Introduction of Knitting

Weft Knitting
• What is Knitting

• Needle Action

• Tuck, Knit and Float

•Single Jersey Machine

Knitting is a process of manufacturing fabric by
intermeshing of loops of yarn. When one loop is
drawn through another loop, a 'stitch' is formed.

Weft Knitting
Weft knitting is defined as a process of making
fabric by forming a set of correlated loops from
the weft yarn insertion into successive rows
across the width of the fabric. The essential
feature is that yarn is introduced in a weft wise
direction, at right angles to the direction of fabric
growth.
Weft knitting is also defined by the fact that the
loops are made horizontally across the fabric and
the fabric can be made with a single yarn or
thread.

Weft knitting is a method of forming a fabric by

knitting means in which the loops are made in a
horizontal way from a single yarn and
intermeshing of loops takes place in a circular or
flat form on a course-wise basis. In this method,
one or more yarns are being fed one at a time, to
a multiplicity of knitting needles, placed in either
lateral or circular fashion.
Technical Face
Technical Back
A Course:
A course is a predominantly horizontal row of needle loops (in an
upright fabric as knitted) produced by adjacent needles during the
same knitting cycle.

A Wale:
A wale is a predominantly vertical column of intermeshed needle
loops generally produced by the same needle knitting at
successive (not necessarily all) knitting cycles.A wale commences
as soon as an empty needle starts to knit.
Wales are connected together across the width of the fabric by
sinker loops (weft knitting) or underlaps (warp knitting).
Wales show most clearly on the technical face and courses on the
technical back of single needle bed fabric.
Stitch Density:

Stitch density refers to the total number of loops in a measured

area of fabric and not to the length of yarn in a loop (stitch length).

It is the total number of needle loops in a given area (such as a

square inch, or three square centimetres).

The figure is obtained by counting the number of courses or

pattern rows in one inch (or three centimetres) and the number of
wales in one inch (or three centimetres), then multiplying the
number of courses by the number of wales. (Using a
measurement of three centimetres rather than one, is preferable
for accuracy in counting).
Loop: The fundamental unit of a knitted structure that is formed by bending of the yarn
and is intermeshed with similar unit at base.

Open Loop: A loop in which the same thread(h) enters and leaves the loop at opposite
side without crossing over itself.
Closed Loop:
A loop which the same thread crossed over itself at the base(K).

Needle Loop:
The aggregate (e) of the top arc and of the two sides of the loop.
Sinker Loop:
The yarn (f) that connects two adjacent needle loops.

Float:
A length of yarn(n) not received by a needle and connecting two
loops of the same course that are not in adjacent wales.
Tuck Loops:
A length (r) of yarn received by a needle and not pulled through the loop of the
previous course.

Underlap:
The yarn that connects two needle loops in consecutive course in a warp knitted fabric.
 Stitch Length: The length of yarn (t) knitted into one stitch.

Stitch length is a length of yarn which includes the needle loop and half the
sinker loop on either side of it. Generally, the larger the stitch length, the more
extensible and lighter the fabric and the poorer the cover, opacity and bursting
strength.
Face Stitch: A stitch(v) that is so intermeshed towards the technical face - side of the
fabric that its legs are visible and are situated above the top arc of the stitch formed in
the same wale in the previous course.

Back stitch:
A stitch that is so intermeshed towards the technical back of the fabric that the top arc of the stitch
together with bottom arc is visible and situated above the legs of the stitch formed in the previous
course.
Latch Needle:

1. Hook
2. Latch
3. Cup
4. Stem or Shank
5. Butt
6. Rivet
1. Latch needle consists of a hooked portion at the top, with a latch or spoon riveted at
a certain distance from the head of the needle.

2. Latch needle forms a stitch with a simple up and down movement.

3. Latch needles are given individual movements, sliding in grooves, called the 'tricks'
of the cylinder.

4. The latch can swing freely.

5. The stem or shank is a straight portion of the needle with a protruding butt, some
distance from the end of the needle.

6. The reciprocating movement to the needle in the vertical direction is given through
this butt part of the needle.

7. The latch needles are self-acting, they require only previous loop on the stem and do
not require any outside agency to close the hook.

8. The swinging latch has a cup at the end to fit the kook in the groove, when the latch
is closed.
9. The latch is riveted to the stem.

10. Because of this the total thickness or the space occupied by a latch needle cannot be
reduced beyond the capacity of the mechanical means of manufacturing.

11. Hence these needles are coarser in dimensions than other type of needles. They are
also expensive because of the assembly of needle and latch.

12. Latch needles are mainly used in circular weft knitting machine for single knit and
double knit fabrics. They are also used for the purl fabrics and in V-bed and flat bed
machines.
Beared Needle:

1. Beard
2. Head
3. Eye or Groove
4. Stem
5. Butt
Head:
The hooked portion of the stem of the needle to draw the new yarn, from a loop
and intermesh through old loop.

Beard:
The continuation of the hooked portion which has a good springiness and
shape of a beard on a chain.

Eye:
A groove cut in the stem to receive the pointed tip of the beard when it is
pressed in by the presser, so that the new loop is entrapped.

Stem:
is the needle around which the loop is formed and fabric is held with the last
loop on it.

Butt:
is bent for location in the machine or is cast with other needles in a metal lead.
It is a single unit but external assistance is needed to close the beard. It does
not require latch, hence riveting. It is therefore finer compared to latch needle.
These are less expensive compared to latch needles.
Compound Needle:
•The spring beard needle and latch needle, both were found to have limitations in their
operating speeds.

