Ring spinning and rotor spinning
Ring spinning twists roving with a spindle and a traveller running on a ring. Rotor (open-end) spinning feeds sliver to a fast rotor: quicker and cheaper, but coarser, weaker yarn.
How ring spinning works
- 1Feed: roving from a bobbin on the creel enters the drafting zone.
- 2Drafting: three pairs of rollers, each faster than the one before, draw the roving down to the final yarn fineness.
- 3★Twisting: the yarn passes through a guide and a tiny C-shaped clip, the traveller, which slides round a steel ring; the fast-turning spindle puts in the twist.
- 4Winding: the traveller lags slightly behind the spindle, so yarn winds onto the bobbin; the ring rail moves up and down to build an even package.
- 5Doffing: full bobbins are removed and the yarn is rewound into large cones.
★ one-way, controls the pace
How rotor (open-end) spinning works
It is called **open-end** because the sliver is broken into single fibres, so the yarn end is open before the fibres join it again.
- 1Feed: drawn sliver enters directly; no roving is needed.
- 2Opening: a toothed opening roller separates the sliver into single fibres.
- 3★Transport: an air stream carries the fibres into a small, fast-spinning cup, the rotor.
- 4Twisting: fibres collect in the rotor groove; the yarn end, drawn out through the centre, turns with the rotor and twists the fibres in as it is pulled away.
- 5Winding: yarn is wound straight onto a large cross-wound package, ready for weaving.
★ one-way, controls the pace
Ring and rotor compared
| Point | Ring spinning | Rotor (open-end) spinning |
|---|---|---|
| Feed material | Roving | Sliver |
| Twisting element | Spindle with ring and traveller | Rotor |
| Speed and output | Slower; limited by traveller speed | Several times faster |
| Count range | Very wide, coarse to very fine | Mainly coarse to medium |
| Yarn strength | Highest | Lower |
| Yarn character | Smooth, compact, soft | More even, bulkier, harsher, with wrapper fibres |
| Cost | Higher (more stages, small packages) | Lower (no roving stage, large packages) |
| Typical uses | Fine shirting, voile, sewing thread, knitwear | Denim, towels, sheeting, coarse fabrics |
Other spinning methods (for awareness)
- Compact spinning: an improved ring system that condenses the fibres before twisting, giving stronger, less hairy yarn.
- Air-jet spinning: jets of air wrap fibres round a bundle; very fast; used for polyester-cotton sheeting.
- Friction spinning: rotating drums twist the fibres; coarse industrial yarns.
- Charkha and Ambar charkha: hand spinning for khadi.
Smooth ring-spun or compact yarn makes soft, less hairy cloth for babywear and hospital gowns. Bulky rotor yarn is common in terry towels and denim: it absorbs well and is cheap, which suits canteen and kitchen towels.
2 marks: “What is open-end spinning?” Rotor spinning: sliver is opened into single fibres that are re-gathered and twisted in a fast rotor; the yarn end is 'open'.
5 marks: “Explain ring spinning with a diagram.” Roving feed, three-roller drafting, guide, traveller on ring, spindle twist, ring rail winding, doffing; sketch the ring frame.
10 marks: “Compare ring spinning and rotor spinning with neat diagrams.” Working of each with a sketch; comparison table of feed, twisting element, speed, count range, strength, character, cost and uses.
Ring = roving, traveller, fine. Rotor = sliver, speed, coarse.