Grey Departmen & Weaving Finishingt

7/29/2019 Grey Departmen & Weaving Finishingt

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GREY DEPARTMENT:It is the first and the most important department of a wet processing mill. It plays an importantrole in further processing. With the help of 100% inspection the fabric fault are counted and

grading of fabric is done and this grading helps us in fabric selection for a particular task. From

this department the sample of fabric is send to the laboratory for checking the followingparameters:

1 Construction

2 Weight3 Count

4 Weight/m

5 Blend ratio

6 % Of sizeMaterial enters in mill through this department and the flow of material here is as follows:

FUNCTIONS OF GREY DEPARTMENT:Following are the main functions of grey department.

To inspect, mend & grade the fabric.Supply the Grey for further processing.To keep the record of store fabric.

The rejected fabric is sent back to the respected Mill.

INITIAL STORAGE:When Grey is unloaded, the 10% inspection is done at the initial stage, which includes testing ofcounts end and pick & meters of fabric. Then whole delivery is sent for 100% checking, if failed

then sent to non-conforming area or rejection area.

MENDING:This is the portion of the grey department where the faults are removed .The lots after clearingthe 10% inspection is sent in mending department for 100% inspection in which the defect are

identified and counted and some are mended, according to them grading of fabric done.

The grading criterion is:A Grade 6-7% defect

B Grade 10% defect /m

C Grade 12-14% defect /m

NP Grade not printable

R Grade Rejected

The faults, which are present at this stage in a fabric, are of three types.a) Weaving faults.

b) Mending faults.

c) Washable faults.a) WEAVING FAULTS: -

They are the faults, which cannot be removed during mending process. These include:


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JALA: - It is due to the entanglement of warp & weft & their breakage during weaving. It cannot

be removed because of breakage of yarn.

CRACK: It is basically the breakage of weft in the middle i.e. lining in the weft direction.

PATTI: It is due to the stoppage of m/c .Its in the direction of weft

DOUBLE PICK: They produce if somehow weft is inserted twice.

BROKEN PICK: It is due to the breakage of pick.(weft)

MISS PICK: When weft is missing then this is produce.

STARTING MARK: This is the line, which is produced in weft direction due to changing of

beam.

REED MARK: It is usually produce throughout the length of fabric. It is due to the presence of

dent in the reed as gap is producing b/w the warp in this case.

TEMPLE MARK: It is a weaving fault, which arises due to the non-movement of ball & pins ofthe temple in the loom.

CONTAMINATION: The embossed yarn due to uneven twists and appears over surface as a dot.

b) MENDING DEFECTS

: They are known as mending because they can be removed during mending process by combing

(snarls, mis comb and slubs), cutting (h/threads, hole and torn) & application of petrol oremrolex (for the removal of stains). The mending defects include:

SNARLS: It is basically the collection of threads at the surface of fabric. This defect arises bythe slow movement of projectile.

H/THREADS: Hanging thread is the piece of yarn attached to the Grey cloth. This fault isremoved by cutting.

SLUBS: The fibers are in bunch form at the fabric.

MISS COMB: It is the entanglement of the warp & weft, which appears as disturbance over the

surface of fabric.

c) WASHABLE DEFECTS:These include the following:

1. Oily weft2. Oil stains


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FOLDING MACHINE: There are 4 folding machines and piles are made of 1m, only the one

end is fixed while the whole folding is automatically done. Four persons were working at 1

folding machine.

TROLLEY: The trolley is capable of carrying 3000-4000 of fabric. It is moved with the help of a

jack.

STITCHING MACHINE: There were 4 jockey machines in stitching section.

FORK LIFTER: the fork lifter is used for carrying bales, rollers and other things and itsweighing capacity is 2.5-3 tons.

COMPUTER SYSTEM FOR DATA COLLECTION:

7. FIRE FIGHTING SYSTEMEXHAUST SYSTEM

PICK GLASS

WEIGHT OF FABRIC CALCULATION

CALCULATION OF FABRIC CONSTRUCTION:

1. 60x50/22x22 = 60x 25.7/22 + 56x 25.7/22 = 135 gm

Similarly:

2. 76x68/30x30 = 76x 25.7/30 + 68x 25.7/ 30 = 65.106 + 58.25 = 123.359 gm

MANAGEMENT INCHARGE:

Mr. Rizwan

Total workers: 200 Pair of workers: 37

Clerks: 03 Head checker: 10Computer operator: 01 Supervisor: 01

OSTHOFF SINGEING MACHINE (1995)

SINGEING:

Singeing is the process applied to both yarn and fabric to produce an even surface by burning off

projecting fibers, yarn ends and fuzz.