•Compound needle consists of a hollow steel tube of finer gauge in which a hook closing
element is inserted.

•The upper end of this element covers the tip of the needle hook when it is raised.

•It is claimed that, a compound needle combines the advantages of both the latch and
the beard needle.

•Strain on the yarn, during the loop formation and the movement required to form a loop
is about half to that of a latch or beard needle.

•Both members of compound needle have straight movement instead of a swinging

movement.

• Thus the knitting speed can be increased. However compound needles are very
expensive to manufacture.
Advantages and Disadvantages of Latch needle and Beard needle.

1. Latch needles are thick and more rigid compared to beard needles.

2. Latch needles do not require external element they are self acting.

3. There is possibility of accumulation of fluff or lint on latch which may cause

a deformation in loops.

4. Compared to beard needle, the latch needle makes a longer stroke in the
cycle of knitting operation.

5. Strain on yarn is less in beard needle compared to latch needle.

6. As Beard needles are mounted on finer gauge machine, loops formed are
tighter.

7. Latch needle takes longer time to knit a loop hence machines with latch
needles run at slower speed compared to beard needle.
Basic Action of Needles
The Loop Forming Cycle of a Latch Needle

1. At the rest position the latch is open and the fabric loop is held by the needle
hook.

2. The fabric is held in position by the fabric take-down tension therefore the fabric
loop slides on to the latch as the needle rises.

3. The needle continues to rise and so the fabric loop slides beyond the latch onto
the steam.

4. Yarn feeding at the high position of the needle and the needle descends after
feeding.

5. The descending needle causes the fabric loop to close the latch and hence
pulling the new yarn through the fabric loop forming a new loop. The fabric take-
down tension also causes the old fabric loop to slide onto the newly formed loop.
1 The rest position. The head of the needle hook is level with the top of the verge of
the trick. The loop formed at the previous feeder is in the closed hook. It is prevented
from rising as the needle rises, by holding-down sinkers or web holders that move
forward between the needles to hold down the sinker loops.

2 Latch opening. As the needle butt passes up the incline of the clearing cam, the old
loop, which is held down by the sinker, slides inside the hook and contacts the latch,
turning and opening it.

3 Clearing height. When the needle reaches the top of the cam, the old loop is cleared
from the hook and latch spoon on to the stem. At this point the feeder guide plate acts as
a guard to prevent the latch from closing the empty hook.

4 Yarn feeding and latch closing. The needle starts to descend the stitch cam so that
its latch is below the verge, with the old loop moving under it. At this point the new yarn
is fed through a hole in the feeder guide to the descending needle hook, as there is no
danger of the yarn being fed below the latch. The old loop contacts the underside of the
latch, causing it to close on to the hook.

5 Knocking-over and loop length formation. As the head of the needle descends
below the top of the trick, the old loop slides off the needle and the new loop is drawn
through it. The continued descent of the needle draws the loop length, which is
approximately twice the distance the head of the needle descends, below the surface of
the sinker or trick-plate supporting the sinker loop. The distance is determined by the
depth setting of the stitch cam, which can be adjusted.
The Loop Forming Cycle of a Bearded Needle

There is only one principle in loop formation using bearded needle. To

accomplish the goal of forming loops, knitting machines using bearded needles
may vary slightly to perform the same principle. However, in most cases the
machine were so designed that there are no movement in the needles.

1. At the start o f the cycle, the fabric loop is held in the hook of the needle at
the top. The fabric loop is held in place with the help of the fabric take-up
tension.

2. The fabric loop is pressed and therefore slides along the hook upwards. It
stops until the fabric loop is on the shank of the needle, and cleared of the
hook region. This stage is referred as clearing.

3. Feeding is done by wrapping a yam around the shank of the needle at the
point between the fabric loop and the tip of the beard.
4. Feeding is complete only when the new yarn is in the needle hook. But
extra knitting element is required to move the yarn form the shank to the
hook region.

5. A presser is required to push and close the beard such that the tip of the
beard is hidden in the eye of the needle with the new yarn trapped in the
needle hook. When the beard is pressed another knitting element is used to
lift the fabric loop from the shank to the outside of the beard. This stage is
known as pressing and landing.

6. After landing the presser releases the beard but the fabric loop is now
rapping around the hook on the beard. Yet another knitting element till then
come into action to further lift the fabric loop towards the head of the
needle. The action is completed when the fabric loop is eventually cast off
from the needle. After Which, the fabric loop will be held by the new yarn
and detached completely from the needle.
Knitting Action Compound Needle
Classification of Weft-knit Structure:

1. Plain Single Jersey

2. Rib
3. Interlock
4. Purl

Plain is produced by the needles knitting as a single set, drawing the loops away from
the technical back and towards the technical face side of the fabric.

Rib requires two sets of needles operating in between each other so that wales of face
stitches and wales of reverse stitches are knitted on each side of the fabric.

Interlock was originally derived from rib but requires a special arrangement of 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 side of the fabric exactly in line with each other,
thus hiding the appearance of the reverse loops.

Purl is the only structure having certain wales containing both face and reverse meshed
loops.
Rib and Interlock are also termed as Double Knit (USA) or Double Jersey(UK)
Knitted fabrics are obtained by intermeshing of loops. One new yarn may be drawn
through a loop already formed on the stem of the needle. Intermeshing of loops may be
carried out in two ways namely face loop and reverse loop stitch.
Formation of Face and Reverse Loop stitch:

Suppose a loop is formed by yarn P as shown in the figure above. So as to intermesh

another loop through this loop, yarn Q may be placed behind this loop as shown in figure
below or the yarn R may be placed in front of the loop as shown in the figure.
Technical Face-Side and Reverse-side

In the simplest weft-knit structure (single jersey) one side consists of face loop stitches
only, as shown in the above figure and the other side consists of the reverse stitches
only.

