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Loom Motions
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Loom Motions
Primary
Secondary
Auxiliary
Prim
ary
mot
ions
Shedding motion
TappetPositive
Negative
DobbyElectrical
Mechanical
JacquardElectrical
Mechanical
Picking motionShuttle
Shuttle less
Projectile
Rapier
Air
WaterBeat Up motionCrank beat up
Cam beat up
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SHEDDINGSeparating the warp threads, which run down the fabric into two layers to form a tunnel known as the shed
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Introduction
o Warp threads are divided into two layers.
o Top layer is called top shed line.
o Bottom layer is called bottom shed line.
o The gap b/w two layers is called shed.
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Objectives
o To raise & lower the healed frames which carry the warp.
o To make an opening for passage of picking media.
o To change the position of warp ends to interlace the warp & weft as per weave.
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Shedding
o Positive sheddingo Raising & lowering of healed frames is with
the help of Double cams.
o Negative sheddingo Lowering of frames is with the help of single
cams & Raising is with the help of reversing media.
o Reversing Mediao The media which brings the frames in original
position, these may be spring, belts & elastic etc.
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Negative Tappet Shedding Mechanism
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Positive Tappet Shedding Mechanism
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Tappet/Cam Shedding
o Healed frames operated by tappet cams
o Cams are designed according to weave structure
o No. of cams depends upon the weave repeat
o Cams are mounted on tappet shaft
o Tappet cam designed for particular weave can not used for other weave
o Storage of cams is necessary in the mill
o Change of cams requires stoppage for long time
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Negative and Positive cam shedding
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Single CamDouble / Conjugate Cam
Advantage Of Tappet Shedding
o Mechanism is simple.
o Initial cost is low.
o Maintenance is easy.
o No problem of design fault in fabric.
o No speed limitations.
o Plain, simple twill & simple satin can be produced.
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Dobby Shedding
o Healed frames are operated by jacks & levers
o Lifting & lowering of frames is controlled by pattern chain
o It can control up to 32 healed frames depending upon the crank shaft length.
o Design possibilities are crepe , honey comb , huckaback , mockleno , bedfordcord etc.
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Positive and Negative Dobbies
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Disadvantage Of Dobby Shedding
o Mechanism is complicated.
o Initial cost is high.
o Maintenance cost is high.
o Can produce design fault in the fabric.
o Limitation in loom speed.
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Jacquard Shedding
o Warp ends are controlled individually by harness cord
o No of cord = No of ends
o No healed frame
o Pattern possibilities are unlimited.
o Complicated designs may be produced like animals, flowers, geometrical figures etc.
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Disadvantage Of Jacquard Shedding
o Mechanism contains more moving parts
o Initial cost is high
o Maintenance cost is high
o Can produce design faults in the fabric
o Design & cutting pattern cords require skilled labour
o Speed limitations
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PICKING
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Shuttle Loom
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Shuttle Loom
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Projectile
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Rapier (Rigid)
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Single Rapier
Double Rapier
Rapier (Flexible)
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Air jet Loom
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BEAT-UP
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Secondary motions
Let off
Take up
Auxiliary Motions
Warp Stop
Weft stop
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