Staple Cotton Spinning Systems

STAPLE / FILAMENT YARN SPINNING SYSTEMS

STAPLE YARNS: Yarns can be made of staple fibres by any one of several techniques The method used is depended upon factors such as: 8. Manufacturers preference of equipment 9. Economic implications 10. Fibres to be used 11. Desired properties of the yarn

The value and character of yarn are determined by 3. Kind and quality of fibre 4. Amount of processing necessary to produce fineness 5. Amount of twist which increases strength in the final yarn Staple spinning Processes: • Conventional ring spinning • Open end spinning or rotor spinning • Friction spinning • Self twist spinning • Electrostatic spinning • Vortex spinning • Air-jet spinning • Twist less spinning (Twilo)

1. Conventional ring spinning: The roved sliver passes through several sets of rollers running at successively higher rates of speed and is finally drawn out to yarn of the size desired Ring spinning is more suitable for the cotton yarn mass production. The highest rpm and constant spinning action provides fast operation. It completes yarn formation through 3 steps. Drawing out the roving Inserting twist Winding the yarn on bobbins

2. Open end spinning (O-E) or rotor or break spinning A relatively recent devpt. in the production of spun yarn This technique is widely accepted as a satisfactory process for spinning coarser yarns of counts of upto about 40 The open end spinning begins with the carded sliver, which Passes through a set of rollers revolving at progressive speeds there by completely opening the sliver.

The fibres are fed individually by a stream of air in to the inner groove of funnel shaped rotor rotating at a very high speed. The centrifugal force of the rotor builds up a multi layer of fibres which is peeled away from the collecting groove as it is simultaneously twisted by the rotation of the rotor and withdrawn continuously, thus being formed in to a yarn.

RING SPINNING

OPEN END SPINNING

Bobbin rotates constantly for insertion of twist

Spool does not need to be rotated to insert twist

Cannot handle spools of bigger size

Much larger spools can be wound

Can spin finer yarns

Can spin coarser/ carded yarns

Faster production

3-5 times faster than ring spinning

Uniform and strong yarn

Uniform but flexible yarn with better dye ability

RING SPINNING

OPEN END SPINNING

Combed yarns (finer)

Carded yarns (coarser)

Yarns for varied applications

Yarns for heavier fabrics such as denims, towels and poplins

Stronger

20% more twisted but 15-20% weaker as the yarn is coarser

Suitable for all staple fibres

Not suitable for man-made staple fibre spinning except rayon as the fibre finish clogs the rotor

• Friction spinning Commercialized under the trade mark DREF It is a variation of the Open end spinning system The principle of the technique is that passing along the longitudinal drum axis a stream of carded fibres in the roll nip of perforated drums, both of which are rotated in the same direction. This action forces the fibres to be wedged along the nip there by becoming compressed; The friction of the rollers cause the fibres to twist around each other

1. Self twist spinning: A process developed for wool and wool like fibres Pairs of rovings are drawn out on a succession of drafting rollers, the last set of which moves sideways causing a rolling action of the strands to wraparound each other Some times additives are used for the cohesion The self twist process can spin worsted yarn of good quality upto 10 times faster than conventional spinning

1. Electrostatic spinning The technique utilises a non uniform electrostatic field which can efficiently separate short staple fibres from the long staples to produce a yarn of more strength and uniformity Twilo: A twist less spinning process, which forms a yarn by temporarily binding the fibres together with an adhesive (water soluble agent) and subsequently removing the adhesive after the yarn has been made in to a fabric

Filament yarn spinning systems: 3. Wet spinning 4. Dry spinning 5. Melt spinning 6. Bicomponent spinning 7. Biconstituent spinning 8. Film splitting 9. Integrated multicomponent yarns 10. Coverspun yarns 11. Selfil tyarns 12. Aerodynamic spinning

Bi component spinning: The technique involves extrusion through a spinneret of two different types of the same polymer There are three methods of bicomponent yarn production 7. Side by side extrusion 8. Extrusion through one spinneret enclosed in an other 9. Distribution of drops of molten polymers

Bicomponent fiber /yarn

Biconstituent spinning: This technique utilizes two different polymers that are combined and extruded in the same manner

Film Splitting: Melt extrusion of polymer through a wide die but with a very narrow slit to form a sheet of film which is later broken /cracked by mechanical means in to a mat of fibres Or embossed with a roller having patterned indentations to fibrillate the film

Integrated multi component yarns: 1. Integrated composite spinning(ICS) The process entails passing a monofilament or a multifilament strand (Carrier) through a poly propylene Polymer (binder resin) and then immediately embedding part of the length of staple fibres in to the polymeric resin Different types of staples of different sizes and colours can be used to incorporate desirable properties, effects and appearances.

2. Cover spun: The technique wraps fine continuous filament man made fibre around a core of untwisted natural or man made staple fibre to produce yarns in a wide range of counts.

Selfil: The self twisted staple core is initially wrapped with a filament yarn in alternating S and Z phases; a second filament yarn is then wrapped around these in alternating opposite Z and S twists.

Aerodynamic Spinning: This system passes a continuous Multi filament yarn together with staple fibre through a Pneumatic device which causes the filaments to twist and curl entrapping the staple fibres in the snarls.

Types and characteristics of yarns: • • • • • •

Single yarns Ply or folded yarns Doubled yarns or compound yarns Cabled yarns or cords Textured yarns: Stretch yarns, Bulk yarns Novelty yarns: • Slub yarns • Flake yarns • Spiral yarns • Ratine yarns • Boucle, Loop or Curl yarns • Nub, Knop, Knot or Spot yarns • Chinelle yarns

Varieties Boucle Loop Gimp Nep Chenille Corkscrew Core spun Metallic

Novelty yarns / Fancy yarns / Complex Yarns ASTM defines fancy yarn as: A yarn that differs significantly from the normal appearance of single or plied yarn due to the presence of irregularities deliberately produced during its formation. In single yarns the irregularities may be due to the inclusion of knots, loops, curls, slubs and the like. In plied yarns, the irregularities may be due to a variable delivery of one or more of its components or twisting together dissimilar single yarns.

Slub yarns: Slub yarns have soft untwisted areas at frequent intervals throughout their length. They are coarse with slight twist, having varying d diameters that show irregularities typical of an incomplete spinning operation Features:

simulates linen yarn not durable used in shantung and tweeds

Flake yarns: Variation of slub yarn The flake or slub effect is made by inserting soft, thick tufts of roving between binder yarns at intervals. Spiral yarns or Cork Screw yarns: The general appearance of spiral yarn is that of a coarse yarn wound around a fine yarn giving the effect of a spiral. The thicker yarn is given a slack twist and wound spirally around a finer yarn which is given a hard twist.

Ratine yarns: A variation of spiral yarn : The outer yarn (effect) and the core yarn are twisted in a spiral manner, but at intervals a longer loop is thrown out by the effect yarn which kinks back on itself and is held in place by a third (binder) yarn. Boucle, Loop or Curl yarns: These yarns are comparable to the ratine yarns but in this type, the yarns are more softer with more pronounced novelty effect or loops

Nub, Knop, Knot or Spot yarns: The effect ply is twisted around the core ply many times within a very short space, causing bumps or nubs that may be spaced at intervals along the yarn. ‘Chenille’ yarns: the name derived from French Caterpillar It is a yarn with a velvet like or pile surface. The effect is achieved by a core of two yarns plied together and firmly holding short tufts of soft-twisted yarns between the twists along the core’s length. A leno weave fabric with soft filling yarns held within the twists of the warp is split in to strips between the warps