Knitting TechnologyKnitting TechnologyEvolution of knittingEvolution of knitting

• Knitting is one of the most important process for Knitting is one of the most important process for producing garments and worldwide represents a producing garments and worldwide represents a considerable and increasing percentage of the considerable and increasing percentage of the population apparelpopulation apparel

• Knitting is used to produce garments that cover Knitting is used to produce garments that cover every part of the human body, in a wide range of every part of the human body, in a wide range of garment types from socks, caps, gloves, underwear, garment types from socks, caps, gloves, underwear, T- Shirts, jackets, Pyjamas, nightwear, sweat shirts, T- Shirts, jackets, Pyjamas, nightwear, sweat shirts, tops, skirts, Bermudas, sports wear, shorts, baby tops, skirts, Bermudas, sports wear, shorts, baby wear, infant wear, hooded T- Shirts, jogging suits etcwear, infant wear, hooded T- Shirts, jogging suits etc

• Knitted fabric may constructed with a single yarn Knitted fabric may constructed with a single yarn that is formed into interlocking loops by the use that is formed into interlocking loops by the use of hooked needlesof hooked needles

• Knitted fabrics also give warmth because of the Knitted fabrics also give warmth because of the insulative air pockets contained in this type of insulative air pockets contained in this type of construction. Yet they are porous and provide construction. Yet they are porous and provide “breathing’’ comfort because body movements “breathing’’ comfort because body movements cause the loops to expand and contract, thus cause the loops to expand and contract, thus pushing air through close fitting garments. pushing air through close fitting garments.

Hand KnittingHand Knitting

• It’s area of origin and time of invention are It’s area of origin and time of invention are unknownunknown

• Hand knitting precedes machine knitting as a Hand knitting precedes machine knitting as a technique by many hundreds of yearstechnique by many hundreds of years

• Hand knitting is one of the oldest of man’s Hand knitting is one of the oldest of man’s construction techniques and is also one of the construction techniques and is also one of the world’s most popular pastimes.world’s most popular pastimes.

Knitting MachinesKnitting Machines

• In 1589, in the reign of Queen Elizabeth I, the In 1589, in the reign of Queen Elizabeth I, the Reverend William lee, presented himself at the Reverend William lee, presented himself at the court of the queen with a request for letters court of the queen with a request for letters patent for his newly invented knitting machine patent for his newly invented knitting machine which knitted 8 loops to 1’’ of width. Mr. Lee in which knitted 8 loops to 1’’ of width. Mr. Lee in 1598 introduced a refined version of his machine 1598 introduced a refined version of his machine – which knitted 20 loops per inch.– which knitted 20 loops per inch.

Knitting IndustryKnitting Industry

• In the middle of 18th century there were total of In the middle of 18th century there were total of 14000 machines in the industry in England.14000 machines in the industry in England.

• There were modifications and improvements in There were modifications and improvements in the machine. The most modifications werethe machine. The most modifications were– The rib frameThe rib frame– JacquardsJacquards– Warp framesWarp frames– Selection device to produce tucked fabricsSelection device to produce tucked fabrics

• All these inventions occurred in Nottingham town. All these inventions occurred in Nottingham town. The first cotton from India was knitted in The first cotton from India was knitted in Nottingham in 1730Nottingham in 1730

• In 1960s every knitting machine builder produced In 1960s every knitting machine builder produced an exclusive, patented, needle selection an exclusive, patented, needle selection mechanism to carry out the functions of lifting mechanism to carry out the functions of lifting needles to knit or leaving them down to miss.needles to knit or leaving them down to miss.

• In the 19th century, the first circular knitting In the 19th century, the first circular knitting machine appeared and during the period 1880 – machine appeared and during the period 1880 – 1910 knitwear became as an established item of 1910 knitwear became as an established item of female fashionfemale fashion

Twentieth Century DevelopmentsTwentieth Century Developments

• Developments in the 20th century have largely Developments in the 20th century have largely involved increasing the productivity of knitting involved increasing the productivity of knitting machine.machine.

• The knitted garment is now established as part of The knitted garment is now established as part of every day dress and most people irrespective of every day dress and most people irrespective of age or gender are usually wearing knitted age or gender are usually wearing knitted garments.garments.

General Terms & Principles of General Terms & Principles of Knitting TechnologyKnitting Technology

• Machine knitting: Machine knitting: Knitted structures are Knitted structures are progressively built up by converting newly fed yarn progressively built up by converting newly fed yarn into new loops in the needle hooks; the needle into new loops in the needle hooks; the needle hook then draws these new loops head first hook then draws these new loops head first through old loops which they have retained from through old loops which they have retained from the previous knitting cycle.the previous knitting cycle.

