Knitting Technology Knitting is fabric-or garment-making by forming a series of interlocking loops in a continuous yarn or a set of yarns. In production situations, work is carried out through movement of hooked needles. (Hand knitting is normally performed with straight needles.) Each row of loops is vertically interlocked with preceding row. With a sufficient number of loops, yarn becomes a fabric. Knitted fabrics have advantage of stretchability, a property not possessed by

woven fabrics. Stretching can be in any direction even if yarn used has little elasticity. Fig. 10D illustrates two types of knitted fabric. Mechanized production knitting utilizes a series of needles commonly operated by cams.

Figure 10D: Two examples of knit fabrics made by interlocking continuous yarn strands: a) a plain knit made on a weft or filler knitting machine. Path of each crosswise yarn is called a course. b) a single-warp tricot knit.

There are two basic types of knitting, weft or filler knitting and warp knitting. Weft knitting is somewhat more common. In weft knitting, courses (crosswise rows of loops) are composed of continuous yarns. Weft knitting can be done by hand or machine but production weft knitting

is a machine operation. Individual yarn is fed to one or more needles at a time. In warp knitting, wales (predominantly vertical columns of loops) are continuous. Separate yarns are fed to each needle. Warp knitting operation is always produced by machine.

Knitted fabrics can be either flat or tubular in form. Warp knits are usually flat; weft or filling knits are most often tubular.

Two types of hooked needles are used in production knitting machines, bearded or spring needle & latch needle. They are illustrated in Fig. 10D-1. With both designs,

needles draw new loops through previous loops that they have retained. Once needle head and new loop have gone through old loop, old loop is cast off. Latch needle is most often used. It operates more automatically than bearded needle which requires other machine elements to present loop & close the hook. Fig. 10D1 illustrates stitch formation with a latched needle in a circular machine.

Figure 10D-1: Production knitting needles. a) bearded spring needle used for fine knitted fabrics & b) more common latch needle.

Figure 10D1: Stitch formation in weft knitting with latch needles in a circular machine.

D1. Weft or Filling Knitting

Can be produced on either flat or circular knitting machines. In weft knitting, one continuous yarn runs crosswise in fabric and makes up all loops in one course. The needles either act in succession or yarn is fed in succession, so that loop formation and

interlocking is not simultaneous. Fig. 10D, view (a), illustrates a basic weft knit jersey cloth. Fig. 10D1 illustrates weft knitting with latch needles and shows that multiple, evenly-spaced, needles have

hooks with latches at the end. Needles are moved upward or downward by cams. As each needle rises, needle hook loops over yarn which it hooks on down stroke, & yarn is held in place by needle latch. At bottom of needle stroke, a previous loop slips off needle, & new loop is held in place with latch. On next cycle, the loop is released from latch as needle rises, another loop is formed & process is repeated. Fig. 10D1-1 shows six stages of weft knitting with bearded needles.

Figure 10D1-1: Six stages of stitch formation in weft knitting with bearded needles. In this example, all stitches in one row are formed at same time.

Figure 10D2: Warp knitting with bearded needles. Loop forming is performed simultaneously with separate yarns fed through warp guides.

Several different stitches can be formed in weft knitting. In knit stitch, loop is drawn from back and passed through front of preceding loop to the front of cloth. In purl stitch, loop is drawn from front through back of preceding loop to the back of cloth. In miss stitch, no loop is formed. In tuck stitch, two courses on one wale are looped over a third. Stitches, and various combinations of them, make all patterns of knit and double knit cloth. Distinct patterns can be made from combinations of knit and purl stitches since knit tends to advance & purl to recede. Double knits are made by machine only, using two yarns and two sets of needles. These knits use a variation of rib & interlock stitches, drawing loops from both directions. Jersey is a common knitted cloth, made from only knit or only purl stitches.

Circular weft knitting machines are used to make hosiery, underwear & simulated furs. They can knit shaped garments. Jacquard effects are possible, & are now generally controlled electronically. Flat knitting machines can also produce shapes by increasing or decreasing loops. Full-fashioned garments can be made on flat knitting machines.

D2. Warp Knitting Is usually accomplished on flat machines but can also be tubular. Warp knitting differs from weft knitting in that each needle has its own yarn. Yarns are fed from a large reel or warp beam as in weaving with a loom. Yarns, then, generally run lengthwise in fabric. The needles all move together & form parallel rows of loops simultaneously. Loops are interlocked on a zigzag or vertical path. Yarn section is held on one end by previous loop & at other end by yarn guide. Yarn is trapped within hook of needle as it descends. With latch needles, hook is closed as needle descends. This allows previous loop to slip off hook while a new loop is held. If bearded needles are used, a yarn guide called a sinker, positions yarn across ascending needles & then retracts as needles descend. Fig. 10D2 illustrates warp knitting.

Warp knitting is a versatile process, but standard warp knitting machines make just three basic stitch variations: open loop, closed

loop or no loop. Various fabric patterns are created from different combinations of these stitches. One simple pattern produces tricot knit, which consists of a zigzag pattern of closed loops of parallel wales. Tricot fabrics are run-resistant. Other warp-knit patterns are simplex, milanese and raschel. Milanese knitting produces run-resistant fabrics with a diagonal rib pattern. Several sets of yarn are used. The raschel knit is made with latched needles rather than spring beard needles used for other knits. One or two sets of latch needles are used. Raschel knit fabrics are used frequently for underwear.

Warp knitting is used to produce fabric for dresses, lingerie, upholstery & draperies among other products. ⇒ Basic feature of warp knitting is that these yarns make vertical

parallel wales. ⇒ The term 'warp knitting' refers to machine knitting. The needles

produce parallel rows of loops simultaneously that are interlocked in a zigzag pattern.

⇒ The stitches on the face of fabric appear vertically and stitches at the back appear horizontally as floats at a slight angle.

⇒ These floats are also called Laps or Underlaps, and are a distinguishing identification of warp knits.

Filling Knits:

Single Knit Double Knit 1) Jersey 2) Jacquard Jersey 3) Stockinette 4) Intarsia

1) Lisle 2) Knit Terry cloth 3) Valour 4) Fake fure 5) Fleece 6) French Terry

1) Interlock 2) Rib Knit 3) Jacquared Knit 4) Purl Knit

Filling Knits: ⇒ Yarns run horizontally ⇒ Loops joined one to another in the same course ⇒ Loops connect horizontally ⇒ More design possibilities ⇒ More open fabric ⇒ Two way stretch ⇒ Run most ravel ⇒ Hand or machine process ⇒ Flat or circular ⇒ Finished edges possible ⇒ Produced as shaped garments, garment pieces or yardage

Single Filling Knits Double Filling Knits ⇒ Are made using a circular or

flatbed machine with one set of needle

⇒ They can be any pattern or weight

⇒ Less stable than double knits tend to curl at edges, and run rapidly, especially if made with filament yarns

⇒ Are made with two beds of needles ⇒ Double knit fabrics may be made with one or more sets

of yarns ⇒ Have two way stretch ⇒ Relatively high dimensional stability ⇒ They do not curl at edges and are less apt to stretch out

than single knits ⇒ They do not run ⇒ Double knits can resemble any woven structure and are

often given the woven fabric name

Warp Knits-Simple structure Tricot-Satin

⇒ Lock stitch is used in most tricots ⇒ The face of the fabric is formed of the vertical portion of the loops ⇒ The back has the horizontal portion of loops ⇒ The face has a much finer appearance than the back ⇒ Does not travel

⇒ Lock-Knit tricots do not run ⇒ The fabric will curl just as filling knit jersey does ⇒ It has little elasticity in length wise direction and some elasticity in cross wise direction ⇒ Used for lingerie, sleepwear, shirts, blouses, uniforms, dresses and automotive upholstery

Warp Knits-Simple structure Tulle

⇒ Has a hexagonal net used for veiling, support fabrics and overlays for apparel ⇒ Can be confusing fabric since it can be made in several ways ⇒ Tricot-knit tulle is one type of tulle ⇒ Automotive tricot upholstery of double knit velvet is made in a manner similar to that of

velvet ⇒ Two layers of fabric are knit face to face with a pile yarn connecting the two layers ⇒ The layers are separated when the pile is cut

Filling Knit-Single Jacquard Jersey

⇒ Patterns are produced by combinations of knit tuck or float stitches ⇒ Combinations of yarns that vary by colour or texture or incorporation of yarns in

specific area within the fabric, much like a true tapestry weaves for woven fabrics ⇒ They are the simplest of these patterned fabrics ⇒ The pattern develops because of different stitch types yarn colours or combinations of

both stitch type and the yarn colour ⇒ The yarn colour changes to create the pattern Filling Knit-Double Rib Knit

⇒ The structure is made of face wales and back wales ⇒ The lengthwise ridges are formed on both sides of the fabrics pulling stitches first to

the face and n0065tx to the back of fabric in adjacent stitches or groups of stitches ⇒ The 1X1 rib is the simplest double-knit fabric produced using rib gaiting ⇒ Usually much thicker than a single jersey ⇒ They do not curl at the edges ⇒ Rib knits run ⇒ They unravel from the end knit last

Warp Knitting Machine: Warp knitting machines were invented in 1775, some 200 years after the invention of first knitting machines.

There was extraordinary growth in warp knitting industry between 1950 and 1970 due to development in yarns

After 1970, warp knitting declined with reduction in sales of nylon shirts and sheets which were the major products of warp knitting at that time.

Types of machine are- 1) Tricot machine 2) Raschel machine

01) Tricot Machine ⇒ In tricot machines, needles mainly

used are beared needle with a pressure bar in tricot machine

⇒ It has one or more than one warp beams mounted above the machine.

⇒ The machine, controlled by yarn guides, set in a guide bar. One guide bar is used for one set of warp yarns.

⇒ The greater number of bars, the greater the design flexibility.

⇒ Movements of guide bar is controlled by chains with links.

⇒ As the guide bar is raised and moves sideways it plays the warp yarn in their respected needle hooks to form a coarse of loops. Simultaneously when the loops of proceeding.

b) Raschel Machine ⇒ Reschel machines are different

from tricot machines as rashel fabrics are made with heavy yarns

⇒ They usually have an implicate lace like pattern where as tricot fabrics are made with five yarns and flat or have simple geometric fabrics.

⇒ The gauge of reschel machine is measured in term of number of needles per two inches.

⇒ Reschel fabrics are knitted on machine having 2-40 guide bars,

Types of Warp Knitted Stitches: a) Tricot Knit b) Milanese Knit c) Simplex Knit d) Raschel Knit e) Ketten Raschel Knit f) Crochet Knit

a) Tricot knit: ⇒ Tricot fabric is soft, wrinkle resistant & has good drapability. ⇒ Tricot knits are used for a wide variety of fabric weights & designs.

Tricot knit

⇒ Some examples of tricot fabric are lingerie, loungewear, sleepwear, blouses, shirts, dresses, slacks etc.

b) Milanese Knit: ⇒ The Milanese stitch produces a fabric very similar to tricot.

It can be identified by the fine rib on the face and a diagonal pattern on the back.

⇒ Milanese fabric is superior to tricot in smoothness, elasticity, regularity of structure, split and tear resistance.

c) Simplex Knit ⇒ Simplex fabric is made of fine yarn and is relatively dense

and thick. ⇒ It is a small part of warp knit production. ⇒ Simplex fabric is used to make gloves, handbags, sportswear

and slip covers. ⇒ Eyelets and other openwork can also be produced on the

simplex machine.

d) Raschel Knit ⇒ The raschel knit ranks in importance of production with tricot but it make varieties of

products ranging from veilings, laces, power nets for foundation garments, to carpets. ⇒ Raschel knitting is done with heavy yarns and usually has an

intricate lace-like pattern.

e) Ketten Raschel Knit ⇒ This is also known as chain raschel. The machine can be

equipped to produce raised pattern effects in one or more colors. Fabric is finer, has a better hand, superior elasticity and cover.

f) Crochet Knit ⇒ This basic stitch is used in hand-crochet. This construction is used in a wide variety of

fabrics ranging from nets and laces to bedspreads and carpets

Advanced knits ⇒ Tucks ⇒ Float

Milanese Knit

Raschel Knit

Crochet