Process%20Control%20in%20Weaving

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Process Control in Weaving
Shri R. P. Tewari International Polytechnic for
Women, New Delhi
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Steps Involved During Weaving Operation
Selection of yarn for warp and weft
purposes Sizing Winding - Spool winding
(for warp) -Pirn winding (for
weft) Preparatory Processes for Sectional
Warping -Creeling -Hecking -Denting
in section guide reed -Leasing Warping on
horizontal drum warping machine Beaming
Drafting arrangement Denting Gait-up the
loom Tie up the loom Weaving
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Selection of Yarn for Warp and Weft Purposes

• Proper selection of yarn by the technical
  supervisor at the institution for warp and
  weft.
• Clear instructions to the weaver (Material
  handling, faults etc)
• Job instruction sheet for a particular design
  should be provided.

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Sizing

• Objectives
• -To reduce the end breakage rate by improving
  the abrasion resistance and also the tensile
  strength of the yarn.
• -To enhance the weavability.
• Precautions
• Use of digital balance.
• Add cold water to the sizing agent.
• Sequence of size preparation
• -Mixing the adhesive component of size with cold
  water.
• -Addition of wetting agent to the adhesive
  component.
• -Mixing the lubricating agent with boiling water
  and then adding it to the mixture of sizing and
  adhesive component.
• -Addition of antiseptic agent to the above.

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-Boiling all the mixed ingredients on slow fire
with continuous stirring. -Continuation of
boiling till the sizing paste becomes transparent
and of constant viscosity. It is checked by
lifting the liquor with the help of a stick. -The
paste is then cooled with continuous stir. -It is
then filtered through fine muslin fabric. -The
boiled and filtered paste is diluted with cold
water to the required volume as per the liquor to
material ratio of 101.
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Confirmation of the readiness of the size paste
Lift the size paste between the thumb and the
forefinger and smudge it for some time. Separate
out the two fingers. Tackiness should be felt
while separating the fingers. Take small amount
of size paste and spread it on a clean glass.
Allow it to dry. A formation of thin film on
drying indicates the good preparation of the size
paste. The absence of tackiness and film
formation indicates that the size paste is not
properly prepared.
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Hank preparation for Sizing
Wetting (use of wetting agent-TRO), Washing and
Cleaning. Conformation of proper wetting Over
and under-squeezing of hanks should be avoided.
Use of hank shaker for squeezing.
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Sizing operation

• Use of rectangular sizing tank in stead of round
  pot.
• Use of cross bars to hang the hanks for sizing.
• Squeeze the sized hank by using hank shaker.
• Over and under-squeezing should be avoided.
• Drying of sized hank
• Drying under direct sunlight should be avoided.
• Avoid spreading the hank on the floor.
• Change the position of hanks time to time.
• Avoid over and under drying of the hanks.
• Give jerks by both the hands to prevent
  entanglement.
• Do not store the sized hanks one over another.
• Hang in a wooden sticks.

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WINDING

•   Spool Winding (For warp)
• Locate the first and the last end of the hank.
• Proper use of swift stand.
• During winding the thread should come out from
  the top side of the swift.
• Location of swift and spool should be parallel
  and right direction with respect to each other .
• The threads should be uniformly distributed in
  the spool and the bobbin should be tightly wound.
  
• The filled bobbin should be stocked one over the
  other in a rectangular container in vertical
  position.

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Clockwise unwinding of hank from swift
Warp Bobbin (Spool)
Swift
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Cross-wound end of filled bobbin
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Pirn Winding (For Weft)

• Proper selection of pirn.
• Pirns should be clean and empty.
• The metallic portion of the pirn (head nose)
  should be rust free.
• Knotting of the thread to the pirn should be
  avoided.
• Pirns should be uniformly and tightly filled up.
• The broken ends should be joined by piecing.
  Knotting should be avoided.
• Over filling of pirn should be avoided.
• Last weft end of the pirn should be crossed
  around the filled pirn (Fig)

