Basically conventional spinning involves sorting and blending, formation of web for ease of handling, alignment of fibers, stretching of fiber bundles and actual spinning of fibres into yarns.
Conventional spinning method of yarn manufacturing
Sorting and Blending
The first step in conventional spinning of staple fibers is sorting and blending. Bales of fibres are loosened and fluffed. Impurities such as dirt and leaves are removed and fibers are blended to product specifications.
It is the second step in conventional spinning. The fibers are formed into web like sheets for ease of handling. These fiber webs are called laps. The forming of staple fibers into laps is called picking.
The fiber web is fed into a carding machine, which straightens the fibers and partially arranges them into parallel rows. The aligned fiber web is then formed into a long, untwisted rope called a sliver . The process of separating and aligning the fibers is called carding.
When only long, smooth staple fibers are desired the short fibers are removed from the slivers in a combing machine. Removal of short fibers and alignment of the remaining long fibers into parallel rows is called combing.
As only long fibers are used, combing increases luster and strength. Thus a fabric composed of yarns than that have been combed will be more expensive than a fabric composed of yarns that have only been carded.
The drawing process uses four sets of rollers, each set rotating at faster rate of the previous set several sliverss are combined and pulled into one long, then slivers. If further blending is desired, sliverss of different fibers may be combined in the drawing process.
In roving the drawn sliverss are pulled to approximately one fourth of their original diameter and slight twist is added. Hence roving is process that reduces the sliverss to a size suitable for spinning.
There are three systems of conventional spinning
They utilize the steps previously discussed. Here the machinery is designed to handle specific type and length of fiber involved.