PRINCIPLE OF FUNCTIONS OF DIFFERENT MACHINES USED IN PREPARATORY PROCESSING

1. Pad Dyeing Machinery or Padder or Padding Mangle

A padding machine is an open width machine that can be used for continuous open width or
batch wise treatment of fabric . It is mostly used in continuous processing of fabric, very simply
a padding machine consists of a small trough to Contain the padding liquor and a pair of bowls
or rolls to squeeze the liquor impregnated fabric . The top roll is a soft roll (rubber recovered)
while the lower roll is a relatively hard one, generally of ebonite.
The function of the padder is to remove the excess liquor absorbed by the fabric in the dying
trough by uniformly squeezing the fabric across its entire width.
The important parts of a padding mangle are ––– i) The main frames ii) Tension elements iii)
Padding mangle bowls iv) The dye liquor trough.
The main frames are made of rigid construction to withstand heavy loads and vibrations.
The tension elements consist of a seat of automatic cloth guides , to keep the fabric in a state of
uniform tension without any bowing.
The Padding Mangle Bowls : The mangle bowls are covered with a rubber having surface
hardness in the range 75° to 80° expressed in terms of shore hardness . There may be 2, 3 or 4
bowls depending upon the necessity and the fabric being processed . The lower bowl is usually
the driven roll while the other is capable of being lowered on to or raised away from the bottom
bowl by means of mechanical or pneumatic pressure. When the two bowls are in close contact
and the bottom roll is run, the top roll too rotates due to frictional contact.
The ‘expression’ or pressure of contact between the two balls can be set to any desired level
within the range of the padding mangle being used . As explained, when a padding mangle has
been set to give an ‘expression’ of say 100%, it's simply means that the pressure of contact is
such that a fabric padded with liquor at this setting would have an amount of liquor equal to its
own dry weight in it as it emerges from the mangle. Similarly a mangle giving an expression of
120% would produce a water fabric and so on.
The padding operation consists of the following operations :
1. Dipping or immersing the cloth into the liquor containing dyestuff or other treatment
chemical or composition in order to facilitate the diffusion and penetration of the liquor into
the material . Mainly , it helps to wet and swell the textile material and also remove air from
the materials.
2. Squeezing or mangling the fabric in between the two bowls at the seat pressure to
compress it at the nip and force the liquor into it.
3. Simultaneous transport of textile material in a forward direction.

There are many types of padding mangles. A specific type is preferred depending upon the
fabric to be treated and process being used. Some examples of padding means are listed
below and depicted in figure.
a. Two Bowl Padding Mangle
b. Three Bowl Padding Mangle
c. Four Bowl Padding Mangle.
2. THE J – BOX
The J-Box was coined because of the peculiar shape of the boiling and treatment vessels which
is similar to the English letter J . The J-box is the most important part of a continuous bleaching
plant it provides a strong chamber capable of simultaneously receiving and delivering large
quantities of fabric, while carrying out the pretreatment in the rope form.
The fabric is piled in at the top of the longer limb of the box and after passing through the hot
vertical chamber at a slow speed , it is taken out from the top of the lower limb of the box . The
weight of the fabric coming in from the top of the longer limb causes the bottom portion of the
piled cloth to move steadily along the curved base of the J-box.
J-boxes are provided with very smooth internal surfaces so that the fabric can slide easily down
the box without any friction what so ever. All the joints inside the body of a J-box are very
throughly ground and mirror polished. The constructional features and design of the bottom of
the J-box are standardised with regard to output and the storage time needed to complete the
entire process.
 Types of J-box
The most significant achievement in the design and development of J-boxes took place in thr
late forties and fifties. Of the types of J-box developed, the most-widely known are as follows :
i) The Open type J-box :- This is one developed by Becco Company and
is generally recognised as the Becco type J-box. All the Becco type J-
boxes have open tops.
ii) The Closed-top J-box :- This J-boxes have there top portion closed.
This type was developed by the Do Pont Company.

Working of the J-box

The J-box is an outstanding example of optimising the relationship between time, temperature and
concentration of bleaching chemicals to achieve economically short duration of reaction times. If the
efficacy of a J-box is compared with that of a kier, it will be realised that J-box is the better of the two. In
a kier, dilute concentrations, longer reaction times and high temperature required, while in the J-box
system, there is an advantageous combination of higher concentrations, lower reaction time and lower
temperature compared with the kier process.

