Fabric and winding Technology: Introduction of Fabrics and Winding technology.
Fabric and winding Technology: Introduction of Fabrics and Winding technology.
Fabric:
The term fabric can be defined as a planner structure produced by
interlaced/interloped yarns or fibers and felts made by interlocking fibers.
It is a manufactured assembly of fibers and/or yarns that has substantial
surface area in relation to its thickness and sufficient mechanical strength to
give the assembly inherent cohesion. Basically, there are three methods by
which fabrics are made.
Manufacturing:
Manufacturing is the use of Machines, tools and labor to make things for use or sale. The term may refer to a
range of human activity, from handicraft to high tech, but is most commonly applied to Industrial production, in which raw materials are transformed into finished goods on a large scale. Such finished
goods may be used for manufacturing other, more complex products, such as household appliance or automobiles, or sold to whole sales, who in turn sell them to retailers, who then sell them to end users - the "consumers".
Technology:
The word technology comes from the Greek technologia.
A strict definition is elusive; technology can be material
objects of use to humanity, such as machines, but can also encompass broader themes, including system,
methods of organization, and techniques.
The term can either be applied generally or to specific areas:
examples include "construction technology", "medical
technology“, “Textile Technology”.
Classification/
Types of Fabric:
Weaving
machine / loom
- Woven Fabric
Weaving Process
Two sets of yarn
(Interlacing/
Interlacement)
a. Warp/ Ends – Vertical yarn
&
parallel to selvedge.
b.
Weft / Picks – Horizontal Yarn
Knitting
machine
2.
Knitted Fabric
Knitting Process
One set of yarn
(Intermeshing/
Interloping)
3.
Non Woven Fabric
Nonwoven Process Fiber web
(Mechanical/
Chemical / Thermal
Bonding)
Braiding
machine
4.
Braid Fabric
Braiding Process
At least three group of
yarn
(Intertwining/
Diagonal interlacement)
from a
set
Woven Fabric:
- Weaving
is the intersection of two sets of straight yarns, warp and weft, which
cross and interlace at right angles to each other. The lengthwise yarns
are known as warp yarns and widthwise yarns are known as weft or filling
yarns and the fabric produced is known as woven fabric.
- Example: Plain, Twill, Satin/ Sateen
- Application: Denim, Gabardine, Poplin, Drill, Damask etc.
Knitted fabric:
- Knitting
is a process of manufacturing a fabric by the intermeshing of loops of
yarns and the fabric produced by this is known as knitted fabric.
- Example: Single Jersey, Double Jersey
- Application: T-Shirt, Polo-Shirt, Sweater,
Stockings, Shocks, Underwear etc.
Non woven:
- Nonwovens
are a sheet, web or bat of natural and manmade fibers or filaments,
excluding paper, that have been covered into yarns and that are bonded to
each other by any of several means – web formation, web bonding.
- Example: Fusible (interlining), Coated
fabrics, Film fabrics.
- Application: Diapers, sanitary napkins,
industrial musk, bandages etc.
Braid:
- Braid
is one kind of narrow fabric. This kind of fabric is formed on braiding
m/c by interlacing three or more strands of yarn. The process of
interlacing three or more threads in such a way that they cross one
another is laid together in diagonal formation.
- Example: Fire brigade water pipe, shoe
lace, cloth lines, electric wire, ropes etc.
Process
flow chart to manufacturing Woven Fabric:
|
Solid
dyed |
Yarn
dyed |
|
Warp yarn Warping Sizing Drawing/denting Looming Weft yarn Weaving |
Soft winding Yarn dyeing Hard winding Warp yarn
Weft yarn Warping Sizing Drawing/denting Looming Weaving |
Weaving
Preparation:
Yarn is
the basic building block in weaving. Therefore, after yarn manufacturing, the
next successive steps would be to weave the yarn into a fabric. However, in
practice, the condition of yarn produced on the spinning machine is not always
good enough to be used directly for fabric formation. Package size, yarn
surface characteristics, and other factors make it necessary for both weft yarn
and warp yarn to be further processed for efficient fabric formation. These
preparatory processes are called weaving preparation.
Warp
and weft yarns are subjected to different conditions and requirements during
weaving. Therefore, the preparation of warp and weft yarns is different. Warp
yarn is subjected to higher stresses which requires extra preparation. The weft
yarns are not subjected to the same type of stresses as the warp yarns and thus
are easily prepared for the weaving process.
Winding is the major preparation process for weft yarn. Warp preparation includes winding, warping, sizing and drawing-in or tying-in.
Winding
Winding:
Winding
is the process of transferring yarns from ring, bobbin, hank etc. into a
suitable package is called winding. It may be electrical or mechanical.
Warp
Cone, Cheese, Flanged bobbin.
Weft
Pirn, Cop.
Objects
of winding:
·
To transfer yarn from one package to
another suitable package, this can be used for the weaving process.
·
To remove yarn faults like hairiness,
neps, slubs, of foreign matters.
·
To clean yarn.
·
To improve the quality of yarn.
·
To store the yarn.
Requirements of winding:
- Minimum fault: During
winding always should be observed if yarn fault becomes less.
