS PER DESIGN &GSM ..................................................................................................... 21
8.1. CAM ARRANGEMENT ........................................................................................................................... 21
8.1.1. THEORETICAL REVIEW ............................................................................................................ 21
8.1.1.1. CAM...................................................................................................................................... 21
8.1.1.2. TYPES OF CAMS ................................................................................................................. 22
8.1.1.2.2. KNITTING CAMS ......................................................................................................... 22
8.1.1.3. TWO ARRANGEMENTS EXIST .......................................................................................... 22
8.1.2. INDUSTRIAL ASSESSMENT ...................................................................................................... 23
8.2. NEEDLE ARRANGEMENT .................................................................................................................... 25
8.2.1. THEORETICAL REVIEW ............................................................................................................ 25
8.2.1.1. NEEDLES ............................................................................................................................. 25
8.2.1.1.1. LATCH NEEDLE ........................................................................................................... 25
8.2.1.1.2. SPRING BEARDED NEEDLE ....................................................................................... 25
8.2.1.1.3. COMPOUND NEEDLE .................................................................................................. 26
8.2.1.2. LOOP FORMING SEQUENCE OF LATCH NEEDLE ........................................................... 26
8.2.1.3. LOOP FORMING SEQUENCE OF SPRING BEARDED NEEDLE ....................................... 27
8.2.1.4. LOOP FORMING SEQUENCE OF COMPOUND NEEDLE .................................................. 27
8.2.1.5. SPECIFICATION OF NEEDLE ............................................................................................. 28
8.3. SINKER ARRANGEMENT ..................................................................................................................... 30
8.3.1. THEORETICAL REVIEW ............................................................................................................ 30
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8.3.1.1. SINKER................................................................................................................................. 30
8.3.2. INDUSTRIAL ASSESSMENT ...................................................................................................... 31
8.4. M/C DIAMETER & M/C GAUGE SETTING MECHANISM.............................................................. 31
8.4.1. THEORETICAL REVIEW ............................................................................................................ 31
8.4.1.1. CYLINDER ........................................................................................................................... 31
8.4.1.2. DIAL ..................................................................................................................................... 32
8.4.1.3. GAUGE ................................................................................................................................. 32
8.4.2. INDUSTRIAL ASSESSMENT ...................................................................................................... 32
8.5. STITCH LENGTH SETTING MECHANISM........................................................................................ 33
8.5.1. V.D.Q PULLEY (VARIABLE DIAMETER QUALITY) ................................................................ 33
8.5.1.1. THEORETICAL REVIEW ..................................................................................................... 33
8.5.1.2. INDUSTRIAL ASSESSMENT ............................................................................................... 34
8.6. CYLINDER HEIGHT ADJUSTMENT ................................................................................................... 35
8.6.1. INDUSTRIAL ASSESSMENT ...................................................................................................... 35
9.
KNITTING MECHANISM ................................................................................................................................. 35
9.1. THEORETICAL REVIEW ...................................................................................................................... 35
9.1.1. CIRCULAR KNITTING MACHINE ............................................................................................. 35
9.1.2. DIFFERENT PARTS OF CIRCULAR KNITTING MACHINE ...................................................... 36
9.1.3. THE KNITTING ACTION OF A LATCH NEEDLE AND HOLDING-DOWN SINKER DURING
THE PRODUCTION OF A COURSE OF PLAIN FABRIC. .................................................................... 37
9.1.5. OILING SYSTEM ......................................................................................................................... 39
9.1.5.1. INDUSTRIAL ASSESSMENT ............................................................................................... 39
9.1.6. AIR CIRCULATION SYSTEM ..................................................................................................... 41
9.1.6.1. INDUSTRIAL ASSESSMENT ............................................................................................... 41
10.
THE ROLL FABRIC WITHDRAW MECHANISM ............................................................................................ 43
10.1. FABRIC SPREADER .............................................................................................................................. 43
10.1.1. THEORETICAL REVIEW .......................................................................................................... 43
10.1.2. INDUSTRIAL ASSESSMENT .................................................................................................... 44
10.2. TAKE DOWN AND WINDING MECHANISM ................................................................................... 44
10.2.1. THEORETICAL REVIEW .......................................................................................................... 44
10.2.1.1. MECHANICAL DRIVE ....................................................................................................... 45
10.2.1.2. ELECTRICAL DRIVE ......................................................................................................... 46
10.2.2. INDUSTRIAL ASSESSMENT .................................................................................................... 46
10.3. WEIGHTING AND ROLL MARKING ................................................................................................ 47
10.3.1. INDUSTRIAL ASSESSMENT .................................................................................................... 47
11.
INSPECTION MECHANISM ......................................................................................................................... 48
11.1. THEORETICAL REVIEW .................................................................................................................... 48
11.1.1. FABRIC INSPECTION ............................................................................................................... 48
11.1.2. GREIGE FABRIC FAULTS ........................................................................................................ 48
11.2. INDUSTRIAL ASSESSMENT ............................................................................................................... 49
12.
GRADING SYSTEM ..................................................................................................................................... 50
12.1. INDUSTRIAL ASSESSMENT ............................................................................................................... 50
12.1.1. GREY FABRIC NUMBERING ................................................................................................... 50
12.1.2. FOUR-POINT SYSTEM.............................................................................................................. 50
12.1.3. ACCEPTANCE CALCULATION ............................................................................................... 51
13.
CONCLUSION ............................................................................................................................................. 52
14.
