Friction+Spinning Original

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Introduction

Friction (DREF) spinning system is an Open-end

spinning system.

Along with the frictional forces in the spinning zone

the yarn formation takes place.The DREF system is used to produce yarns with high

delivery rate about 300mpm.

It produce a highly uniform yarn from diverse stockincluding short or difficult to handle at high production

rates and low labor and energy expenses.

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Principal of friction spinning

Fibers are delivered onto the drum surface, which

transports and stacks the fibers to the fiber bundle rotating

between two surfaces moving in opposite directions.

The fibers wrap around the bundle surface.wrapped fiber bundle (yarn tail) is tugged by the yarn

delivery roll.

Therefore twists by fiber arrangement are generated.

Due to separate yarn winding and method of twist insertion,

it has capability to go for high production rate.

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Principal of friction spinning system Cont

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Type of DREF spinning

DREF-1

DREF-2

DREF-3

DREF-5

DREF-2000

DREF-3000

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DREF-1

DREF-1 friction spinning system was developed in 1973 by

Dr.Fehrer.A.G. of Austria.

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DREF-2

DREF-2 was exhibited in the year 1975 at ITMA exhibition.

It operates on the basis of mechanical/aerodynamic spinning

system with an internal suction and same direction of drums

rotation.

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DREF-2 Cont Drafted slivers are opened into individual fibers by a rotating

carding drum covered with saw tooth type wire clothing. The individualized fibers are stripped off from the carding

drum by centrifugal force supported by an air stream from theblower.

Fibers are transported into the nip of two perforated frictiondrums where they are held by suction helping in the removalof dust and dirt thereby contributing to production of cleaneryarn.

The fibers are sub-sequentially twisted by mechanical friction

on the surface of the drums. The low yarn strength and the requirement of more number of

fibers in yarn cross-section (minimum 80-100 fibers) wererestricted the DREF-2 spinning with coarser counts (0.3-6s Ne).

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DREF-3

The DREF-3 machine is the next version of DREF-2 forimproving the yarn quality came to the market in the year

1981.

Yarns up to 18s Ne. can be spun through this system.

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DREF-3 Cont

This is a core-sheath type spinning arrangement.

The sheath fibers are attached to the core fibers by the false

twist generated by the rotating action of drums.

Two drafting units are used in this system, one for the corefibers and other for the sheath fibers.

This system produces a variety of core-sheath type structures

and multi-component yarns, through selective combination and

placement of different materials in core and sheath.Delivery rate is about 300 m/min.

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DREF-5

It was developed by Schalafhorst, Suessen and Fehrer.

The range of count to be spun from this system is from 16sto

40sNe.Production speed is up to 200m/min.

This spinning system was not commercialized due to some

reasons.

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DREF-5 Cont

The individualized fibers from a single sliver are fed through a

fiber duct into the spinning nip at an angle to the yarn axis.

They are stretched as far as possible, when fed into the nip.

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DREF-2000

It is the latest development in friction spinning demonstratedin ITMA 99.

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DREF-2000 Cont

DREF-2000 employs a rotating carding drum for opening the

slivers into single fibers and a specially designed system being

used for sliver retention.

The fibers stripped off from front the carding drum by

centrifugal force and carried into the nip of the two perforated

spinning drums.

The fibers are subsequently twisted by mechanical friction on

the surface of the drums.

Drums are rotates in the same direction.

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DREF-3000

In the ITMA 2003, the first public appearance of the DREF 3000

was made.

The yarn can be spun form 0.3Ne to 14.5Ne.

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Yarn formation in Friction spinning system

The mechanism of yarn formation is quite complex. It consists

of three distinct operations.

Feeding of fibers

Fibers integration

Twist insertion.

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Properties of Friction Spun Yarns

Friction spun yarns (DREF) yarns have bulky appearance (100-

140% bulkier than the ring spun yarns)

The twist is not uniform and found with loopy yarn surface.

Usually weak as compared to other yarns.

The yarns possess only 60% of the tenacity of ring-spun yarns

and about 90% of rotor spun-yarns.

The breaking elongation of ring, rotor and friction spun yarns is

equal.

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Properties of Friction Spun Yarns Cont

Depending on the type of fiber, the differences in strength ofthese yarns differ in magnitude.

100% polyester yarns-strength deficiency is 32%

100% viscose yarns-it ranges from 0-25%

In polyester-cotton blend, DREF yarns perform better than theirring-spun counterparts.

70/30% blend yarn-superior in strength by 25%

DREF yarns are inferior in terms of unevenness, imperfections,strength variability and hairiness.

The friction spun yarns are more hairy than the ring spun yarns

DREF yarns are most irregular in terms of twist and lineardensity while ring spun yarns are most even.

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Limitations of Friction spinning system

Low yarn strength and extremely poor fiber orientation made thefriction spun yarns very weak.

The extent of disorientation and buckling of fibers arepredominant with longer and finer fibers.

Friction spun yarns have higher snarling tendency.

High air consumption leads to high power consumption.

The twist variation from surface to core is quite high; this isanother reason for the low yarn strength.

It is difficult to hold spinning conditions as constant.

The spinning system is limited by drafting and fibertransportation speeds.

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Friction+Spinning Original