- No damage to yarn: The yarn must
not be damaged in any way in the winding process.
- Easy unwinding: So that yarn
can be wound easily.
- Suitable size and shape of the package: size and
shape should be proper.
- Economical condition: The package
size should be controlled the economical requirements.
- Avoid excess looseness and tightness: Should be
taken care.
- Cheap cost of package: The package
should be cheap.
 |
| Weaving Machine |
Types of Winding:
According to the necessity of yarn dyed:
a.
Soft winding
b.
Hard winding
According to density:
a.
Precision winding
b.
Non-precision winding
According to types of packages:
a.
Cone winding package
b.
Pirn winding package
c.
Flange winding package
d.
Cheese winding package
e.
Cop winding package
According to the build of the package:
a.
Parallel winding
b.
Near parallel winding
c.
Cross winding
According to the methods of drive:
a.
Positive or direct drive.
b.
Negative or friction or Indirect
drive
According to the features automation:
a.
Conventional winding
b.
Modern winding
Soft Winding:
Where the gray yarn is wound onto special “Dye Spring” and the
package (Spool) is made softer and bulkier to make it suitable for dye liquor
penetration in the (package) dyeing machine.
Hard Winding:
Where the gray yarn dyeing machine is converted from spool to
paper cone, to make the yarn easily be fed to the sectional warping machine.
Types Of packages:
1. Parallel wound package
a. Warp beam
b.
Weaver's beam
2. Near parallel wound package
a. Pirn
b. Cop
3. Cross wound package
a.
Cone
b.
Cheese
1.
Parallel wound package / Parallel winding:
These packages are similar to warp beams; there are many yarns, which are parallel to each other. It is necessary to have a flanged package or beam; otherwise the package would not be stable and would collapse. There is no necessity of traversing.
2. Near parallel wound package:
In
this type of package, there is usually one yarn end that is wound on the
package. A near parallel wound package is not self-supported. Therefore, for
stability, the ends of the package need tapering, flanges or shoulders.
3. Cross-wound packages:
A
single yarn end is wound on the package at a considerable helix angel, which is
generally less than 80°. This type of winding provides package stability and
therefore, there is no need to tapper or flange the edges. Thus, a cone or tube
could be used in the winding process.
Winding Process:
There are three main regions in winding; those are shown in the following figure.
a) Unwinding Zone:
Unwinding of yarn from the spinning package - The yarn package is
held in the creel in an optimum position for unwinding.
Yarn withdrawal can be done in two ways-
I.
Side
withdrawal
II.
Over end withdrawal
I.
Side withdrawal:
In this method the spool is rotated and therefore the yarn does
not rotate during withdrawal. As a result, the yarn twist does not change,
which is an advantage.
Since the yarn does not rotate, the spool must rotate for side
withdrawal. This requires additional energy and equipment, which is a
disadvantage.
- Over end withdrawal:
In this system, the spool does not rotate. Therefore, the
problems associated with rotating a spool are avoided. The method
is simple and does not require driving the spool.
The disadvantage of this system is ballooning which is due to the
way the yarn is withdrawn and unwound from the package at high speeds.
Ballooning leads to uneven tensions in the yarn.
In cases where flat yarns of metal, polymer or rubber are used, even one twist is not allowed since yarns must remain flat. These yarns cannot be unwound using the over-end method; therefore, the side withdrawal method must be used.
- Tensioning and clearing zone:
This
region includes –
i.
Tensioning device
ii. Yarn Clearers (Clearing Device)
Tension Device:
The tension device maintains a proper tension in the yarn to
achieve a uniform package density. It also serves as a detector for excessively
weak spots in the yarn that break under the added tension induced by the
tension device.
There are three major types of tension devices;
a.
Capstan (or multiplicative)
b.
Additive tensioner
c.
Combined tensioner
a.
Capstan (or multiplicative):
The output tension depends on the input tension, coefficient of
friction between the yarn and the disc (µ), and the total angle of warp (α):
Tout = Tin eµα
Here,
Tout = Output Tension
Tin = Input Tension
e =
exponential
function and equals to 2.718
µ,α = constants,
If, Tin is zero, so is the Tout
- Additive Tensioner:
According to this type of tensioning device the load is applied in
the form of small discs or other shapes mounted on stationary pegs. The yarn
passes through in between the lowest two discs. The tension is calculated by
multiplying (i) coefficient of friction of the yarn and discs by (ii) the
load applied. The multiplied result is then added to the input tension. Let us
consider a particular case where tension is applied as shown in the figure. The
resultant tension will
Tout = Tin + 2µN where Tout = output tension, Tin is the input + 2µ is the coefficient of
friction between yarn and tensioning device, N is the amount of load applied by
the tensioning device.
Here,
if Tin is
zero, there is still an output tension Tout = 2µN. Tout may be changed simply by
changing the normal force N.
- Combined
tensioner:
This is the most common type, which
consists of at least a disc and capstan type tensioner. Tension is changed by
normal force and warp angle.