OBJECTS OF SINGEING: Following are the main objects of singeing:

Surface hairs help to trap the air in the fabric when it is immersed in water. This means that it

takes longer time for water to enter the fabric since it must first displace the air. Singeing,therefore, helps to increase the fabric wet ability.

It creates a smooth surface for printing on. It may be possible to print fine details on hairy

surface but once the hair move again after printing the details will become fuzzy.

To emphasize the woven structure of the fabric if that is considered essential.It prevents frosty appearance after dyeing a hairy fabric who has been dyed may have somewhat

a cloudy appearance.

To minimize or prevents the tendency of blend fibers composed of cellulose and synthetic fibersto form pills.


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MACHINARIES USED IN SINGEING PROCESS

The machines that are used in singeing process are:Plate Singeing Machine

Roller Singeing Machine

Gas Singeing Machine.In case of plate singeing machine a plate is red hot and the fabric is passed at a specific distanceand hence the pills reduces. But the draw back is this when fabric passes continuously the plates

get cooled and uneven results occur and hence gas-singeing machines are commonly used in

almost all the mills.

DRAW BACKS OF ROLLER AND PLATE SINGEING MACHINES

Local cooling

Groove formation as the fabric remains in contact with the platesProper maintenance is required

The process is very slow (speed is 60 m/min)

Only single face of the fabric is singed (not in case of roller singeing)

GAS SINGEING MACHINE:

It has the following advantages;

Fabric face and back singe at the same timeEfficient process

No local cooling

Even singeing

There are 2 types of gas singeing machines:

DIRECT HEATING SYSTEM: In this system the fabric is exposed directly against flame. It is

mostly used in industries.INDIRECT HEATING SYSTEM: In this system the fabric is introduced in a heating chamber

against infrared radiation. This system is efficient in case of lightweight fabric.

DESIZING (STEEPING):

As looming process involve stretching so fabric strength should be improved by applying certain

sizing adhesives. These adhesives may be gum, cellulose based compounds or synthetic sizingagents. Industries do not prefer synthetic thickeners because they are expensive and use natural

thickeners, that is, starch. To remove the effect of sizing desizing is done. Main object of

desizing is to attain absorbency of fabric.

TYPES OF DESIZING: The four types of desizing are:

Rot desizing

Acid desizing

Oxidative desizingEnzymatic desizing

ROT DESIZING: In this fabric is soaked in water for 24 hours at room temperature. This is atime consuming process and requires large vats. The results may be uneven from where the


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fabric is not completely dipped in water. Mildew may be developed because of long time dipping

in water.

ACID DESIZING: This is a quicker process and starch easily degrades by acid. The fabric is

soaked in oxalic acid for 3-4 hours. The draw back of this process is cellulose degradation that is,

hydro cellulose formation occurs and hence strength of fabric decreases.

OXIDATIVE DESIZING: Different oxidizing agents for e.g. Hydrogen peroxide, chlorides,

bromides are used. Oxidative desizing is preferred when scouring, bleaching and desizing are

done at a time.

ENZYMATIC DESIZING: Enzymes are the catalysts, which do not participate and takes the

reaction to completion without any increase in temperature. Enzymes are proteinic nature

compounds .At very high temperature the enzyme becomes dead and non-reactive but thestrength of the fabric is not affected and this is the main advantage of this process and therefore,

this is commonly used in industries. The sources of enzymes are malt, bacterial and pancreatic.

In case of bacterial enzymes the pH range is 5.5 to 7 and temperature of 50 to 70C can be beardtherefore these enzymes are preferred in industries.

IMPORATNT PARTS OF MACHINE:

There are 3 singeing machines in Gul Ahmed, which consists of the following parts:

GUIDE ROLLERS: These are used to guide the fabric in open width form to the machine.

BOWING ROLLERS: These are used to make the irregular yarn regular that is, for weft

straightening.

DRYING CYLINDERS: These are used to remove the moisture from the fabric, thus drying itcompletely so that dust, attaching impurities and hanging threads are easily removed which is not

possible in case of moist fabric.

BRUSHING ROLLERS: Two brushes move opposite to the fabric and perform the following

functions:

To remove attached or stick fiber from the fabric.Dust particles and other impurities are also removed.

It is done to avoid hard black residue form on surface of fabric.

Hairs are raised by brushing and thus easily burned.

5. BURNERS: This is the most important part of a singeing machine. It is a direct heating system

that is; the fabric is exposed to flame directly at a high speed.