Technical Face Technical Back

Symbolic Representation of Weft-Knit Structure
In a graph paper , a cross (X) represents a face loop stitch, while a hollow circle (O) in a square
represents a reverse loop stitch.

On a point paper, only points are given as shown in figure and face loop are represented on the
second line, a) indicating all face loop stitches and in b) indicating all reverse loop stitches.

a b

Laddering Effect

As the intermeshed loops are held at cross-over points, if one of the knit loop yarn
breaks, then local disintegration of the other knitted loops takes place. Needle loops
unmesh down the wale. This shows laddering effect.
Single jersey or Plain structure
 The three dimensional structure of plain weft knitted structure
Knitted structures have a three-dimensional structure as shown in above figure. At the
point where the new needle loop is drawn through the old loop (I), the structure is
composed of two yarn thicknesses (diameters) instead of one. The needle loop is
therefore held down, both at its head (H) and its feet (F), by loops in the same wale, but
its side limbs tend to curve upwards at (II).

When the fabric is cut, the loops are no longer held in this configuration so that the fabric
curls towards the face at the top and bottom and towards the back at the sides.
Production of single-jersey fabric on a circular latch needle machine

Most single-jersey fabric is produced on circular machines whose latch needle

cylinder and sinker ring revolve through the stationary knitting cam systems
that, together with their yarn feeders, are situated at regular intervals around
the circumference of the cylinder. The yarn is supplied from cones, placed
either on an integral overhead bobbin stand or on a free-standing creel, through
tensioners, stops motions and guide eyes down to the yarn feeder guides.

The fabric, in tubular form, is drawn downwards from inside the needle cylinder
by tension rollers and is wound onto the fabric-batching roller of the winding-
down frame. The winding-down mechanism revolves in unison with the cylinder
and fabric tube and is rack-lever operated via cam-followers running on the
underside of a profiled cam ring. As the sinker cam-plate is mounted outside on
the needle circle, the centre of the cylinder is open and the machine is referred
to as an open top or sinker top machine.
The knitting head

Figure shows a cross section of the knitting head all of whose

stationary parts are shaded.

1 Yarn feeder guide, which is associated with its own

set of knitting cams.
2 Latch needle
3 Holding-down sinker – one between every needle space
4 Needle cylinder (in this example, revolving clockwise)
5 Cylinder driving wheel
6 Cylinder driving gear
7 Sinker-operating cams, which form a raised track
operating in the recess of the sinker
8 Sinker cam-cap
9 Sinker trick ring, which is simply and directly attached to
the outside top of the needle cylinder thus causing the
sinkers to revolve in unison with the needles
10 Needle-retaining spring
11 Needle-operating cams which, like the sinker cams,
are stationary
12 Cam-box
13 Cam-plate
14 Head plate
15 Cylinder driving pinion attached to the main drive shaft
The knitting action

Figure below shows the knitting action of a latch needle and holding-down sinker during
the production of a course of plain fabric.

(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 knockover its
old loop on the sinker belly.

(e) Holding-down. The sinker moves forward to hold down the new loop in its throat
whilst the needle rises under the influence of the upthrow cam to the rest position where
the head of the open hook just protrudes above the sinker belly.
The cam system

Figure below shows the arrangement and relationship between the needle and
sinker cams as the elements pass through in a left to right direction with the
letters indicating the positions of the elements at the various points in the
knitting cycle. The needle cam race consists of the following: the clearing cam
(1) and its guard cam (4), the stitch cam (2) and upthrow cam (3) which are
vertically adjustable together for alteration of stitch length, and the return cam
(5) and its guard cam (6). The three sections of the sinker cam race are the
race cam (7), the sinker withdrawing cam (8) and the sinker-return cam (9)
which is adjustable in accordance with the stitch length.
Sinker timing

The most forward position of the sinker during the knitting cycle is known as the push
point and its relationship to the needles is known as the sinker timing. If the sinker cam-
ring is adjusted so that the sinkers are advanced to the point where they rob yarn from
the new stitches being formed, a lighter-weight fabric with oversized sinker loops and
smaller needle loops is produced. If the ring is moved in the opposite direction, a tighter,
heavier fabric is produced having smaller sinker loops and larger needle loops. The
timing is normally set between the two extremes.

Characteristics of a single jersey structure

The simplest and the most widely used weft-knit fabric is Jersey or plain knit fabric. It
consists of face loop stitches only. The main characteristic features and properties of this
fabric are:
•The loops have a V-shaped loop appearance on technical face side and show semi-
circular loops on the technical back side.
•Because of the side limbs (legs) of the loop on the face side, it feels smoother on face
side than the back side. It is thus not reversible, from the feel and appearance point of
view.
•The interlocking semi-circles at the technical back can be used to produce interesting
effects in alternate courses are knitted in different coloured yarns.
•Knitted loops in plain knit fabrics tend to distort easily under tension which help to give a
form fitting and comfort due to property of elastic recovery.

•It has potential recovery of about 40% in width after stretching. Its width shortens if the
length is extended by tension while the length shortens if width is stretched. Normally
widthwise extensibility is approximately twice the length way extensibility.

