Weft knitting machine & parameters of weft knitted fabric

Submitted ToDr. Md. Mahbubul Haque

Professor & Head,Department of Textile EngineeringDaffodil International University

Prepared By:MD.AZMERI LATIF BEG

ID: 142-32-257

Course Title : Advanced Fabric Manufacturing.Course Code: TEF-502

M. Sc in Textile EngineeringDepartment of Textile Engineering

"Analysis on the different parts of weft

knitting machine & parameters of weft

knitted fabric"

IntroductionKnitting is the interloping of yarn which is

interlocking in various ways to form fabric. Knitting is the process of manufacturing fabric by transforming continuous strands of yarn into a series of interlocking loops, each row of such loops hanging from the one immediately preceding it. The basic element of knit fabric structure is the loop intermeshed with the loop adjacent to it on both sides and above and below it.

Process Flow Chart for Weft Knitting:

Yarn in package form

↓ Place the yarn package in the creel

↓ Feeding the yarn

↓ Set the m/c as per design & GSM

↓ Knitting

↓ Withdraw the roll fabric and weighting

↓ Roll marking

↓ Inspection

↓ Numbering

Different Parts of Knitting Machine:

Knitting machines are mainly two types; they are circular knitting machine and flat bed knitting machine. This two types are hugely use in knitting machine. A knitting machine is composed of lots of parts. Every parts of a machine are important for run the machine smoothly. Every part has a specific function during operation.

Creel: Creel is a part of a knitting machine. Here yarn package are store and ready to feed in the machine.

Feeder: Feeder is help yarn to feed in to the machine.

VDQ Pulley: It is a very important part of the machine. It controls the quality of the product. Altering the position of the tension pulley changes the G.S.M. of the fabric. If pulley moves towards the positive directive then the G.S.M. is decrease. And in the reverse direction G.S.M will increase.

Pulley Belt: It controls the rotation of the MPF wheel.

Brush: Its clean the pulley belt.

Tension Disk: It confronts the tension of the supply yarn.

Inlet and Outlet Stop Motion: It is an important part of

the machine. It stops the machine instantly when a yarn is break.

Yarn Guide: Its help the yarn to feed in the feeder.

MPF Wheel: Its control the speed of the MPF. Pulley belt gives motion to the wheel.

MPF: It is Mamenger positive feed. It is also an important part of the machine. It’s give positive feed to the machine.

Feeder Ring: It is a ring. Where all feeders are pleased together.

Disk Drum: Use in jacquard machine to produce various types of design.

Pattern Wheel:Pattern Wheel use in Pai Lung and Auto Stripe machine because of that that help to produce various types of design and stripe.

Needle Track: Where all Needles is placed together in a decent design.

Needle: It is a principal element of the knitting machine. Its help the yarn to create a loop. And by this way fabric are produce. Prior to yarn feeding the needle is raised to clear the old loop from the hook, and received the new loop above it on needle stem. The new loop is then enclosed in the needle hook as the needle starts to descend.

Sinker: It is most important element of the machine. Its help to loop forming, knocking over and holding down the loop.

Sinker Ring: Sinker ring is a ring, where all sinkers are pleased together.

Cam Box: Where the cam are set horizontally. In cam box, practically 4

cams is set.

Cam: Cam is device s which converts the rotary machine drive in to a suitable reciprocating action for the needles and other elements.

Lycra Attachment Device:Lycra is placed hear and feeding to the machine.

Lycra Stop Motion:It is one kind of stop motion to stop the machine when the Lycra is break.

Cylinder:Needle track are situated hear.

Cylinder Balancer: It helps the cylinder to set in a proper alignment.

Uniwave Lubrication/Auto lubrication: The Uniwave lubricator provides uniform lubrication to needles,

cam tracks, lifters and other knitting machine components. The patented nozzle construction separates the air-oil mixture into air and droplets of oil.

Adjustable Fan : This part removes lint, hairy fibre from yarn and others. To clean the dust by air flow.