SPECIFICATIONS:Flame colour: blue (oxidative flame is used)

Fabric speed: 120m/min (also depends on quality)

Burner's temperature: 400-500CPressure on compensators: 2-3 bars


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Burner angle: 180 when fabric is moving at high speed. As the speed of fabric

Decreases (upto 50m/min) the angle becomes 90

Width of fabric: 120 inchesGas consumption: 240-250 cm3 per day

Two rows of burners are provided so that the fabric can be singed from face and back. Watercirculation is also provided in the rollers for their cooling.

COMPENSATORS: They are used to maintain the tension over the running fabric and they work

with the help of pneumatic pressure. They maintain the tension over the fabric by charging anddischarging. Charging is defines as:

DESIZING BATH: It is tank containing desizing liquor for the removal of size so that the fabric

becomes absorbent for further processing. It consists of 8 pair of rollers so that the fabric remainsin contact with the liquor for 5 min. Squeezing rollers are provided after this tank that removes

the extra liquor from the fabric, which comes again into the tank through a tray.

SPECIFICATIONS:

Temperature of the tank: 70C

CHEMICALS:

For PC: NaOH (It acts a s a surfactant)Imrolex (It destroys the size)

For Cotton: Oxalic acid

Sandozen MRN (It acts as a surfactant and wetting agent)The capacity of this tank is 1000 liters, which is usually used to treat 3000m of fabric.

8. MACHINE UTILITIES: the machine utilities are current, water, gas and air.

GOLLER SCOURING AND BLEACHING MACHINE

SCOURING:

All natural impurities in textile fibers other than coloring matter are removed by means ofscouring. The ultimate aim of scouring is to make the material uniformly and highly absorbent in

a cost-effective manner so that there are no difficulties in the later processes of dyeing, printing

and finishing.Natural impurities include:

a. Mineral matters

Oils and waxes

Leaf particlesColoring pigments

Dust

Pectates

a. MINERAL MATTERS:

These are salts of calcium and magnesium present in soil. These are water-soluble and can be

removed easily. If these are not removed from the fabric, spotting occurs on fabric.


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b. OILS AND WAXES: There are two types of oils: Edible oil and Non edible oil

- Edible oils can be removed by sponification that is, they are converted into water-soluble

component with the help of alkali.- Non-edible or lubricating oils are dispersed into fine droplets and remain in suspension and the

process is called emulsification. These oils can also be removed by extraction with organic

solvents.

c. COLOURING PIGMENTS: These are the nitrogen containing compounds (azo group) and

these cannot be removed in scouring but in bleaching.

d. LEAF PARTICLES: These are removed in ginning but if not removed completely they are

dissolved with the help of alkali.

e. DUST: Dust comes from atmosphere and can be removed easily. Dust must be in suspensionform otherwise the removal will not be 100% .So dust removing agents are added which makes

the sand (dust) in suspension.

f. PECTATES: These are long chain carbohydrates, insoluble in water and soluble in alkalis.

Yellowing tint is present on the fabric due to the presence of pectates and also the problem of

absorbency occurs.

BLEACHING:

Scouring removes almost all the impurities of cotton fibers except husk and natural coloring

matters that are ultimately removed by oxidizing agents. The oxidation treatment or bleaching isnecessary for producing white goods as finished products or for dyeing pastel shades. Even for

dark shades, bleaching improves the brilliance and evenness of shade. Bleaching may be

Oxidative or Reductive.

OXIDATIVE BLEACHING: In case of this type of bleaching the process is irreversible that is,

whiteness for always. Oxidative bleaching is done with the help of following bleaching agents.

CHLORINE CONTAINING: Sodium hypovchlorite, calcium hypochlorite and sodium chlorite.OXYGEN CONTAINING: Hydrogen peroxide, sodium peroxide and barium peroxide.

Chlorine containing agents gives more whiteness as compared to oxygen containing but problem

in this is chlorine retention that is, chlorine can not be removed 100% and chlorates forms on thefabric and yellowness appears that is why oxygen containing bleaching agents are preferred.

REDUCTIVE BLEACHING: In case of reductive bleaching the process is reversible that is the

fabric again gets yellow on exposure to air due to the oxygen present in the atmosphere.Reductive bleaching agents are sulfur dioxide, sodium thio-sulphite and Na2S2O8.

For effective bleaching pH, temperature, time, concentration and impurities are to be controlled.

For bleaching the compound must be present in unstable form that is, ionizes easily. Market form

is stable form so the bleach must be converted into unstable form for the process. It is to bechecked what is the stable form of bleach. If it is stable in acidic medium then alkali is added for

instability and vice versa.