•The structures can be unroved from the course knitted last by pulling the needle loops
through from technical back or from the course knitted first by pulling the sinker loops
through from the technical face side.

•If the unrelaxed plain knit fabric is kept flat on the surface, it curls upwards at the top
and bottom and backward at the sides.

•Its production rate is very high because of stitch simplicity and its cost is low because
on machine simplicity and rate of production is high.

•The stitch length can be varied with cam setting giving more courses per unit length
with short stitch length and vice-versa. The properties such as rigidity, air permeability,
weight per unit area, bursting strength changes with the stitch length. The fabric may
appear thick or flimsy if the stitch length is reduced or increased.

•It is knitted on single cylinder machine with a single set of latch needles.
Weft Knitting Machine

Schematic diagram of a circular weft knitting machine is as shown below.

Yarn supply is in the form of cones/cheeses. Depending upon the number of
yarn feeds on the machine the number of cones are creeled. Driving
arrangement, clutch, brake, stop motion controller, hand turning wheels etc. are
situated on one side. The yarn is guided through ceramic guides and stop
motion upto the feed point. Here knitting elements like latch needles in the
cylinder and sinkers in the sinker rings are provided. The knitted fabric from the
inside of the cylinder is taken down on the fabric collection roll.
Knitting Elements:

Cylinder
The needle bed - the needles are maintained in a needle bed which is a metal cylinder.
Tricks are cut in the outside wall of the cylinder as shown in figure below. The number of
tricks cut per 25mm(one inch) is called the 'cut' of the machine. A needle is placed into
each trick so that the back of the needle lies against the needle bed. The needles are
perfectly vertical and the butt protrudes. This butt moves along the cam track, which
gives the desired motion to needle.
Sinker

A sinker is another knitting element which is a thin metal strip, used between each
needle to assist in knitting by holding down the formed stitches or helping to from
stitches. Figure below shows a sinker blade with neb, throat and belly parts. There is a
sinker ring in which tricks are cut radially so that sinkers are held horizontally. The butt of
the sinker is actuated by the sinker cam so that the sinkers can move horizontally at the
appropriate time of the needle movement.
The figure below shows an isometric view of a section of needle cylinder, and sinker ring
with positive cams and yarn feed in a schematic manner.
Cams
The details of needle cam are shown in figure below. It consists of guard cams, a rising or clearing
cam, a stitch cam, an upthrow cam and running cams. out o these cams the stitch cam controls the
downward movement of the needles by adjusting its vertical movement of the needles by adjusting
its vertical movement. If the stitch cam is raised then a shorter loop is drawn below the sinker level
and a tighter fabric will result. With lowering of the stitch cam, a stitch length will increase and a
flimsy fabric will result.
Sinkers are supposed to move backward and forward in relation to needles. a separate set of cams
is contained in the sinker ring. Its time is synchronized to needle timing.
Feed Yarn Carriers
e; where Ne = English Count.
Feed yarn carriers are fitted on a ring which is fastened to the cylinder cam ring. The
yarn carriers serve two purposes i) feeding the yarn into the needle hooks and ii)
keeping the needle latches in an open position while the needle is in their clearing
position so that the new yarn is received in the hook.

Take-up Mechanism

This mechanism is bolted to the underside of the gear ring. The cloth is drawn from the
sinkers between the two fluted rollers which exert a constant tension. Below the take-
down is the cloth roll-up mechanism on the roller of which the knitted cloth is wound in a
roll form.

Stitch length

Though the stitch length can be adjusted as required by the tightness or flimsiness of the
fabric, the general formula is –

Stitch length in inches = 16.66 d

where d = Diameter of yarn; d = 1/24

1. Double Jersey

2. Rib Getting

3. Interlock Getting
Rib Knit Structure

The simplest Rib fabric is 1 X 1 Rib shown in above figure. Rib unit stitch is shown in black colour.
As shown rib unit consists of two loops - a face loop shown in wale b and a reverse loop shown in
wale c. If the fabric is seen from back side wale c will be face loop and wale b will be reverse loop.
Hence there is no technical face and technical back and the fabric is reversible
Symbolic representation of 1 X1 Rib Structure
It is normally knitted with two sets of latch needles cylinder needles and dial needles as shown in
figure below.
Rib has a vertical cord appearance because the face loop wales tend to move over and
in front of the reverse loop wales. As the face loops show a reverse loop intermeshing
on the other side, 1 X 1 rib has the appearance of the technical face of plain fabric on
both sides until stretched to reveal the reverse loop wales in between.

1 x 1 rib is production of by two sets of needles being alternately set or gated between
each other. Relaxed 1 X 1 rib is theoretically twice the thickness and half the width of an
equivalent plain fabric, but it has twice as much width-wise recoverable stretch. In
practice, 1X 1 rib normally relaxes by approximately 30 per cent compared with its
knitting width.

1X 1 rib is balanced by alternate wales of face loops on each side; it therefore lies flat
without curl when cut. It is a more expensive fabric to produce than plain and is a
heavier structure; the rib machine also requires finer yarn than a similar gauge plain
machine. Like all weft-knitted fabrics, it can be unroved from the end knitted last by
drawing the free loop heads through to the back of each stitch. It can be distinguished
from plain by the fact that the loops of certain wales are withdrawn in one direction and
the others in the opposite direction, whereas the loops of plain are always withdrawn in
the same direction, from the technical face to the technical back.