Expander:To control the width of the knitted fabric. No distortion

of the knitting courses. Even take down tension in the knitting machine. As a result, an even fabric structure is achieved over the entire fabric width. The deformation of the knitted fabric goods can be reduced.

Needle Detector: This part detect the any type of faults of needles.

Air Gun Nozzle: To feed the yarn; sometimes it is used for cleaning purpose.

knitting parameter

Knit fabrics are the fashion of new age. Various designed fabrics are produced in knitting machine. Knitting flow chart should follow during operation. During production processes following machine parameters are considered.

Machine diameterMachine rpm (revolution per minute)No. of feeder in useMachine gaugeCount of yarnRequired timeMachine running efficiency

Relationship between knitting parameter

1. Stitch length increase with decrease of GSM.2. If stitch length increase then fabric width increase

and Wales per inch decrease.3. If machine gauge increase then fabric width

decrease.4. If yarn count increase (courser) then fabric width

increase.5. If shrinkage increases then fabric width decrease

but GSM and Wales/inch increase.6. for finer gauge, finer count yarn should use7. Grey GSM should be less than finish GSM

Diameter of fabric: Diameter of the fabric is another factor. Fabric may be

open diameter or tube diameter. Any how grey dia. will be selected with response of finished dia. of the fabric.

Type of yarn: Different types of yarn are used for knit production. Cotton yarns may be combed or carded. Also synthetic fiber like lycra is used with cotton for some special case. All depends on the buyer requirement.

Stitch length The fundamental unit of a knitted fabric is the loop. Any

circular knitted fabric is composed of row after row of interloping or interlacing of loops. Different types of fabric are made of different method. The gross dimension of knitted fabric is simply a reflection of any shape & size of individual loops. There are several key variables in the production which affect the average shape & size of the loops. After knitting the grey fabric is dyed to required shade & finished to required weight & width. Stitch lengths vary depending on yarn count and shade of the fabric. If stitch length is not fixed with respond to finished G.S.M then knitting faults appear.

So, we have to consider above points before knit fabrics production.

Fabric GSM:The GSM of fabric is one kind of specification of fabric

which is very important for a textile engineer for understanding and production of fabric. ‘GSM’ means ‘Gram per square meter’ that is the weight of fabric in gram per one square meter. By this we can compare the fabrics in unit area which is heavier and which is lighter.

For measuring GSM, a GSM cutter is used to cut the fabric and weight is taken in balance. Both of these measurement and method is equally used for both woven and knitted fabrics.

Calculation of knitted fabric GSM:Weight per unit area can be measured by a portable

balance by cutting the fabric in 10″×10″ with the template or by calculation with the formula:

GSM =(Course/cm × Wales/cm× 100 × 100 × l × tex)/1000 × 1000

l = stitch length in millimeter.The result is expressed in gm/sq.meter, popularly

known as GSM.

We can control GSM by controlling stitch length (S/L) which is controlled by VDQ pulley diameter.

If we increase diameter of VDQ pulley then increase

yarn feed, stitch length and decrease GSM and vice verse.

Diameter of VDQ Pulley

Yarn feed

S.L GSM

↑ ↑ ↑ ↓

↓ ↓ ↓ ↑

GSM SL COLOR COUNT FABRIC DIA

125+

3.0 Blanco

30/1 Card S/J Dia to dia

Or

Dia to -ve

3.1 Marino3.1 Plomo3.3 Negro


1503.10 Black

26/1 Card S/J

Dia to +ve

3.00 Blue Dia to dia

2.90 White

2.55 Dark Blue


175

2.60 Orange

30/1 Card D/ L

Dia to +ve

(Ex. 36/47,21/26

)

2.65 Blue

2.70 Red

2.90 White


2002.80 Blue

26/1 Card D/ PK

Dia to +ve

(Ex. 34/47,20/2

6)

2.75 Red

2.65 Blue

D/L2.60 Black

S/J = Single Jersey.D/L = Double Lacoste D/PK= Double Piqua

Above the chart we can say that when stitch length of knitted fabric increase this time fabric GSM will be decrease. In other hand, when stitch length of knitted fabric will be decrease this time fabric GSM will be increase.