Pre-treatment in a Saturator

In the J-box system, the process involves pre-treatment of the incoming wet fabric in a saturating bath
with a relatively concentrated solution of caustic soda. The two squeezing units mounted on the
saturator vessel are so adjusted to provide differential pick-up of the impregnating liquor, such that a
desirable pick-up of caustic soda is attained.

Advantages of J-box Pre-treatment

The J-Box continuous bleaching system has the following processing advantages

a. It achieves a much better bleaching production.

b. It saves processing time.
c. It gives continuously uniform results as against the ‘batches’ resulting from the conventional
methods.
d. The process considerably reduces manpower requirements since it is very much less labour
intensive.
e. It also reduces the total beaching costs.
f. This system is the most effective way to complete the bleaching of a fabric from start to finish
on the same day.

DESCRIPTION AND WORKING OF A KIER

A kier is a cylindrical vessel, generally vertical, capable of holding 1 to 3 tons of cloth. They are provided
with a pressure gauge and a safety valve High-Pressure kiers have a hole at the top through which cloth
is introduced or removed. As the kier is made of iron, a lime wash is given to its inner wall to avoid the
formation of rust stains on the cloth when it comes in contact with the inner wall of the kier.
Loading the Kier

The grey fabric, after desizing, is loaded into the kier in a ‘rope form' by piling it uniformly either by
means of an automatic piler or by manual piling. This is generally achieved by passing a wet fabric in
open-width form through a ‘pot-hole’ shaped stainless steel or porcelain ring of appropriate size.

The Kier should not be filled beyond 80 to 85% of its rated capacity as overfilling may create undue
hydraulic pressure and would also compress the fabric at the top of the kier and hinder the circulation of
the liquor, Thereby increasing the temperature gradient between the top and bottom of the kier.
Conversely too, small quantities of material , very much below the capacity of the Kier, should not be
boiled in a large kier ; The kiet should be at least half full ; otherwise the cloth may turn around due to
the circulating liquor and get hopelessly entangled.

It is most important to ensure even and regular packing of the goods, be it fabric or yarn, in the kier.
Only then will the scouring liquor be able to pass evenly through the material. Uneven piling will cause
‘channeling’.

When scouring yarn in hank form in a kier, there are two ways of handling the yarn. In one, the hanks
are linked together by short lengths of cotton twine to form a continuous chain of hanks that is
convenient to handle as a long ‘rope’. Another way of doing it is to prepare a small, loosely tied bundles
of the hanks and pile them evenly in the kier.

After the material is piled in a kier, heavy stones are placed uniformly on it to prevent it from being
tossed up during boiling and thereby forming channels, which is explained above would lead to an event
scouring result. Clean jute cloth or cotton sheeting may be placed between the material and the stones.
Before it entering the kier, the cloth may be impregnated the alkaline liquor in a trough and mangled to
ensure event treatment of the cloth.

Removal of Air from the Kier

After loading the fabric the clear liquor is let in from the bottom of the kier to sweep out the air inside.
The M:L ratio in a kier is usually 1:4 or 1:5.

Types of fabric mercerising machines

Fabric Mercerising Machines:

There are three types of fabric mercerising machines:

1. Pad Chain Mercerizing Machine

2. Pad Chainless Mercerizing Machine

3. Padless Chainless Mercerizing Machines

1. Pad Chain Mercerizing Machine

A typical clip chain mercerizing machine for woven cloth is shown in Fig. In this type of mercerizing
machine shrinkage is allowed in the primary stage of the process and tension is applied in the later stage
to bring the material to the original dimensions. The cloth is impregnated with cold concentrated caustic
soda solution by passing through padding mangles.

Pad Chain Mercerizing Machine

In between the padding mangles the cloth is passed over timing drums to allow thorough action
of alkali on the cloth. The cloth is led to an open stenter frame for applying tension both the filling and
warp direction. After the cloth has traveled about 20 ft in a stretched condition alkali is rinsed from the
fabric by overflowing water from a series of cascades. The washing on the stenter can be carried out in a
counter current system. The residual alkali concentration should not be more than 8% on the cloth. After
leaving the stenter the cloth passes over compensating rollers which regulate the tension. The cloth is
squeezed and washed. These washing units are the final portion of the mercerizing range and may be a
series of 7 to 8 washers followed by neutralizing washer using either sodium bicarbonate or acetic
acid.

The chain mercerizing machine has one inherent disadvantage. As the force for keeping the
material under tension acts mainly on the outer edges and the line of force diminishes towards the middle,
a greater elongation takes place at the edges than in the middle of the fabric shown in Fig.

