Monday, March 9, 2020

AIRJET/ VORTEX SPINNING METHOD (A OPEN END SPINNING PROCESS)


AIR-JET SPINNING SYSTEM:

• The production is 2-3 times more than rotor spinning yarn and 10-20 times more than ring frame.

• A yarn delivery rate of 450 metres per minute can be achieved in air jet spinning method. This production rate is much higher than ring spinning system ( 15 - 27 metres per minute) and rotor spinning system ( 130 - 250 metres per minute).

• The twist insertion system in the airjet spinning machine has the capability to insert 200000 turns per minute. This speciality helps to increase the productivity by many times.

• The higher twist insertion rate in this process  makes airjet spinning method  system much cheaper and cost effective than any other yarn  spinning system.

• Since we know  that the twist insertion process in the yarn spinning has an direct and decisive impact on  the rate of production of spinning machine, so that improved rate of production gets achieved just because of very high speed of twist insertion system in airjet spinning process.

• A very high air flow gets used  to impart the twist into the yarn in air jet spinning system.

•  The carded or draw frame sliver gets used as feed material in this system like rotor spinning method.

• This spinning method gets used to spin coarse to medium count of yarn.

• Murata company' of japan and Rieter company of Switzerland have introduced air-jet spinning machines with improved technology which has the capability to  spin  yarn upto  60 s count. Mainly the Polyester or polyester/cotton blends get spun on this machine.

• The yarn getting spun on airjet spinning machine poses low tensile strength in comparison of ring frame and rotor spinning yarn.

• It is mainly used in manufacturing of woven sheeting and knitted lightweight shirting.

•  Theair-jet yarn poses good tenacity, evenness, lower tendency of snarling, and pilling, high stiffness and shrinkage. This yarn has harsh feel.

STRUCTURE AND WORKING PRINCIPLE OF AIR-JET/ VORTEX SPINNING SYSTEM:

• The carded or draw frame sliver is used as fed material in the Murata vortex spinning system.

• The sliver is fed to the drafting arrangement. 4 over 4 drafting arrangement is used in this machine which efficiently perform the drafting action at very high speed without damaging the fibres.

•  Whenthe drafted fibres strand comes out from the front drafting roller, they are drawn into a fibre bundle passage by air suction created by the air nozzle.

• Now the fibre bundle passes between a block of nozzle and a needle holder. The needle holder has a substantially central, longitudinal axis and a guide surface that twists relative to the longitudinal axis. A pin-like guide member attached with the needle holder protrudes toward the inlet of the spindle. From this point fibres are smoothly sucked into a hollow spindle.

• A force of the compressed air at the inlet of the spindle acts and process of twist insertion begins.

• The twisting motion tends to propagate from the spindle toward the front rollers.  Guide member prevents this propagation which temporarily plays a role as the centre fibre bundle.

• The rotational  force of the air jet separates fibres from the bundle, after fibres have left the guide member. Since the leading ends of all fibres are moved forward around the guide member and drawn into the spindle by the preceding portion of fibre bundle being formed into a yarn, they present partial twist and are less affected by the air flow inside the spindle.

• In other words, when the trailing ends of the fibres which have left the front rollers move to a position where they receive the powerfully whirling force of the nozzle, they are separated from the fibre bundle, extend outwardly and twine over the spindle. Subsequently, these fibres are spirally wound around the fibre core and formed into a vortex spun yarn as they are drawn into the spindle.

Twist insertion method in air-jet/vortex spinning:

A high speed air flow gets used to insert twist into the yarn in vortex spinning system. This high speed air flow  helps go increase the rotational speed of the fibre strand. This fibre strand can get rotated at  200, 000 turns/min maximum. In the vortex spinning system, the twist insertion system  is composed of an air-jet nozzle and a hollow spindle with a yarn passage through it. The fibres coming from the front drafting rollers are held together and twisted with the action of the high speed air flow inside the nozzle. The fibres that rotate around the hollow spindle tip attach to the core fibres by wrapping onto them and yarn with a similarly real-twisted structure is formed. The formed yarn is then delivered out of the nozzle through the yarn passage of the hollow spindle with the drag of the delivery rollers and fed to the winding unit.

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