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Introduction to Textile Fabrics

Knitting

Dr Jimmy Lam

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Room Location: QT718

Subject Lecturer: Dr Jimmy Lam Contact No.: 2766-6439

E-mail: tclamj@inet.polyu.edu.hk

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KNITTED FABRIC STRUCTUES

There are two main industrial categories ofmachine knitting : warp knitting and weftknitting. Fabrics in both these categories

consist essentially of a series of interlinkedloops of yarn.

Warp Knit Weft Knit

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WARP KNITTING

Warp knitting is the process of making a fabric

in which the loops form in a vertical or warpwise

direction; the yarn is prepared as warp on

beams with one or more yarns for each needle.The fabric has a flatter, closer, less elastic knit

than weft knit and is very often run resistant.

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WEFT KNITTING

Weft knitting is the most common type ofknitting, it is the process of making a fabric byforming a series of connected loops in a

horizontal or filling-wise direction; produced onboth flat and circular knitting machines.

Most of the sweaters, cardigans, and other

knitted outerwear are weft knitted fashionedgarments, produced with a minimum of linkingfrom shaped, generally flat garment pieces.

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INTRODUCTION TO (WEFT)

KNITTING (1)

Knitting is a method of constructing fabric byintermeshing series of loops of one or moreyarns.

Knitted fabric is unique in that it possesses ahigh order of elasticity and recovery. It can bestretched to a considerable length and yet willgradually return to its original shape or

conformation. It is this feature of the fabric, plusits air permeability arising from its loopedstructure, that imparts to it such desirable andappealing properties from the consumer's pointof view as:

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INTRODUCTION TO (WEFT)

KNITTING (2)

(a) A diversity of constructions, and the variety offibres and finishes available.

(b) Generally soft and light weight.

(c) Good drapability. Knitted fabrics conform tothe figure without constricting the wearer.

(d) A high order of wrinkle resistance. Creases inknitted fabric brush right out.

(e) Comfort. The knitted structure is porous. Itallows the skin to breathe freely. Its elasticitypermits greater freedom of body movements

(f) Ease of care. Knitted apparel launders withoutdifficulty.

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Principle of Knitting

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PRINCIPLE OF KNITTING

LOOP AND STITCH

The loop is the fundamental element of all

knitted fabrics. It is a basic unit consisting of a

loop of yarn meshed at its base with previously

formed basic units (stitches). Components of a

knitting loop are the needle loop and the sinker

loop.

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LOOP

A needle loop is one

which has been

drawn through a

previous loop.

A sinkerloop is one

which connectsadjacent needle loops.

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STITCH

The stitch is the smallest dimensionally stable

unit of all knitted fabrics. It consists of a yarn

loop, which is held together by being

intermeshed with another stitch or other loops.There are three basic knitted stitches : KNIT,

TUCK and MISS (float or non-knit) which form

the starting point for the entire range of weft

knitted structure.

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KNIT AND PURL

Knit stitch (technical face)is of V-shape appearancewhere the shanks are

above, and the feet arebelow the head of thepreceding stitch.

Purl stitch (technical back)

is of the semi-circleappearance where thelegs are below, and thefeet are above the head ofthe preceding stitch.

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TUCK

Tuck stitch is made

when a needle rises

to take a new loop

without casting off theold. It consists of a

held loop and a tuck

loop, both of which

are intermeshed inthe same course.

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MISS (NON-KNIT)

A length of yarn not

received by a needle

and connecting twoloops of the same

course that are not in

adjacent wales.

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WALE AND COURSE

The series of loops

that intermesh in a

vertical direction are

known as 'Wale'. The loops that are

inter-connected

widthwise are known

as 'Course'. (one

traverse is equal to

two courses.)

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KNITTING METHOD

Knitting was originallydone by hand onstraight or round

needles by slippingstitches from oneneedle to the otherand making a newstitch with each

change. Hand pins ofwood or plastic areused for hand knittingand crochet.

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Knitting Methods

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KNITTING METHOD

While hand knitting continues, the maincommercial product now is turned out bymachine.

Knitting Machine - V-bed flatmachine

The latch needles, mountedin bedsopposedinan inverted V formation,are operatedbycamsin a reciprocatingcarriage. Machinesare built

with E1 - E18 (needles /inch),in severalcm(for ribtrims)toabout210cm. The V-bed flatmachine isprobablyone ofthe mostversatilemachines forthe production of knitwear.

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ELECTRONIC FLAT MACHINE

Because of the almost unlimited patterning

scope available with electronic flat machines,

considerable numbers are used for the

production of patterned fabrics and garmentlengths and some models are being offered with

full fashioning capability.

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ELECTRONIC FLAT MACHINE

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FORMATION OF KNIT STITCH

(1) Start position (2) Clearing

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FORMATION OF KNIT STITCH

(3) Latch opening (4) Feeding

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FORMATION OF KNIT STITCH

(5) Drawing (6) Knock over

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FORMATION OF TUCK STITCH

Tuckon latch

The formation oftuckstitchon a machine

whichis notequippedwith movable upperclearingortuckcamsisonlypossible byraisingthe stitchcam.Thispreventsknockingovertakingplace andis known as'tuckingon latch'.

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FORMATION OF TUCK STITCH

Tuckon hook

A tuckstitchis formedona machine equipped with

movable upperclearingortuckcamsbywithdrawingthe tuckcamsandpreventingthe needlesfrom being raisedtotheclearingposition. Thisisasafer wayof formingtuckstitches,andis known as 'tuckingin the hook'.

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Discussion

What are warp and weft knitting

Discuss the formation of Knit, Tuck and

Miss stitches What are wale and course in knitting