Knitting Practical 2

7/28/2019 Knitting Practical 2

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KNITTING TECHNOLOGY

PRACTICAL-02


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Title: Activities of the different knitting elements in circular knitting machine.

Practical:

a) Main knitting elements and their functions

b) Loop formation in Single Jersey & Rib Kitting process

c) Mechanism of forming Tuck & Miss stitches

a) Main knitting elements and their functions

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.

We can divide a needle into three main parts:

A. The hook, which takes and retains the thread tube looped;

B. The hook opening and closing device, that allows the hook to alternatively take a new thread

and release the previous one;

C. A system allowing the needle to move and form the loop.

1=Butt 2=Butt height 3=Back shank 4=Stem 5=Crimp

6=Groove 7=Cheek 8=Hook 9=Hook width 10=Latch

11=Rivet


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SINKER

The sinker is the second primary knitting element. It is a thin metal plate with an individual or

a collective action operating approximately at right angles from the hook side of the needle

bed, between adjacent needles.

SINKER 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.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.

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.

NEEDLE BED

The needle-bed of a knitting machine is made up by the needles. The needles can be all fixed on

the same needle bar or can be driven individually in a grooved plate, according to the type of

knitting machine.

All knitting machines can be equipped with one or two needle-beds, according to the model.

1=Butt 2=Butt breadth 3=Height of shank

4=Buldge 5=Neb 6=Length of neb

7=Throat angle 8=Sinker platform height

9=Breadth of lower shank 10=Clearance

11=Throat


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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.

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.

CAMS

The knitting cams are hardened steels and they are the assembly of different cam plates so that

a track for butt can be arranged. Each needle movement is obtained by means of cams acting on

the needle butts.

The upward movement of the needle is obtained by the rising cams or clearing cams. The risingcam places the needle at a certain level as it approaches the yarn area. Cams controlling the

downward movement of the needles are called stitch cams.


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The stitch cam draws the needle down below the knitting level, thereby drawing a loop formed

by the fed yarn through the loop already on the needle. The lowest point to which the needle is

drawn by the stitch cam is called the "cast-off" position. They are screwed to the cylindrical

cam ring and are adjustable in vertical direction. If the stitch cam is raised, then shorter loop is

drawn below the sinker level and a tighter fabric will result. With lowering of stitch cam, a

reverse result is obtained. Guard cams keep the needle butts in their race-way. Running camsor the needle butts at a low level until they meet the next rising cam.

b) Loop formation in Single Jersey & Rib Kitting process

Single Jersey Fabric

If every needle is feed a yarn and goes to basic knitting cycle the product referred to as single

jersey. All loops are knitted and all loops look exactly alike. Look closely at this drawing a back

ground of knit loop the length of yarn in neck loop is called the stitch length. Notify each loophas what can identify as legs and crown. The fabric in the left is technically face side, and the

stitches has an overall vertical apparent. And this side we see primarily legs rather than crown.

The fabric at the right is technically in the back, which takes on horizontal appearance. In this

view we see mainly crown. Referred to a jersey stitch, stitches arrange in this pattern have a

distinguishly different look and feel face to the back.


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Rib Fabric

In knitting, ribbing is a pattern in which vertical stripes of stockinette stitch alternate with

vertical stripes of reverse stockinette stitch. These two types of stripes may be separated by

other stripes in which knit and purl stitches alternate vertically; such pliss stripes add width

and depth to ribbing but not more elasticity.

The number of knit and purl stripes (wales) are generally equal, although they need not be.

When they are equal, the fabric has no tendency to curl, unlike stockinette stitch. Such ribbing

looks the same on both sides and is useful for garments such as scarves.

c) Mechanism of forming Tuck & Miss stitches

Tuck Stitch Formation

Two consecutive strokes of the carriage are necessary to form the tuck stitch.

During the first stroke, the tucking cam of the cam is out and the looping cam is not working.Therefore the needle only raises as high as the tucking plane; the loop cannot slip on the stem,

and therefore remains inside the hook after having completely opened the latch, in this way

allowing the yarn to be fed.

During the second stroke both the tucking cam and the looping cam are activated; the needle

rises up to the maximum height allowing the loop and the yarn to travel along the stem.

Thereafter, the needle is fed with the thread for the second time; the loop and the first yarn

close the latch and knock over on the new yarn. The first yarn does not knock over as a knit

stitch but takes a particular position, and fixes on top of the previous knit stitch and at the

bottom of the new one, creating a particular effect on the fabric, called tuck stitch.


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Miss Stitch Formation

High-butt and low-butt needles are also needed for the formation of the miss stitch

The cam (with a half-way tucking cam and looping cam) meets with the needles: the high-butt

needles rise while low-butt needles remain in a non-knitting position.

During the downward stroke, the needles which have raised till their maximum height and

have transferred the loops on the stem, are fed with a new thread. With the successive

downward stroke the latches are closed and the loops is knocked over on the new thread.

The stitches are bound together by longer interloops while the stitch of the non-knitting

needle, which can be only knocked over on the next stitch, shows a stretch effect.

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Knitting Practical 2