The single yarn has more hairiness due to which there will be fly and fluff generation during shed formation on the weaving machine. To avoid this problem yarn doubling (folding) is done. But folding requires additional one process. So that the cost of production is increased. Hence, there is need of development of Siro spinning system.
IWS- developed a basic idea of winding two ply yarn on spinning cops.
In 1968 Jim Lappage at CSIRO Textile Division invented a system of producing a two-strand yarn, by combining the yarns from two adjacent drafting units onto one spindle the strand-twist periodically changed in direction.
By the end of 1990, the commercial installation of Siro spun spindles was estimated to be about 175000 which was about 7% of world capacity of worsted yarn spindles.
Passage Of Material Through Siro Spinning
The two parallel strand of rovings which are fed to the drafting system through the separate condenser, where the material is drafted as per the requirement. After drafting, the rovings come at the front roller nip.
Here from the front roller nip to the traveller these two strands are combined together and then with the help of ring and traveller twist insertion takes place and finally, the yarn is wound on the cop.
Conversion Of Ring Spinning To Siro Spinning
- Bobbin holders will be twice to normal with the possibility of creel modifications.
- Double Roving guides.
- Back zone condensers should be behind the aprons.
- Simple condensers replaced with double main zone condensers.
- Stop motions to identify singles fitted between the nip of the front roller to yarn guide.
- Recess width on an apron and top roller are widened.
- Roving traverse mechanism must be stopped and locked in central position.
- Special types of rings and travellers should be used.
- The yarn is more even than single yarn at the same count which was produced from single roving.
- It is twisted lively like single yarn as compared to two-fold yarns.
- The yarn is clean and less hairy than the two fold yarns.
- Round and less easily deformed so shed height can be lowered during weaving.
- Two strands of the yarn remain well defined if roving of different colours are fed into the drafting zone a marl yarn can be produced.
- Mechanical properties are similar to normal two fold yarns.
- Siro yarns T.F. is 28 and the two fold yarns T.F is 37.5
- The tenacity of SIRO YARN is 5% more than two fold yarns.
- 10-30% more extension.
- Less hairy.
- Abrasion resistance lying between those two-fold yarns and single yarn of the same count.
- With higher synthetic content, fabric handle tends to be harsher than for two fold yarns and low T.F. may be desirable.
Advantages Of Siro Spinning
- The twist in the yarn is unidirectional.
- Smooth & good abrasion resistance.
- Good wear resistance.
- Better fibre orientations.
- Fewer joints.
- No singing & sizing is required.
- Unwinding is smooth & positive.
- Fewer variations in the uniformity in the yarn.
- Used for all types of fibres and counts.
- Light weight fabrics can be produced from this yarn.
- Less floor & space is required.
- The fancy yarn is produced by feeding two different colours of rovings.
- Good moisture management property.
- The number of processes is removed like R/F, Steaming, winding.