YARN PRODUCTION

 

 

INTRODUCTION:

 

To convert textile fibers into fabrics some type of fiber arrangement is required. Probably the most common method is to convert fibers into yarns, which are then constructed into fabrics. Yarns are essential for knitted, woven or knotted structures and for many braided ones.

 

'Yarn' is defined by the American Society for Testing and Materials (ASTM) as 'A generic term for a continuous strand of textile fiber, filament, or material suitable for knitting, weaving to form a textile fabric. Yarn occurs in the following forms.

 

                    Yarn forms:

 

                   A number of fibers twisted together.

 

                   A number of filaments laid together without twist.

 

                   A number of filaments laid together with more or less twist.

 

                   A single mono filament. e.g. Silk

 

TYPES OF YARNS:

 

Yarns can be made either from short staple length fibers or from filament fibers. There are two types of yarns, i.e., spun yarns and filamentous yarns.

Types of Yarns :

1.Spun Yarns

2.Filament Yarns

 

If filaments are used to make yarns they may be either multifilament or monofilament .

 

Filamentous Yarns

1.Monofilament

2.Multifilament -> Twisted,Flat

Mono filaments are filament yarns composed of one single filament.

Multi filaments are composed of many filaments.

 

Characteristics of Spun Yarns and Filament Yarns

 

Spun Yarn

 

1.     Yarns made from short length fibers and the fabrics are like cotton and wool.

 

2.     Short fibers twisted into continuous strand, has protruding ends

1.     Dull, fuzzy look

2.     Lint

3.     Subject to pilling

4.     Soil readily

5.     Warm (not slippery)

6.     Loft and bulk depend on size and twist

7.     Do not snag readily

8.     Stretch depends on amount of twist.

 

3.     Are absorbent

 

4.     Size often expressed in yarn number

 

5.     Various amount of twist used

 

6.     Most complex manufacturing process

Filament Yarn

 

1.     Yarns made from long length filament fibers and fabrics are like silk.

 

2.     Long continuous, smooth, closely

3.     packed strand.

1.                 Smooth, lustrous

2.                 Don not lint

3.                 Do not pill readily

4.                 Shed soil

5.                 Cool, slick

6.                 Little loft or bulk

7.                 Snagging depends on fabric construction

8.                 Stretch depends on amount of twist

 

4.     Absorbency depends on fiber content

 

5.     Size in denier

 

6.     Usually very low or very high twist

 

7.     Least complicated manufacturing process

a. Balanced Yarns:

Smooth fabrics are made from balanced yarns.

b. Unbalanced Yarns:

Crepe and textured surface may be created from unbalanced yarns.

DIRECTION OF TWIST:

 

In addition to the amount of twist in a yarn, the direction of the twist is also designated. There are two types of yarn twist S and Z.

Yarn Numbering System:

 

Yarn numbering systems are therefore used to express a relationship between a unit length and weight of yarns. There are two main numbering system in use.

Numbering system

1.Direct -> 1.Denier (900 m1 gms=1 Denier) 2.Tex (1tex=1gm/km  840)

2.Indirect -> 1.Matric No.(840 yds=1lbs=1S) 2.English No.(50/1=50 single yarns)

 

yarns)

 

YARN MANUFACTURING SYSTEM:

 

The twisting process by which fibers are formed into a yarn is referred to as spinning. Spinning includes all the processes required to prepare and clean the fibers from the opening of the bale to the twisting of the yarn in its preparation for the textile loom.

 

1. Opening and Picking:

 

In order to produce a uniform product, the fibers from numerous bales be blended, or thoroughly mixed together, and from this composite, the final yarns will be produced . The masses of fibres from these numerous bales will be fed into a machine called a blending feeder. As these masses of fiber are loosened and thoroughly mixed, some remaining heavy impurities such as dirt, remnants of seeds, leaves or stems, are removed by a line of machine known respectively as pickers, breakers, intermediates and finishers each in succession being a somewhat more refined cleaner of the raw fibres. From these machines, the fabric emerges as a lap, a loose, formless roll.

 

2. Carding:

 

The lap is unrolled and drawn onto a revolving cylinder covered with fine hooks or wide bristles. These wide bristles pull the fibers in one direction, separate those which are individually tangled together and form them into a thin film. This process is known as carding. The thin film is drawn into a funnel shaped opening which molds it into a round rope like strand approximately an inch in diameter; this is called the sliver.

 

3. Combing:

 

The comber is a refining device by which the paralleling and straightening of the individual fibers is carried to a more exact degree. The longer fibers are again formed into a sliver, known as the comb sliver.

 

4. Drawing:

 

In the drawing operation, further blending is accomplished by working together several slivers and drawing or pulling them out in the drawing frame without twisting but reducing the several slivers to a single one about the same diameter as each of the components.

 

5. Roving:

 

The combined or condensed combed sliver is taken to the slubber of a series of machines called roving frames.

 

6. Spinning:

 

Spinning is a continuation of the roving and on the spinning frame many spools containing the roving pass through the ring spinning mechanism which further draws and twists to a yarn of the required size and twist and winds it on bobbins preparatory to the weaving operation.