SIR Dr. Rafique Ahmed Jhatial
HAMMAMA SOHAIL (11TE47)
PRINCIPLE OF ROTOR SPINNING
FIBER COLLEDTION ON ROTOR
TWIST INSERTION IN ROTOR
• open-end spinning is a technology for creating yarn without
using a spindle.
•It was invented and developed in Czechoslovakia.
•Open End spinning is also known as break spinning or free
•In this process the fibrous material is highly drafted to separate
out the individual fibres. The individual fibres are subsequently
collected onto the open end of the yarn.
•This is rotated to twist the fibre into the yarn structure to form a
continuous strand of yarn.
•This is wound onto a bobbin to form the yarn package.
Advantages of Open End Spinning
•Lower power consumption per unit
quantity of yarn produced
•Higher speed of twist insertion resulting
in very high yarn delivery speed
• A significant resulting increase in productivity.
• Larger delivered package size
• Elimination of some processes such as
roving and winding
• More uniform yarns.
•The first functioning of rotor spinning ,machine was presented at
the ITMA in 1967.
•Yarn spinning according to the rotor spinning principle
predominates for all non conventional spinning methods. It omits
the step of forming a roving. After drafting, the sliver is fed into a
•This device ensures that the fibers are beaten into a thin supply
which enters a duct and gets deposited on the sides of the
•The transportation of the fibers is achieved through air currents.
The fibres are twisted together by the spinning action of the rotor,
and the yarn is continuously drawn from the centre of the rotor.
•The resultant yarn is cleared of any defects and wound onto
•Rotor spinning is a stable spinning process, i.e. it functions trouble-free
under normal spinning conditions, without variations in running behavior
or yarn quality.
•As a rule rotor spinning operates with normal draw frame sliver of a
quality customary in spinning mills. Special preparatory passages, such
as are sometimes necessary for other spinning processes (e.g. air-jet
spinning), are not required here.
•Rotor spinning is appropriate for mill operations in that its technology
can be implemented with relatively simple and robust spinning
•The process imposes no special requirements on the atmosphere in the
spinning mill as regards temperature, humidity and air conditioning and
in many cases is actually less critical in this respect that ring or air-jet
Sliver feed: A card or draw
frame sliver is fed through a
sliver guide via a feed
roller(f) and feed plate (B) to a
rapidly rotating opening
In rotor spinning, a sliver is fed into the opening
unit. The fed sliver is opened into individual fibres
and then the individualised fibres are reassembled,
twisted and wound on a package.
Sliver opening: The rotating teeth of the opening roller
comb out the individual fibers from the sliver clamped
between feed table and feed roller. After leaving the rotating
opening roller, the fibers are fed to the fiber channel
Fibre transport to the
rotor: Centrifugal forces
and a vacuum in the rotor
housing causes the fibers to
disengage at a certain point
from the opening roller and
to move via the fiber channel
to the inside wall of the
Fibre collection in the rotor
groove: The centrifugal forces
in the rapidly rotating rotor
cause the fibers to move from
the conical rotor wall toward
the rotor groove and be
collected there to form a fiber
Yarn formation: The rotor rotates
at high speed creating a centrifugal
force. To start spinning, a length of
yarn already wound onto the
package of the take-up mechanism is
threaded through the nip line of the
delivery rollers and into the draw-off
tube . Because of the vacuum, the
tail end of this yarn is
sucked into the rotor. The rotation of the rotor pulls the
yarn end onto the part collected ribbon of fibres through
the air drag and the centrifugal forces, and simultaneously
inserts twist into the yarn tail. A little of this twist
propagates into that part of the ribbon in contact with the
yarn tail, binding it to the yarn end.
If a yarn breaks, the spinning process is interrupted at the
particular spinning position. Re-starting the spinning
process is called "piecing". The robot "pieces" the newly
spun yarn onto the yarn-end to be found on the package.
Robot locks onto the spinning position with an end
The feed roller starts. Fibers are fed into the rotor
where they form a fiber ring.
The yarn end, prepared by the Robot is "dropped"
into the rotor and connects itself with the fiber ring.
The yarn is withdrawn from the rotor. The fiber
ring is broken and the spinning process starts.
Yarn Take-up and Winding:
Once the yarn tail enters the rotor, the delivery rollers
(K) are set in motion to pull the tail out of the rotor.
The pulling action on the tail results in a peeling of
the fibre ribbon from the rotor groove. The newly
formed yarn (Y) is wound up on a cheese (P) by a
winding drum. A yarn stop motion interrupts material
supply to the opening roller (O) when an end breaks.
Capacitive or optical sensors incorporated in the yarn
path record yarn faults (thick and thin places),
enabling them to be cleared in limits are exceeded.
