Yarn is a long continuous length of interlocked fibers, 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
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 to immature 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