REFFERENCE .............................................................................................................................................. 53
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1. INTRODUCTION
Fabric is a manufactured assembly of fibers and yarn that has substantial surface area
in relation to its thickness and sufficient cohesion to give the useful mechanical
strength. Fabric are most commonly woven or knitted. Our project is basically on
various mechanisms used in circular knitting machine.
Now a day’s knit fabric very popular in the whole world. Knit sector represent the
largest share of our export oriented RMG sector. Therefore development of knit
product is really a challenging matter. Recently many system has develop that allow a
manufacturer or user to fully understand the knit fabric and control the knitting
machine as well as stitch length , GSM processing , selection of yarn etc.
Our project work is various types of mechanism used in circular knitting machine.
There are many problems in our industries to produce knitted fabric with required
GSM as well as other specification like fabric width, stitch length etc. Because of this
problem is maximum industries of our country maintain previous data sheet.
Our intention of this project is to get well idea about various mechanism used in
circular knitting to produce knitted fabric to which we may produce knitted fabric
with required fabric specification.
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2. KNITTING
Knitting is a method by which thread or yarn is turned into cloth or other fine crafts.
Knitted fabric consists of consecutive rows of loops, called stitches. As each row
progresses, a new loop is pulled through an existing loop. The active stitches are held
on a needle until another loop can be passed through them. This process eventually
results in a fabric, often used for garments.
In other word, the process in which fabrics are produces by set of connected loops
from a series of yarns in weft or warp direction is called knitting.
Knitting may be done by hand or by machine. There exist numerous styles and
methods of hand knitting.
Different yarns and knitting needles may be used to achieve different end products by
giving the final piece a different color, texture, weight, and/or integrity. Using needles
of varying shape and thickness as well as different varieties of yarn can also change
the effect.
3. TYPES OF KNITTING
Knitting is done by set of connected loops from a series of yarn in warp or weft
direction. Knitted fabrics are divided into two main types; they are
1. Warp knitting
2. Weft knitting
Weft
Knitting
Warp
Knitting
Flat-bed knitting
Knitting
machine
loom
(spring beard
needles)
(spring beard
needles)
Flat and circular
Raschel
knitting machines
loom
(latch needles)
(latch needles)
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3.1. WARP KNITTING
In a warp knitted structure each loop in the horizontal direction is made from
different thread. Sweater is made by this warp knitting techniques.
Fig: Looping Diagram of Warp Knitting.
3.2. WEFT KNITTING
In a weft knitted structure a horizontal row of loops can be made using one thread
and the thread runs in the horizontal direction. Most of the knitted fabrics are
produced by weft knitting.
Fig: Looping Diagram of Weft Knitting.
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4. CIRCULAR WEFT KNITTING
Fig: Circular Weft Knitting Machine.
Process Flow Chart for Knitting
Yarn in package from
↓
Place the yarn package in the creel
↓
Feeding the yarn
↓
Set the m/c as per design & GSM
↓
Knitting
↓
Withdraw the roll fabric
↓
Weighting And Roll Marking
↓
Inspection
↓
Grading
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5. YARN IN PACKAGE FORM
5.1. THEORETICAL REVIEW
There are many types of package are used in textile.
Such as-Hank, Cone, Cop, Cheese etc.
5.1.1. TYPES OF PACKAGE
5.1.1.1. HANK
Used for dyeing, sewing, package forming.
Fig: Hank Package.
5.1.1.2. CONE
Used for knitting and weaving.
Fig: Cone Package.
5.1.1.3. CHEESE
Used for knitting and weaving.
Fig: Cheese Package.
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5.1.1.4. COP
Used in spinning, winding.
Fig: Cop Package.
In knitting, cone and cheese package are mostly used. So, before creeling cone,
cheese package form is essential.
So winding process is done.
5.1.2. WINDING PROCESS
It has three sections:
1. The unwinding zone.
2. The tension & clearing zone.
3. The winding zone.
5.1.2.1. THE UNWINDING ZONE
To rewind the yarn on a new package, it must first be removed from the old package.
This is accomplished in the unwinding zone. This zone merely consists of a creel,
which holds the old package in an optimum position for unwinding. The common
yarn withdrawal methods, side withdrawal & over-end withdrawal.
5.1.2.2. THE TENSION & CLEARING ZONE
The next zone is the tension & clearing zone. It is in his zone that yarn receives the
proper tension to provide an acceptable package density & build for further
processing. This zone consists of a tension device, a device to detect thick spots or
slubs in the yarn & a stop motion which causes the winding to stop in the case of a
yarn break or the depletion of a supply package. The yarn is directed into this zone by
a guide.
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5.1.2.3. THE WINDING ZONE
In this section, winding process is done here.
Fig: Winding Machine.
5.2. INDUSTRIAL ASSESSMENT
 Generally cone and cheese package of yarn is used in knitting industries.
 Cone yarn package is used for natural and blended yarn and cheese package is
used for polyester & Lycra yarn.
 If we need to produce stripe fabric then dying operation is done through the
yarn before the winding.
Fig: Cone Package.
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Fig: Cheese Package.
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6. CREELING MECHANISM
6.1. THEORETICAL REVIEW
6.1.1. CREEL
Creels are the knitting elements which carry the yarn packages to feed the knitting
zone. The number of feeders in the knitting machine is equal to the number of cones
in the creels. Reserve cones also can be placed in each position. In accordance with
the number of feeders, two cone supports per feed are equidistantly fixed on a ring
over the circumference of the machine is mounted in the lower part. On machines
having yarn meters or yarn storage devices, an additional ring is mounted in the lower
part. Fan blade with motors, oiling system for needles and sinkers, knot catchers and
stop motion are also mounted on creel section.