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Shape of the filled pirn
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Sectional drum warping
Preparatory processes a) Creeling -The end of
the thread from each bobbin should be released
from the top. -In order to prevent the
entanglement of the broken ends of the thread
tie a strong cord in tight condition on the
center of each section vertically. -Use of over
filled warp bobbin should be avoided. -All the
filled bobbins should be of equal weight and
size.
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b) Hecking -The threads of the creel should be
divided in odd and even series (all the odd
numbered threads should be drawn in to the eye of
the heck heald and all the even numbered threads
should be drawn in to the dent of the heck). c)
Denting in section guide reed -Denting in reed
(threading) should be according to the weave
pattern so that the total width of the warp in
the warp beam should tally to the width of warp
in the actual weaving reed. d) Selection of
appropriate counting device e) Leasing
-Use of leasing reed for cross formation. -Inser
tion of the two lease cord in to the section
should be formed after half metre distance.
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Warping

• -Tension of all the ends in each section must be
  uniform and constant at the time of withdrawal
  from the supply package. Use tension device.
• -Spools should be properly aligned in the creel.
  
• -Maintain the proper sequence of ends by
  aligning the spool in the creel.
• - Routine checking of any interruption in the
  path of warp ends between creel to section guide.
  

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• -Cleaning of complete warping set at regular
  intervals.
• -Tension of all sections should be moderate.
• -Too soft or too tight warping should be
  avoided.
• -Warp beam along with its flanges should be
  carefully handled.
• -The yarn should not be subjected to sharp
  abrasive action to avoid the size removal.
• -Spreading of the yarn throughout the whole
  width of warping must be as uniform as possible.
• -Predetermined length of warping should be
  strictly observed for every section, beam, ball
  or journey of mill warping, as the case may be.

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Beaming

• -The width of the warp ends in the warp beam
  should be equal to the width of the reed. The
  flanges should be fitted at right angles to the
  beam surface and it should be fitted at the
  center in equal distance from both side end of
  the beam.
• -Use of warp beam apron is essential.

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Drafting

• If a new type of fabric is to be woven,
  calculate the total number of heald shafts
  required.
• The total number of heald eyes required in each
  heald frame should be calculated according to
  design patern.
• All the frames should be parallel to each other.
  
• Filled warp beam should be fitted just over the
  heald shafts.
• Proper selection of heald hook required as per
  the need of the heald gauge. A heald hook is
  shown below.

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Denting

• -Appropriate reed count should be selected
  according to the yarn count and the total number
  of ends per centimeter.
• -The denting order should be according to the
  design pattern.
• -The surplus portion of the reed should be
  equally divided in both the sides.
• -Use of reed hook as shown below is required
  instead of heald hook.

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Gait-Up the Loom

• -Warp beam should be accurately fitted in to the
  brackets.
• -All the heald shafts should be joined with the
  shedding device (rollers/pulleys/jacks etc) so
  that their tops are in a straight line
  horizontally.
• -Reed should be properly fitted to the grooves
  (sley groove and reed cap groove)
• -The bottom and the top of the reed should
  completely sink in to the grooves in horizontal
  position.
• -The reed grooves and reed cap grooves should
  not be too wide or too narrow. Otherwise it will
  bend to either side.
• -Discard the use of too old, damaged or rusted
  reed.

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Tie-Up the Loom

• -Each section of the warp should be parallel and
  with equal tension.
• -Each section should tie-up just parallel to the
  reed to the cloth beam.
• -In lieu of the section-tying rod, apron should
  be used.
• -According to the design pattern, required
  number of paddles should be accurately fitted at
  the middle of the loom width.
• -Required number of lamb rods should be
  accurately fitted below parallel to the heald
  frames.
• -All connections (with the paddles, lamb rod and
  shedding device) should be accurately tied up.
• -Everywhere, only slipknots should be used.