SCOURING & BLEACHING: In our project CONTINUOS SCOURING &BLEACHING (one


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step) is carried out for following purposes;

For A High Degree Of Whiteness

Complete Degrading Of Seeds & Removal Of All Impurities Outstanding &Even Absorbency

Low Fiber Damage

Improved Hand Of The Fabric Reproducibility Of Finishing Result High Efficiency

Short Amortization Time

PARTS OF A MACHINE:

PRE WASHING: It is done with pure water at a temperature of 98C to remove the chemicals,

which are applied in the desizing bath. This washing both contains 22m of fabric hover and 8pairs of rollers.

VACO SET: This arrangement is mounted over the machine and is used for sucking extra flufffrom the surface of fabric with the help of vacuum. The vacuum is created by a separate motor

and pump arrangement by maintaining a pressure of150m bar. It consists of a rectangular

ceramic piece having slots in its center throughout the length from where the suction is done. A

wire is provided over the slot and fabric passes between the wire and ceramic piece. The functionof the wire is to block the slot upto the portion other than the width of fabric.

SQUEEZING ROLLERS: Expander is provided before the squeezing rollers. Its function is toremove the creases from the fabric if present. After passing through it, the fabric squeezes by

means of squeezing rollers. The pressure over squeezing rollers is up to 2-3 bars and the pick up

is 65%, but these can be varied according to the type of the fabric. Then the fabric passes over

the bowing roller, its function is to straighten the weft, it is a curved rubber roller, which gets thedrive from the friction of the fabric.

COMPENSATOR: It serves the following three functions:

1: CREASE REMOVAL: Creases are removed by the weight of the compensating roller that is

equal to 25kg. For heavy weight we can even increase the tension by applying the pressure from1bar to 4bar. This is called as charging position, where as for lightweight fabric we can reduce

the tension by applying the negative pressure, which range between 17-12 bars. This is known as

discharge.

2.SYNCHRONIZATION: If the compensator is down, then the speed of the processes following

increases automatically and vice versa.

3: AUTOMATIC STOP: It provides an automatic stop to the machine if the fabric torn out.Total number of compensators used in this machine is 12.

DIP SET#01: This is a tank like arrangement in which we apply the chemical for scouring overthe fabric, thats why it is also known as scouring chemical bath.


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CONSTRUCTION OF DIP SET: It has a special arrangement for the feeding of the chemical

that consists of a narrow tray over which the feeding pipe is provided. When the tray over flow,the chemical falls over the fast moving fabric through out the width. This is done to prevent

staining of the chemical over the fabric. After impregnation of the fabric in the chemical, it

passes between the doctor rolls, they have blade like structures on two sides. This helps tosqueeze the excess liquor.

FEEDING MECHANISM OF DIP SET: The solution of chemical according to the type of fabric

is made in the main or mother tank. From there it is fed to the dip set according to the speed ofthe fabric. To keep the concentration constant, the chemical from the dip set is continuously

removed and mixed with the solution in the mother tank along with fresh chemicals.

STEAMER# 1: Fabric containing the chemical from the dip set enters into the steamer for thecompletion of the reaction. Here the fabric stays for 15min and the temperature is maintained

at102C.

CONSTRUCTION OF STEAMER: It consists of two parts. The upper portion has roller

arrangement while the lower is consists of a roller bed. The fabric after passing through the

roller, stay over the roller bed. Below the roller bed, sump is provided which contains water.

Super heated steam is injected in it, thus water evaporates and saturated steam passes through theroller bed and finally over the fabric. In this way, the temperature of the steamer is maintained at

102C. At the end of the roller bed, mechanical sensors are provided which is star shaped. The

function of the mechanical sensor is that, it touches the roller bed, thus stopping the feeding offabric in the steamer.

INTERMEDIATE WASHING: Just after scouring steamer, two intermediate washing baths are

provided to remove the scouring chemical. Here the washing is done with plane water at 98C.

DIP SET # 02: This is also a chemical tank where the chemicals for bleaching are provided. Its

construction and feeding mechanism are same as of dip set 01.

STEAMER# 02: The function is same as mentioned in steamer 01, the only difference is dwell

time i.e here the fabric remains for 30min and another difference is the type of the sensor i.e herewe use photo cell instead of mechanical sensor.

WASHING TANK: After bleaching 5 washing tanks are provided. The capacity of the4 tanks is

22m fabrics each and the washing in them is done with water at 98C. The 5th tank treats thefabric with acid to get the neutral pH and then do the washing with plain water. Its capacity is

25m fabric. In between each washing tank, expander, squeezing roller, bowing roller and

compensator is provided and their functions are same as mentioned above.