Fig: Cheese Package on the Top Creel.
Apart from the over head ring creels, depending on the number of feeders and space
availability, creels are arranged on two or three sides of the machine. These
constructions keep off fibre fly from the machine and are more suitable for high speed
circular knitting machines. Differences in yarn tension due to variation in yarn length
from the cone to the feeder can be eliminated with these side creels compared to
overhead creels. Yarn guiding via yarn guide tubes normally reduce the yarn tension
than the open guiding system. Closed yarn guiding also reduces fibre fly and yarn
entanglements. Side creels also make easier threading in operation.
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Fig: Cheese Package on the Side Creel.
6.2. INDUSTRIAL ASSESSMENT
 Though there are many types of creeling mechanism but most of the cases side
creel mechanism is used.
 Side creel mechanism is used for cone, cheese package and top creel
mechanism is used for cheese package.
 In side creel mechanism piping is used to protect the yarn from dirt, dust,
foreign matter etc.
 According to design of feeder stripe or auto stripe, cone or cheese must be
arranged.
 Fabric design is affected by Fault creel arrangement.
Fig: Cheese Package on the Side Creel According To Design.
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7. YARN FEEDING MECHANISM
7.1. THEORETICAL REVIEW
The yarn fed to the needles in order to form the fabric must be conveyed along a
predetermined path from the spool/cone to the knitting zone. The various motions
along this path guide the yarn (thread guides), adjust the yarn tension (yarn
pensioners’), and check for eventual yarn breaks.
The yarn is taken down from the spool arranged on a special holder called creel if
placed beside the machine, or rack if placed above it. The yarn is then guided into the
knitting zone through the thread guide, which is typically a small plate with a steel
eyelet for the yarn. In order to obtain particular designs such as intarsia and vanisé
effects, the machines are equipped with special thread guides.
A uniform feeding tension is fundamental for obtaining regular loops. On flat-bed
machines, this parameter is controlled through the yarn tensioner, which consists
essentially of a metal arm adjusted by means of springs in order to contrast and level
off the spool unwinding tension peaks. On circular knitting machines, the yarn
feeding control on the various systems is performed with various methods.
7.1.1. YARN PATH SEQUENCE FROM CREEL TO NEEDLE
Creel
Cone
Tube
Tube/Pipe
Magnetic Tensioner
Sensor
Ceramic Eye Pot
Yarn Wheel (Positive/negative feeder)
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Previous Sensor Guide
Sensor
After Sensor Guide
Ceramic Eye Pot (feeder Ring)
Feeder
Needle
There are two types of feed device
7.1.2. POSITIVE FEED DEVICE
Positive feed device is a knitted loop-shape and loop-length control device which
employs small pulleys moved by belts, or gears etc., to exactly control the yarn
feeding speed and keep it constant.
Positive feed device are designed to overcome loop-shape and loop-length variation
by positively supplying yarn at the correct rate under low yarn tension to the knitting
point instead of allowing the latch needles or loop forming sinkers to draw loops
whose length could be affected by varying yarn input tension.
A continuous tape driven from the machine drive by a single pulley encircles the
machine above the feeders and provides identical and constant feed for any yarn
threaded through the nip it forms with a free running feed wheel at each feed position.
The faster the tape speed relative to the machine speeds, the faster the rate of yarn
feed and the longer the resultant course length. The tape speed is altered by adjusting
the scrolled segments of the drive pulley (V.D.Q pulley) to produce a larger or smaller
driving circumference.
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Fig: Positive Feed Device.
7.1.3. NEGATIVE FEED DEVICE
Negative feed device is a knitted loop-shape and loop-length control device as a yarn
guide which employs direct drive by yarn tension.
Fig: Negative Feed Device.
7.2. INDUSTRIAL ASSESSMENT
 Positive feed device is the most commonly used for feed mechanism system
because main advantages of this system is no slippage of yarn by wrapping
yarn with it.
 In negative feed device, yarn is not wrapped.
 Positive feed device control knitted loop-shape and loop-length by supplying
efficient amount of yarn during knitting.
 According to design of feeder stripe or auto stripe, yarn must be feed with
positive feed device and negative feed device.
 Fabric design is affected by Fault yarn feeding with positive feed device.
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7.3. YARN ARRANGEMENT FOR FEEDER STRIPES AND
ENGINEERING STRIPES
Feeders are the yarn guides placed close to the needles to the full circumference of the
knitting zone. The feeders feed the yarn into the needle hooks and control the needle
latches in their open position while the needle attain their clearing position. They
consist of a yarn guiding hole and a bevel edge to guard the latches of the approaching
needles. They are slightly curved to the corresponding curvature of the needle bed.
Feeders may have two holes also for the purpose of plating.
Fig: Feeder.
The feeder brackets can be adjusted to set their distance from the needle and to ensure
yarn feed into needle hooks. Stripers are the feeders designed to deliver two or more
yarns individually to the same feed. They can be considered as moving guide
replacing the holes of fixed guides. In a two color striper, two different colored yarns
are supplied by two stripper fingers and their engagement is controlled by an endless
control chain which governs the guide change at the appropriate feeds. At each
revolution, a counter may select the movement of all the striper chains. The stripers
are used on both single and double bed machines.