Above the chart we can say that finished GSM of knitted fabric can not depends only stitch length. It is also depends on the color shade of the fabric. If the shade % increase then the fabric GSM will be increase.

Shade%

Count Design Formula Finished GSM Grey GSM Stitch Length

20/s S/J (20 x 10.5)- (5x1) 205 162 2.8821/s S/J (20 x 10.5)- (5x2) 200 158 2.8522/s S/J (20 x 10.5)- (5x3) 195 155 2.7923/s S/J (20 x 10.5)- (5x4) 190 151 2.7424/s S/J (20 x 10.5)- (5x5) 185 147 2.6925/s S/J (20 x 10.5)- (5x6) 180 143 2.6626/s S/J (20 x 10.5)- (5x7) 175 140 2.6127/s S/J (20 x 10.5)- (5x8) 170 135 2.6028/s S/J (20 x 10.5)- (5x9) 165 132 2.5729/s S/J (20 x 10.5)- (5x10) 160 128 2.5630/s S/J (20 x 10.5)- (5x11) 155 124 2.5631/s S/J (20 x 10.5)- (5x12) 150 120 2.5632/s S/J (20 x 10.5)- (5x13) 145 116 2.5633/s S/J (20 x 10.5)- (5x14) 140 112 2.5734/s S/J (20 x 10.5)- (5x15) 135 108 2.5835/s S/J (20 x 10.5)- (5x16) 130 105 2.5936/s S/J (20 x 10.5)- (5x17) 125 101 2.6137/s S/J (20 x 10.5)- (5x18) 120 97 2.6538/s S/J (20 x 10.5)- (5x19) 115 93 2.6939/s S/J (20 x 10.5)- (5x20) 110 89 2.7440/s S/J (20 x 10.5)- (5x21) 105 85 2.80

0

50

100

150

200

250

20 22 23 25 27 29 31 33 35 37 39

Finished GSM S/J Grey GSM S/J

Yarn Count

Fabr

ic G

SM

Formula for setting parameter of Weft knitting

For S/J fabric590.5 x 16.1countS/L=Grey GSM590.5 x 16.1count Grey GSM = S/L590.5 x 16.1 Grey GSM S/L = countFinished GSM1.3= Grey GSM+5

For Interlock fabric590.5 x 32.2countS/L=Grey GSM590.5 x 32.2count Grey GSM = S/L590.5 x 32.2 Grey GSM S/L = countFinished GSM1.3= Grey GSM+5

For Rib fabric590.5 x 19.1countS/L=Grey GSM590.5 x 19.1count Grey GSM = S/L590.5 x 19.1 Grey GSM S/L = countFinished GSM1.3= Grey GSM+5For Lacoast/Pique fabric590.5 x 18.1countS/L=Grey GSM590.5 x 18.1count Grey GSM = S/L590.5 x 18.1 Grey GSM S/L = countFinished GSM1.3= Grey GSM+5For Thermal fabric590.5 x 1.4countS/L=Grey GSM590.5 x 1.4count Grey GSM = S/L590.5 x 1.4 Grey GSM S/L = countFinished GSM1.3= Grey GSM+5

Conclusion:For this lab report I have visited in the JK Knit composite Ltd. Knitting department are performing to produce different types of weft knitted fabric. The Knitting capacity of JK knit per day 14 tones. There are 62 knitting machines; 11 Rib/interlock machine, 3 Engineering stripe (jacquard), 6 three thread fleeces, 22 single jersey and 8 flat knit collar machine. A process of fabric manufacturing by converting yarn into loop form and then these loops interlock together, which forms a structure, is called knitting. Stitch/Loop length is the fundamental unit which controls all the properties of weft knitted fabrics. Mainly stitch length & knit structure affects all the dimensional, comfort, handle & other properties. I worked on different parts of knitting machine and also parameters of knitted fabric with structure also. But feeding is very important to control stitch length, stitch length also plays a great roll on other structures also. From the analysis, I can get idea about Knits are most commonly known for their natural softness, bulk, stretch, recovery and conformability.