• Knitted loop structure: Knitted loop structure: Intermeshing of loops Intermeshing of loops is securely achieved by the needles. Knitted loops is securely achieved by the needles. Knitted loops are arranged in rows and columns roughly are arranged in rows and columns roughly equivalent to warp and weft of woven structures equivalent to warp and weft of woven structures termed courses and Wales respectively.termed courses and Wales respectively.

• Role of loop structure in quality knitting:Role of loop structure in quality knitting: Loop length plays a key role in determining the Loop length plays a key role in determining the dimensional behavior of knitted fabricdimensional behavior of knitted fabric

• Length of yarn in an unit cell is the fundamental Length of yarn in an unit cell is the fundamental unit of weft knitted fabricunit of weft knitted fabric

• Loop shape determines the dimensions of the Loop shape determines the dimensions of the fabric & this shape depends upon yarn & the fabric & this shape depends upon yarn & the treatment which the fabrics has receivedtreatment which the fabrics has received

• The fabric compactness & looseness depend on The fabric compactness & looseness depend on the length of yarn in one loop & yarn count valuethe length of yarn in one loop & yarn count value

Fabric QualityFabric Quality

• The term fabric quality is sometimes used when The term fabric quality is sometimes used when referring to wales and courses per inch or referring to wales and courses per inch or centimeter, either in knitted or finished relaxed centimeter, either in knitted or finished relaxed state. As knitted loops tend to assume a state. As knitted loops tend to assume a recognizable configuration the results can give an recognizable configuration the results can give an indication of the approximate stitch length and indication of the approximate stitch length and possible machine gauge used in knitting the possible machine gauge used in knitting the structure provided the state of relaxation and type structure provided the state of relaxation and type of structure is taken into consideration. Generally of structure is taken into consideration. Generally the higher the figure for a given linear the higher the figure for a given linear measurement, fabric structure and state of measurement, fabric structure and state of relaxation, the finer the machine gauge and the relaxation, the finer the machine gauge and the smaller the stitch lengthsmaller the stitch length

Face Loop Back Loop

Wale: Wale:

• Wale is predominantly vertical column of needle Wale is predominantly vertical column of needle loops produced by same needle knitting at loops produced by same needle knitting at successive knitting cycle.successive knitting cycle.

Course

Wale

Course: Course: • Course is a predominantly horizontal row of loops produced Course is a predominantly horizontal row of loops produced

by adjacent needles during the same knitting cycle.by adjacent needles during the same knitting cycle.Course LengthCourse Length• In weft knitting, the term ‘course length’ refers to the In weft knitting, the term ‘course length’ refers to the

measurement of a straight length of yarn knitted by all or a measurement of a straight length of yarn knitted by all or a fraction of the needles in the production of a particular fraction of the needles in the production of a particular course.course.

Stitch Density: Stitch Density: • The term stitch density is frequently used in knitting The term stitch density is frequently used in knitting

instead of a linear measurement of courses or Wales; it is instead of a linear measurement of courses or Wales; it is the total number of needle loops in a square measurement.the total number of needle loops in a square measurement.

• It is obtained by multiplying, the no. of courses and Wales It is obtained by multiplying, the no. of courses and Wales per inch together.per inch together.

• SD = WPI x CPISD = WPI x CPI

LATCH NEEDLELATCH NEEDLE

• The latch needle has nine main features

• The hook which draws and retains the new loop.

• The slot or saw-cut which receives the latch-blade (not illustrated).

• The cheeks or slot walls which are either punched or riveted to fulcrum the latch-blade (not illustrated).

• The rivet which may be plain or threaded. This has been dispensed with on most plate metal needles by pinching in the slot walls to retain the latch blade.

• The latch-blade which locates the latch in the needle.

• The latch spoon which is an extension of the blade and bridges the gap between the hook and the stem covering the hook when closed as shown in broken lines.

• The stem which carries the loop in the clearing or rest position.

• The butt which enables the needle to be reciprocated when contacted by cam profiles on either side of it forming a track. Double-ended purl type needles have a hook at each end, whilst one hook knits; the inactive hook is controlled as a butt by a cam reciprocated element called a slider.

• The tail which is an extension below the butt giving additional support to the needle and keeping the needle in its trick

• MACHINE GAUGEMACHINE GAUGE• In Latch needle weft knitting machines the In Latch needle weft knitting machines the

gauge is normally expressed in needles per gauge is normally expressed in needles per inchinch

•• This in the USA is referred to as This in the USA is referred to as

“CUT”“CUT”• CAM ARRANGEMENTCAM ARRANGEMENT• Cams are the devices which converts the rotary Cams are the devices which converts the rotary

machine drive into a suitable reciprocating machine drive into a suitable reciprocating action for the needles.action for the needles.