In modern age, Stripers are used automatically, these are called finger which are used
in auto stripe machine.
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Fig: Auto Stripe Finger.
7.3.1. INDUSTRIAL ASSESSMENT
 In plain circular knitting machine, an individual feeder is used for each single
yarn.
 In case of Auto stripe knitting machine four or six finger is used in each
feeder.
 Yarn tension must be adjusted by feeder position adjustment.
 According to design of feeder stripe or auto stripe, yarn must be feed with
feeder or finger.
Fig: Auto Stripe Four Finger.
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Fig: General Feeder.
8. SETTING THE M/C AS PER DESIGN &GSM
To maintain the requirement of design & GSM, bellow points must be considered.
1. Cam arrangement.
2. Needle arrangement.
3. Sinker arrangement.
4. M/C diameter.
5. M/C gauge.
6. Stitch Length.
8.1. CAM ARRANGEMENT
8.1.1. THEORETICAL REVIEW
8.1.1.1. CAM
Cams are the devices which convert the rotary machine drive into a suitable
reciprocating action for the needles and other elements. The cams are carefully
profiled to produce precisely-timed movement and dwell periods and are of two types,
engineering cams and knitting cams. The movements may be represented in the form
of a time-displacement graph.
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8.1.1.2. TYPES OF CAMS
There are two cams
1.Engineering cam
2.Knitting cam
8.1.1.2.1. ENGINEERING CAMS
Circular engineering cams or high speed eccentrics control the motion of bars of
elements which move en masse as single units in Cottons Patent and warp knitting
machines. They are attached to a rotary drive shaft situated parallel to, and below, the
needle bar. A number of identical cams are positioned along the shaft to ensure
correctly aligned movement. The drive is transmitted and adapted via cam followers,
levers, pivots and rocker shafts. One complete 360-degree revolution of the drive
shaft is equivalent to one knitting cycle, and it produces all the required movements of
the elements in their correctly-timed relationship.
8.1.1.2.2. KNITTING CAMS
The other type of cam, the angular knitting cam acts directly onto the butts of needles
or other elements to produce individual or serial movement in the tricks of a latch
needle weft knitting machine.
8.1.1.3. TWO ARRANGEMENTS EXIST
(a) Revolving cylinder machines – the needle butts pass through the stationary cam
system and the fabric hanging from the needles revolves with them.
(b) Reciprocating cam-carriage flat machines or rotating cam-box circular machines –
the cams with the yarn feeds pass across the stationary needle beds.
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Fig: Cam Path Diagram..
8.1.2. INDUSTRIAL ASSESSMENT
 Cam arrangement is directly depend on the design of the fabric such as
plain single jersey, single lacost, Double lacost, Terry etc. Generally three
types of knitting cam is used in industries. They are
1. Knit cam
2. Tuck cam
3. Miss cam
Fig: Different Types of Cam.
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 When four track cam boxes are not suitable a critical design then jacquard is
used.
Fig: Jacquard Cam.
 For auto stripe machine, adjustable cam is used.
Fig: Auto Stripe Adjustable Cam (Out Side View).
Fig: Auto Stripe Adjustable Cam (Inside View).
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8.2. NEEDLE ARRANGEMENT
8.2.1. THEORETICAL REVIEW
8.2.1.1. NEEDLES
The needles are the most important stitch forming elements. They are displaced
vertically up and down and are mounted into the tricks or cuts of the knitting cylinder.
There are three types of needles namely:
1. Latch needle
2. Spring bearded needle
3. Compound needle.
Fig: Different Types of Needle.
8.2.1.1.1. LATCH NEEDLE
It consists of a hook portion at the top and a latch riveted at certain distance from the
needle head. Latch needles are given sliding movements in individual grooves called
tricks of the cylinder. The latch swing freely and the stem is a straight portion with a
protruding butt. Through the butt the reciprocating movement to the needles is given.
The latch needles are self acting, and requires only previous loop on the stem and do
not require any outside agency to close the hook. The swinging latch has a cup at its
end and is riveted to the stem. Therefore, the total thickness of the needle cannot be
reduced and hence these needles are coarser in dimensions than the bearded needles.
8.2.1.1.2. SPRING BEARDED NEEDLE
This needle consists of a top hook curved downwards with a finished tip and the
downward continuation is called beard. A small eye or groove is cut in the stem, to
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receive the point of the needle beard when it is closed. It does not require latch, it is
finer in cross section and more number of needles per unit space can be and hence
finer machine gauge can be achieved (gauge is the number of needles per inch). It
requires additional element to close the needle which is done by a presser. The
bearded needle produces superior knitted stitches than the latch needle.
8.2.1.1.3. COMPOUND NEEDLE
The speed of the bearded needle machine is restricted by two factors. The presser
required to close or open the beard and the length of the beard. The swinging action of
the latch may cause damages to fine filament yarn and also latch needles are much
expensive to manufacture. To overcome the above difficulties, compound needles are
developed. It consists of a hollow steel tube of fine gauge in which a hook-closing
element which is also a steel tube of finer gauge, is inserted. To the tip of the upper
element, a needle hook is arranged. It claims the advantages of both bearded and latch
types. There is no yarn strain and the movement required to form a loop is half to that
of other needles. Both pieces have straight movement instead of swinging. Hence the
high speed and high productivity.
