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![• Yarn twist =
𝑆𝑝𝑖𝑛𝑑𝑙𝑒 𝑠𝑝𝑒𝑒𝑑
𝑦𝑎𝑟𝑛 𝑑𝑒𝑙𝑖𝑣𝑒𝑟𝑦 𝑠𝑝𝑒𝑒𝑑
=
𝑁𝑠𝑝
𝑣𝑑
• To realize the variable linear densities along the yarn axis, the speeds of
the feed rollers (𝑉𝑖 ) are altered periodically i.e.
Altered speed : 𝑉𝑖
′
= 𝑉𝑖 + ∆𝑉𝑖 periodically
• The linear density of slub yarn ∶ 𝜌′ = 𝜌𝑦0 + ∆𝜌𝑦
• ∆𝜌𝑦 = σ1
3
𝜌𝑅𝑖
∆𝑉𝑖
𝑉𝑎𝑝
[ rovings are same linear density]
• Where,
• 𝜌𝑦0 = linear density of the base yarn
• ∆𝜌 = the yarn linear density variation.
R Chatopadhyay IITD 24 9
Cui P, Xue Y, Liu Y. Manufacturing a ring spun slub yarn using multi-channel drafting
technique. Journal of Engineered Fibers and Fabrics. 2020;15. doi:10.1177/1558925020958518](https://image.slidesharecdn.com/2-slubandfancyyarn-250319103938-7dfbb678/85/2-Slub-and-fancy-yarn-description-how-it-work-9-320.jpg)
![Twisting process
• Threads have circular X section
• 𝑡𝐺
′
= twist in basic thread before delivery
• 𝑡𝐺 = twist in basic thread in twisted yarn
• 𝑣𝐺= feed speed to twisting point
• 𝑣𝐸= delivery speed of yarn
• 𝑣𝐸 < 𝑣𝐺
• 𝑣𝑍 = speed of feeding decorative thread
• Twist in fancy twisted yarn (𝑡𝐸)
𝑡𝐸 =
𝑛
𝑣𝐸
… (1)
• Twist in the basic thread reduces to
𝑡𝐺 = 𝑡𝐺
′
− 𝑡𝐸 = 𝑡𝐺
′
−
𝑛
𝑉𝐸
… (2) [ opposite twist direction]
R Chatopadhyay IITD 24 16
G G
ℎ
𝑣𝐺 𝑣𝐺
𝑣𝐸
𝑣𝑍
𝑑𝐺
Z
𝑡𝐺
𝑡𝑍
𝑡𝐸
𝑑𝐺
′
𝑑𝐺
′
𝑡𝐺
′
E](https://image.slidesharecdn.com/2-slubandfancyyarn-250319103938-7dfbb678/85/2-Slub-and-fancy-yarn-description-how-it-work-16-320.jpg)
![Degree of cover by decorative thread
• 𝑑𝐺
′
= diameter of basic thread , 𝑑𝑍 = diameter of decorative thread
• 𝑡𝑍 = twist in decorative thread
• Degree of cover
length of basic thread covered by coils of decorative thread to its
total length:
• 𝜆 =
𝑑𝑍
ℎ
=
𝑑𝑍
Τ
𝑣𝐸 𝑛
=
𝑛𝑑𝑍
𝑣𝐸
= ⋯ . (6)
• 𝜆 = 1 → 𝑑𝑧 = ℎ 𝑂𝑟 Τ
𝑣𝐸 𝑛 : wrapping would be obtained
• 𝜆 < 1 → 𝑑𝑧 < ℎ = Τ
𝑣𝐸 𝑛 ( form spiral)
• 𝜆 > 1 : nubs/lump
• 𝜆 = ∞ : knots [ since 𝑣𝐸= 0]
• 𝜆 = 2 𝑜𝑟 3 : a two/ three layered wrapping is obtained
• As 𝜆 increases , the last wrapping layer is incompletely formed, and it
gives an uneven appearance.