Cams are of two types Cams are of two types namelynamely

Engineering Cams:Engineering Cams: are used in warp are used in warp knitting machinesknitting machines

Knitting Cams:Knitting Cams:• Cams acts directly on to the butts of Cams acts directly on to the butts of

needles to produce individual needles to produce individual movement in the tricks of latch movement in the tricks of latch needle weft knitting machines.needle weft knitting machines.

• Knitted Stitch: -Knitted Stitch: - is the basic unit of is the basic unit of intermeshing and usually consists of intermeshing and usually consists of three or more intermeshed three or more intermeshed

Selvedge Fabric: -Selvedge Fabric: - A selvedge fabric is one having A selvedge fabric is one having a “self edge” to it and can only be produced on a a “self edge” to it and can only be produced on a machine whose yarn reciprocates backwards and machine whose yarn reciprocates backwards and forwards across the needle bed so that a forwards across the needle bed so that a selvedge is formed as the yarn rises upto the selvedge is formed as the yarn rises upto the next course at the edge of he fabric.next course at the edge of he fabric.

Cut Edge Fabric: -Cut Edge Fabric: - is usually produced by slitting is usually produced by slitting open a tube of fabric produced on a circular open a tube of fabric produced on a circular machine.machine.

Tubular Fabric: -Tubular Fabric: - is produced in circular knitting is produced in circular knitting machine and also in flat knitting machine.machine and also in flat knitting machine.

Basic Weft knit Basic Weft knit StructuresStructures

• In Woven fabric structures, three weaves are called In Woven fabric structures, three weaves are called basic weaves namelybasic weaves namely

• PlainPlain• TwillTwill• SatinSatin• All other modification of the structures is derivatives All other modification of the structures is derivatives

of these basic weaves.of these basic weaves.• In a similar way in weft knit structures, the following In a similar way in weft knit structures, the following

four structures are considered as basic weft knit four structures are considered as basic weft knit structures namelystructures namely

• Plain – Single JerseyPlain – Single Jersey• RibRib• InterlockInterlock• PurlPurl

PlainPlain• Plain is produced by the needles knitting as a single set, drawing the Plain is produced by the needles knitting as a single set, drawing the

loops away from back and towards the face side of the fabric.loops away from back and towards the face side of the fabric.RibRib• Rib requires two set of needles operating in between each other so Rib requires two set of needles operating in between each other so

that the wales of face stitches and wales of reverse stitches are that the wales of face stitches and wales of reverse stitches are knitted on each side of fabric.knitted on each side of fabric.

InterlockInterlock• Is originally derived from rib but requires a special arrangement of Is originally derived from rib but requires a special arrangement of

needles knitting back-to-back in an alternate sequence of two sets needles knitting back-to-back in an alternate sequence of two sets so that the two courses of loops show wales of face loops on each so that the two courses of loops show wales of face loops on each side of the fabric exactly in line with each other thus hiding the side of the fabric exactly in line with each other thus hiding the appearance of the reverse loop.appearance of the reverse loop.

• Inter lock is the interlocking of two 1x1 Ribs structures in such a way Inter lock is the interlocking of two 1x1 Ribs structures in such a way that the face wale of one rib fabric is directly is front of reverse wale that the face wale of one rib fabric is directly is front of reverse wale of rib fabric.of rib fabric.

PurlPurl• Purl is the only structure having certain wales containing both face Purl is the only structure having certain wales containing both face

and reverse meshed loops.and reverse meshed loops.

Knitting NotationsKnitting Notations• A knitting notation is a simple, easily understood A knitting notation is a simple, easily understood

symbolic representation of a knitting repeat symbolic representation of a knitting repeat sequence and its resultant fabric structure sequence and its resultant fabric structure

• The notational method for weft knitting is The notational method for weft knitting is developed by Leicester school of textiles. In this developed by Leicester school of textiles. In this method, a square represents a needle or stitch, method, a square represents a needle or stitch, and ‘X’ symbol is placed in a square represents a and ‘X’ symbol is placed in a square represents a face stitch occurs and ‘O’ symbol is represents a face stitch occurs and ‘O’ symbol is represents a back or reverse stitchback or reverse stitch

Characteristics of single Characteristics of single jersey structuresjersey structures

• The simplest and the most widely used weft knit The simplest and the most widely used weft knit fabric is jersey or plain knit fabric. It consists of fabric is jersey or plain knit fabric. It consists of face and back stitches.face and back stitches.

