a group of production processes used to convert wool or a blend of wool with chemical or cotton fibers into yarn.
Wool is blended to reduce the cost of yarn, to improve certain properties (such as wear resistance), and to permit standardization of production processes. Depending on the type of wool being processed, the length-to-weight ratio of the yarn, and the intended use of the yarn, the process used may be French, Bradford, semiworsted, or woolen spinning, which differ mainly in the type of carding.
The French system of spinning wool is used to make yarns with length-to-weight ratios from 15.5 to 42 tex from pure wool and wool blended with chemical fibers. The raw material is opened and blended before being carded. The sliver obtained is then processed by several passes through two-stage drawing frames to prepare it for combing, which is done on a batch-type comber. The sliver is then straightened on drawing frames. In order to remove stresses in the fibers and to fix them in a straightened condition, the sliver is smoothed on a machine; this process may sometimes precede dyeing. Sliver prepared in this manner is aged for several days in a humidified compartment, which helps reduce the static electricity in the fibers. The sliver is sent to a shop to be processed into a spun roving. The roving is again aged, after which it is delivered to ring spinning frames.
The Bradford spinning system produces yarns (usually from coarse and semicoarse wool) having a length-to-weight ratio from 30 to 83 tex. The principal features of the system are the use of continuous combers and roving (fly) frames to produce twisted roving.
Semiworsted spinning is used to make yarns with a length-to-weight ratio of 42 tex or higher from semifine, semicoarse, and coarse wool blended with chemical fibers. Carded sliver is processed in several transfers on drawing frames, one of which has an automatic thickness regulator, and is then sent directly to a ring spinning frame.
Woolen spinning is used to make yarns with a length-to-weight ratio from 42 to 400 tex from grease wool, chemical fibers, and the waste spinning materials from woolen and worsted spinning. Cotton fibers and reclaimed wool obtained by processing all-wool or part-wool rags may also be used. The components are blended on blending machines, after which oil is added and the stock is opened up on a mixing picker. The stock is carded on carding frames that include two or three roller cards. A flyer separates the fibers longitudinally into individual slivers, which are rubbed to form the roving that is sent on to a spinning frame. (See alsoSPINNING.)
V. V. ZHOKHOVSKII