DRYING ARRANGEMENT: 22 drums containing steam are provided in3 rows for the drying

mechanism. After passing through them, fabric comes in to J shaped tray. Just above the J

shaped tray we have moisture meter over the roller, which is in contact with the fabric andmeasures the moisture, which is usually, maintained at6%. One compensator before drying


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drums and one before the J shaped tray is provided to control the speed of the fabric through the

machine.

BATCH MAKING: The fabric after drying is stored over the batcher, which can then be sending

for further processing.

IMPORTANT ASPECTS OF THIS MACHINE:

HEAT RECOVERY SYSTEM: The water in the pre wash is at 98C. It is not wasted but with the

help of the heat recovery system, it is used to increase the temperature of feeding water unto70C. This system is consist of a drum having filler to remove the impurities and the used water

then comes in the large diameter long pipe having pipes of small diameter in it. It carries fresh

feeding water & by the transfer of heat it gets the temperature of about 65-70C, where as the

used water after loosing the heat is disposed off.

WATER RECOVERY SYSTEM: The dirty water is disposed off and the fresh water is feeded to

each washing tank separately. But there is also a special arrangement by means of which thewater is transferred, if it is in the condition to be used, from 7th washing to 6th and then to 5th

and so on by piping system.

MOTOR ARRANGEMENT: There are 22 AC motors provided in the machine these are of twotypes: main motors and auxiliary motors. Main motors are with chain and auxiliary motors have

belts.

RUBBER ROLLERS: Main motors drive all rubber rollers. A separate main motor drives each.

STEEL ROLLER (TOP): auxiliary motors drive these. Many steel rollers are driven by one

single motor.

STEEL ROLLER (BOTTOM): These are driven frictionally by fabric.

BED ROLLS: All are driven by one single main motor.

GOLLER BLEACH SPECIFICATIONS:

PH =7-8

ABSORBANCY: (for printing) 30-40mm.(For dyeing) above 60mm

WHITENESS: PC (both dyeing and printing) above 70

Cotton (for printing) 65-70Cotton (for white) 75

Cotton (for dyeing) 65-70

PROCESS: Desize to bleach wt. Reduction is 12%


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SHRINKAGE: Cotton 17-19%

PC stain 4-5%PC 7-8%

ELONGATION: Cotton 3-5%PC 1-1.5%

MERCERIZE SHRINKAGE: cotton 2%

MACHINE UTILITIES:

1: The machine requires 5 workers during operations.

2: The length of running fabric in it is 500m3: The time of insertion of running fabric is 8 hrs.

4: For about 100000m of fabric

Water needed =275m3Electricity=1078kwh

Steam=44tons

CHEMICALS:For scouring: NaOH liquid 48 Be

Sandozin MRN (wetting agent)

For bleaching: hydrogen peroxide 50%

NaOH liquid 48 Be

Stablical A (stablizer)

Sandozin MRNSirrix 2UD (sequestering agent)

J-BOX

This machine is used for scouring and bleaching in rope forms. In J box the fabric is feeded in

piled form and stored. The J box is well insulated to retain the heat and is lined with steel. It is

used in Gul Ahmad for local dyeing.

ROPE FORM: It can be

1: scour bleach (in old J box)

2: solomatic (new J box)

SCOUR BLEACH (hot boiling) this is also known as boiling off or boil bleach. It includes

scouring and bleaching of the fabric and is done in old J box. The flow of the material throughthis machine is attached in flow chart.


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PARTS:

GREY PITS: The fabric from Osthoff singing machine is stored in grey pits for the completion

of the reaction. There are total 12 chambers in which 8000-10000m of narrow width fabric and5000m of wider width fabric can be stored.

PRE WASHING: This is done with hot water i.e at a temperature of 70C. It consists of 6 pairs of

rollers and about 80-100m of fabric remains in it. After washing, fabric enters in to saturator bypassing through padder rollers.

SATURATOR (scouring tank): This is the portion of the machine where scouring takes place

and all the natural impurities are removed. NaOH is fed from the mother tank whose capacity is1000m where as other chemicals are fed from a separate drum of 500lites. 3-4m of fabric

remains in contact with the chemical for about 3-4 min.

STEAMER# 01: It is a 20 ft high J shaped box whose capacity is about 1200kg and the fabric

remains under 100C for about 2-2.5 hours. The maintenance of J box is done if in any case

staining occurs on the fabric. For this purpose two openings one at the top and other at the

bottom are provided and this maintenance normally takes 8 hrs. From the steamer, the fabricenters into mid washer.