• The loops have a v – shaped appearance on The loops have a v – shaped appearance on technical face and show semi circular loops on technical face and show semi circular loops on the technical back sidethe technical back side

• It has potential recovery of about 40% in width It has potential recovery of about 40% in width after stretching. Its width shortens if Length is after stretching. Its width shortens if Length is stretched. Normally width way extensibility is stretched. Normally width way extensibility is approximately twice the lengthwise extensibility.approximately twice the lengthwise extensibility.

• Singly Jersey curls upwards at the bottom Singly Jersey curls upwards at the bottom & top and backwards at the sides& top and backwards at the sides

• Production Rate is high because of its Production Rate is high because of its simplicity and its cost is low because of simplicity and its cost is low because of machine simplicitymachine simplicity

• It is knitted on a singly cylinder or on a It is knitted on a singly cylinder or on a single bed with a single set of needlessingle bed with a single set of needles

• Tuck stitch appears on the back of the fabric as an Tuck stitch appears on the back of the fabric as an inverted “V” inverted “V”

• Tuck stitch is made when a needle receives a new yarn Tuck stitch is made when a needle receives a new yarn while still holding its farmer loop, thus forming two while still holding its farmer loop, thus forming two loops in open needle hook.loops in open needle hook.

• Miss (or) Float is another variation, which is created Miss (or) Float is another variation, which is created when one (or) more needles are deactivated, as no when one (or) more needles are deactivated, as no loop is formed the yarn forms a loop is formed the yarn forms a floatfloat on the back of the on the back of the fabricfabric

• The fabric that has both more wales & more courses The fabric that has both more wales & more courses per area will have better recovery from stretching.per area will have better recovery from stretching.

• Fabric that has more wales will shrink less in width & Fabric that has more wales will shrink less in width & that have more courses will shrink less in length.that have more courses will shrink less in length.

• The quality of the needles will affect the quality of the The quality of the needles will affect the quality of the knitted fabricknitted fabric

• Needle are actuated through butt by camsNeedle are actuated through butt by cams

Mechanism of loop Mechanism of loop formation with latch formation with latch

needlesneedles

• For producing weft knitted fabrics the For producing weft knitted fabrics the individually moveable latch needles are individually moveable latch needles are arranged either in a line (flat knitting machines) arranged either in a line (flat knitting machines) or radially (circular knitting machines), during or radially (circular knitting machines), during stitch formation the following needle positions stitch formation the following needle positions are to be noted:are to be noted:

1.1. Rest position:Rest position: The needle is in its rest position The needle is in its rest position when it is outside the camwhen it is outside the cam

• Tucking position:Tucking position: The needle cam takes over The needle cam takes over the needles butts and these are pushed the needles butts and these are pushed upwards. In the tucking position the old loop is upwards. In the tucking position the old loop is still in the area of the needle hook. This position still in the area of the needle hook. This position can also be used for patterning.can also be used for patterning.

• Clearing Position (Knitting position): Clearing Position (Knitting position): The The old loop is now on the needle stem behind the old loop is now on the needle stem behind the needle latch. Safety elements, like small needle latch. Safety elements, like small brushes or even the yarn feeder itself, prevent brushes or even the yarn feeder itself, prevent the closing of the latches.the closing of the latches.

• Yarn feeding position:Yarn feeding position: A new yarn is presented to the needle A new yarn is presented to the needle hook while the needle is moved downwards by the draw-down hook while the needle is moved downwards by the draw-down cam. When the needle moves further down, the loop closes the cam. When the needle moves further down, the loop closes the needle book (cast-on) and will be able to slide over it.needle book (cast-on) and will be able to slide over it.

• Knock over position:Knock over position: The new yarn can now be drawn The new yarn can now be drawn through the old loop. This process is over when the needle is at through the old loop. This process is over when the needle is at the lowest position of the draw – down cam. If the knock – over the lowest position of the draw – down cam. If the knock – over point is shifted by altering the position of the draw – down cam point is shifted by altering the position of the draw – down cam vertically, the stitch length is changed. Knock over / cast off vertically, the stitch length is changed. Knock over / cast off means new loop is drawn into the old loopmeans new loop is drawn into the old loop

• Brush in flat knitting m/cBrush in flat knitting m/c

• The object of brush in flat knitting m/c is to open the latch to The object of brush in flat knitting m/c is to open the latch to enable to receive the new yarn on to the hook of the needle to enable to receive the new yarn on to the hook of the needle to form new loop into the old loop.form new loop into the old loop.

KnittingKnitting

Weft knitting Warp Knitting

Flat Knitting Circular knitting

Hand flat knitting Automatic/ computerizedFlat knitting Single Jersey

Double Jersey

Double Cylinder

Jacquard Non Jacquard

Rib Inter lock

Jacquard Non Jacquard

Jacquard Non Jacquard