Air Jet Loom in Weaving Technology: Definition, Features, working principle, Advantages and Disadvantages

Air Jet Loom in Weaving Technology: Definition, Features, working principle, Advantages and Disadvantages


Air Jet Loom:

Weft insertion by means of air jet has made a major breakthrough in the early 70s and its importance is increasing further because of its ability to weave a wide range of fabrics at a very high speed weft insertion rate of about 2000 mpm. Air jet weaving machines were invented in Czechoslovakia and later refined by the Swiss, Dutch, and Japanese were designed to retain the tension less aspect of the picking action of the water jet while eliminating the problems caused by the use of water.

Scope of Air Jet Loom:
 To insert the weft threads here used compressed air.
 Not suitable for the coarser count or heavier fabric.
 The timing of jet activity should be controlled in such a way that the main nozzle is supplied with compressed air from the beginning of the weft insertion phase and the relay nozzles also receive compressed air.
 High maintenances is needed.

Features of Air Jet Loom:
1. Air jet weaving machine is high speed machine having good quality
2. For instance on a weaving machine having a speed of 600 rpm the weaving cycle is 100m/s.
3. Cam control valves have the advantages of high speed precision of action whilst the electrically controlled solenoid valves permit easy setting.
4. Finer count of yarn is used as the weft thread to produce fancy type of fabric.

Features/SCOPE of AIR JET LOOM
Image source - Google | Image By - Exporters India 





Main Parts of Air Jet Loom for Weft Insertion:

1) Tensioner: Additive Disk Type Tensioner Is Used For Weft Insertion Which Maintain Proper Tension In The Weft Yarn.
2) Weft Break Sensor: It Is An Electric Sensor Which Detect Any Weft Break In The Region Between Weft Package And Accumulator And Automatically Stop The Loom In Case Any Weft Break.
3) Accumulator: It is adevice which fitted between weft package and main nozzle that unwinds a predetermined length of weft from the package and store it in the form of no. of coils on a cylindrical drum. This yarn then fed in to insertion device.
4) Stopper: It is an electronically controlled electromagnetic device integrated along with the accumulator. Its function in releasing the yarn at starts of insertion and stop it at the end of insertion.
5) Balloon Breaker: It is fitted just after accumulator, its function is to separate the balloon formation. So as to reduce as ballooning tension as well as minimize the tension fluctuation. It is generally used for coarser yarn.
6) Fixed Main Nozzle: Its function is to form the air jet from compressed air with the required velocity and acceleration characteristics and project it in a proper direction in to air guide channel.
7) Relay Nozzle Or Sub Nozzle: Fitted in series along the sley. It creates an additional air flow in the direction of air jet. So as to comensate the loss of air velocity.
8) Profile Reed: Here the reed is profiled. So as to form a guide channel which guide the air jet as well as weft during insertion.
9) Weft Cutter: It is cam operated device fitted in the region between the moveable main nozzle and the reed at picking side. Its function is to gripping and cutting the weft after every pick at around beat-up.
10) Air Guide Channel: It is formed on the reed. Its function is guiding and confining the free expansion of the air jet in order to maintain the velocity over larger distance as possible.
11) Weft Detector: It is an optical device fitted at the end of reed at the receiving side. Its function is to check the arrival of weft at the receiving side. In case of late arrival or miss pick, then it sense and automatically stopped the loom.
12) Stretch Nozzle: Located just beside the weft detector. It supplements the effect of enhanced stretching action on the weft by the closely spaced relay nozzle at the end of insert ion. So as to prevent the chance of weft recoiling due to action of stopper.
13) Selvedge Cutter: Located at the receiving side. It is an electronically operated mechanical device which cut the weft yarn extending between fabric and auxiliary selvedge .So as to separate the auxiliary selvedge which is passed out as a waste.

Air jet weaving machines are under constant development. Current research is mainly focused on interaction between air and yarn as well as the guide system to increase the yarn velocity.