MID WASHER: This consists of two chambers one is for hot washing 70C and other is for coldwashing 30C. This is done to remove the chemicals from the fabric. The problem of dissociation

of hydrogen peroxide can arise at the temperature of 70C so cold washing is provided to keep the

fabric at room temp. The capacity of this washing chamber is 102m.

SATURATOR (bleaching tank): Here the pre mixed chemicals from the mother tank by means

of motor and a pump. The fabric is impregnated in the chemicals for about 3-4min. After it, the

fabric passes through the padder roller to the steamer. The pick up of the fabric depends on thequality but it is normally 90%.

STEAMER #02: This is the second J box and the fabric remains in it for about 1.5-2 hrs so thatthe bleaching reaction completes. The capacity of this J box is about 800kg and the temp here is

100C.

FINAL WASHING: The final washing also consists of hot and cold wash. From here the fabricis stored in white pits. There are total 9 white pits these are called as white pits because the fabric

comes here after bleaching.

SOLOMATIC PROCESS:

This is done in new J box. This process involves only bleaching of the fabric. The flow of the

material in this process is given as:


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Pre washing-------- saturator------------steamer---------- final wash-------- white pits.

PARTS:

PRE WASHING: It consists of six pairs of rollers and has the capacity of holding 120m of fabric

at a time. First hot washing at 70-90C and then cold washing at 30-35C takes place. This is doneto cool down the fabric because the heated fabric is sent to the saturator then due to the increasein temp, hydrogen peroxide dissociates so in normal practice we provide a cold wash to the

fabric so that the reaction takes place at room temperature.

SATURATOR (bleaching tank): The fabric us treated with hydrogen peroxide and NaOH. 3-4m

of fabric remains in contact with the chemical for3-4min.

STEAMER: Here the fabric remains for 1.5hrs under 100C and its capacity is 2600kg. The steamis provided from bottom, mid and top of the J box. There are 3 pressure gauges indicating the

steam pressure and also a temperature indicator, which indicates the temp of steam in the J box.

FINAL WASHING: It also consists of hot and cold washing and is done top removed the

remaining impurities or chemicals after bleaching. Their are4 hot chambers and 2 cold chambers.

After this the fabric gets stored in white pits.

WATER MANGLE

Textile materials require drying after washing that is carried out in two stages. First water is

removed mechanically and then by application of heat. Evaporation of water by heat is expensive

and so maximum quantity of water is extracted by mechanical means, which are

(a). Centrifuging,

(b) Mangling and(c) Suction methods.


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Mangling is the most economical of all the three methods of extraction and its cost is about half

of centrifuging and one third of suction method. Here in Gul Ahmad, there are 2 water mangles.They are distinguished by:

OLD WATER MANGLES NEW WATER MANGLESThis is for narrow width this is for wider width

In this machine only batch formation is possible Pilot as well as batch can be made

The speed is about 50-70m/min its speed is usually 1/3 of the speed Of J box

In this there is no arrangement for neutralization here a trough for the acid isof the fabric. Provided for neutralization.

The flow of the material through water mangle is attached.

WORKING:

The fabric from the white pits enters here through the guide rolls in the form of a rope. At thebeginning of the mangle there is beater rope opener arrangement that helps to open the rope by

continuous rotations. Just after it, expanders are present which will open the fabric width wise

and remove the crease upto some extent. This whole arrangement is repeated twice. Afterpassing through the roller the fabric is dipped in acid then in water trough to maintain the pH.

After passing through bowing, squeezing and finally guide rollers, the fabric moves towards the

drying drums and finally wounded over the batcher or can be stored over pilot.

MERCERIZATION

(GOLLER MERCERIZATION MACHINE)

Mercerization is a very important operation in the cotton wet processing industry and by virtue

of the resultant effects it may be considered both a pre treatment and a finishing process.

Mercerization is the treatment of the fabric with strong caustic soda solution of about 20%

strength. The changes appear on cotton after the treatment is as follows:

1. Shrinkage in area of fabric and length of yarn.

2. Increase in moisture absorption.3. Great increase in dye up take.


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4. Increase in chemical reactivity.

5. Increase in tensile strength of the material.

TYPES OF MERCERIZATION MACHINE: These are of two types:

1. Chain type

2. Chainless type.Chainless machines are normally used in all mills. The differences between the two are asfollows:

CHAIN MACHINES:a. The chain machine gives a better tension control or better mercerization in both the warp and

weft direction and imparts a comparatively better luster to the heavier weight fabrics.

b. The maintenance of the chains is high because these cannot be lubricated and so wears off

rapidly.

