Textile Yarns and Threads

Textile Yarns and Threads

Yarn is a long continuous length of interlocked fibres, suitable for use in the production

of textiles, sewing, crocheting, knitting, weaving, embroidery, and rope making.

Thread is a type of yarn intended for sewing by hand or machine.

Yarns can be described as single or one-ply; ply, plied, or folded; or as cord, including

cable and hawser types.

Single yarns

Single, or one-ply, yarns are single strands composed of fibers held together by at

least a small amount of twist; or of filaments grouped together either with or without

twist; or of narrow strips of material

Single yarns of the spun type, composed of many short fibres, require twist to hold

them together and may be made with either S-twist or Z-twist. Single yarns are used

to make the greatest variety of fabrics.

Ply yarns:

Ply, plied, or folded, yarns are composed of two or more single yarns twisted together.

Two-ply yarn, for example, is composed of two single strands; three-ply yarn is 

composed of three single strands. 

In making ply yarns from spun strands, the individual strands are usually each twisted

in one direction and are then combined and twisted in the opposite direction. When 

both the single strands and the final ply yarns are twisted in the same direction, the

fibre is firmer, producing harder texture and reducing flexibility. Ply yarns provide

strength for heavy industrial fabrics and are also used for delicate-looking sheer 

fabrics.

Cord yarns:

Cord yarns are produced by twisting ply yarns together, with the final twist usually

applied in the opposite direction of the ply twist. 

Cable cords may follow an SZS form, with S-twisted singles made into Z-twisted plies

that are then combined with an S-twist, or may follow a ZSZ form. Hawser cord may 

follow an SSZ or a ZZS pattern. Cord yarns may be used as rope or twine, may be

made into very heavy industrial fabrics, or may be composed of extremely fine fibres 

that are made up into sheer dress fabrics.

Novelty yarns:

Novelty yarns include a wide variety of yarns made with such special effects as slubs,

produced by intentionally including small lumps in the yarn structure, and man-made 

yarns with varying thickness introduced during production.  

Textile Yarn Faults

Article by RESIL

What are Yarn Faults?

Yarn quality is influenced by various types of yarn faults that also affect the quality of fabric

produced. During the yarn manufacturing process various types of irregularities are generated

in the yarn diameter regularly or at intervals, commonly known as yarn faults. These faults are

categorized as below:

1. Frequently Occurring Faults( Analyzed by Uster Evenness Tester)

2. Seldom Occurring Faults( Scanned by Uster Classimat Tester)

Frequently Occurring Faults:

  

• Thick Places

• Thin Places

• Neps

Thin places and thick places are produced due to drafting irregularities and neps are generated due toimmature fibers in raw material.

Why to avoid yarn faults:

• Causes breaks during post spinning operations.

• Reduces aesthetic appeal of the fabric, if allowed to pass.

Objectionable yarn faults can be categorized in three groups:

1. Faults due to raw material

2. Faults due to piecing

3. Faults due to Spinning machine

 

Calendering Process :- A Technical article By RESIL TEAM

Calendering Process :- A  Technical article By RESIL TEAM

What is Calendering Process?

Calendaring is the process of smoothing and compressing a textile material by passing a single

continuous sheet of fabric through a number of pairs of heated rolls.

The rolls in combination are called calenders. Calender rolls are constructed of steel with a

hardened surface, or steel covered with fiber.

Purpose of doing Calendering Process for textiles:

The fabric is then run through rollers that polish the surface and make the fabric smoother and

more lustrous. Due to High temperatures and pressure the Fabrics that go through the

calendering process feel thin, glossy and papery.

Types of calandering Machine:

Nipco-Flex Calender:

The pressure application concept of this calender is different from the conventional

calendering system.

The pressing roller consists of a rotating shell that is covered with a highly elastic plastic

material named as RACOLAN.

The roller has fixed axels on which hydrostatic support elements are mounted that press the

racolan shell against either steel or a cotton/paper roller.

The hydrostatic pressure is applied with oil and is adjustable according to width of the cloth.

The NIPCO roller can be arranged in vertical position or in L shape with a hot steel roller at top

and a cotton bowl in front of it.

The main advantages of NIPCO calender over a conventional calender are;

1. Attainment of very high pressure.

2. Adjustment of pressure line according to width of cloth.

3. No over load at the fabric selvedge.

4. Easy installation and removal of the rollers.

Felt Calender:

Felt calenders are mainly used for imparting lustre and smoothness to silk, rayon and cotton

knitwear materials.

These work at low pressure and temperature than used for cotton.

The cloth is pressed between an endless felt blanket and a hot steel cylinder at a speed of 20 to 40 meters/minutes