Knitting a fabric manufacturing

Knitting

The second most often used technique of fabric construction is knitting. Knitting is that the art of constructing a knitted fabric with knitting needles by interlooping one or more number  of yarns in many series of interlinked loops. From the figure 3 the loops are hanging and supporting each other.

History of knitting

Knitting is a “timeless arts” and be in this world forever. But the truth is, it give the impression to have been invented in the first millennium, possibly as near the beginning of 8th C. Development of knitting from hand knitting with one to two hand needles and forward to peg frames, peg frames, stock frames, commercial knitting machines and modern fully automatic knitting machines.

14th century – Peg Frame: For the period of 1390, it absolutely was said that fashion accessory (gloves) were manufactured using knitting and its knitting elements. Peg frames was used to knit both gloves and caps.

16th century – Stocking Loom: In the 16th century, knitted stockings developed into high fashion. Stocking frame was designed Rev William Lee to construct fine silk stockings. Because of reasonable production and quality, hand knitters opposed the concept of stocking knit frames. Consequently, development in framework knitting took much more time and later it developed very gently in the next century.

18th century – Framework Knitting: In 1759 Jedediah Strutt and Belper introduced “Derby rib frame.” This might be the primary conversion of single bed knitting frame to a double bed knitting frame and it was a great motivation for growth of knitting frames. Samuel Betts joint the tuck with rib frame to expand his tickler bar knitting.

19th century – The Lamb Knitting Machine: Mr. Lamb developed the first domestic knitting machine about 1867. This machine have 84 needles with 15 lbs. In 1879, the Crane Knitter was introduced with 106-needle which is similar to modern flatbed knitting machines. About this period, the circular sock knitting machines also start to come out.

Modern Machines: Subsequent to the turn of the century, modern machines began to come into view shortly. The principle mechanisms of today‟s machines remain same. However, the advanced electronics devices have replaced mechanical punch cards systems and fully automatic computerized machine developed for many new design innovations.

Hand knitting

Thousands of years the hand knitting has been experienced for the manufacturing of knitted and crochet fabrics. Still it is a mystery that where this art was invented. Hand knitting is to construct a fabric by means of yarn using two or more hand knitting needles shown in figure

Usually two needles used and the loops are transferred from one hand needle to the other. It fabricates rows of linked loops to create a fabric.

On first needle, number of loops are formed and then the loops are grows as a fabric by drawing further loops from side to side. The loops are passed back and forward along with the needles from the row to row. Two kinds of stitches are formed in all kind of knitting. First one is “knit stitch,” and the second is “purl stitch.”

The Industrial and economic revolution took over the hand knitting to the invention of machine knitting.

Growth of knitting

There are number factors involved in the reason for the growth of knitting industries.

• No yarn preparatory machineries are required for weft knitting. Only beaming process required for warp knitting.

• Labour force requirement is less.

• Capital investment cost is less than other fabric forming techniques.

• Productivity of machine is high.

• Design and style can be changed and modified rapidly.

• More flexible operation.

• Give better wearing and fitting comfort.

• Fabric is wrinkle free and easy to maintain.

• Seamless garment can be possible

• Good demand for fabric and garment export.

• Used for special applications like technical textiles.

• Characteristics required for knitting yarns

A good knitting yarn ought to have the subsequent characteristics within the order of their comparative importance:

• Uniformity of diameter

• Flexibility

• Elasticity

• Strength

Uniform in Diameter

A good knitting yarn ought to be as uniform in diameter as is feasible. Variations in yarn diameter exposed by knitted fabrics far more than any other fabric manufacturing system. The strange loop configuration places a superior length of yarn within a comparatively minute space in the fabric. Because of this, a thin or thick place present in the yarn is exaggerated in the fabric appearance. The uniformity in diameter is of such significant characteristics, which improve the appearance and uniformity in a knitted fabric.

Flexibility

Flexibility is important characteristics during knitting and knitting yarn, the yarn can knit the loops without delay. Knitted fabrics consist of a sequence of yarns interloped together. A rigid, stringy supply yarn refuses to accept the loops formation and is not good for knitting process. The soft twist hosiery yarns provide addition elasticity to increase fabric flexibility.