𝑙𝑧
𝜋 𝑑𝐺 + 𝑑𝑍
ℎ
G G
ℎ
𝑣𝐺 𝑣𝐺
𝑣𝐸
𝑣𝑍
𝑑𝐺
Z
𝑡𝐺
𝑡𝑍
𝑡𝐸
𝑑𝐺
′
𝑑𝐺
′
𝑡𝐺
′
E
𝑑𝑍
Length
covered
𝑑𝑍
R Chatopadhyay IITD 24 18](https://image.slidesharecdn.com/2-slubandfancyyarn-250319103938-7dfbb678/85/2-Slub-and-fancy-yarn-description-how-it-work-18-320.jpg)
2-Slub and fancy yarn description how it work
- 1. Slub and Fancyyarn R Chattopadhyay
- 2. Yarn type ImageStructural feature General character Slub yarn Sudden change in yarn thickness over short length Weak, uneven texture, fancy look Gimp yarn Crimpy in nature Weak, uneven texture, fancy look Slub gimp Combination of change in yarn thickness over short length and crimp Weak, uneven texture, fancy look Loop yarn Projecting out loop at regular interval from the core Weak, uneven texture, fancy look Snarl yarn Projecting out twisted yarn end from the yarn body Weak, uneven texture, fancy look Chenille yarn Projecting out fibre ends from the core Weak, uneven texture, bulky in appearance Fancy yarns R Chatopadhyay IITD 24 2
- 3. Slub yarn R ChatopadhyayIITD 24 3
- 4. Slub yarn • Characteristics •yarn is thin and thick, • thick section is called slub, • slub is distribution: regular or random • Parameters of the slub yarn • thickness of the slub, • length of the slub and • the distance between the slubs. • Slub dimension : 1.3 to 1.8 times higher than normal yarn diameter R Chatopadhyay IITD 24 4 (a) Single-component slubs and base yarns. (b) Two-component slubs composed of alterable segments. (c) Two-component slubs and base yarns composed of alterable segments. (d) Three-component slubs composed of alterable segments. (e) Three-component slubs and base yarns composed of alterable segments. (f) Three-component slubs composed of alterable segments and variable compositions.
- 5. Thickness profile ofslub yarn R Chatopadhyay IITD 24 5
- 6. Principle of slubgeneration • Computer control of Drafting system in ring sinning • Slub injection device • It consists of a pair of roller driven aprons which guide the sliver or roving into the front drafting zone. The control system is programmed to stop the aprons when the front roller grip the injected fibres, with the result that a fibre-tuft is pulled into the main effect component. R Chatopadhyay IITD 24 6
- 7. Method • Manipulation ofdrafting • Drive system : five servo motors driving • Three Feed rollers • Apron roller • Middle roller • The 5 servo motors are independent of each other • The rovings are fed to the three feed rollers (1,2,&3) and • Draft between feed and apron rollers can be manipulated separately • Three independent drafting channels can be used to control the blending ratio and linear density. • To realize the variable linear densities along the yarn axis, the speeds of the feed rollers are adjusted • The system response time : 0.001 s. R Chatopadhyay IITD 24 7 Apron roller Middle roller Feed roller
