1. Yarns Flashcards
Distaff:
A stick for holding unspun fibres
Spindle:
A shaft for spinning fibres
Drop spindle:
A simple spindle that is allowed to fall to the ground as yarn is spun – its weight draws the yarn out into a thinner strand
Spinning:
The formation of yarn or thread by drawing out and twisting fibres
Spinning wheel:
A simple hand- or foot-operated device with a spindle rotated by a belt and wheel system
Whorl:
A disc of wood, clay, metal or other material that serves to keep a spindle in rotation and holds spun yarn on the spindle
Wool card:
A wire brush that is used to comb and straighten woollen fibres before spinning
Spinning
Carding:
A process in which staple fibres are sorted, separated and partially aligned
Combing:
A process in which staple fibres are sorted and straightened, and the short fibres re- moved, resulting in a higher-grade fabric owing to the longer length of the remaining staple fibres
Woollen yarn:
Carded wool yarns containing both short and long fibres; alignment of fibres is not as parallel as in combed yarns
Worsted yarn:
A smooth-surfaced yarn spun from long staple fibres, combed to produce a parallel fibre alignment
1.2.1 Spinning systems
Yarns can be made from short staple fibres, long filament fibres or a combination of both. Yarns made from filaments can be composed of several filaments (multifilament) or a single filament (monofilament). Depending on the length and type of fibre, there are different industrial processing methods for producing yarns.
Ring spinning
Ring spinning produces a strong, fine yarn, whereas open-ended spinning increases the speed of production and is therefore less expensive.
Short-staple (cotton) spinning
Long-staple spinning
Woollen system
Worsted system
Open-end spinning
Open-end spinning produces a yarn that is bulkier, rougher and more absorbent. It is used as filling yarns in fabrics where yarn strength is not as important, in denim and as towelling pile yarns. Knitwear manufacturers favour the fine, strong ring-spun yarns.
Rotor spinning
Friction spinning
Ring spinning
Method:
Opening, cleaning and blending
Carding
Drawing
Combing
Roving
Spinning
Opening, cleaning and blending
Staple fibres, from large bales into which they have been tightly packed, are fed into a cleaning, opening and blending machine. The fibres are separated or ”opened”, dirt and other impurities are removed and cotton from different bales is blended for a more uni- form product. A thin layer of fibres, also called a batt, of between 1,5 and 2 cm thick, is formed. The fibre batt is rolled up to form a pickerlap. This looks like an oversized roll of absorbent cotton.
Carding
The picker lap is passed between cylinders covered with fine wire teeth. This cleans and straightens the fibres so that their longitudinal axes are somewhat parallel. A thin web of fibres is formed, which is brought together as a soft rope, 2 to 2,5 cm in diameter, and called a carded sliver. The carded sliver has no twist and very little strength.
Drawing
Several carded slivers are fed between drawing rollers that combine the slivers to form one drawn sliver. Each set of rollers is set to run successively faster than the preceding set. The sliver becomes thinner as it is drawn out.
Combing
If a high-quality cotton or a worsted yarn is desired, the fibres go through an additional process called combing. The purpose of combing is to parallel fibres and to remove all the short fibres so that only long uniform staple fibres are left. This is an expensive opera- tion because as much as 20 per cent of the fibre is combed out as waste. The product of combing is called a comber sliver.
Roving
The roving frame has rollers similar to those of the drawing frame. It reduces the diameter of the sliver and gives it a slight twist. The roving is a softly twisted strand of fibres about as thick as a pencil. The sliver is drawn out to about one-eighth of its original thickness by three pairs of rollers rotating at different speeds. The product of the roving frame is called a roving.
Spinning
During the final spinning process, the roving again goes through a set of rollers, the front set rotating about 30 times faster than the back set. This makes the yarn even, smooth and uniform. It is then tightly twisted.