Tout = Tin + Tin eµα + 2µN
= Tin (1 + eµα )+ 2µN
Yarn Clearers:
The purpose of a yarn detector is to remove thin and thick places.
Weak places and some of the soft slubs are removed very easily due
to the winding tension but some of the thick faults like hard slubs, embedded
fluff, and piece-ups need to be removed deliberately during winding. The
related arrangements are known as yarn clearer and are described below;
The yarn clearers can be divided as follows
(I)
Mechanical types- conventional blunt blade type
-Serrated
blade type
The mechanical clearers are used in conventional winding machines
- Electronic type-Capacitance type
-Photoelectric
type
The electronic cleaners are used in autoconer or auto splicer or
automatic winders. This is the latest system of detecting and clearing
yarn faults. According to this system all the yarn faults are divided into 23
groups. The clearing system is programmed to detect and clear pre-selected
faults. After clearing of the fault the two ends are joined by applying a
splice in such a way so that it becomes difficult to detect the joined place in
the yarn. The clearing system is also capable of memorizing the statistics of
various types of faults in a particular length of yarn. This statistics acts as
a valuable guide line to control the quality at various stages of spinning.
Savio Winder, an Italian autoconer displays the following information in the
monitor attached to the winder; (i) No package produced, (ii) Efficiency, (iii)
Splices or knots/kg, (iv) Average waiting time for manual adjustment and stops.
Comparison between mechanical and electronic clearers
i.
Electronic clearers are more
sensitive than mechanical clearers
ii.
In case of mechanical clearers there
is abrasion between yarn and clearer parts, but in case of electronic clears no
such abrasion.
iii.
Mechanical clearers do not prevent
some soft slubs from escaping through clearer where as electronic type does not
allow passing any type of fault.
iv.
Mechanical type does not break the
thin places and also the length of the fault is not considered.
v.
Mechanical clearers are simple and
easy to maintain, while the electronic clearers are costly and requires high
standard of maintenance.
C)
Winding Zone:
The winding region - In this region, the yarn package which is
suitable for further processing is wound. Many types of package configurations
can be obtained including cone, tube or cheese, dye tube or spool processing
depending on the next stage of processing.
The basic requirement of winding is uniform tension on the yarn.
Uniform tension is necessary for consistent winding and yarn uniformity with
respect to properties that are functions of tension. If the tension on yarn
passing the tension device is constant, the tension in the package should be constant
provided that the yarn speed is constant, i.e., the tension on the package is
only a function of the yarn speed.
The yarn is wound on the package by only rotating the package. Consider a disc of radius R, rotating at an angular velocity . Then, the Linear velocity (or the tangential speed) of any point on the circumference of the package is:
Winding defects
a.
Formation of patches on the
yarn
b.
Incorrect winding speed
c.
Tension variation
d.
Dirty package
e.
Incorrect shape of package
f.
Too much knots/join in the yarn
g.
Excessive full bobbin
h.
Piecing up
i.
Two ends winding
j.
Mixing of yarns of different linear
density
k.
Pattern winding
l.
Greasy and dirty yarn
m.
Poor yarn clearing and snarling
Wound package faults
i.
Cut cheese
Cause:
-Damaged drum surface
-sharp edges or burns on knotted parts
-bent suction tube shear of
knotter
Effect
on the subsequent processes- (i) increase the stoppage in warping
(ii) Low efficiency
ii.
Stitching or jali formation
This fault refers to the case when
the layers of yarn fall outside the package edge and occurs due to a. large
variation in yarn tension during traverse, b. excessive play of package on
spindle, c. improper setting of traverse restrictor.
iii.
Patterning or ribbon formation:
This fault refers to a case when
successive layers of coils are laid exactly on the previous coil. The reason
for this fault lies with the machine design. If the rotational speed of the
package and that of the traversing unit (drum) is a whole number.
iv.
Soft nose
As the name implies the nose of the
package is soft so that during unwinding there is possibility of slough off.
Apart from this uneven compactness leads to uneven dyeing or dye pick up.
The reason for this fault is
incorrect alignment of the axis of the package with that of the drum affects
uniformity of pressure between the package and the drum across the width of the
package.
v.
Excessive hard package edge:
This fault refers to the condition
when the edges of the package edges are excessively hard due to the reversal of
yarn at these places. The hardness is further enhanced by using high tension
and pressure between the package and the drum. Due to hardness at the two edges
the dye pick up will vary.
vi.
Tendency to slough off:
This fault refers to a condition when several coils like a ribbon are unwound at a time. The main reasons for this type of fault are; a. excessive speed of unwinding, b. improper build and compactness of the rung tube. Slough off ultimately results in end breakage and machine stop.
vii.
Snarls:
This is a twist of loose ends of a
high twisted yarn. Cause: carelessness of the operator in releasing the yarn
after knotting. The main reason for snarling is high yarn twist. Snarls may
either (i) break, or (ii) will go to the final fabric and produce an unsightly
appearance.
viii.
Wild yarn:
These are loose yarns that accumulate
in the guides; tensioners etc. and then adhere with a parent yarn and finally
escape to the fabric. In loom these loose yarn will definitely result in a
break.
Post a Comment