- 8. • Mathematical relationship •Rovings linear density (tex) : 𝜌𝑅1, 𝜌𝑅2, 𝜌𝑅3 • Feed roller speed : 𝑣1, 𝑣2 𝑣3 • 𝑣𝑚 = speed of middle roller • 𝑉 𝑎𝑝 = speed of apron roller • Draft for roving 𝑖 : 𝑒𝑖 = 𝑉𝑎𝑝 𝑣𝑖 … . (1) • Linear density of yarn :𝜌𝑦 = σ1 3 𝜌𝑅𝑖 𝑒𝑖 = σ1 3 𝜌𝑅𝑖 𝑣𝑖 𝑉𝑎𝑝 … (2) • Blend % of roving 𝑖 : (𝑘𝑖) • 𝑘𝑖 = 𝜌𝑅𝑖 ×𝑣𝑖 𝑉𝑎𝑝 σ1 3 𝜌𝑅𝑖 𝑣𝑖 𝑉𝑎𝑝 = 𝜌𝑅𝑖 ×𝑣𝑖 σ1 3 𝜌𝑅𝑖×𝑣𝑖 … . (3) • Changing the speeds of the feed and apron rollers , the linear density of the spun yarn and the blend % and draft ratios of the rovings can be changed. R Chatopadhyay IITD 24 8 𝑣𝑚 𝑉 𝑎𝑝 𝑣1 𝑣2 𝑣3 Middle roller Feed roller Apron roller
- 9. • Yarn twist= 𝑆𝑝𝑖𝑛𝑑𝑙𝑒 𝑠𝑝𝑒𝑒𝑑 𝑦𝑎𝑟𝑛 𝑑𝑒𝑙𝑖𝑣𝑒𝑟𝑦 𝑠𝑝𝑒𝑒𝑑 = 𝑁𝑠𝑝 𝑣𝑑 • To realize the variable linear densities along the yarn axis, the speeds of the feed rollers (𝑉𝑖 ) are altered periodically i.e. Altered speed : 𝑉𝑖 ′ = 𝑉𝑖 + ∆𝑉𝑖 periodically • The linear density of slub yarn ∶ 𝜌′ = 𝜌𝑦0 + ∆𝜌𝑦 • ∆𝜌𝑦 = σ1 3 𝜌𝑅𝑖 ∆𝑉𝑖 𝑉𝑎𝑝 [ rovings are same linear density] • Where, • 𝜌𝑦0 = linear density of the base yarn • ∆𝜌 = the yarn linear density variation. R Chatopadhyay IITD 24 9 Cui P, Xue Y, Liu Y. Manufacturing a ring spun slub yarn using multi-channel drafting technique. Journal of Engineered Fibers and Fabrics. 2020;15. doi:10.1177/1558925020958518
- 10. Slub effect production •Sliver/ roving is fed to the nip of front drafting rollers • Injection unit consist of roller driven aprons that guide the roving into the front drafting zone • The control system is programmed to stop the aprons when the front rollers grip the injected fibres • This results in fibre tufts being pulled into the main effect component and spun into final yarn • Because the slub part • the slub yarn is thicker, • twist added to the slub part during spinning is also less • fibers of the slub segment are looser • dye absorption of the thick and thin sections of the slub yarn is inconsistent when dyeing, depending on the length of the slub. R Chatopadhyay IITD 24 10
- 11. Relationship between Normaland Slub yarn count • 𝐿𝑒𝑡 𝑆𝑙𝑢𝑏 𝑦𝑎𝑟𝑛 𝑐𝑜𝑢𝑛𝑡 = 𝑁𝑒𝑆 • 𝑁𝑒𝑆 = 100 𝑆𝑙𝑢𝑏 𝑓𝑟𝑒𝑒 𝑦𝑎𝑟𝑛 𝑙𝑒𝑛𝑔𝑡ℎ (%) 𝑆𝑙𝑢𝑏 𝑓𝑟𝑒𝑒 𝑦𝑎𝑟𝑛 𝑐𝑜𝑢𝑛𝑡 𝑁𝑒 + 𝑇𝑜𝑡𝑎𝑙 𝑠𝑙𝑢𝑏 𝑙𝑒𝑛𝑔𝑡ℎ % × Τ 𝑠𝑙𝑢𝑏 𝑑𝑖𝑎𝑚𝑡𝑒𝑟 𝑦𝑎𝑟𝑛 𝑑𝑖𝑎𝑚𝑡𝑒𝑟 𝑆𝑙𝑢𝑏 𝑓𝑟𝑒𝑒 𝑦𝑎𝑟𝑛 𝑐𝑜𝑢𝑛𝑡 𝑁𝑒 Example • Let , Slub frequency = 2/m, slub length (𝑙) = 1.5 inch, slub diameter (d ) = 3 times normal yarn diameter. Calculate normal yarn count. • Solution • Number of slubs in 100m = 2 × 100 = 200 • Total length of sub in 100m = 200 × 1.5 = 300 𝑖𝑛𝑐ℎ = 300 39.37 𝑚 = 7.62𝑚 • Slub free yarn length =100𝑚 − 7.62𝑚 = 92.38𝑚 • 30 = 100 92.38 𝑥 + 7.62×3 𝑥 = 100 115.24 𝑥 , 𝑥 = 115.24×30 100 = 34.57 (𝑁𝑒) R Chatopadhyay IITD 24 11 Slub yarn schematic Slub Slub 𝑙 𝐿 𝑑 Normal yarn part
- 12. Fancy yarn R ChatopadhyayIITD 24 12