8.2.1.2. LOOP FORMING SEQUENCE OF LATCH NEEDLE
In the running position, the held old loop rests on the top of the open latch. Clearing
occurs as the held loop slips of the latch and on to the stem as the needle moves
upwards. A downward movement enables the needle hook to engage a new piece of
yarn. This is known as feeding. As the needles continue downwards the latch is forced
to close under the influence of the held loop. Knock over occurs as the help loop
disengages from the needle. Following knock over, the loop pulling occurs and a new
knit loop is formed. The needle must return now to the running position to complete
the cycle. This is essential, otherwise, cleaning, knock over and loop pulling would
not take place. Control of the held loop is usually achieved by the use of sinkers or by
the application of the fabric tension.
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Fig: Loop Forming Sequence of Latch Needle.
8.2.1.3. LOOP FORMING SEQUENCE OF SPRING BEARDED
NEEDLE
The held loop is initially just below the tip of the beard in the running position. The
upward movement by the needle repositions the held loop further down the stem, at
which time a new yarn can be fed to the needle i.e., feeding occurs. The needle moves
down until the newly fed yarn enters the hook. An auxiliary element known as presser
closes off the hook to unable the held loop to leave the needle by deflecting the beard
tip into a recess cut in the needle stem. The movement when the held loop is securely
located to the outside of the beard is known as the landing position. As the needle
continues downwards, knock over and loop pulling take place after which the needle
returns to the running position to complete the cycle.
8.2.1.4. LOOP FORMING SEQUENCE OF COMPOUND NEEDLE
The held loop is shown on the needle stem in the running position. The hook and
tongue elements move upwards to that anew yarn may be presented to the hook and
hence feeding occurs. Both elements descend, although at different velocities, which
causes the tongue to close-off the hook. Thus the held loop is free to leave the needle,
knock over pulling occurs. The needle now returns to the running to complete the
cycle. As the needle returns to its starting position, the hook and tongue elements once
again move at different velocities resulting in the opening of the hook.
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Fig: Loop
Forming Sequence of Latch Needle
8.2.1.5. SPECIFICATION OF NEEDLE
The typical “European” specifications for a needle includes a word, a number
(usualrly a four digit number) and a final combination of letters and numbers. For
example: Vota 78.60 G.02 The capital letter at the beginning of the word ( “V”),
identifies the origin of the needle (obtained from a wire, pressed or die-cut), the type,
the number of butts and the type of tail. The other capital letters have a very precise
meaning, except for the vowels “e” and “a” which are added to make the word
pronounceable, and indicate the shape and the height of the butt, the eventual
existence of a groove and its size, the length of the tail and some other features of the
needle.
Fig: Needle
The next group of numbers identifies the needle according to the length and the
gauge. The first part indicates the whole length rounded off to the mm (in our case
that makes 78 mm); the second part indicates the gauge of the needle in hundredths of
millimeters (in our case the gauge of the needle is equal to 0.60 mm).
The final group of letters and numbers has to be read as follows. The first capital
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letter indicates the needle manufacturer (For example Z for Torrington, E for Exeltor,
G for Groz-Beckert). The next number is used to distinguish a specific needle among
all the needles produced by the same manufacturer.
The next letter refers to some particular features of the needle: for some needles an
“A” indicates that the latch has been fixed with an angular pressed pin while an “R”
means that the latch has been fixed with a straight pressed pin. For other needles, the
latch fixing method is indicated by a “0” before the last number. A “0” indicates that
the latch has been fixed with a standard pressed pin; no “0” means that the latch has
been fixed with a screw pin.
8.2.2. INDUSTRIAL ASSESSMENT
 In circular knitting machine Latch needle is used. Three points must be
considered for producing loop related to needle.
1. Needle must have to pass through clearing cam.
2. Needle must have caught the feed yarn.
3. Needle must have to pass through stitch cam.
Fig: Latch Needle Arrangement before Setting.
 Needle arrangement is totally depend on cam arrangement. Maximum 4 track
needle can be used in circular knitting machine.
 Common butt based needle are used in auto stripe machine.
 Needle height and thickness must be considered.
 Rib and Inter lock Machine use different types of needle that means relatively
short needle are used.
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8.3. SINKER ARRANGEMENT
8.3.1. THEORETICAL REVIEW
8.3.1.1. SINKER
Sinker is a thin metal plate with action at right angles to and fro between adjoining
needles. It may perform one or more of the following functions:
1. Loop formation
2. Holding down, and
3. Knocking over.
The main object of a sinker is to assist the needles in loop formation by sinking or
knitting the newly laid yarns into a loop. As its forward edges of catch [c] advantages
between the two adjoining needles. This is only for bearded needle where as in case of
latch needles and warp knitting loop formation is not the function of sinkers. It also
holds down the loops at a lower level of the needle stems and prevents the old loops
from being lifted as the needles rise to clear them for their hooks. The third function is
a knocking over at which the needle passes through the old loop by drawing a new
loop.
Fig: Sinker.
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8.3.2. INDUSTRIAL ASSESSMENT
 Two types of sinker are used in the industry.
1. Horizontal sinker. (PAI LUNG)
2. Vertical sinker. (MAYER &CIE)
 Sinker’s cam is used for moving sinker but for vertical and horizontal sinker’s
cam is different.
 Vertical cam also known as’ Relanit’.
