IPPTA Workshop, Saharanpur

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IPPTA Workshop, Saharanpur 29th Oct 2009
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Background

• Historically, forming fabric developments have
  been
• focused on following
• Form a quality sheet
• Convey the sheet from the head box to the press
  section
• Run for an economic life
• Although sheet quality improvements will always
  be a top priority, reducing chemical and energy
  costs, while improving overall machine
  runnability, have become equally important for
  todays papermakers
• Therefore It is today's need to engineer and
  specifically design the fabric to achieve paper
  qualities , mechanical stability, energy
  chemical efficiency and runnability.. in the
  same structure.
• .

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The Perfect Fabric
Formation
Freedom from Marking
Retention
Sheet Release
The Perfect Forming Fabric
Dewatering Characteristics
Stability MDCMD
Wear Resistance
Easy to Keep Clean
Runnability
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Conventional Fabrics

• Single Layer
• Single Layer fabric have one layer of warp (MD
  Yarns) one layer of Weft (CD Yarns)
• Most single layer forming fabrics are woven with
  4 to 5 shed.
• The FSI of single layer fabric ranging from 50
  80.
• The drainage is straight through.
• It is used for all paper grades on low/ medium
  speed smaller width machines.

• Multi Layer
• Multi Layer fabric has one layer of warp yarns
  two or three layers of weft yarns.
• Multi layer design offers high FSI i.e. 100 -134.
• The fabric has greater dimension stability over
  single layer resistance to stretching.
• Higher gentle drainage capacity but at a lower
  rate.
• Multi Layer fabric are mainly available in 7, 8 ,
  14 16 shed.

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Limitations of Conventional Fabrics

• Single Layer Fabrics suffered from.
• Fibre bleeding problems
• Poor sheet surface due to straight through
  drainage
• Double-layer fabrics have significant
  tradeoffs
• Maximizing fiber support can severely retard
  drainage by closing the holes at high mesh
  counts.
• Non-uniform drainage hole sizes and relationships
  in double-layer designs can mark the sheet,
  retard release, and cause fiber carry (run
  dirty).
• Relatively unstable weaves can contribute to
  unsatisfactory CMD profile, especially on long
  unsupported runs and gap formers.
• Relatively low stiffness factors can cause
  excessive deflection into drainage elements,
  thereby increasing drag loads.
• Conventional triple-layer fabrics have their own
  negative attributes..
• The separate stitch yarn can cause non-uniform
  drainage velocity, leading
• to sheet defects (dimple mark).
• These two layers can become unstable and produce
  a sheet with poor profile, slowed overall
  drainage, or can ultimately lead to delamination

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Present Scenario

• Emphasis on improvement of paper quality
• Improvement in printing technologies.
• Rising use of re-cycled fibre in furnishes in
  most paper grades
• More fillers in the sheet
• Highly variable stock quality
• Faster machine speeds
• High Operational Efficiency Demands
• Wider width machine configurations

• Heightened Competition.Pressure on costs

STL.Welcome to the Fourth Generation Fabric
Need for a multi-functional fabric
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• STL Features
• Plain Weave Top
• Homogeneous Structure.
• Very High FSI.
• Low Fabric Thickness.
• Good Dewatering surface.
• High wear volume.
• More dimensional stability.

STL
Shute support Triple Layer the 4th generation
Forming Fabric
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STL Features
In Shute support Triple layer (STL) fabric the
binder yarn binds all the yarns together
spending two-third of its time on the surface of
the fabric, - thus producing a single
homogeneous structure. This ensures a plain
weave paper side surface for optimum sheet
quality a rugged m/c side surface for
extended life potential.
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STL Features
A very high FSI fabric for better paper finish
and good sheet release.

• Improved Retention.
• Improved Formation.
• Smoother Sheet.
• Reduced wire mark
• Better sheet support
• Cleaner fabric
• helps in reducing over-all drag

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STL Features
A large number of small drainage holes with short
frame length for a uniform and high drainage
surface area giving excellent fiber retention
STL
2.5L
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STL Features
An increase in the wear volume from approx. 18
cm3/m2 in standard fabrics, up to approx. 45
cm3/m2 leading to longer life

• Wear Volume is a function of,
• Diameter of CD bottom Yarn,
• Cross machine Crimp differential.
• Number of yarns on bottom side.

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STL...High Dewatering

• A more open machine side
• The fabric cross-section
• is designed for
• a gentle and high dewatering as it creates a
  very open structure on the machine side of the
  fabric
• The principle of the
• inverted funnel

Inverted Funnel Principle.
Open machine side.
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STL...Higher CD stability

• Designed for all high speed twin wire
  operations
• Less width contraction
• Reduced sleaziness/cross direction waves
• Improved guiding behavior.

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STL.....Lower power consumption

• Improved HB freeness yields better
  drainage/reduced vacuum
• To get the same paper properties , better
  retention and formation, STL can use lower
  freeness stock, which also helps in reducing
  refining power.
• Less drag load helps in lesser drive power
  consumption
• Cleaner fabric helps for easy drainage and this
  results in lower power in vacuum pumps

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STL.....
In totality, the well-balanced-dewatering, fine
mesh fabric surface, having an even CD profile,
contributes significantly to the structural
homogeneity of the paper sheet.
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STL...Properties indices
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STL...Few Experiances
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STL...Benifits Expected

• Reduction in Drag load by upto 15 ,
• and remain constant through out the fabric
  life.
• Refining load reduction by upto 10 .
• Improvement in Retention by 3 - 4 .
• Formation improvement by upto 10
• Basis weight profile improvement by upto 20 .
• Saving of retention aid dosage by 50 gms/ton of
  paper
• means if production is 10 tons per hour,
• retention aid would be LESS by 0.50kg/hr
  (saving of appox 10-12 kg/day.)
• Minimise width shrinkage and elimination of
  guiding problem.
• Fabric can run at low shower pressure of 15kg /
  cm2.
• Reduction/elimination of paper breaks in Forming
  Section,
• hence improve runnability and productivity.
• Increased wear volume by 20 (compared to 16 DL
  2.5 layer )
• ie use of STL fabric would mean a reduction of
  consumption from 18 fabrics to 15 fabrics
  annually in a Twin wire M/c plus the time
  saving for 3 fabrics installation.

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STL Forming Fabrics are manufactured on
dedicated, modern, computerised high precision
rapier Projectile looms at our works in Jaipur
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The speed of change can only continue to
accelerate and ...
.we are ready for the challenge

Thanks