Chain Mercerizing Machine

2. Pad Chainless Mercerizing Machine

Diagram shows a traditional chainless mercerizing machine with the roller arrangement. In this
system the fabric is pre stretched, tension is maintained till the mercerizing process and after-washing are
completed. The cloth enters the padding set-up exactly in a similar manner to that of chain type. The cloth
after padding with mercerizing liquor is passed through specially curved and specifically dimensioned
expander rollers which make possible an even expanding effect over the whole width. The expansion
depends on the diameter of the roller, the curvature of the roller as well as the angle of warp.

Pad Chainless Mercerizing Machine

3. Padless Chainless Mercerizing Machines

In padless chainless mercerization machine the fabric is just soaked in NaOH solution and then after
giving dwell time of 40-45 sec stretched on the expander rollers as on chainless machines. Then the fabric
is washed and neutralized.
Hydro Extractor:
Hydro extractor is a machine used in textile processing industry. Hydro-Extractors are
also called Centrifuges. Centrifuges are used for water extraction (dewatering, pre-
drying) of textile materials. Textile centrifugal extractors (hydro extractors) are a robust
spin dryer and normally operate on a batch principal. Values of approximately 15% for
residual moisture content can be achieved depending on the type of textile fiber.

Working Principle of Hydro Extractor Machine:

When using conventional batch hydroextractor, fiber is unloaded from the dyeing
machine into specially designed fabric bags which allow direct crane loading of the
centrifuge. When the perforated drum is revolved, the water is thrown out because of
the centrifugal force. An extraction cycle of 3–5 min reduces the residual moisture
content to approximately 1.0 L/kg dry fiber (in the case of wool). In case of hanks, they
are unloaded directly into the rotating perforated cage. Hydroextraction reduces the
moisture content approximately 0.4 L/kg dry weight. Hydroextraction is used
for drying the washed clothes in domestic washing machines.

Fig: Schematic diagram of Hydro extractor machine

Centrifuges with perforated drums or baskets (Ø up to approx. 2000 mm) which

oscillate vertically in ball-and-socket joints suspended on three points are produced in
various designs as pendulating, suspension, cage and vertical centrifuges, also with so
called gliding support bearings as gliding support centrifuges or in horizontal
respectively vertical arrangements as open-width, horizontal and warp-beam
centrifuges, etc. Most centrifuges have electric drives for speeds of approximately 750–
1200 rpm and are generally provided with automatic control over various ranges. For
safety reasons, an interlocking lid is essential on a centrifuge so that the motor cannot
be started until the lid is locked, nor the lid raised until the basket is stationary again
after the machine has been stopped.

When used for dewatering loose stock, the cake of loose fibers is transferred from the
dyeing machine to the centrifuge and hydro-extracted before it is run into the fiber
opener as a preliminary stage of drying in a perforated drum drier. If an immersion
centrifuge is used, impregnation of the loose fibers with a spinning lubricant is also
possible. In this case, the material is loaded into the centrifuge, liquor is then pumped in
(until it covers the material), and the goods are finally hydro-extracted.

The advantage of such a procedure lies in the fact that a separate treatment of the textile
material in an impregnation vat and the reloading of wet goods into the centrifuge are
eliminated. Impregnation of textile material in the impregnation basket of a centrifuge
is generally quicker and more effective for all processes than in a vat. The centrifugal
force which drives the liquor through the goods during centrifuging accelerates
penetration. It is possible to carry out several processes one after the other in an
immersion centrifuge. In this case, however, separate drain channels and liquor tanks
must be provided.

The basket of an immersion centrifuge has an outer casing without perforations which
surrounds the cylindrical basket of a normal centrifuge (extended conically at the top).
By this means, it is possible to fill it with liquor to the level of the upper rim. Only when
the basket is set in motion does the liquor, which is driven outwards by centrifugal force,
rise up the basket casing and run over the upper rim. Loose fiber material (loose stock)
can also be centrifuged continuously. For the dewatering of yarn packages, other
possible options besides the asymmetrical dewatering of columns of yarn packages in
suitably shaped compartments of the centrifuge include symmetrical dewatering by the
rotation of individual packages or columns of yarn packages which involves less risk of
package deformation.

Technical Data of Hydro Extractor:

▪ Working width 1300mm
▪ Machine speed 5~30M/min
▪ Machine for the hydro extractor, softener, air ballooning type of cotton knitted
tubular fabrics without tension, with fabrics entwisting, air balloon, control of the
squeezing pressure and control of the final width of the fabric.
▪ Automatic control of the feeding without tension, no edge mark, final folding
without stretching. Versions with simple or double squeezing and imbuing with
softeners.