CHAINLESS MACHINES:

g. These have a lower capital cost per unit productionh. These machines are more efficient in use of caustic soda and there is a less possibility of

physical damage to the delicate fabrics.

i. Chainless machines have also higher productivity because two or more layers of fabric can be

mercerized simultaneously by placing these side by side or by superimposing one on the other.

IMPORANT PARTS OF MACHINE:

1: CREELING: The fabric is fed in batch form that comes from continuous bleaching and

scouring machine. The fabric passes through the tension rolls and the series of bowing rollers.

There are total 9 bowing rollers for straightening of the weft because the mercerization the fabric

has to swell.

2. MERCERIZATION CHAMBERS: There are three chambers for mercerization containing a

strong lye of 30 Be(299 gm/liter). Here the fabric passes between two rollers in which top one isof rubber and bottom one is of grooved steel. NaOH softens the fabric where as grooved steel

rollers straightens the fabric. There are 4 pairs of rollers in each chamber and each chamber

contains 7m of fabric .The fabric passes through these chambers in 45 seconds at roomtemperature.

3.SQUEEZING ROLLERS: There are 4 squeezing rollers having 75% pick up and the pressure

applied on these rollers is 4 bars.

4.STABLIZATION CHAMBER: There are 4 stabilization chambers containing weak lye of 7-8

Be and the dip time is 60 seconds. This is done for permanent straightening of the fabric. Here

also 7m of fabric are present in each chamber and the temperature of the chamber is 85C. Afterthis the fabric passes through squeezing rollers (5 bar pressure and pick up=80%) to the batcher

and then to the washing pad steam water mangle.

There are 2 mercerization machines in Gul Ahmed .One (new model 1999) is for wider width(3.2m) and the other (old model 1965) is for narrow width (1.6m). The old machine also contains


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the washing chambers whereas the new one does not.

LYE PREPARATION:Strong lye (NaOH) is feeded from a mother tank (1000liters) to a bottom dip tank of 2500 liters

from where the lye is pumped to the mercerization chamber. The concentration of caustic soda is

controlled automatically. For filtration of caustic, a round filter is provided. To prepare weal lyefor stabilization chamber 4.5 liters/kg of water is provided before the second set of squeezingrollers so that the concentration decreases upto 7-8 Be and then pumped by means of 16 pumps

to the stabilization chamber.

CAUSTIC RECOVERY UNIT (CRU)

During the process of mercerization we use a large amount of caustic whose initial concentration

is 30 Be and is reduced to 7-8 Be in the stabilization chamber. For reduction of concentration we

add a large amount of water i.e 4.5lit/kg. If this dilute solution is wasted directly to the sewagethen a large amount of caustic will waste. To overcome this problem we use CRU.

It is a unit where caustic is recovered by a simple process of evaporation.

WORKING:

Caustic from mercerization chamber is pumped to the pre filter that is made of nylon and then

enters into buffer tank for storage. After reaching a certain level caustic passes to the heat

exchanger where it is heated by exchanging heat with hot water and then comes into evaporator.Steam is supplied in first evaporator for evaporation. In evaporator the caustic circulates in pipes

where as steam is in surrounding. When caustic begins to evaporate it passes to the separator

where the vapors being lighter goes up where as caustic enters into second evaporator. Thisevaporator is heated by means of paper present in separator. This process is repeated one more

time so that the water separates completely. Then the required concentration of caustic is

obtained i.e 30Bu (specific gravity 1.26) the caustic enters into the lye cooler above which a heat

exchanger is provided in which cold water circulates and hence the caustic cools down.A sensor called lye measurement sensor (LMS) controls the conc. of caustic. After reaching a

certain level in lye cooler caustic is stored in concentrate tank. From here the caustic again pass

to the mercerization tank.OSTHOFF SINGEING MACHINE (1995)

SINGEING:Singeing is the process applied to both yarn and fabric to produce an even surface by burning off

projecting fibers, yarn ends and fuzz.

OBJECTS OF SINGEING: Following are the main objects of singeing:Surface hairs help to trap the air in the fabric when it is immersed in water. This means that it

takes longer time for water to enter the fabric since it must first displace the air. Singeing,

therefore, helps to increase the fabric wet ability.

It creates a smooth surface for printing on. It may be possible to print fine details on hairysurface but once the hair move again after printing the details will become fuzzy.

To emphasize the woven structure of the fabric if that is considered essential.