8.4. M/C DIAMETER & M/C GAUGE SETTING MECHANISM
8.4.1. THEORETICAL REVIEW
8.4.1.1. CYLINDER
The cylinder is a steel circular bed having grooves/tricks/cuts on its outer periphery
into which the needles are mounted. With reference to the tricks, the needles move
vertically up and down by their butt being in contact with the cam track. The number
of tricks per inch i.e., number of needles per inch decides the gauge of the machine.
Machines are built as low as 4 NPI to as high as 32 NPI. Based on the machine gauge,
the fineness of the yarn to be knitted can be varied. The diameter of the cylinder also
varied based on the type and width of the fabric and a maximum of 75 cm diameter
machines are available.
Fig: Cylinder.
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8.4.1.2. DIAL
Dial is the upper steel needle bed used in double knit machines. Into the grooves of
the dial, the needles are mounted horizontally and are allowed to move radially in and
out by their dial cams. The number of grooves per unit space conforms to the cylinder
gauge in most of the cases.
8.4.1.3. GAUGE
Gauge is defined as number of needle in one inch. When needle gauge is increased then
Wales per inch is increased and GSM is increased.
Fig: Needle Gauge.
8.4.2. INDUSTRIAL ASSESSMENT
 Needle gauge is depending on the WPI of the given fabric which we want to
produce.
 Cylinder is actually produced on basis on needle gauge.
 Fabric width depends on the diameter of the machine.
 For double jersey fabric cylinder & dial are used.
 Needle gauge also depends on yarn count.
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8.5. STITCH LENGTH SETTING MECHANISM
Stitch length is controlled by V.D.Q Pulley.
8.5.1. V.D.Q PULLEY (VARIABLE DIAMETER QUALITY)
8.5.1.1. THEORETICAL REVIEW
In a knitting m/c, V.D.Q. Pulley is used to supply the specific length of yarn. There
are two or more adjustable pulleys which are known as V.D.Q. Pulley. By adjusting
the V.D.Q. pulley we can control the speed of accumulator which supply the required
amount of yarn. V.D.Q. pulley is very important to set up the correct loop length. The
amount of yarn wound on accumulator by one revolution of cylinder is called the
course length of fabric.
H
G
D
E
F
C
diameter
F‘
B
A
E’
Fig: Passage Diagram of V.D.Q Pulley.
Course length= 1 
A C E G
    d Where d is the diameter of accumulato r
B D F H
Course length=K X G
K = constant =
A C E 1
    d
B D F H
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K 
Course length
G
Course length=K X G
nl  KG
K G
n
K
 G
n
l
 MG M 
K
Which is fixed for a specific Cylinder
n
Sometimes, for a specific loop length, the required V.D.Q pulley is needed more or
less than the numbered V.D.Q pulley value. For this condition, we have to change the
constant value ‘k’. For change the ‘k’ we have to change E,F,E’,F’ gear.
8.5.1.2. INDUSTRIAL ASSESSMENT
 We know diameter of VDQ pulley is the main factor for controlling the stitch
length which is the very important parameter for knitted fabric.
 GSM of knitted fabric is related to the stitch length of a fabric. If stitch length
is high then GSM will be decreased.
 When it is need to increase stitch length then the diameter of VDQ pulley also
need to increase and cylinder is adjusted as well as the take down speed also
need to increase. But when stitch length is decrease then vice – versa.
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Fig: V.D.Q Pulley.
8.6. CYLINDER HEIGHT ADJUSTMENT
8.6.1. INDUSTRIAL ASSESSMENT
 This term is related with yarn tension adjustment and cam setting adjustment
for particular design of a fabric.
 It is done in the industry for maintaining the uniform yarn tension. Whether
yarn tension is low or tension is high.
 It is done for accurate needle action.
9. KNITTING MECHANISM
This is the section or step of producing a fabric.
9.1. THEORETICAL REVIEW
9.1.1. CIRCULAR KNITTING MACHINE
The principle for circular knitting machine feed from the knitting elements yarn
moves from the yarn supply or creel through guides to stop motions control above the
machine, then back down to tension controls and yarn feeding devices to the knitting
elements. Quality products can be produced only on stop motion and yarn feeding
functions are properly set.
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Then inter get action knitting and needles form loops. The course at the needle of the
machine between the take up and yarn feeding mechanism. Circular weft knitting,
needle let one after the other in a sequence for each yarn. Loops are formed
horizontally by needle knitting around the cylinder forming a tube. After yarn is knit
on the knitting elements the knitted fabric passed over a spiral mechanism through
take-up roller and round a roll. This electrical spiral distribute the take-up tension
uniformly and reliable to fabric confirm flat tube.
Fig: Circular Knitting Machine
9.1.2. DIFFERENT PARTS OF CIRCULAR KNITTING MACHINE
1. Chassis
2. Main foot
3. Side foot
4.Supporting ring
5.Needle cylinder
6.Guide
7. Yarn carrier
8. Cam box
9. Yarn feed device
10. Yarn feeder
11.Central machine axis
12.Protective cover
13. Holding rods
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9.1.3. THE KNITTING ACTION OF A LATCH NEEDLE AND
HOLDING-DOWN SINKER DURING THE PRODUCTION OF A
COURSE OF PLAIN FABRIC.
Fig: Knitting Action.
(a) Tucking in the hook or rest position. The sinker is forward, holding down the old
loop whilst the needle rises from the rest position.
(b) Clearing. The needle has been raised to its highest position clearing the old loop
from its latch.
(c) Yarn feeding. The sinker is partially withdrawn allowing the feeder to present its
yarn to the descending needle hook and also freeing the old loop so that it can slide up
the needle stem and under the open latch spoon.
