Combing is a process in which the ends of the fibre bundle are alternately combed by a machine with a combing needle implanted on the surface to remove the short fibers that are not required. In the combing process, the uniformity of fiber length is improved, twisted fibers are separated into a single state, impurities and fiber granules (neps, wool, granules, cocoon skin, etc.) are removed, and the spinnability of raw materials is greatly improved. Therefore, combing process is widely used in spinning fine count and high quality yarn production. After combing, the yarn is even, smooth and strong, and the texture of the fabric is clear, with few stripes and even surface.
After the sliver is combed, 42%~50% of the staple fibers, 50%~60% of the impurities and 10%~20% of the neps can be eliminated. The straightness of the sliver can be increased from about 50% to 85%~95%. Therefore, the combed yarn is superior to the ordinary combed yarn with the same linear density in terms of physical and mechanical properties and visual gloss.
The noil rate of combing process is higher, and the noil contains some long fibers. At the same time, the cost of combing process increases because of the increase of equipment and labor. Therefore, the selection of combing process should consider the technical and economic effects from improving yarn quality, saving cotton and reducing cost.