Twist Insertion Mechanism
category
Twist is inserted into the yarn by the rotation of the spindle carrying the bobbin, while the traveller acts as a brake, causing the yarn between the front roller nip and the traveller to rotate and insert twist at a rate equal to spindle speed minus traveller speed. Twist per metre (TPM) = spindle speed (RPM) / delivery speed (m/min). Twist direction (Z or S) is set by spindle rotation direction. Twist multiplier (TM) = TPM / √count (Ne).
Role
Twist insertion is the defining mechanical action of ring spinning. The twist level determines yarn strength (increases to an optimum then decreases with over-twisting), handle (harder with more twist), and suitability for end-use. Every yarn specification includes a twist level, and getting it wrong means the yarn fails tensile testing, weaves poorly, or produces fabric with incorrect handle.
Subtopics
- Twist Per Metre and Twist Multiplier Twist per metre (TPM) is the number of helical turns inserted per metre of yarn length. Twist multip…
- Z and S Twist Direction Z-twist fibres spiral from bottom-left to top-right (like the diagonal of Z); S-twist from bottom-ri…
- Twist Contraction and Count Change Twist contraction is the reduction in yarn length and increase in linear density that occurs as twis…
- Spinning Triangle and Twist Triangle The spinning triangle (twist triangle) is the region between the front roller nip and the yarn forma…
- Yarn Balloon and Balloon Control The yarn balloon is the conical rotating loop of yarn formed between the thread guide (lappet) and t…
- Twist Propagation and Twist Stoppers Twist propagates from the traveller up through the balloon to the spinning triangle. Twist stoppers …
- End Breakage Rate and Causes End breakage rate (EBR) is measured in breaks per 100 spindle hours (b/100 s/h); world-class mills a…
- Cop Building and Winding Cop building is the process of layering yarn on the bobbin in a conical package by varying the ring …
- Spindle Speed Optimisation Spindle speed is limited by: traveller speed limit (max 35–40 m/s surface speed before fly-off due t…
- False Twist Devices False twist devices (magnetic false twisters, ceramic pins, or grooved discs) are inserted between t…