Elasticity

The ultimate knitted fabric performance can be increased by elasticity in a knitting yarn. . Elasticity is that property that sources a yarn to presume its original length of yarn subsequent to stretch through any tension smaller than its elastic limit. This elasticity creates an additional compact, slighter looped and added elasticity in knitted fabric.

Strength

The relative necessary of strength during a knitting yarn is a smaller amount than the other characteristic. The knitting action is comparatively easy by using any yarn. A flexible weak yarn can provide sufficient characteristics while knitting. But in rigid yarn have brittle nature and not able to knit. However that is not because of lacks strength of yarn, lacks of flexibility and elasticity. The comparative significance of yarn strength as a quality in a knitting process permits a yarn to be knit and support fabric with flexibility and elasticity.

Classification of Knitting

In the knitting method one set of yarns is employed from one direction that might be horizontally (weft knitting) or vertically (warp knitting) direction. Horizontally or vertically direction yarn formed through loops and stitches for the manufacturing of knitted fabric. In knitted fabrics, the loop is the primary component and stitches all the corresponding loop of all the knitted fabrics. Loop is the fundamental unit interlooped with the formerly formed loops by means of hooked needles Based on the method of loop formation knitting can be classified in two weft and warp knitting shown in figure 7. In weft knitting, loops are created in a horizontal course direction but in warp knitting, loops are created in a vertical wale direction

Weft Knitting

Weft knitting is that the commonest form of knitting, it is the method of constructing a fabric by means of shaping a sequence of linked loops in a horizontal or course-wise direction shown in figure 8. Weft knitting machines can be sub classified into circular and flat knitting according to the fabric delivery, form of needle bed, type of needle and type of fabric. Circular knitting machine needles are placed parallel in one or more circular needle beds. Alternatively, flat knitting machine make use of straight needle beds having separately functioned needles.

Applications:

• Garments like T-shirts, polo shirts, dresses and children‟s, casual skirts, jackets, suits dresses are made.

• Tubular seamless hosiery knitted fabric/garment can be manufactured circular knitting machines.

• High stretch sportswear with good dimensional stability is produced.

• Collar and cuffs manufactured by flat knitting and even some times sweaters are too made.

• Using tuck stitches, highly complicated textured patterns fabrics are made.

• Through weft knitting hats and scarves are made to use in the winter season.

• Industrial application fabrics also made like filter material, cars upholstery etc.

Warp knitting

Warp knitting is that the methods of constructing a cloth by shaping a loops in a vertical or wale-wise direction and it shown in figure 9. Yarn in beams is a supply material as warp and one or more yarns feed for each needle. The warp knitted fabric is flatter and less elastic than weft knitted fabrics.

Applications:

• Fabric type of tricot warp knitting is used to manufacturing lightweight fabrics frequently inner wear.

• Raschel warp knitting system is used for manufacturing a material for straight skirts, coats, jackets, and dresses.

• Sportswear, tracksuits, leisurewear and safety vests also used to manufacture.

• In home textile, warp knitted fabrics are used for constructing mosquito nets, mattress, furnishing, laundry bags, and fishnets.

• Industrial safety shoes are finished through warp knitting inner linings.

• From warp knitted fabrics head rest lining, car cushion, motorbike helmets lining and sun shades are being made.

• Industrial PVC/PU backing, caps, gloves and production masks are also made.

• Three-dimensional knitted constructions can be manufactured through simplex warp knitting machines.

• Bio-textiles products are also made from warp knitting process

  
  

• Knitting terms and definitions

Knitting processes manufacturing the fabrics with specific details on fabric structure by using the different techniques in knitting machine. It can be grouped into two categories.

• Fabric Terminology

• Machine Terminology

• 1 Fabric Terminology

Fabric terminology represents all the terms and function related to fabric structure and geometrical properties.

Loop

The primary unit of a knitted structure is loop and that is shaped by „kinking‟ (bending) of the feed yarn and it is intermeshed with similar loop. The loop contains two segments head and foot that are connected by loop leg shown in figure 10. Apart from this the loop is shaped by the knitting element of needle and sinker forming needle loop and sinker loop in figure 11 and 12.