Introduction to Spinning
- The fibre contained in cotton bales, for example, is first opened and cleaned. The trash is removed and a lap or sheet of fibre is produced.
- Selection of layers of cotton from different bales allows fibre blending to take place at this early stage. Material losses can be 5% or more. Carding converts the lap to a parallel sliver, removing more of the trash and some lint.
- In some modern systems, tufts are fed through tubes directly to the card. The carding action takes place between the surfaces of a large cylinder and a system of overhead revolving flats, which are covered with fine wire points. This process produces about another 4% to % in waste. The fibres collected at the end of the card in the form of a filmy web, are condensed into a card sliver of about 25mm diameter.
- The sliver is then delivered into a tall can. Combing, the next process (although optional, depending on the end use of the yarn), removes short fibres and any remaining trash or nep. A lap forming machine is used to combine a number of slivers into a wide ribbon of fibre which is then presented to the comber. The total material loss up to this stage can be as much as 15%, depending on the grade of cotton.
- In drawing, the card sliver is drafted down to an intermediate roving. It is at this stage that man-made fibres are blended into the final roving. At the speed frame a single draw frame sliver is drafted 5 to 10 times and a slight twist added. This is wound onto a roving bobbin. The roving is then spun into yarn. Total losses from fibre to yarn can be large. For example 100 kgs of 50/50 polyester cotton yarn can require 56 kgs of polyester and up to 70 kgs of cotton.
- In ring spinning a fine sliver of fibres is fed downwards from a roving bobbin through a drafting zone, which drafts out the strand of fibres to the correct thickness. The yarn is then wound onto a second package called a ring bobbin. Twist is then inserted by the combined action of the spindle and the traveller. The ringframe, in one form of another, is used for spinning all types of staple fibre, wool, cotton and synthetics.