Advantages of Hydro Extractor Machine in Textile:

1. No deformation of the packages.
2. Excellent rewinding properties. Rewinding can even be eliminated in a lot of cases.
3. Low residual moisture.
4. Even humidity distribution through the package.
5. Low energy consumption.
6. Dyeing tubes last longer.
7. Processes many different size packages.
8. Operator of centrifuge can also load dryer.
9. Maintenance-free brakes.
10. Closed system for effluent.
11. Low compressed air consumption.
12. Significant energy savings
 SINGEING

• Objects of Singeing : Singeing is the process of burning off of protruding fibers from the surface
of yarn or fabric in order to improve the lustre and smoothness of material. The ‘fuzz’, as the
protruding fibers are also called, tends to scatter light incident on the yarn or fabric surface and
contributes to a dull appearance of textile material. Removal of fuzz results in a smoother and
more uniform surface that reflects more light and therefore a brighter appearance. Singeing is
also referred as ‘gassing’, specially when yarn is subjected to this process.
• Singeing machines :
Three different types of machine can achieve singeing . These are listed below:
1. Hot plate singeing machine
2. Roller singeing machine
3. Gas singeing machine.
1. Hot Plate Singeing Machine :
This machine consists essentially of two or three carved copper plates that are
kept red hot by means of heating arrangements under them. As shown in figure
, the cloth to be singed, A , is passed, with the aid of guide rollers B, over the
hot plates C (heated by gas burners D) such that the fabric and hot plates are in
continuous contact with each other. An automatic traverse motion is fitted to
the machine so that the plates change their surface of contact with the cloth as
it moves continuously. This helps to prevent cooling of the hot plates due to the
same part coming in contact with the incoming cloth at ambient temperature.
After passing the last hot plate, the cloth is immediately passed through a
water-filled trough E, into which cold water is continuously flowing from inlet
tap F. This ‘quenching’ is to counteract any tendency of hot cloth to catch fire.

Advantages : Hot plate singeing is suitable for back filling finishing process as the fiber ends in the
interstices are not removed.

Disadvantages : 1. Fiber ends in the interstices of warp and waft are not signed. 2. Produces an
undesirable fabric lustre due to the frictional contact with the hot plate . 3. Causes uneven singeing due
to difficulty in maintaining uniform plate temperature.
Roller Singeing Machine

Roller changing is similar to hot plate singeing . Here, instead of hot plate a large cylinder or roller is
used. The inside of the cylinder is heated to maintain its outer surface very hot. As shown in figure, the
cloth to be signed F passes around a guide roller B and then over the heated cylinder A, touching its top .
It then goes around two more guide rollers to pass under the cylinder, touching its bottom. The guide
rollers also serve to keep the fabric under adequate tension. In roller singeing too the cloth is
immediately passed into a trough of cold water E to prevent the hot fabric from catching fire.

The advantages and disadvantages are same as the hot plate singeing machine except that uneven
singeing takes place to our lesser extent in roller singeing.

GAS SINGEING MACHINE

A gas-singeing machine consists essentially of one or more burners that are designed to produce a
continuous, uniform flame by burning a mixture of compressed air and cold or natural gas. The flame
issues form a narrow slit that is adjustable with respect to its width and thickness. When the cloth is
drawn over the flame at high speed , the flame impinges on its surface and burns the protruding fibers
without damaging the cloth. The speed of transmission of cloth through the singeing machine has to be
adjusted to suit the amount of singeing required, without the risk of burning the cloth. The flame is
adjusted to be long enough to ensure that when it impinges on the cloth surface the fiber ends present
in the interstices of the warp and weft threads are also singed.

After passing over the flame , i.e. when the singeing operation is over, the cloth is passed into a trough
of water and then through the nip of a two-row water mangle. This is merely to quench the fabric
immediately and extinguish any sparks of fire or glowing fiber ends. Alternatively, the surface of the
cloth is hit by a sharp spray of water. In order to remove the burnt fibers and exhaust gases, a hood and
exhaust fan are provided over the singeing machine.

• Advantages : Gas-singeing has the following advantages —

a. Both sides of the cloth are singed simultaneously .
b. Uniform singeing of the cloth is obtained .
 c. There is no question of unwanted cloth sheen (lustre) as there is no contact with
any metal surface as in the case of the other singeing machines such as the
roller and plate types of singing machines.
d. Fibres in the interstices between the warp and weft threads are also burnt
effectively. This is not entirely possible in the case of the other singeing
machines.
e. The flame can be controlled so as to be equal to the width of the cloth being
singed.
f. Machine speed can be high and in the range 80 to 125 m/min, a feature not
achievable in the other types of singeing machine .
g. Different varieties of clothes can be conveniently singed.