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Weaving
Steps involved Shedding Picking Beating-up
Let-off motion and Take-up motion.
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Shedding
Appropriate shedding device should be selected.
-Connecting cords for the shed formation should
be even and strong. -The cords should not be
directly linked with the heald shafts. In lieu of
this the use of loop cord is suggested through
which the connecting cord should pass and should
be tied by slip knot to either side of the heald
shaft. -Connecting cord from the central bottom
of the heald shaft to the paddle should also be
tied by slip knot to the loop cord. -Before
weaving it is important to check the formation of
uniform shed. Instead of using two heald shafts
use four heald shafts.
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• The defective shed formation may be due to
• Incorrect selection of heald wires such as length
  and gauge
• Imbalance connection\on of connecting cords
• Wrong drafting of the warp threads
• Damaged healds
• Broken ends of warp
• Use of undesirable high count of reed
• Uneven tension of the warp threads
• Improper fitting of back rest
• Improper fitting of the reed in to the grooves of
  the sley
• Imbalance level of the shuttle rest board
• Undesirable distance of lease rods
• Uneven pressure through the paddle and
• Improper selection of the shuttle

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PICKING

• Picking should be uniform.
• Too early and too late picking should be avoided.
  
• All connections of the picking cord should be
  well balanced
• The picking cord should be even and strong
• The picking handle should be comfortable.
• Direct connection of picking cord to the picker
  should be avoided. In lieu of this the use of
  loop cord with picker is suggested.
• For proper picking the loom width should be
  according to the width of the fabric to be woven.
• The length of the reed should be equal to the
  distance between sley arms and the reed should be
  fitted parallel to the sley arms.
• For even picking proper selection of shuttle is
  necessary.
• The weft thread pirn should not be too tight or
  too loose.

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• The pirn dimensions (length and circumference)
  should be such that the pirn is properly fitted
  in to the shuttle.
• Shuttle board (Shuttle race) should be smooth and
  even.
• Shuttle holder should be properly fitted to the
  picker. It should not too narrow, too high or too
  thin.
• The use of proper shuttle eyelets is necessary
  for getting desired pick supply.
• The use of fur in the inner wall of shuttle is
  necessary for every fine and smooth weft thread.
• The knots in weft thread should be as minimum as
  possible.

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Beating-up

• Uniform beating force should be applied.
• The beating should be in right angle to the
  fabric. In this regard it is necessary that the
  distance of both side-hanging noses of the sley
  should be in equal distance from the cloth guide
  roller.
• Trembling force should be avoided.
• The beater should be held centrally during
  beating.
• Far shed beating should be avoided.
• Open shed beating should be avoided. In lieu of
  this cross pick beating is suggested.
• The weaver should hold the sley cap from the
  center while giving beating force to the fabric.

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Let-off Motion

• Too much or too little release of the warp
  threads should be avoided.
• The release of warp threads should be uniform.
• The tension on warp threads should be uniform.
• The let off motion device should be in both sides
  of the warp beam.
• The arrangement should be such that the let off
  motion operates automatically.
• The let off and take up motions should match with
  each other.
• Leasing rods should function smoothly.

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Take-up motion

• Winding of the woven fabric should not be too
  tight or too loose.
• After weaving the winding of the fabric should be
  carried out at regular intervals.
• Take up motion device should be easily
  approachable to the weaver.
• If too tight fabric is to be woven, the use of
  tooth wheels for both take up motions and let off
  mechanisms necessary. Otherwise, for normal
  weaving the use of weight system is most
  appropriate.

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Use and Function of Temple
To maintain a constant width of the fabric
parallel to the warp threads.
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Checking the Loom for Errors
The mistakes are -A missed heald eye -A missed
warp yarn. -Crossed drafted and dented
threads -Too many yarns either in a heald eye or
in a dent reed. -Missing dents of the reed.
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Selection of Shuttle
Select shuttles taking in to account the weave
pattern, count of warp and weft, loom make and
reed width. Avoid the use too old shuttle. Avoid
the use of shuttle made of fibrous wood. Avoid
the use of blurred and bended nose shuttles. The
tongue of the shuttle should tightly grip the
pirn. Shuttle eye should not project outside. It
should be within the grip of the wood. The
center of gravity of the shuttle should be
towards the shuttle eye. It can be checked by
holding the shuttle nose across the grip of the
two forefingers. So that it tilts towards the
shuttle eye let.
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Maintenance and care of each part of machine etc.
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Working conditions