- 13. Principle • 1st twistingoperation • Fig 1 a. : Two basic threads ( G) are twisted together and thereafter wound around with one or more decorative thread Z • Fig. 1 b: Decorative thread (Z) is twisted into two basic threads G twisted together. • 2nd twisting operation • Twisted threads produced by both methods ( G + Z) is then twisted with additional fixing thread(F) in the opposite direction. • If the rate of delivery of fixing thread (F) is greater than twisted roving , it is wound around (G+Z) by this thread ( II b ) • Fancy twisted yarns E are obtained R Chatopadhyay IITD 24 13 1st twisting stage 2nd twisting stage Z Z F F
- 14. Production • 1st twistingstage: Twist direction : S • Two basic roving /threads (G) are passed to the twisting zone • Leading decorating thread Z is wound in a spiral around the basic threads (G) and covers them to a greater or lesser degree depending upon the twisting condition. • The twist reaches up to the nip of delivery rollers • Decorative thread runs faster than basic threads , no twist are transferred to this. • 2nd Twisting stage: ( Twist direction : Z ) • Twisted roving/ thread (G + Z) and the fixed thread (F) are passed together to the twisting zone maintaining a certain distance . As they are twisted together ( opposite direction ) , they form a fancy yarn • Z twist propagate in both branches of twist triangle. • Fixing thread ( Z twisted ) is further twisted and arrives in fancy twisted yarn in this state. • S-Twisted rovings ( G ) are untwisted and remains in free sate before the point of combination in twist triangle • Decorative thread thereby becomes looser according to degree of untwisting and thereby loops are formed. R Chatopadhyay IITD 24 14 1st twisting stage 2nd Twisting stage S twist Z twist Z F Decorative thread Theoretical principles of fancy yarn twisting: by Erich Marton, Melliand English, E242-243, 8/1987 , Melliand Textileberichte 8/1987, P546- 550
- 15. R Chatopadhyay IITD24 15
- 16. Twisting process • Threadshave circular X section • 𝑡𝐺 ′ = twist in basic thread before delivery • 𝑡𝐺 = twist in basic thread in twisted yarn • 𝑣𝐺= feed speed to twisting point • 𝑣𝐸= delivery speed of yarn • 𝑣𝐸 < 𝑣𝐺 • 𝑣𝑍 = speed of feeding decorative thread • Twist in fancy twisted yarn (𝑡𝐸) 𝑡𝐸 = 𝑛 𝑣𝐸 … (1) • Twist in the basic thread reduces to 𝑡𝐺 = 𝑡𝐺 ′ − 𝑡𝐸 = 𝑡𝐺 ′ − 𝑛 𝑉𝐸 … (2) [ opposite twist direction] R Chatopadhyay IITD 24 16 G G ℎ 𝑣𝐺 𝑣𝐺 𝑣𝐸 𝑣𝑍 𝑑𝐺 Z 𝑡𝐺 𝑡𝑍 𝑡𝐸 𝑑𝐺 ′ 𝑑𝐺 ′ 𝑡𝐺 ′ E
- 17. Relationship • Let • 𝑣𝐸=delivery speed of yarn , • 𝑣𝐺= feed speed to the twisting point , • 𝑣𝑍 = speed of feeding decorative thread • 𝑣𝐸 < 𝑣𝐺 • 𝑖 = 𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑡ℎ𝑒 𝑑𝑒𝑐𝑜𝑟𝑎𝑡𝑖𝑣𝑒 𝑡ℎ𝑟𝑒𝑎𝑑 𝑆𝑝𝑒𝑒𝑑 𝑜𝑓 𝑡𝑤𝑖𝑠𝑡𝑒𝑑 𝑏𝑎𝑠𝑖𝑐 𝑡ℎ𝑟𝑒𝑎𝑑 = 𝑣𝑍 𝑣𝐸 = 𝑙𝑍 ℎ … (3) • 𝑙𝑍= length of decorative thread in one coil, • ℎ = spiral pitch • 𝑙𝑧 2 = ℎ2 + 𝜋2 𝑑𝐺 + 𝑑𝑍 2 … (4) • 𝑑𝐺and 𝑑𝑍 = diameter of yarn formed and decorative thread • Decorative thread (Z) winds around basic thread in spiral form • Dividing by ℎ2: 𝑙𝑧 2 ℎ2 = 1 + 𝜋2 𝑑𝐺+𝑑𝑍 2 ℎ2 … (5) lz 𝜋 𝑑𝐺 + 𝑑𝑍 ℎ G G ℎ 𝑣𝐺 𝑣𝐺 𝑣𝐸 𝑣𝑍 𝑑𝐺 Z 𝑡𝐺 𝑡𝑍 𝑡𝐸 𝑑𝐺 ′ 𝑑𝐺 ′ 𝑡𝐺 ′ E 𝑑𝑍 R Chatopadhyay IITD 24 17
