Analysis of common problems of fibers and yarns

(1) Cotton grain (Nep)

Appearance: The cloth surface presents cotton fibers with a size similar to the joint, and is spun into the yarn. If it is pulled out, the yarn is in a state of breaking or about to break. Rovings spun from low-grade raw cotton often have such defects.

Causes: 1). There are dead cotton fibers in the raw cotton, which are not completely removed during the cleaning process. 2). When carding, the needles of the cylinder or the needle plate are not sharp enough, or the distance between the two is not properly set, so that the carding effect cannot be fully exerted.

(2) Cottonseed Bark (Seeds)

Appearance: The surface of pure cotton or cotton fiber blended fabric, with some small black or dark non-fiber fibers.

Causes: 1). When the cotton fiber is separated from the cottonseed in the cotton ginning process, the root end of the fiber has cottonseed skin, or the cottonseed is crushed and mixed into the raw cotton. 2). The cottonseed skin was not completely removed during the cleaning process.

(3) Slub

Appearance: On the warp or weft of the fabric, there is occasionally a small section of tufted fibers with a length of about 5 to 20mm, which is thicker than the normal diameter of the yarn and less than the normal number of twists in the frying.

Causes: 1). In the roving fed during worst spinning, the density of the fibers is not uniform, and there are small and dense fusiform fiber bundles. 2). The top rollers and aprons of the worst spinning machine cannot uniformly hold the fed roving.

(4) Flyer

Appearance: Similar to the thick knot, but it is thicker, not as slender as the thick knot, and the fibers are lumpy. The yarn is slightly untwisted to prevent the yarn from breaking.

Cause: The fiber mass floating in the air between the spun yarns, or the fiber mass accumulated on the nearby table fed by the machine, is entangled on the yarn.

(5) Cockled Yarn

Appearance: In a section of yarn about the width and length of the fiber, there are large and thick knots at intervals. The thickness of the yarn changes like a slub, which is generally more common in the weft of roving fabrics, so it is also called slub weft.

Cause: The setting of the drafting roller of the worst spinning machine is too tight, the roller cover is too loose, and there are occasionally abnormal fibers in the fed roving.