•Releasing the fibers from the wire of the opening roller and
transporting the fibers through the fiber channel requires a
rather fast air speed.
•Extracting a high amount of dirt requires a rather slow air
speed in the trash-chute.
•The bypass provides an adjustable air opening, next to trash
chute, which allows for adjusting the air speed inside the trash
•A certain amount of air, required to release the fibers from the
wire of the opening roller and for drafting the fiber flow in the
fiber channel, is lead away by the bypass.
•. According to the adjustment of the bypass, the amount of
spinning air entering the trash chute can be reduced. More
trash will be extracted. The amount of trash extracted can be
Bypass open to 50%:
High amount of trash
Carded cotton with
high trash content
Normal setting of trash
Carded cotton with low
amount of trash, and
blends of synthetic
fibers and cotton
Low amount of trash
very clean sliver, for
blends of synthetic
fibers and cotton,
FIBER COLLECTION IN THE ROTOR GROOVE (BACK-
• The process of yarn formation
in rotor spinning involves the
separation by an opening roller
of a fiber bundle fed in into
individual fibers or small groups
•Which are then transported by
the air current into the rotor,
where they slide down the rotor
wall. They are only combined
again into fine layers of fibers in
the rotor groove.
• A layer of these individual fibers is deposited in the
rotor groove with each revolution of the rotor until the
yarn reaches the required thickness. This buildup of fiber
layers to the final yarn thickness is described as back-
doubling, with the number of fiber layers resulting from
the (genuine) yarn twist set and the
diameter/circumference of the rotor used.
•The fibres are finally pressed into the rotor groove with
considerable force due to the high centrifugal
acceleration on the rotor wall and on adjacent fibres, and
are held in this position up to the twist imparting point.
The way in which this fibre sliding phase takes place
from striking the rotor wall to organized fibre deposition
in the rotor groove has a considerable effect on yarn
quality and also spinning stability.
Many parameters affect optimum fibre placement in the
rotor groove, and that all parameters affect each other
mutually. The most important factors exerting influence
in this respect are:
Fibre feed height and direction on the rotor wall
Fibre arrival speed relative to the peripheral speed
of the rotor wall
Fibre and rotor wall coefficient of friction
Rotor wall fibre slip angle (inclination angle)
Rotor speed, rotor diameter.
Fibre placement in the rotor
TWIST INSERTION IN ROTOR SPINNING
•The twisting process in rotor
spinning is different from that
in ring spinning system. In
ring spinning, fibres are
translated from a thin ribbon
to a roughly circular shape.
To spindle Yarn Delivery rollers
•Fibres are gripped at the nip of the front rollers as well as in
the twisted structure. The outermost fibres are strained in
tension and, unless there is excessive yarn tension, the core is
subjected to compression. As the fibres on the outside edges are
under the greatest stress, they are pulled towards the centre,
causing a radial migration in the yarn. The fibres in the central
region are subjected to much lower levels of stress and some
may be slack, allowing migration outward towards the edges.
As a result, the fibres depart from a purely helical conformation
to give an interlocking structure.
•In order to begin spinning, one end of an existing yarn (Y),
is introduced into the rotor through the yarn withdrawal tube.
The free end of the seed yarn is thrown to the peripheral
surface of the rotor by the centrifugal force produced. The
high speed of the rotor causes the yarn end to rotate in the
same direction as the rotor itself. When the rotating end of
the yarn touches the fibres assembled in the rotor groove, it
acts like a crank and twists the yarn section following the
draw-off nozzle outside the rotor. In this way, twist is
produced primarily outside the rotor, between the draw-off
nozzle and the subsequent yarn deflection or yarn nip point.
•In rotor spinning, the fibre
collecting surface, (rotor groove), is
v-shaped and therefore fibres are
usually translated from a triangular
to a circular shape. The fibre
assembly, being formed in the rotor
Yarn in Rotor
•The rotor groove enter as a thin stream of fibres and it takes
many layers to make up sufficient linear density to make a yarn.
there are many doublings, which tend to even out any short-term
irregularities in the yarn. Thus, rotor yarns tend to be more even.
•On the other hand, these doublings have an adverse influence
on the twist structure of the yarn. The first few layers make the
core of the yarn and the other layers twist without any firm link
being established between the layers. Due to the lack of
interlinking, these layers form concentric sleeves. These sleeves
easily slip when the yarn is subjected to a tensile load.
•Apart from the layers, which form the body of the yarn, the
fibres caught by the rotating yarn arm also form a layer.
•These fibres are irregularly distributed throughout the length of
the yarn and wrapped around the yarn with a non-uniform
winding angle and hardness. Thus, the twist in the core is not the
same as in the outer layers.
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