Mock Rib is plain fabric knitted on one set of needles, with an elastic yarn inlaid by
tucking and missing so that the fabric concertinas and has the appearance of 1 X 1 rib. It
is knitted at the tops of plain knit socks and gloves.
Rib set-outs
There is a range of rib set-outs apart from 1X 1 rib. The first figure in the designation indicates the
number of adjacent plain wales.

The second figure, the number of adjacent rib wales. Single or simple ribs have more than one
plain wale but only one rib wale, such as 2/1, 3/1, etc. Broad ribs have a number of adjacent rib as
well as plain wales, for example, 6/3 Derby Rib. Adjacent wales of the same type are produced by
adjacent needles in the same bed, without needles from the other bed knitting in between them at
that point.
The standard procedure for rib set-outs is to take out of action in one bed, one less needle than the
number of adjacent needles required to be working in the other bed.
In the case of purl machines, the needles knit either in one bed or the other, so there are
theoretically the same number of needles out of action in the opposite bed as are knitting in the
first. In the case of 2/2 rib, Swiss rib , this is produced on a rib machine by taking one needle out of
action opposite the two needles knitting.
Swiss rib is sometimes confusingly termed 2/3 rib because 2 out of 3 needles in each
bed are knitting. It is not possible to commence knitting on empty needles with the
normal 2 X 2 arrangement because the two needles in each bed will not form individual
loops – they will make one loop across the two hooks. One needle bed must be racked
by one needle space so that the 2 X 2 needle set-out is arranged for
1 X 1 rib; this is termed ‘skeleton 1 X 1’; after knitting the set-up course, the bed is
racked back so that 2 X 2 rib knitting can commence.
The knitting action of the circular rib machine
The knitting action of a circular rib machine is shown in Figure below:
(a) Clearing. The cylinder and dial needles move out to clear the plain and rib loops
formed in the previous cycle.
(b) Yarn Feeding. The needles are withdrawn into their tricks so that the old loops are
covered by the open latches and the new yarn is fed into the open hooks.
(c) Knocking-over. The needles are withdrawn into their tricks so that the old loops are
cast off and the new loops are drawn through them.
Needle timing
Needle timing (as shown in figure below) is the relationship between the loop-forming positions of
the dial and cylinder needles measured as the distance in needles between the two stitch cam
knock-over points. Collective timing adjustment is achieved by moving the dial cam-plate clockwise
or anti-clockwise relative to the cylinder; individual adjustment at particular feeders (as required) is
obtained by moving or changing the stitch cam profile.
Synchronized timing (Shown in Figure below), also known as point, jacquard and 2X 2
timing, is the term used when the two positions coincide with the yarn being pulled in an
alternating manner in two directions by the needles, thus creating a high tension during
loop formation.
With delayed timing, also called rib or interlock timing (as shown in Figure below) the
dial knock over occurs after about four cylinder needles have drawn loops and are rising
slightly to relieve the strain. The dial loops are therefore composed of the extended
loops drawn over the dial needle stems during cylinder knock-over, plus a little yarn
robbed from the cylinder loops. The dial loops are thus larger than the cylinder loops and
the fabric is tighter and has better rigidity; it is also heavier and wider, and less strain is
produced on the yarn
Features and Properties of Rib Fabric:
1. It is a reversible structure i.e. face and back side has the same appearance in 1X1,
2X2, 3X3 ribs etc. The appearance shows vertical cords and thin ridges, in between.

2. 1X1, 2X2, 3X3 ribs etc. are balanced structures because of alternate number of face
and reverse wales on each side.

3. It is heavier and thicker structure than the plain knit structure with similar gauge used
for plain knit and rib structure.

4. It requires a knitting machine with cylinder and dial and two sets of needles - cylinder
needles and dial needles.

5. Rib structure cannot be unroved from the course knitted first because sinker loops
are securely anchored by the cross-meshing between face and reverse loop wales. It
can be unroved from the last course knitted.

6. It has the maximum extensibility in widthway and hence rib trimmings are most
suitable for neck bands, collars, arm bands, sleeve cuff bands and waist bands in
sweater knitting and for tops of socks, as fit tighter to the body than the plain knit and
give smart appearance.

7. Rib fabric dose not curl at the edges due to its balanced nature.

8. The structure is more opaque than jersey fabric.

Interlock Knit Structure.
Interlock is the interlocking of two 1X1 rib structures in such way that the face wale of one rib fabric
is directly in front of the reverse wale of rib fabric.
In complex structures like interlock diagrammatic method shown below is preferable.

4 needles are represented in knit course 1 and knit course 2, but second modification
(at right) needles are represented by short and long lines, instead of dots in first.

For knitting interlock structures short and long, cylinder and dial needles are used.
These needles can be represented by lines of different lengths as shown at the right
side.
Production of interlock fabric
Interlock is produced mainly on special cylinder and dial circular machines and on some double-
system V-bed flat machines (As shown in figure below). An interlock machine must have the
following:
1. Interlock gating, the needles in two beds being exactly opposite each other so that only one of
the two can knit at any feeder.
2. Two separate cam systems in each bed, each controlling half the needles in an alternate
sequence, one cam system controlling knitting at one feeder, and the other at the next feeder.
3. Needles set out alternately, one controlled from one cam system, the next from the other;
diagonal and not opposite needles in each bed knit together.
Originally, the interlock machine had needles of two different lengths, long needles
knitting in one cam track and short needles knitting in a track nearer to the needle
heads. Long needle cams were arranged for knitting at the first feeder and short needle
cams at the second feeder. The needles were set out alternately in each bed, with long
needles opposite to short needles. At the first feeder, long needles in cylinder and dial
knit, and at the second feeder short needles knit together; needles not knitting at a
feeder follow a run-through track. On modern machines the needles are of the same
length.