(d) Knock-over. The sinker is fully withdrawn whilst the needle descends to knock
over its old loop on the sinker belly.
(e) Holding-down. The sinker moves forward to hold down the new loop in its
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9.1.4. SINKERS OPERATION
1. The held loop is positioned in the throat of the sinker when the sinker moves
forward and the needle moves upward for clearing. The held loop is held by the throat
and hence its movement along the needle is restricted.
2. The sinker remains at its forward position when the needle attains its clearing
position.
3. The sinker retracts when the needle comes down after feeding. At this stage, due to
sinkers retraction, fabric or held loop is eased out. Also the sinker belly supported the
fabric or held loop and hence its movements along the needle is prevented.
4. Sinker remains in backward position and the needle descends to its lowest position
drawing the new loop through the old one.
5. Before the needle ascends, the sinker moves forward to push the knitted fabric a
little and to hold the old loop away from the head of the needle and to be in a position
to control the fabric.
Fig: Sinker Operation..
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9.1.5. OILING SYSTEM
9.1.5.1. INDUSTRIAL ASSESSMENT
 For avoiding needle breakage and relative frictional problem oiling is
necessary.
 By air pressure, oil is supplied from a can to cam, sinker and needle as a
lubricant.
 Oiling amount depend on Machine RPM. When RPM is raised then oiling
speed is increased.
 The used oil is come back in another can which are used for machine
maintenance.
 Oiling amount is adjusted by programs setting in the machine.
Fig: Oiling System.
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Fig: Oiling System By Nozzle.
Fig: Oil Can/Gar.
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9.1.6. AIR CIRCULATION SYSTEM
9.1.6.1. INDUSTRIAL ASSESSMENT
 For removing dirt, dust, lint etc. Air circulation fan are used.
 Dust, dirt, lint etc. removing by air suction.
 Air is used for oil spreading equally.
Fig: Air Circulation System For Oil Spreading.
 Air circulation fan are used for removing fly dirt or dust.
Fig: Air Circulation Fan for Removing Fly Dirt Or Dust.
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 Air circulation nozzle is used for removing fly dirt or dust and yarn feeding.
Fig: Air Circulation for Removing Fly Dirt or Dust and Yarn Feeding.
 Compressed air are used for
1. Breakage yarn feeding.
2. Lint removing from needle.
3. Machine Maintenance.
4. Oil supplying.
So air circulation control systems are used.
Fig: Air Circulation Control System.
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10.THE ROLL FABRIC WITHDRAW MECHANISM
10.1. FABRIC SPREADER
10.1.1. THEORETICAL REVIEW
In circular knitting, the tubular fabric descends from the needles is converged into
flattened double layer and rolled into yard goods. During such conversion, irregular
tensions are developed throughout the fabric due to distance variations which leads to
unwanted wrinkles, crease marks and stitch deformations. They can be only removed
with great difficulty during fabric finishing. To overcome this problem knitting
machines are equipped with spreaders which apply a more uniform tension to the
fabric. A simple fabric spreader is a solid wooden plate, placed above the takedown
rollers and held in position by the fabric tube. Another type of fabric spreader consists
of two curved metal bars with adjustment for their length. The device is placed
secured inside the fabric roll. It is important that the spreaders should not bend the
courses and increase the takedown tension. Heavy tension on the fabric affects the life
span of the knitting elements such as needles, cams and needle bed. Because of the
rectangular shape of this spreader, the circumference of the fabric tube, obtained
directly after knitting, is not altered over the entire distance up to the take down
rollers. This results in the required evenness of the take down tension of the knitting
machines and leads to a uniform stitch shape across the entire fabric width.
Fig: Fabric Spreader.
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10.1.2. INDUSTRIAL ASSESSMENT
 Fabric spreader is used for original fabric shape during production of fabric.
Fig: Fabric Spreader.
10.2. TAKE DOWN AND WINDING MECHANISM
10.2.1. THEORETICAL REVIEW
This mechanism withdraws the fabric from the needles and winds them into the cloth
roll. The takedown mechanism consists of grooved rollers through which the fabric is
nipped and pulled downwards. The roll winding mechanism facilitate the convenient
storage of fabric in which the flat, double ply fabric is wound on a revolving square
bar. The take-down and winding devices are either driven mechanically by the main
drive of the motor or through an additional direct current motor.
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10.2.1.1. MECHANICAL DRIVE
At the take down, the fabric is nipped between two rollers or with some devices
having three rollers. The pressure between the rollers is readily adjustable. The lower
part of the machine frame is fitted with a circular rail or ring with the same central
axis as the cylinder, but positioned inclined to the horizontal. There are two rollers or
followers placed diagonally opposite and ride over the rail as the cylinder rotates. The
running of the follower over the rail gives oscillating motion to the lever to which
they are fixed. The levers intern drives a toothed ratchet wheel by means of a pawl.
This ratchet wheel is fixed to the grooved takedown roller and thus drives the same. A
fixed pawl prevents the ratchet wheel from the reversing while the lever oscillates.
The extent of the rail inclination governs the withdrawal rate of fabric through the
take down rollers. Exactly similar mechanism is extended to the cloth roll through
connecting levers from the takedown oscillating lever. Similar kind of ratchet wheel
with driving pawl and fixed pawl rotates the cloth roll and wind the fabric.
Fig: Mechanical Takedown Mechanism.
