FABRIC MANUFACTURING (KNITTING)

Knitting • Knitting is a process of manufacturing a

fabric by inter looping of yarns.• Knitting is the second most important

method of fabric formation.• It can be defined as a needle technique of

fabric formation, in which, with the help of knitting needles , loops are formed to make a fabric or garment.

• Fabric can be formed by hand or machine knitting , but the basic principle remains exactly the same i.e. pulling a new loop through the old loop.

• Knitted Fabric are popular for their shape fitting property, soft handle, bulkier nature and high extension at low tension.

Development of Knitting• The word knitting is derived from the Sanskrit word Nahyati. According to the textile history, it

is said that finger knitting started since 1000 BC. In finger knitting, the fabric was produced on the hand using the fingers. The looping was done on the fingers. The fabric was produced by removing a new loop through an old loop.

• Since the fabric produced on the hand was smaller in width the peg knitting was introduced. The finger knitting had only 4 loops in width but in peg knitting more numbers of loops was possible. According to the width of the fabric the number of pegs was decided.

• Hand knitting with 2 pins was practiced since 256 AD. The knitted fabrics were prepared with the help of 2 pins. In about 5th century AD an oldest knitted article (sock) was seen.

• Reverent William Lee, in 1589 a resident of England invented the first knitting machine with bearded needle. The gauge of the machine was 8npi and afterwards it was made upto 20npi. The machine had a potential of knitting 10 times more than hand knitting with two pins. Further many more warp and weft machines were developed but the principle remained the same.

• In the 18th century , rib knitting machine, warp knitting machines and circular knitting frame was invented

• In the 19th century, latch needle, compound needle, fashioning mechanism, seamless heal and toe i.e. sock, flat knitting machine, interlock knitting were invented all over the world.

• In the 20th century, double cylinder circular machine, electronic needle selection, relanit principle, Pizo electronic jacquard etc were invented

Types of KnitsKnitted fabrics

Weft Knitting

Single jersey

Warp knitting

Classification of Knitting

Knitting is primarily classified as weft knitting and warp knitting. This classification is based on the direction of movement of yarn with respect to the direction of fabric formation

Classification of Knitting

Weft Knitting Warp Knitting

Warp Knitting

In case the yarns run in length direction, i.e. the direction of fabric formation during knitting, the process is called warp knitting.The yarns inside the knitted fabrics are just like the warp yarns in woven fabrics Such knitted fabrics are called warp knitted fabrics, and the machine which produces such fabric is known as warp knitting machine.

Warp Kitting• Tricot• Raschel

Weft Knitting

If the yarns run in the width or crosswise direction with reference to the direction of fabric formation during knitting, then the process of knitting is called weft knitting.

Needle loop• basic unit of knitted structure. • consists of a head (H) and two

side limbs or legs (L). • At the base of each leg is a foot

(F), which meshes through the head of the loop formed at the previous knitting cycle

• The yarn passes from the foot of one loop into the foot and leg of the next loop formed by it

Applications of Knitted Fabrics• Sportswear(conformity, flexibility) • Casual wear (comfort) • Dress wear • Technical textiles application

Advantages of Knitting

• Fabric can be produced from minimum number of yarns, even only one yarn

• Loop size can be varied to a wide extent and that too very easily.

• The extensibility and stability of the knitted fabric can be engineered

• Wastage of yarn during conversion of yarn into fabric by knitting is negligible.

Advantages of Knitting

• The desired porosity or compactness of the fabric can be achieved easily.

• The extensibility and stability of the knitted fabric can be engineered.

Comparison of woven and Knitted fabric

Knitting is comparatively economical(no need of preparation of yarn) and faster

process to convert yarn into fabric or even into direct apparels ,

Woven vs. knitted

Woven• Produce by interlacing of

yarn• Set of yarn is required for

warp and weft• Elasticity and stretch ability

is poor• Dimensionality stable• More durable• Less moisture absorption

Knitted• Produce by interloping of

yarn• Minimum one yarn is

required• Good elasticity and stretch

ability• Dimensionally not stable• Less durable• Wicking and moisture

property is better

Woven vs knitted• Good drape property• Less crease resistant

property• Air permeability property is

poor• Tensile and Tear strength

can be checked

• Poor drape property• Good crease resistant and

no need of ironing• Excellent air permeability• Fabric is comparatively

strong and Durable • Bursting strength check

rather than tensile strength

Common knitting terms

Technical Face:The side of the knitted fabric having all of face of Knit loop is called Technical face of the fabric.

Technical Back:The side of knitted fabric consist of back loops is called technical back of the fabric.

Common knitting terms

Fabric Weight : Followings units are provided for fabric

weight. Grams per meter Square (g/m2) GSM = weight in (g) / Area ( length cm *

width cm)*10000 Ounces per Square Yard (Oz/Yd2) Ounces to GSM = Ozs / Yd2 *33.906

Common Knitting terms

• Stitch Length :- the stitch length is one of the most important factor controlling the properties of knitted fabrics. The stitch length , measured in millimeter is the length of the yarn in the knitted loop. Generally longer the stitch length, the more open and lighter the fabric.

• Stitch density :- Stitch density is a term frequently used in knitting and represents the total number of needles loop in a given area. Stitch density is the product of Courses and Wales per unit length and is measured in units of loops per square centimeter.

Common Knitting terms• Wales :- A wale is a vertical column of

loops produced by the same needle knitting at successive knitting cycles. The number of Wales determine the width of the fabric and they are measured in units of Wales per centimeter.

• Courses :- Courses are rows of loops across the width of the fabric produced by adjacent needles during the same knitting cycle and are measured in units of courses per centimeter. The courses determine the length of the fabrics