INSERTION CONFIGURATIONS, NOZZLES AND YARN FLIGHT IN THE WEFT PASSAGE OF PROFILE REED


The movement of the inserted yarn in weft passage is a complex motion. It is not a positively controlled process. Three different systems have been used on commercial air jet looms:
1. Single nozzle, confusor guides and suction on the other side.
2. Multiple nozzles with guides
3. Relay nozzles with profile reed.

In system 1 a single nozzle is used to insert the yarn with air guide. Confusor wires are placed across the entire width to guide the air stream which is injected into the open shed . Weaving machines with this configuration are of limited reed width (commonly max up to 165 cm) .
In system 2 in addition to the main nozzle relay nozzles are used. They are arranged across the warp width at certain intervals and inject air sequentially and in groups in the direction of yarn movement. System 3 has reed dents built in the reed and relay nozzles (also called subnozzles) across the open warp . With the profile reed, the restriction on warp density also less severe than in the case of the confusor guide system. Although all the three systems have been used on air jet looms, system 3 relay nozzles with profile reed is the standard in the market today.


Air jet filling insertion with open profile reed, Air jet loom
Image source - Google | Image By - aessweb


Displacement of confusor, Air jet loom

Image source - Google | Image By - research paper


Working principle of air jet loom:

The yarn is pulled from the supply package at a constant speed, which is regulated by the rollers, located with the measuring disk just in front of the yarn package. The measuring disk removes a length of yarn appropriate to the width of the fabric being woven. A clamp holds the yarn in an insertion storage area, where an auxiliary air nozzle forms it into the shape of a hairpin.

Image source - Google | Image By - research paper


The main nozzle begins blowing air so that the yarn is set in motion as soon as clamp opens. The hairpin shape is stretched out as the yarn is blown into the guiding channel of the reed with the shed open. The yarn is carried through the shed by the air currents emitted by the relay nozzles along the channel. The initial propulsive force is provided by a main nozzle. Electronically controlled relay nozzles provide additional booster jets to carry the yarn across the shed. The maximum effective width for common air-jet weaving machines is about 165 cm. At the end of the each insertion cycle the clamp closes; the yarn is beaten in, and then cut, after the shed is closed. Again some selvage- forming device is required to provide stability to the edges of the fabric.

These weaving machines use a jet of air to propel the weft yarn through the shed at rates of up to 600 ppm. Date from manufacturers indicate that air-jet looms operate at speed up to 2200 meters of pick inserted per minute. They can weave multicolored yarns to make plaids and are available with both dobby and jacquard patterning mechanism. Air jet weaving is more popular because the machines cost less to purchase, install, operate, and maintain than rapier or projectile weaving machines, and the air jet can be used on a broader variety of yarns than a water jet.






Advantages of Air Jet Loom Over Conventional Loom:

 The conventional loom requires shuttle or shuttle like substance to insert the weft yarn, comparatively in air jet loom there is no need to any kind of shuttle instead of shuttle here the compressed air force is used.
 In the conventional loom the pick insertion rate is very low compare to the air jet loom.
 The weft stop motion is machine controlled over the differ from conventional loom
 In conventional loom the mechanical or hand shuttle reach the weft thread to the fell of the cloth, but in air jet through air force this is done, here uniform let up, take up, uniform picking, uniform beta up is possible.
 It has the automatic weft repair device.


Disadvantages:

 Short or buckle pick
 Loose pick
 Snarling
 Excess dynamic pressure
 Weft stop problem
 Tip problem
 Timing of shed may not be proper
 Too high or too low main nozzle pressure
 Loose left side warp yarn.






Air Jet Loom in Weaving Technology: Definition, Features, working principle, Advantages and Disadvantages Air Jet Loom in Weaving Technology: Definition, Features, working principle, Advantages and Disadvantages Reviewed by Suraj Gupta on May 09, 2020 Rating: 5

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