Example of an interlock cam system

Figure below shows the cylinder and dial needle camming to produce one course of
ordinary interlock fabric, which is actually the work of two knitting feeders. In this
example, the dial has a swing tuck cam that will produce tucking if swung out of the
cam-track and knitting if in action
The cylinder cam system
A Clearing cam which lifts the needle to
clear the old loop.

B, C Stitch and guard cams respectively,

both vertically adjustable for varying
stitch length.

D Upthrow cam, to raise the cylinder

needle whilst dial needle knocks-over.
E, F Guard cams, to complete the track.

G, H Guide cams that provide the track

for the idling needles.

The dial cam system

1 Raising cam to tuck position only.
2, 3 Dial knock-over cams (adjustable).
4 Guard cam to complete the track.
5 Auxiliary knock-over cam to prevent
the dial needle re-entering the old loop.
6, 7 Guide cams that provide the track
for the idling needles.
8 Swing type clearing cam, which may
occupy the knitting position as shown at
feeder 1 or the tuck position as shown at
feeder 2.
Features and Properties of Interlock Structure
1. As the face loops are directly in front of the reverse loops in each wale, if the fabric is
viewed from one side and then from the other side, it would present the appearance
of a plain knit (jersey) structure. Simple interlock structure is therefore reversible as
the rib structure.
2. The fabric is firm (less extensible than single jersey or rib) due to the interlocking
structures knitted in two separate planes by the sinker loops.

3. The structure do not curl at edges when cut and more ladder resistant.
4. The knitting of structure with cylinder and dial needles makes the structure thicker,
stronger, less elastic and hence sewing operations are easier for garment making.
5. It unroves from the course knitted the last.

6. As two courses of knitting make one effective course in the knit structure, the
production rate is half (at same speed) that of rib or single jersey.
7. Due to complicated mechanism of cam tracks and short and long needle operation,
the speed and number of feeds are reduced thus affecting the production.
8. The fabric becomes costlier per linear metre due to increase in thickness and less
production.

9. The interlock machines are in finer gauge than the other as alternate needles only
knit.
Purl Knit Structure
Purl is least commonly used weft-knit structure as it has very little commercial and
apparel end-uses.

Following figure shows the simplest purl structure that course marked 1, consists of
reverse loop stitches and course marked 2, consists of all face loop stitches.
Thus face and reverse courses are knitted in alternate courses whereas earlier we had
seen that face and reverse wales are knitted alternately in 1X1 rib structures.
Therefore rib structure creates more extensibility in width way and purl structure creates
length way.
Graphical representation of purl structure can be shown as in figure below.
As the successive courses are knitted in opposite direction it is necessary to have a
needle with a hook and a latch at each end of the needle.
Purl Knitting Machine (Links-Links)
1X1 Purl structure has both face and reverse loop stitches in the same wale. It is usually
made on a machine fitted with double ended needle. Figure below shows the cross
section of the knitting elements of purl machine.

Two needle beds are set at 1800 to each other, with a gap between, straddled by a
double ended latch needle. There is cam carriage which moves form right to left and left
to right alternately, above the needle beds. The carriage has cams which activate the
needles in knitting action. The needle as shown in figure below has no butts.
They are operated by devices called sliders or jacks.
As shown in figure below the same needle is shown in dotted line to the left side, the
hook B is making face loop stitch (x when the front bed slider moves the needle hook to
the left.

When the back bed slider moves the needle to the fight side the hook A, is making a
reverse loop stitch (o). The yarn is fed between the front and back bed with a black dark
line showing line the old loop of knitted fabric and the shaded yarn is fed to either needle
hook B or A.
Figure below shows a jack or a slider used on a circular purl knitting machine.
The sliders have butts, a knitting butt (A) near to its head and the needle hook and a transfer butt
(B) near to its tail. Each butt is connected to its own cam track. The needle beds are in two
cylinders superimposed one above the other.

The double cylinder as shown in figure below has dividing cams (C), with internal
holding down sinkers and stationary cam boxes.

Flat bed purl Knitting machine

Circular purl Knitting machine
The principle of the dividing cam operation is that it forms a wedge shape of increasing thickness
between the upper surface of the needle hook and the under surface of the extended nose (N) of
the delivering slider. Pivoting it away from the cylinder so that it disengages from the needle hook
as can be seen in above figure.
1. The delivering slider (D) advances with its nose, so that the nose of the slider, enters the
profiled recess of the dividing cam (C) so that the outer hook of the needle contacts the hook
underneath the head of the receiving slider pivoting it out of the cylinder but it immediately
return.
2. It engages with the needle hook due to the pressure of the coiled spring band (S), which
surrounds each cylinder, so that the slider heads are depressed into contact with the needle
hook as shown.
3. As slider (D) revolves with the cylinder, it passes along with the wall of the dividing cam(C)
which when increases in thickness causes the slider pivot outwards and disengages for the
needle hook as shown in above figure. Slider (D) then returns to its cylinder while the slider (E)
retires into its cylinder taking the needle with its, ready for the next knitting head.
Features and Properties of Purl Structure

1. In the simplest purl structures each wale consists of face and reverse loops.
Hence semicircles of needle and sinker loops are seen on both face and
back sides of the fabric due to reverse loops. This has led to the term 'links-
links' being applied to the fabric and the machine.

