After loosening and carding, the fibre material has been made into continuous strip semi-finished products, namely raw strips. But it can not be directly spun into yarn, because the quality and structure of raw strip is far from the final yarn requirements, and the fiber straightness and separation are poor. Most of the fibers in the raw strip are still in the state of flexion or hook, and some small bundles exist, while the combed strips have better straightness of the fibers, but the uniformity of the strips is poor. If these strips are directly warped and spun, the yarn quality will inevitably be affected. Therefore, they must be processed through drawing process first.
The raw strip produced by carding machine has the initial shape of yarn after initial orientation and straightening. However, carding raw strip unevenness is very large, and the arrangement of fibers in the raw strip is disordered, most of the fibers are hooked. If this raw strip is spun directly into a spinning yarn, the quality of the spinning yarn is poor. Therefore, before further spinning, carding raw strip should be combined to improve evenness and fiber state.