Drawing is the operation by which slivers are blended, doubled and leveled. In short staple spinning the term is only applied to the process at a draw frame. In drawing slivers are elongated when passing through a group of pair rollers, each pair is moving faster than previous one. This permits combing, drawing and elongating of several slivers to make them strong and uniform.In most modern worsted drawing sets there are 3 passages of pin drafting and roving process.
Objects of drawing
- To straighten the crimped, curled and hooked fibers.
- To make the fiber parallel to their neighbors.
- To improve uniformity of fibers by drafting and doubling.
- To reduce weight per length unit of sliver.
- To remove dust from slivers.
- To blend raw material of same hank perfectly.
- To parallelization of fiber and blending the carded sliver, draw frame is needed.
- In carded sliver, fibers are present in hook form i.e. trailing hooks and leading hooks. To parallel these hooks raw frame is used.
- Majority of the fiber hooks in a carded sliver are trailing hooks while leading hooks are comparatively less.
- Trailing hooks are also known as major hooks, while leading hooks are known as minor hooks.