• Disadvantages : The measure disadvantage of gas-singeing is obviously that there is a great risk
of fire if proper care is not taken on this count. However, any risk of fire can be avoided
completely if
a. The flame is adjusted to be at its optimum size.
b. Careful monitoring of the singeing process is carried out.
c. The necessary fire-fighting equipment is available close at hand.
d. The operators at the machine are properly trained to run the singeing machine and to use
the fire-fighting equipment in an emergency.

The Precautions : The following precautions are vital to safe and proper running of gas-singeing
machines.

i. Arrangements must be provided such that the supply of gas to the burner is automatically turned off
in case the mixture of gas and air does not burn or if, for any reason, the fabric fails to move.

ii. An overhead hood should enclose the machine at the top and an exhaust fan must also be provided.
Otherwise the dashed and fluff caused by the process will hamper operative efficiency.
 iii. Glass windows are fitted the hood such that the flame and fabric are both clearly visible from the
outside.

iv. The fabric taken for singeing is dry.

v. The temperature of the singed cloth surface is measured frequently with the help of a suitable device
such as a thermocouple arrangement.

vi. The speed of the fabric is measured with a speed-monitoring device and the machine is provided
with automatic fabric threading devices .

It must also be borne in mind that the rate of combustion of some fibres is considerably greater than
that of others. For example, the combustion of cellulose fibers is considerably quicker than that of
protein fibre fabrics. Suitable adjustments must be made to the flame size and machine speed for the
inflammable fibres.

Why Gas Singeing is More Popular than Plate and Cylinder

Singeing?

1. The projecting/floating fibers burn better in gas singeing than in

plate or cylinder singeing.
2. Uniform singeing can be done by gas singeing m/c, which is not
possible in plate or cylinder singeing m/c.
3. The smoothness and brightness of the fabric is higher in gas singeing
than in plate or cylinder singeing.
4. The speed of gas flame can be changed according to the types fabric.

5. Production is more in gas singeing than plate or cylinder method.

In gas singeing m/c, singeing is done on both sides of the fabric, on
the other hand only one side is done in plate and cylinder method.
6. Uniform temperature can be maintained in gas singeing.
7. Gas singeing process does not generate excess lusters in the fabric.
Due to the above advantages, gas singeing is more popular than plate or cylinder
singeing methods.

Bio-Polishing:
We usually understand singeing by burning woven fabric but now singeing is also
done on knit fabric and it is done in a complete chemical process. Cellulase
enzymes are used in this chemical process to remove floating fibers from the knit
fabrics. This process is also called biopolishing or enzyme wash as it is done with
the help of bio-chemicals. The basic difference between them is that singeing is a
mechanical & thermal process but bio-polishing is a wet process.

Some Conditions and Recipes of Bio-Polishing:

1. Cellulose enzyme: 1-3%
 2. Wetting Agent: 0.5-1.0 gm/L
3. Acetic acid: 0.5 gm/L
4. pH of Batch: 4.5-5.5
5. Temperature: 40-500C
6. Time: 45-55 min.
7. M: L: 1:10
Mechanism
Cellulose enzymes are located in acidic (pH = 4.5-5.5) medium and at certain
temperature break down the cellulose of the fiber floating from the surface of the
fabric into water soluble glucose. This is how the hairiness of the fabric is
removed. However, processing time is a big issue in case of enzyme washes or
biopolishing, because if enzyme washes are done for a long time, the floating fiber
may run out and damage the yarn. So, by continuous follow-up and checking the
samples, the washes should be kept running till the floating fiber is removed.

Advantages:

1. The process can be completed at low cost.

2. Improves the quality of the fabric.
3. Convenient for cotton fabric because even the micro fibrils of cotton
can be removed.
4. The surface of the fabric is clean.
5. It takes less time so the production is more.
Disadvantages:

1. Eliminates less hairiness than singeing.

2. Only cotton fabric can be processed.

Difference between Singeing and Biopolishing

Singeing Biopolishing

1) Singeing is a
1) Biopolishing is a
mechanical
wet process.
process.
 2) Less hairy fiber
2) More hairy
removed compare
fiber removed
to Singeing.

3) No need of
enzymes, 3) Need enzymes,
wetting agents wetting agents and
or any other other chemicals.
chemicals.

4) High speed 4) Low speed

process. process.

5) Costly
5) Cheap process.
process.

6) Increase
6) Decrease Luster.
luster.