2. It is reversible in appearance and has soft hand with full cover.

3. Its thickness is theoretically double to that of a jersey fabric.

4. Like jersey fabric, it can be unrove from either end.

5. As the link machine has a horizontal bed for the needles to reciprocate, the
speed of the machine and the production is much less compared to other
weft knit fabrics. However as it is knitted on coarse gauge machine, the
coarse yarn can result in higher production by weight.

6. It does not curl at the edges and because of alternate face and reverse
courses it is a balanced structure.

7. In its circular version two small cylinders located one above the other to knit
socks.
Knitted stitches
Weft knitted stitches described so far have been composed entirely of knitted loops. A
knitted loop stitch is produced when a needle receives a new loop and knocks over the
old loop that it held from the previous knitting cycle. The old loop then becomes a needle
loop of normal configuration.

Other types of stitch may be produced on each of the four-needle arrangement base
structures by varying the timing of the intermeshing sequence of the old and new loops.
These stitches may be deliberately selected as part of the design of the weft knitted
structure or they may be produced accidentally by a malfunction of the knitting action so
that they occur as fabric faults.

Apart from the knitted loop stitch, the two most commonly-produced stitches are the float
stitch and the tuck stitch. Each is produced with a held loop and shows its own particular
loop most clearly on the reverse side of the stitch because the limbs of the held loop
cover it from view on the face side.
How Float and Tuck stitches are formed

To intermesh a newly formed loop, the needle in which the new looped yarn is trapped should rise
high enough to clear the old loop rising in the closed latch or needle hook by the raising or clearing
cam action on the butt of the needle. The clearing cam is the most important cam in the system
because by simple modification or adjustment of this clearing cam, a float(or miss) stitch, and tuck
stitch can be formed in addition to a knit stitch.

Knit Loop:

Knit loop is produced by clearing the old loop below the latch by rising the old loop below the latch
by rising the needle and feeding a new yarn into the hook as shown in figure below.
Float (or Miss) loop:

If the needle is not raised by the clearing cam it does not receive the new yarn and the yarn goes
behind the needle as shown in figure below. The yarn remains behind the needle and appears in
the fabric as a float. The knit loop not clearing is called the held loop. When the needle is raised on
a subsequent course the new knit loop is pulled through the held loop only.
From Technical Face side From Technical Back side
From Technical Face side with Graphical and symbolic notation
Tuck loop:
If the needle is partially raised by the clearing cam as shown in figure below so that the old loop is
not cleared from the latch of the needle but the feeder has fed a new yarn into the hook then a tuck
stitch is formed when the needle moves down in this case the new yarn and the held loop is in the
hook of the needle. This forms a tuck stitch when the needle moves down the held loop and the
new yarn-both are in the hook
 From Technical Face side From Technical Back side

The tuck loop is typically shaped like an inverted U and is open at the neck because it is
not pulled through another loop. It may also be noted that each side of the head of a
tuck loop is held by a sinker loop of feed number 3.
From Technical Face side with Graphical and symbolic notation
Swing Cam:
Symbolic Representation: Float and Tuck Stitch
Effect of Float Stitch

1. Float stitches are used in designing when an unwanted coloured yarns is to

be hidden fro the face side by allowing it to float at the back side.

2. Float stitches make the basic fabric thinner because there are fewer loops.

3. It also makes the fabric narrower because the floats pull the structure from
both sides.

4. The structure also becomes less extensible because less yarn is available
for extensibility than looped structure.

5. The fabric also becomes lighter in weight as minimum yarn is used in the
construction of the structure with float stitches. The fabric also appear
filmsy or less rigid.
Effect of Tuck Stitch

1. Usually the fabric with tuck stitches appear thicker compared to fabric
having only knit stitches. This is because of the accumulation of yarns at
the places where tuck stitches are held.

2. The fabric with tuck stitches is wider than the normal knit structure as loop
shape at the tuck stitch is distorted and has a wider base as the side wales
are not pulled together.

3. The tuck stitched structure also becomes less extensible as at every tuck
stitch, on loop length is shortened.

4. Fabric with tuck stitches becomes open and more porous than a knit
structure.
Designing of Weft-Knit Structures

Ornamentation of Plain Knit Fabric:

Horizontal Stripes:
If different dyed or contrasting colours are used at different feeds by supplying
packages (cones) of coloured yarns on a multi-feed machine of a single jersey
or plain knit structure, a variety of horizontal stripes can be obtained on the
surface of the knitted fabric.

Twist:
If some courses are knitted with S-twist followed by some courses of Z-twist
then a zigzag path of wale lines is created on the surface of the fabric.

Fancy Yarns:
Instead of simple yarn, fancy yarns can be carefully knitted in the fabric to give
some interesting results.

Plain knit fabric can also be ornamented by piece dyeing and printing.
Derivatives of Plain Knit (Single Jersey)
The float and tuck stitches are used in great extent in designing plain knit structures by modifying
the order of knitting. The plain knit structures can be modified with following alternatives.

1. Knit and float

2. Knit and tuck
3. Knit, float and tuck.

Knit and Tuck Type: LeCoste

For Course 1 and 2 it is knitted on 1, 3, 5 etc needles
and Tucked on 2, 4, 6 etc needles.

For Course 3 and 4 the sequence is reversed i.e.

Tucked on 1, 3, 5 etc needles and
Knitted on 2, 4, 6 etc needles.

