Shortly describe the knitting with Single Truck Single Jersey Circular Knitting m/c.

Assignment Topics : Shortly describe the knitting with Single     Truck Single Jersey Circular Knitting m/c.

Types of weft knitting m/c:

1. According to the end product, the weft knitting m/c may be broadly classified as either:

I) Fabric m/cs  II) Garment length m/cs

2.According to their frame design and needle bed arrangement, the weft knitting m/c may be broadly classified as either:

I) Straight bar frame m/cs  II) Flat knitting m/cs  III) Circular knitting m/cs

1(I) Fabric m/cs: 

Large diameter, circular, latch needle m/cs, knit fabric, at high speed, that is manually cut away from the m/c after a conventional length has been knitted. Most fabric is knitted on circular m/cs either single cylinder or cylinder and dial

1.(II) Garment length m/cs:

Flat and circular m/cs, knitting garment length sequences which have a timing or counting device to initiate an additional garment length programming (m/c control) mechanism. This coordinates the knitting action to produce garment structural repeat sequence in a wale wise direction. The garment width may or may not vary within the garment length.

2.(I) Staright bar frame m/cs: 

Special type of m/cs having a vertical bar of bearded needles whose movement is controlled by circular engineering cams attached to a revolving cam-shaft in the base of the m/c. the length of the m/c is divided into a number of knitting heads.

2.(II) Flat m/cs: 

The typical flat m/c has two stationary beds arranged in an inverted V formation. The m/cs range from hand-propelled and manipulated models to automated, electrically-controlled, power-driven m/cs.

2.(III) Circular m/cs: 

Circular m/cs whose needle beds are arranged in circular cylinders and/or dials including latch, bearded or compound needle machinery.

Features of fabric m/cs:

· Large diameter, circular, latch needle m/cs (also known as yarn goods or piece goods) knit fabric, at high speed.

· The fabric is manually cut away from the m/c usually in roll form after a convenient length has been knitted.

· Most fabric is knitted on circular m/cs either single-cylinder (single jersey) or cylinder and dial (double jersey) of the revolving needle cylinder type, because of their high speed and productive efficiency

· Sinker wheel and loop wheel frames could knit high quality speciality fabrics eith bearded needles although circular m/cs employing bearded needles are now absolute, the production rates of these m/cs were uncompetitive

· Unless used in tubular body-width, the fabric tube requires splitting into open-width

· The fabric is finished on continuous finishing equipment and is cut-and-sewn into garments or it is used for household and technical fabrics

· The productivity and patterning facilities of fabric m/cs vary considerably.

· Generally; cam settings and needle set-outs are not altered during the knitting of the fabric

Classification of Wear:

I) Underwear: It may be knitted either in garment-length or fabric form.

II) Knitwear: Knitwear is normally in garment-length form which is a generic term applied to most weft knitted outer wear garments such as pull overs, jumpers, cardigans and sweaters usually knitted in m/c gauge coarser than E14. [E = English gauge; 1″, 14 needles]

III) Jersey wear: It is generic name applied to weft knitted fabric (single jersey, double jersey). It is cut and made up from fabric usually knitted in large circular m/cs (26″ or 30″ dia) although there are larger and smaller diameter m/cs used. Generally gauges are finer than E14

Mainly two types of knit wear:

Fully fashion wear (Garments length m/c)

Cut and sewn knit wear (Fabric m/cs)

Methods to obtain Tuck/Held loops:

1. Without casting off operation in loop forming cycle

    i.e. Tucking o the latch

2. Without clearing operation in loop forming cycle

    i.e. Tucking in the hook

3. With switching a needle out of action from loop forming cycle

Tucking on the latch: 

When tuck stitch formation is performed without casting-off and sinking are excluded from the loop formation cycle. In this case, the needles 4 and 7 knit the loops 3 and 6, while the needle 5 performs all the operations upto joining and stops. Then a new yarn 2 is fed in its hook and this will be the tuck loop, the old loop 1 remains on the closed latch and this will be the held loop.

After the needle 5 is lifted for clearing, in the following loop formation cycle it receives a new yarn and knits a loop from it, casting-off upon it old held loop 1 and the tuck loop 2

Step of forming held loop in 5 needle:

With switching a needle out of action:

Held loop formation by switching a selected needle out of action can be performed by two methods:

I) One of them is based on simple leaving the needle idle in lowest position for one (or two, three) loop formation cycle

II) The another method consists in leaving the needle in it’s top most position for the rest of loop formation cycle.

In this cycle, the needle 4 and 7 knit the loops 3 and 6   form the fed yarn, performing all necessary operations In the next cycle the needle resting in its top position forms a new loop.

III) In both cases, the yarn of which loops 3 and 6 are made remains in form of a long floating link between loops 3 & 6, the long link (a float) is laid on the held loop 1. The process of producing held loop is described with the term ‘Missing’

Stitches produced by varying the sequence of the needle loop intermeshing:

1. Held loop/Stitch

2. Tuck stitch

3. Float/Miss stitch

4. Drop/Press-off stitch

Held loop:

A held loop is an old loop that the needle has retained. And not released and knocked-over until the next yarn feed. A held can only be retained by a needle for a limited number of knitting cycles before it is cast-off. A new loop is then drawn through it. Otherwise the tension on the yarn in the held loop becomes excessive.