- 18. Degree of coverby decorative thread • 𝑑𝐺 ′ = diameter of basic thread , 𝑑𝑍 = diameter of decorative thread • 𝑡𝑍 = twist in decorative thread • Degree of cover length of basic thread covered by coils of decorative thread to its total length: • 𝜆 = 𝑑𝑍 ℎ = 𝑑𝑍 Τ 𝑣𝐸 𝑛 = 𝑛𝑑𝑍 𝑣𝐸 = ⋯ . (6) • 𝜆 = 1 → 𝑑𝑧 = ℎ 𝑂𝑟 Τ 𝑣𝐸 𝑛 : wrapping would be obtained • 𝜆 < 1 → 𝑑𝑧 < ℎ = Τ 𝑣𝐸 𝑛 ( form spiral) • 𝜆 > 1 : nubs/lump • 𝜆 = ∞ : knots [ since 𝑣𝐸= 0] • 𝜆 = 2 𝑜𝑟 3 : a two/ three layered wrapping is obtained • As 𝜆 increases , the last wrapping layer is incompletely formed, and it gives an uneven appearance. 𝑙𝑧 𝜋 𝑑𝐺 + 𝑑𝑍 ℎ G G ℎ 𝑣𝐺 𝑣𝐺 𝑣𝐸 𝑣𝑍 𝑑𝐺 Z 𝑡𝐺 𝑡𝑍 𝑡𝐸 𝑑𝐺 ′ 𝑑𝐺 ′ 𝑡𝐺 ′ E 𝑑𝑍 Length covered 𝑑𝑍 R Chatopadhyay IITD 24 18
- 19. Various possibilities atconstant speed of decorative thread • 𝜆 = 𝑑𝑍 ℎ = 𝑑𝑍 Τ 𝑣𝐸 𝑛 = 𝑛𝑑𝑍 𝑣𝐸 = ⋯ . (6) • 1 𝜆 = 0 i.e. 𝑣𝐸 = 0 [ No wrapping, A normal twisted yarn is obtained • 2 0 < 𝜆 < 1 with 𝑣𝐸 < 𝑣𝑧 corresponds to spirals • 3. At 𝜆 = 1 means 𝑑𝑍 = ℎ = Τ 𝑣𝐸 𝑛 , a wrapping forms • 4. For fancy twisted yarn speed in the interval 1 < 𝜆 < ∞ : Nubs / lumps form • 5. 𝜆 = ∞ i.e 𝑣𝐸 = 0 , Knots form 𝜆 = 0 𝜆 = 1 𝜆 = 2 𝑇 Normal Normal Knot 𝑣 Spiral Nub 𝜆 = ∞ ℎ 𝑣𝐸 𝑣𝑍 𝑑𝐺 Z 𝑡𝐺 𝑡𝑍 𝑡𝐸 E 𝑑𝑍 Length covered𝑑𝑍 R Chatopadhyay IITD 24 19
- 20.
- 21.
- 22. R Chatopadhyay IITD24 22
- 23. R Chatopadhyay IITD24 23
- 24. • Mathematical relationship •Rovings linear densities ( tex) : ρb1, ρb2, ρb3 • Feed roller speeds : Vb1, Vb2, Vb3. • 𝑉 𝑚 = speed of middle roller • 𝑉𝑓 = speed of apron roller • Draft for roving 𝑖 : 𝑒𝑖 = 𝑉𝑓 𝑉𝑏𝑖 … . (1) • Linear density of yarn : ρ = σ1 3 𝜌𝑏𝑖 𝑒𝑖 = σ1 3 𝜌𝑏𝑖 𝑉𝑏𝑖 𝑉𝑓 … (2) • • Blend % of roving 𝑖 : 𝑘𝑖 = 𝜌𝑏𝑖𝑉𝑏𝑖 𝜌 = 𝜌𝑏𝑖𝑉𝑏𝑖 σ1 3 𝜌𝑏𝑖𝑉𝑏𝑖 … . (3) • Changing the speeds of the feed and apron rollers , the linear density of the spun yarn and the blend % and draft ratios of the rovings can be changed. R Chatopadhyay IITD 24 24 𝑣𝑚 𝑣𝑓 𝑣𝑏1 𝑣𝑏2 𝑣𝑏3
- 25. • Yarn twist= 𝑆𝑝𝑖𝑛𝑑𝑙𝑒 𝑠𝑝𝑒𝑒𝑑 𝑦𝑎𝑟𝑛 𝑑𝑒𝑙𝑖𝑣𝑒𝑟𝑦 𝑠𝑝𝑒𝑒𝑑 = 𝑁𝑠𝑝𝑖𝑛𝑑𝑙𝑒 𝑣𝑑 • To realize the variable linear densities along the yarn axis, the speeds of the feed rollers (𝑉𝑏𝑖 ) are adjusted to a certain extent i.e. 𝑉𝑏𝑖 ′ = 𝑉𝑏𝑖 + ∆𝑉𝑏𝑖 periodically • The linear density of slub yarn ∶ 𝜌′ = 𝜌𝑦0 + ∆𝜌 = σ1 3 𝜌 𝑉𝑓 𝑉𝑏𝑖+∆𝑏𝑖 • Where, • 𝜌𝑦0 = linear density of the base yarn • ∆𝜌 = the yarn linear density variation. R Chatopadhyay IITD 24 25 Cui P, Xue Y, Liu Y. Manufacturing a ring spun slub yarn using multi-channel drafting technique. Journal of Engineered Fibers and Fabrics. 2020;15. doi:10.1177/1558925020958518