Yarn Manufacturing (Spinning)
The spinning sequence
For short-staple cotton the sequence is blow room, carding, drawing, combing (for fine yarns), roving and ring spinning. Each stage has a clear purpose: opening and cleaning in blow room, individualisation and sliver formation in carding, drafting and doubling for evenness in drawing, removal of short fibres and neps in combing, attenuation and twist insertion in roving and ring spinning. Know the machines in order; sequence questions are common.
Key parameters
Understand draft, doublings, twist and count relationships. Production of a card or draw frame depends on delivery speed and sliver count. Twist multiplier links twist per unit length to yarn count, and the twist direction (Z or S) affects yarn character. Combing noil percentage indicates fibre loss and quality. Winding and cone density matter for downstream weaving efficiency.
Traps
- Confusing draft (attenuation) with doubling (multiplication of mass); total draft = mechanical draft × doubling.
- Using the wrong count system; cotton count (Ne) is indirect, tex is direct.
- Assuming combing always improves strength; it removes short fibre but adds cost.
Worked example
Eight card slivers of 4 ktex are doubled and drafted to a single sliver. If the delivery sliver is 4 ktex, total draft = input mass/output mass = (8 × 4)/4 = 8, so mechanical draft = 8/8 = 1. This shows doubling must be accounted for before quoting draft.