It is generally made with cotton yarn and used for Sports ware.
Knit and Float Type Check Effect:
Two different coloured dyed yarns are used say Black and White.
The needle will knit the yarn which is to appear as the face of the
Fabric but the remaining yarn will float to the back, whereby they
are hidden from the face

The fabric appearance as shown in the figure below:

Knit, Tuck and Float Type: Accordian Type

These fabrics are made in wool with a combination of knit, tuck and float stitches in the
same course.

In this structure a long float over five wales is bound in by tucking the float on the third
wale amongst the five.
Simple tuck and float stitch single-jersey fabrics
Ornamentation of Rib-Structure:
Earlier we have seen 1X1 rib structure.

A 2X2 rib is formed by knitting on two needles out of every three in both dial and cylinder as shown
with notation on

graph paper and diagrammatic notation in the figure below. This is called a Swiss Rib
Another common variation found in outer ware are 3X3 rib and 6X3 rib (Derby Rib) are as shown in figure below.

3X3 rib 6X3 rib (Derby Rib)

Derivatives of Rib Structure:

Common Derivatives of rib structure are as shown in figure below. In 'Half-Cardigan' or 'Royal Rib' on one course
1X1 rib is produced and on another course Tuck loop and reverse loop is produced. It is therefore unbalanced
structure.
In 'Full-Cardigan' or 'Polka Rib', first course is knitted with face and tuck loop and second course
with tuck and reverse loop as shown in figure below. It is therefore a balanced structure.
Derivatives of Interlock Structure: One of the important derivative of inter lock structure is an
'Eight Lock' as shown in figure below. Two 2X2 ribs are intermeshed in interlock structure.
Few examples of Double-knits (Interlock gaiting)
Single Pique
It is a tuck-knit interlock structure. Repeat completes on six fees as shown in figure below.

Needle Layout: Interlock gaiting: Long and short needles in dial and cylinder, long needles facing
short needles.
Knitting sequence for a repeat:
First Feed: knit on all long dial and all long cylinder needles.
Second Feed: Knit on all short dial and on all short cylinder needles.
Third Feed: Tuck on all long dial and knit on all long cylinder needles.
Fourth Feed: Knit on all short dial and on all short cylinder needles
Fifth Feed: Knit on all long dial and on all long cylinder needles.
Sixth Feed: Tuck on all short dial and knit on all short cylinder needles.
 PONTE-DI-ROMA

Needle Layout: Interlock Gaiting

First Feed: knit on all dial and on all cylinder long needles.
Second Feed: Knit on all dial and on all cylinder short needles.
Third Feed: Knit on all long and short dial needles only
Fourth feed: Knit on all long and short cylinder needles only.
 OTTOMAN RIB

Needle Layout: Interlock gaiting

First Feed: Knit on all long dial and cylinder needles.
Second Feed: Knit on all short dial an d cylinder needles.
Third Feed: Tuck on all long dial needles and knit on all long cylinder needles.
Fourth Feed: Tuck on al short dial needles and knit on all short cylinder needles.
Fifth Feed: Tuck on all long dial needles and knit on all long cylinder needles.
Sixth Feed: Tuck on all short dial needles and knit on all short cylinder needles.
Seventh Feed: Knit on all long dial needles and on all long cylinder needles.
Eighth Feed. Knit o all short dial needles and on all short cylinder needles.
 BOURRELET:

Needle layout: Interlock gaiting

First Feed: Knit on all long dial and cylinder needles
Second Feed: Knit on all short dial and cylinder needles.
Third Feed: Knit on all long cylinder needles only.
Fourth Feed: knit on all short cylinder needles only.
Fifth Feed: Knit on all long cylinder needles only.
Sixth Feed: knit on all short cylinder needles only
 TEXI-PIQUE

Needle layout: Interlock gaiting

First Feed: Knit on all long dial and cylinder needles
Second Feed: Knit on all short dial and cylinder needles.
Third Feed: .Tuck on all long dial and cylinder needles
Fourth Feed: knit on all short dial and cylinder needles.
Fifth Feed: Knit on all long dial and cylinder needles.
Sixth Feed: Tuck on all short dial and cylinder needles.
PIN-TUCK:
Sixth Feed: Tuck on all long dial and knit on all long cylinder needles.

Needle layout: Interlock gaiting

First Feed: Knit on all long dial and cylinder needles
Second Feed: Tuck on all short dial needles and knit on all short cylinder needles.
Third Feed: .Tuck on all long dial and knit on all long cylinder needles
Fourth Feed: knit on all short dial and cylinder needles.
Fifth Feed: Tuck on all short dial and knit on all short cylinder needles.
Few Rib Gaiting examples:

MILANO RIB

Needle layout: Rib Gaiting: Long needles in dial and cylinder or alternate staggering long and short needles, both
in cylinder and dial.

First Feed: knit on all dial and on all cylinder needles.

Second Feed: Knit only on all dial needles.
Third Feed: Knit only on all cylinder needles.
FRENCH PIQUE:

Needle Layout: Rib gaiting

First Feed: Knit on all (short and long needles) in cylinder and only on short needles in dial.
Second Feed: Knit only on all long needles in dial.
Third Feed: Knit on all (short and long needles) in cylinder and only on long needles in dial.
Fourth Feed: Knit only on all short needles in dial.
SWISS PIQUE:

Needle layout: Rib Gaiting

First Feed: Knit on all long and short needles in cylinder and only on short and long needles in both dial and
cylinder.
Second Feed: Knit on all long dial needles only.
Third Feed: Knit on all long and short needles in cylinder but only on short needles in dial.
Fourth Feed: Knit only on short needles in dial.
Some Non Jacquard Double Jersey Structures: