Prof. Shakeel Iqbal

Knitted Fabrics:–

Application and Scope

Haqiqat Ali (11)

1. INTRODUCTION

Knitting is one of several ways to turn

thread or yarn into cloth (compare to

weaving, crochet). Unlike woven fabric,

knitted fabric consists entirely of

horizontal parallel courses of yarn. The

courses are joined to each other by

interlocking loops in which a short loop

of one course of yarn is wrapped over the

bight of another course. Knitting can be

done either by hand, described below, or

by knitting machine. In practice, hand knitting is usually begun (or "cast

on") by forming a base series of twisted loops of yarn on a knitting needle.

Knitting can also be done by machines, which use a different mechanical

system to produce nearly identical results.

The knitting process consists of interconnecting loops of yarn on powered

automated machines. The machines are equipped with rows of small,

hooked needles to draw formed yarn loops through previously formed

loops. The fabric is designed to take force in two directions (0° and 90°).

For this can be used roving of glass, high tenacity polyester, armid or

carbon as pillar threads and weft threads. These fabrics are used for

reinforced composites.

Considering though orientation of the force taking yarns (0°, 90°) this fabric

is comparable to a woven

fabric. However, there is

the advantage that yarns

are directly oriented and

lie absolutely straight in

the fabric. This means that

there is no loss of tenacity

as in the woven due to its

crimp effect. Furthermore,

the yarn-protective inlay

system prevents all fiber damage.

Fig. 2 Knitting

Fig. 1 Knitted and Woven fabric

2. KNITTING – MANUAL TO MACHINES

The oldest artifact with a knitted

appearance is a type of sock. It is believed

that socks and stockings were the first

pieces produced using techniques similar

to knitting. These socks were worked in a

technique of making fabric by creating

multiple knots or loops with a single

needle and thread. Several pieces, done in

now obscure techniques, have been

mistaken for knitting or crocheting.

The earliest known knitted items in

Europe were made by Muslim knitters employed by Spanish Christian royal

families. Several paintings from Europe portray the Virgin Mary knitting

and date from the 14th century. At this time, the purl stitch (the opposite

action to the knit stitch) was unknown and purely stockinet fabric was

produced by knitting in the round on multiple knitting needles. Sometimes

the knitting was cut open, a process now known as steeking. Knitting was

such a vast occupation among those living

on the Scottish Isles during the 17th and

18th centuries that whole families were

involved in making sweaters, accessories,

socks, stockings, etc.

With the advent of the Industrial

Revolution, wool spinning and cloth

manufacture increasingly shifted to

factories. Women were employed to

operate the machinery, rather than

spinning and knitting items at home. The

consistency of factory spun wool was

better in that it was more uniform, and its weight could be gauged better as

a consequence.

The city of Nottingham, particularly the district known as Lace Market,

dominated the production of machine-knitted lace during the Industrial

Revolution and the following decades.

Fig. 3 one of the oldest socks

pair

Fig. 4 knitted machine at

industrial revolution period

The 21st century has seen a resurgence of

knitting. Natural fibers from animals, such

as alpaca, angora, and merino, and plant

fibers, chiefly cotton, have become easier and

less costly to collect and process, and

therefore more widely available. Exotic fibers,

such as silk, bamboo, and qiviut, are growing

in popularity as well. The yarn industry has

started to make novelty yarns which produce

stunning results without years of knitting

experience. Designers have begun to create

patterns which work up quickly on large

needles, a phenomenon known as instant-

gratification knitting.

As time and technology change, so does the art of knitting. The Internet

allows knitters to connect, share interests and learn from each other,

whether across the street or across the globe. Among the first Internet

knitting phenomena was the popular Knit List with thousands of members.

In 1998, the first online knitting magazine, “KnitNet”, began publishing.

Blogging later added fuel the development of an international knitting

community.

Fig. 5 An advanced

knitting machine

Fig. 6, 7 complex knit patterns achieved with the help advancement in

technology

3. APPLICATION AND USES

Knit fabrics are versatile and are used to create not only clothing, but

certain home furnishings as well. Made from interlocking stitches, knits are

available in five different categories: firm, stable double knits that don't

have a lot of stretch; single knits, which are lightweight; textured knits, such

as velour or terry cloth; two-way stretch knits, which have a lot of stretch in

them; and ribbing, which is for finishing garments, like the necklines of T-

shirts.

3.1. Technical and Medical Textiles

Knitted fabrics and knitting technology play very

important role on the fields of technical and

medical textiles and their importance is ever

greater. Experts estimate that their annual

consumption is increasing by 3.8% in average

and it can reach about 24 million tons in 2010.

Within this the consumption of each sector is

increasing. Roughly one third of the world's fiber

consumption is used for production of technical

textiles.

Most of technical textiles are made of non-conventional materials; they are

usually man-made fibers, in many cases special types developed for specific

applications. Metallic yarns (thin wires) alone or parallel to other yarns are

also used in some technical knitted fabrics. However, traditional materials,

including those of natural origin, play important role in some fields.

There are various technical textiles which are manufactured by taking the

use of knitting technology. Some of them are discussed below:-

3.1.1 Nets

Application field of nets is extremely wide.

Agriculture, fishing, packaging, transport,

sports, shading technology, construction,

healthcare, surgery, safety technology and

military present many good examples for that.

Many of these nets are made by paschal or

crocheting technology the great advantage of

Fig. 7 knitted textile

supporting the joints

Fig. 8 a knitted net

which is that they do not contain knots. This makes the nets easier to handle

because the layers do not tangle up and there are no knots that could harm

the good packed into the net.

Materials used for net manufacture are very different, depending on the end

use. Spun yarns or filament yarns, narrow plastic tapes are commonly used

for this purpose. Elastic nets are made with using of elastane yarns.

3.1.2 Spacer fabrics

Among knitted fabrics perhaps the most

spectacular development can be registered in case

of spacer fabrics. Though the principle of the

fabrication is not new, it goes back to the

manufacture of plush fabrics on raschel machine;

the adaptation of this technology to make a

completely new type of fabric is very ingenious.

At the beginning they were developed really on

two needle bar raschel machines but now there are

also circular knitting machines on the market for

manufacturing of such products and, of course, V-

bed flat knitting machines are also able to make spacer fabrics of some

kinds.

The two surface layers of spacer fabrics are usually linked by relatively

thick monofilaments which make the fabric elastic when pressed in

thickness direction. This is the most important reason why spacer fabrics

have found many fields of application. They can substitute foam in seats or

beds, in orthopedics support devices, in bras and shoes. It can serve in smart

clothes as heat insulation or for forming of ventilation passages. As a type

of geotextiles spacer fabrics can be used to

lead off water from the soil. In

manufacturing of composites used in the

motor industry or ship building they can

work as reinforcement inlay. Using proper

yarns or with application of special

treatment they can be electrically

conductive, flame retardant, antibacterial,

etc.

Fig. 9 spacer fabric

Fig. 10 spacer fabric –

sandwich technology

As we see at this moment, most spacer fabrics used are made on raschel

machines or, in recent times, also on crochet machines. Needle bed distance

on these machines can be varied within wide range and fabric thickness can

reach even 60 mm. On circular knitting machines needle bed distance is

much more limited, only thinner (thickness of some millimeters) spacer

fabrics can be made on them. However, these variants are also very

important and can be found in many products.

3.1.3 Stitch bonded fabric

These fabrics have great importance in almost

each class of technical textiles. They are used

very often as reinforcing materials in

composites or for heat or sound insulation,

filling materials in clothes or furniture, etc.

Stitch bonding machines combine knitting and

sewing. They have grown from warp knitting

technology and their products occupy an

intermediate position between knitted and

nonwoven fabrics. This fabric contains a

carded web which is reinforced by yarns or

loops formed from fibers pulled out from the web itself. A further variant of

such fabrics is when not only carded web but lots of yarns are laid in

various directions over the web and all of these are stitched together. This

formation may be called “composite fabric” since it is a composition of

various types of textiles (web and yarns). They find application fields

among filters, geotextiles, reinforcement materials in composites, etc.

Advantage of these fabrics is that the carded web may be made of various

fibres which, because of their length or quality, cannot be spun, even in

various blending, fabric thickness and stitch density (number of stitches in

length unit) as well as yarn counts (in accordance with machine cut) can be

varied in relatively wide range. The fabric can be easily formed. At the end

of its lifetime it can be torn and recycled.

Fig. 11 stitch bonded fabric (Maliwatt)

3.1.4 Knitted fabrics with orientated behaviors

Knitted fabrics with orientated behaviors

are made usually with lots of yarns laid

lengthwise, crosswise and/or diagonally

into the fabric. Their keeping together is

performed by warp knitted loops. Aim of

these structures is mainly to reduce the stretch and/or to increase the fourth

of the fabric in one or more directions. If this effect is realized only in one

direction (lengthwise or crosswise) the fabric is called unidirectional or

monoaxial. If this behavior asserts itself in both directions the fabric is

called biaxial. Multiracial or multidirectional fabrics have almost the same

behavior in every direction.

To manufacture such fabrics special tricot and raschel machines have

been developed completed by equipment to prepare and lead the lots of

reinforcing yarns into the place of loop formation. In these fabric

constructions the laid-in yarns play the main role, the loops only link

them together.

There are a great number of end uses for these fabrics. Biaxial fabrics

with PVC coating, for instance, are used for manufacture of stressed

roof constructions by which very wide spaces can be covered. Fabrics

with directed behaviors are available also as reinforcement materials of

composites or for geogrids.

3.1.5 Medical treatment Many kinds of textiles are used in medical

treatment. It is not surprising that a great

part of clothing worn by doctors and nurses

in hospitals and clinics is product of the

knitting industry (e.g. undershirts, socks).

But sometimes they are not conventional

ones, they are made from yarns or with

finishing that make them antibacterial

against infections or against of rising of

unpleasant sweaty smell. Various types of bandages (both rigid and

elastic), surgical stockings, certain parts of

orthopedic equipment (or theses) (like knee-

, wrist- and elbow-braces, calf and lumbar

Fig. 13 Artificial blood

vessel

Fig. 12 surgical mesh

supports, etc.) are also made by knitting technology. An important

application field for spacer fabrics is manufacturing of mattresses for

beds, operating tables and wheel-chairs. Knitted products find

application field also among implants: artificial blood vessels (they can

be circular knitted or warp knitted, the latter is made on double needle

bar raschel machine and can be made also in Y form), surgical meshes

(made on tricot machine), coverings of artificial heart valves.

Structure of the textiles used as implants is determined by its material

composition, fibers behavior and features of degradation. Materials of

sutures and implants having biologically good

properties, designable absorption and

degradability and that endure the sterilization

process are continuously subjects of research. At

the same time, continuous development of textile

technologies and machines enables to develop

newer and newer methods in surgery and

medical treatment. For this mutual development

textile technologists and doctors must closely

cooperate, while all the

Administrative procedures concerning

manufacturing and trading of such products must be strictly respected.

3.1.6 Construction Industry Construction industry is a great market for

textiles and also for knitted fabrics among them.

Around buildings being under construction or

renovation the scaffold is usually covered by

raschel-knitted net made of polypropylene foil

tapes. Knitted fabrics can be used also to

reinforce wall coverings, both outside and

inside. Some types of geotextiles and geogrids

are also knitted structures, as mentioned above.

Many buildings, and not only provisional ones,

have roofs made of textile fabrics (sports

stadiums, air terminals, halls for various

functions, etc.). If this roof is made from knitted fabric bi- or multiaxial

knitted structures are used with waterproof and weatherproof coating.

Fig. 14 artificial heart

valve

Fig. 15 knitted net

used for

construction

purpose

Huge areas, many hundreds of square meters can be covered by such

fabrics.

Another possible application of knitted fabrics in construction is textile

reinforced concrete. There are warp knitted structures developed

especially for this purpose. Textile reinforced concrete has the

advantage that it is much lighter than the one reinforced by steel bars.

3.2 Sports and functional textiles. One of the major applications of knitted

fabrics in technical textiles is in

sportswear and functional textiles. Knitted

fabrics can be conveniently made into

multi-layered fabrics with or without

finishing to get different characteristics

depending on end-use applications. For

example, cotton as a next-to-skin layer in

the presence of heavy moisture between

the skin and the fabric will not be able to

wick away the moisture immediately. This

will result in clinginess and uneasy

comfort level. However, if the next-to-skin layer is a synthetic

material such as polyester, moisture will be wicked away

instantaneously resulting in dry skin.

The adjacent layer next to the synthetic

layer can be typical cotton knit which

will be able to absorb the moisture.

Such multi-layer knitted structures can

increase the comfort and performance

level of athletes.

Recently an interesting project was

undertaken at Texas Tech University to

develop highly breathable knitted fabrics. This project looked at the

possibility of identifying different varieties of cotton, which will give

enhanced moisture transport. This way, if suitable cottons were

identified that have superior breathability characteristics, these

cottons can be selected to develop highly breathable sportswear and

performance fabrics. Results showed that chemistry of cotton, in other

Fig. 17 Indian cricket team

shirt

Fig. 16 functional textile

words the constituent sugar types in cotton influenced the structure of

cotton and hence the transport of vapor through them. This project

identified certain sugars in cotton fiber, which provide good

breathability characteristics. This project showcases the impact of

multidisciplinary research involving agriculture and engineering

disciplines to develop next generation functional knits.

Knitted fabrics can be surface

enhanced by different methods such

as brushing, calendaring,

embossing, and plasma

functionalization to impart a myriad

of functionalities. Knitted fabrics

when raised by calendars can give

bulkiness, which will enable them to

be used as blankets for providing

necessary warmth in cold environments. Similarly, plasma

functionalized knitted fabrics can have different characteristics such

as water absorbency, water repellency and oil repellency and so on.

Another application of knitted fabrics in the industrial set-up is its use

in the automobile industry. Warp knitted fabrics are preferred as

headliner fabrics in the luxury automobiles. Predominantly, they are

made from polyester and blends of polyester and spandex. Nylon can

also be used depending on the end-use

requirements. Depending on the requirements,

the face fabric can range from 80-300 grams

per square meter.

Knitted fabrics on their own can find technical

textile applications. These fabrics can also be

made into multi-layer composites involving

knits, woven and nonwoven fabrics giving

them different characteristics. In addition,

knitted fabrics can also be chemically modified

and finished to get a number of diffe rent end-

use characteristics. It is up to the knitted fabric

producer to use a number of processes both

mechanical and chemical to enhance the use

and sales values of knitted fabrics.

Fig. 19 use of net in NIKE shoe

Fig. 18 taekwondo

clothes

3.3 Knitted fabric for clothing

Clothing is the most popular item to make

with knits because of the many varieties of

knit fabrics available. Use jersey, which is a

single knit, to make clothing with a soft, fluid

design, suggests Claire Shaeffer in her book

"Claire Shaeffer's Fabric Sewing Guide,"

such as dresses, T-shirts, soft jackets and

coats. Use double knits to create jackets,

coats and pants. Interlock knits are suitable

for evening wear and lingerie. Tricot is

perfect for active wear, such as leotards and

bathing suits. Sweater knits can be used to

make tops, sweater dresses and skirts.

In fact knitted fabrics plays very important roles in our day to day life.

Here are some illustrations showing the daily uses of knitted clothes:-

Fig. 20 men’s casuals

Fig. 21 baby’s hand

knitted jersey

Fig. 22 warm

clothing for

winters

Fig. 23 warm

cloths for new

borne

Fig. 25 legging and

stockings for casual

wears

Fig. 27 tee shirts

Fig. 26 knitted flexible

shoes for babies (hard

socks)

Fig. 24 female clothing

(net)

4. The scope of knitted fabric/clothes

In a rapidly changing world - where demand

and supply opportunities change equally fast -

it is not enough to simply project the present

into the future. Alternative visions of the future

are needed in order to broaden understanding of

issues that should be addressed today. Building

scenarios that describe the world six years from

now is necessary in order to adapt current

practice and arrive at a more robust, future-

oriented practice should a particular future

occur.

With the advancement of the knitting

technology, the use of knitted fabrics is

expanding rapidly all over the world. The

Knitwear sector and its markets are constantly evolving worldwide.

This segment of the garment industry has experienced many changes

in recent years. With improved technology, the limitations like

shrinkage and torque in knitted fabrics or garments have been reduced

to a great extent and this has opened more opportunities.

Many global players are eyeing the Indian Market with great interest

as one of leading markets in the Post Quota Scenario. The Knitwear

Exporters from all over India like from Delhi, Mumbai, Bangalore,

Chennai and Tirupur have already been equipped with making new

designs and collections which complements with the current fashion

trend and to meet with International Buyers’ requirements. Tirupur is

one of the few Indian towns that took advantage of globalization and

economic reforms, along with export-led growth. The export of

knitwear products from Tirupur is always on the rise every year and

the industry continues to show rapid growth.

There are many reasons for the growth of the India knit garment

industry. These are as follows:

Fig. 28 the future of

knitting industry

Compared to the setting up of other fabric producing industries,

the capital investment for starting a new knitting unit is

relatively small.

The high productivity of knitting machine is also an important

factor for the growth of the industry.

As the preparatory process for knitting is less than weaving, the

time required to get an order completed is less than that required

in the case of woven fabrics.

The setting up of knitting machines to produce a given type of

fabric is a fast and simpler operation than the setting up of a

loom.

Knitting is more flexible than weaving in the sense that styles

and designs can be changed with unparalleled rapidity. Knit

garments are geared to quick turnover in keeping with the rapid

fashion changes in the apparel market.

There are wide varieties of new yams that have brought new

standards of performance and new aesthetics into the knit

market.

The knit fabrics are very comfortable and are in tune with the

times.

The present generation demand wrinkle-free, ease-of-care

fabrics and knit garment is the perfect solution for this. The

recent success of knit garments has been greatly due to their

easy-care properties.

Knitted garments generally require no ironing and are therefore

it is cool for traveling persons.

Knitted fabrics are the most comfortable ones for swimwear and

sportswear.

All problems related with labor organization like wages,

benefits to labor etc. are reduced in the knitting industry because

knitting units require very less labor.

The machinery manufacturers with the aim of high productivity

and versatility have developed highly innovative machinery

which has also led to the boom in the knitting industry.

Bibliography

http://ara-texworld.com

http://eurofound.europa.eu

http://sourcing.indiamart.com

http://www.shmtraders.com

http://www.jihsin.com

http://www.ehow.com

http://www.indiantextilejournal.com

http://textile-articles.bravehost.com

http://english.ctei.gov.cn