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10.2.1.2. ELECTRICAL DRIVE
A separate motor drives the take down and winding devices. The fabric takes down
and fabric wind on form a compact unit and are as such attached to the rotating base
plate in the lower machine frame. The unit consists of two lateral supports, between
which the three take down rollers, the winding roll and the fabric winding spindle are
provided. The fabric is led through the take-down rollers which are driven by a
gearing motor over a chain gear. The takedown tension can be infinitely and
sensitively set on the control panel with a potentiometer without disturbing the
machine running. The fabric encircles the take down rollers and is then led down to
fabric winder and wound into fabric roll
Fig: Passage Diagram of Fabric Takedown.
10.2.2. INDUSTRIAL ASSESSMENT
 We saw in factory mechanical take down device. Take down mechanism is
proportional to the fabric production. If the production is high then it is need
to high speed in take down roller and vice versa.
 In knitting industries two types of take down mechanism is used
1. Gearing take down mechanism.
2. Pulley system takes down mechanism.
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Fig: Pulley System Take Down Mechanism.
10.3. WEIGHTING AND ROLL MARKING
After cutting a roll, weighting and roll marking must be done.
10.3.1. INDUSTRIAL ASSESSMENT
 After weighting the fabric in industries marking is done on the roll including
Buyer name, Yarn lot number, M/C number, M/C diameter, M/C gauge, Yarn
count, Stitch Length; Finish GSM, Weight of the roll etc.
Fig: Fabric Lot.
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Fig: Fabric Weighting Balance.
11.INSPECTION MECHANISM
11.1. THEORETICAL REVIEW
11.1.1. FABRIC INSPECTION
The inspection of fabric is a procedure by which the defects of fabric are identified
and fabric is classified according to degree or intensity of defects. The fabric
inspection is done for both grey and finished fabric.
11.1.2. GREIGE FABRIC FAULTS
Following faults are found in the grey fabric:
Problem
Reason
Remedy
Problem for hole
Broken needle head
Change the needle
Problem for missing yarn
Missing of one end of double
Careful observation and
yarn
instant machine stop
when fault found
Problem for needle line
Bent needle latch
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Problem for thick thin
Yarn fault
yarn
Replace the yarn cone to
a more uniform yarn
cone
Problem for slubs
Yarn fault
Replace the yarn cone to
a more uniform yarn
cone
Problem for drop needle
Needle failed to receive the
Reset the needle
yarn while knitting, needle
missing
Problem for Barrie mark
Irregular tension of take
Adjust the take down
/ patta
down roller
tension or synchronize
the take down speed
with knitting.
Problem for pin hole
Due to missing stitches or
Concentrate on needle
loops
and latch
Problem for oil line
Improper lubrication
Proper lubrication
Problem for fly contact
Fly coming from the adjacent
Separate one machine
machine
from other
Dirty machine and improper
Proper lubrication and
handling of fabric
clean machine
Problem for oil stain
11.2. INDUSTRIAL ASSESSMENT
 Manually fabric inspection is done spreading the fabric on the table but now a
day’s fabric inspection machine is used to inspect the fabric.
 In this machine three switches is attach at right side. One switch is used to
forward the fabric, one switch is used to backward motion for the fabric, and
one switch is used to control the fabric speed.
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Fig: Fabric Inspection Machine.
12. GRADING SYSTEM
12.1. INDUSTRIAL ASSESSMENT
12.1.1. GREY FABRIC NUMBERING
According to ISO, grey fabric inspection is performed according to 4 point system.
12.1.2. FOUR-POINT SYSTEM
Size of Defect
Penalty
0 inches to 3 inches
1 Point
3 inches to 6 inches
2 Point
6 inches to 9 inches
3 Point
More than 9 inches
4 Point
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12.1.3. ACCEPTANCE CALCULATION
Any Hole – 4 Point
Up to 20P/100m = Class “A”
Up to 20-30P/100m = Class “B”
Up to 30-40P/100m = Class “C”
More than 40P/100m = Reject.
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13.CONCLUSION
Now a day’s knitted fabric is popular all over the world. So we have to need maintain
its quality as high as possible. Knitted fabrics are two types: warp knitted fabric and
weft knitted fabric. We have discussed about mechanism used for producing weft
knitted fabric. In our project work we have tried best to show how a knitted fabric is
produced by circular knitting machine. We have elaborated about different kind of
mechanism which are must be need to produce knitted fabric. Our target is to find out
how a knitting machine can produce fabric efficiently according given specification.
Actually maximum knitting factory of our country follow the previous sheet to
produce fabric but we have tried to find out how we can produce fabric accurately by
using proper mechanism in weft knitting machine.
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14.REFFERENCE
1. Belal, E. A. Understanding Textiles for a Merchandiser. Dhaka: BMN
Foundation.
2. Knitting – fundamentals, machines, structures and developments. (2003).
England.
3.
Spencer, D. J. (2001). Knitting Technology. England: Woodhead Publishing
Limited.
4. Textile Lerner. (2012, December 09). Retrieved December 25, 2012, from
www.textlelearnerblogspot.com:
http://textilelearner.blogspot.com/2012/09/process-flow-chart-of-knitting.html
5. Photographs from industries and Google image.
6. Haque, M. Hand Note, Dhaka: Daffodil International University.
7. Islam, A. Hand Note, Dhaka: Daffodil International University.
8. Morshed, D. Hand Note, Dhaka: Daffodil International University.
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