Yarn Processing Yarn processing from natural staple fibres is called spinning, although spinning is the last stage in the processing. Earlier young unmarried girls were commonly involved in spinning the finest yarn because of their nimble fingers. The term ‘spinster’ for unmarried women originated in that context. Yarn processing, i.e., conversion of fibre into a yarn involves a number of stages.
Let us take them one by one. (i) Cleaning: Natural fibres generally contain extraneous impurities depending upon their source, like seeds or leafy matter in cotton, twigs and suint in wool. These are removed, fibres sorted out and converted into laps (rolled sheets of loose fibres). (ii) Making into a sliver: Laps are unrolled and subjected to straightening processes which are carding and combing .
The process is similar to combing and brushing your hair. Carding disentangles the fibres and lays them straight and parallel to one another. For finer fabrics the laps are subjected to combing after carding. This process removes finer impurities and short fibres as well.
The lap then passes through a funnel shaped device which helps to convert it into a sliver. Sliver is a rope like mass of loose fibres, - cms in diameter. (iii) Attenuating, drawing out and twisting: Now that the fibres have been converted into a continuous strand, it needs to be made to the size required. This is called attenuation .
Several slivers are combined for uniformity. The slivers are gradually drawn out so that they become longer and finer. If a blended yarn is required (e.g., cotswol-cotton and wool) slivers from different fibres are combined at this stage. The resultant sliver is still of the same size as the original sliver.
The sliver after drawing is taken to the roving machine where it is further attenuated till it becomes of its original diameter. It is given a slight twist to keep the fibres together. The next stage is spinning. Here the strand is given the final shape as the yarn.
It is stretched to the required fineness and the desired amount of twist given to it and wound on cones. F igure : C otton spinning All manufactured fibres are first made as filaments. The yarn can be composed of a single filament or a multifilament yarn when a number of individual filaments are taken together and twisted as one. It is also possible to cut the filament into staple length fibres.
These are then subjected to spinning process as for natural fibres and are called spun yarns. Staple length fibres are also required when a mixed fabric/ blend like ‘terecot’ (terene and cotton) or ‘terewool’ (terene and wool) or ‘polycot’ (rayon and cotton) is required.