Held stitch:

Held stitches are formed by a held loop and one or more tuck loops, and one or more miss loop and more knit loops.Held stitches are used for producing three-dimensional shapping such as heel and toe pouches for foot wear.

Tuck stitch: 

A tuck stitch is composed of a held loop, one or more tuck loops and knitted loops. It knitted loops.

It is produced when a needle holding its loop also receives the new loop which becomes a tuck loop, because it is not intermeshed through the old loop.

Miss/Float stitch: 

A float stitch is compressed of a held loop, one or more float loops and knitted loops. It is produced when a needle holding its old loop fails to receive the new yarn that passes, as a float loop, to the back of the needle and to the revereseside of the resultant stitch.The miss stitch can occur accidentally as a fault due to incorrectly set yarn feeders.

Drop/Press-off stitch: 

A drop stitch fault will result if a needle releases its old loop without receiving a new one. This technique is used to achieve a press-off on all needles at the end of a garment-length sequence. A drop stitch is used very occassionlly in flat knitting to cause certain loops in plain structure to be much larger than the next

It causes due to:-

· Not properly/correctly placement of yarn feeder

· Not properly threaded in yarn feeder

· Due not proper tension on warp

· Take up roller bed

· Not correct relationship between dial loop and cylinder loop

Hold loop	Tuck loop
Held loop is an old loop that is retained by needle	Each new loop become a tuck lop loop and not inter-meshed through the old loop
It is not released until the new yarn feed

Fabric m/c	Garment length m/c
Circulate, latch needle m/c	Flat and circular m/c
Fabric have no garment length control device	Which have additional garment length control device
Have not timing or counting device	Have timing or counting device
Finer gauge m/c compare to garment length m/c	Coarser gauge m/c
High speed m/c	Low speed m/c
High production	Low production
Fabric cut away from the m/c in roll form manually	-in tubular(open width) form
Fabric used in household and technical fabrics	Unit wear, underwear

Difference between Rib & Interlock:

Rib	Interlock
Rib has vertical cord appearance	It has technical face of plain fabric on both sides
Rib gating as bellows	Interlock gating as bellows
It is not so thick, heavy or narrow as interlock	It is thicker, heavier and narrower than rib
Relaxation is less	Relaxation is more
Simple structure	Complex structure
No need of high quality yarn	Need of high quality yarn
More production	Less production
More extensible	Less extensible

Plain	Purl
All are fce other wese all are back loops i.e. technical face or technical back	Purl structure have one or more wales which contain both face and back loops
Plain is less thicker	Very much thicker than plain
It’s technical face is smooth and technical back rough	It has similar appearance to pearl droplet
Extensibility in to the lengthwise is normal but widthwise is high	Moderate in width but very high in length in length wise
Tendency of curling yarn	No curling tendency
Has ladering problem	No laddering problem

Warp knitting	Weft knitting
The loops are produced to the length of fabric	The loops are produced to the width of the fabric
The threads runs in the vertiacal direction	The threads runs in the horizontal direction
Each loop in the horizontal direction is made from a different thread	A horizontal row of loops can be made by using on thread
It is elastic to the length	It is elastic to the width
It’s elasticity is less	Higher elasticity
Yarns are supplied from beam	From cone
At least one yarn is needed for each needle	Any number of needle are required for on e yarn
Less shrinkage	More/Higher shrinkage

Single Truck Single Jersey  Circular Knitting Machine:

Objectives:

To know about the different parts of this machine.

To learn the functions of these parts.

Two draw the yarn path diagram of this machine.

To know about the gearing diagram of this machine for production calculation of this machine with the help of gearing diagram.

Machine description :

1. Latch needle: This type of needle has a special sliding latch with other common features. This part is used to form loops.

2. Cams: There are three types of cams:

a. Knit cam: This cam helps needle to form knit loops.

b. Tuck cam: This cam helps needle to form tuck loops.

c. Miss cam: This cam helps needle to form miss loops.

                             

3. Sinker: There are three types of sinkers:

a. Loop forming sinker: This sinker is used to sink or kink the newly laid yarn.

b. Holding down sinker: This sinker is used to hold down the old loops.

c. Knocking-over sinker: This sinker supports the old loop as the new loop is drawn through it.

4. Feeding unit :-  A feeder supplies yarn to needles. A positive feeder contains the following parts:

a. Knot catcher: This part finds any fault in yarn.

b. Yarn tension-er: This part gives proper tension to yarn for proper knitting.

(5) Timing belt/Tooth belt: This part helps machine to stop immediately

6. VDQ Pulley: This part is used to control stitch length of the knitted  

  fabric.

7. Cylinder:        This frame contains needles, cams, jacks and sinkers.

8. Sinker Ring: Sinkers are placed on the sinker cam in the sinker ring.

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

10. Fabric Detector: This part detects any fault of fabric.

11. Adjustable Fan: This part removes lint, hairy fibre from yarn and  

     others.

12. Take up Roller: This part is used to take up the fabric from cylinder.

13. Cloth Roller: The final product i.e. cloth is wound on this roller.

14. Expander: This part is used to control the width of fabric.

16. Creel: This part is used to contain yarn packages.