It prevents frosty appearance after dyeing a hairy fabric who has been dyed may have somewhata cloudy appearance.


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To minimize or prevents the tendency of blend fibers composed of cellulose and synthetic fibers

to form pills.

MACHINARIES USED IN SINGEING PROCESS

The machines that are used in singeing process are:

Plate Singeing MachineRoller Singeing MachineGas Singeing Machine.

In case of plate singeing machine a plate is red hot and the fabric is passed at a specific distance

and hence the pills reduces. But the draw back is this when fabric passes continuously the platesget cooled and uneven results occur and hence gas-singeing machines are commonly used in

almost all the mills.

DRAW BACKS OF ROLLER AND PLATE SINGEING MACHINESLocal cooling

Groove formation as the fabric remains in contact with the plates

Proper maintenance is requiredThe process is very slow (speed is 60 m/min)

Only single face of the fabric is singed (not in case of roller singeing)

GAS SINGEING MACHINE:It has the following advantages;

Fabric face and back singe at the same time

Efficient processNo local cooling

Even singeing

There are 2 types of gas singeing machines:DIRECT HEATING SYSTEM: In this system the fabric is exposed directly against flame. It is

mostly used in industries.

INDIRECT HEATING SYSTEM: In this system the fabric is introduced in a heating chamberagainst infrared radiation. This system is efficient in case of lightweight fabric.

DESIZING (STEEPING):As looming process involve stretching so fabric strength should be improved by applying certain

sizing adhesives. These adhesives may be gum, cellulose based compounds or synthetic sizing

agents. Industries do not prefer synthetic thickeners because they are expensive and use natural

thickeners, that is, starch. To remove the effect of sizing desizing is done. Main object ofdesizing is to attain absorbency of fabric.

TYPES OF DESIZING: The four types of desizing are:

Rot desizingAcid desizing

Oxidative desizing

Enzymatic desizing


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ROT DESIZING: In this fabric is soaked in water for 24 hours at room temperature. This is a

time consuming process and requires large vats. The results may be uneven from where the

fabric is not completely dipped in water. Mildew may be developed because of long time dippingin water.

ACID DESIZING: This is a quicker process and starch easily degrades by acid. The fabric issoaked in oxalic acid for 3-4 hours. The draw back of this process is cellulose degradation that is,hydro cellulose formation occurs and hence strength of fabric decreases.

OXIDATIVE DESIZING: Different oxidizing agents for e.g. Hydrogen peroxide, chlorides,bromides are used. Oxidative desizing is preferred when scouring, bleaching and desizing are

done at a time.

ENZYMATIC DESIZING: Enzymes are the catalysts, which do not participate and takes thereaction to completion without any increase in temperature. Enzymes are proteinic nature

compounds .At very high temperature the enzyme becomes dead and non-reactive but the

strength of the fabric is not affected and this is the main advantage of this process and therefore,this is commonly used in industries. The sources of enzymes are malt, bacterial and pancreatic.

In case of bacterial enzymes the pH range is 5.5 to 7 and temperature of 50 to 70C can be beard

therefore these enzymes are preferred in industries.

IMPORATNT PARTS OF MACHINE:

There are 3 singeing machines in Gul Ahmed, which consists of the following parts:

GUIDE ROLLERS: These are used to guide the fabric in open width form to the machine.

BOWING ROLLERS: These are used to make the irregular yarn regular that is, for weft

straightening.

DRYING CYLINDERS: These are used to remove the moisture from the fabric, thus drying it

completely so that dust, attaching impurities and hanging threads are easily removed which is notpossible in case of moist fabric.

BRUSHING ROLLERS: Two brushes move opposite to the fabric and perform the followingfunctions:

To remove attached or stick fiber from the fabric.

Dust particles and other impurities are also removed.

It is done to avoid hard black residue form on surface of fabric.Hairs are raised by brushing and thus easily burned.

5. BURNERS: This is the most important part of a singeing machine. It is a direct heating system

that is; the fabric is exposed to flame directly at a high speed.

SPECIFICATIONS:

Flame colour: blue (oxidative flame is used)Fabric speed: 120m/min (also depends on quality)


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Burner's temperature: 400-500C

Pressure on compensators: 2-3 bars

Burner angle: 180 when fabric is moving at high speed. As the speed of fabricDecreases (upto 50m/min) the angle becomes 90

Width of fabric: 120 inches

Gas consumption: 240-250 cm3 per day

Two rows of burners are provided so that the fabric can be singed from face and back. Water

circulation is also provided in the rollers for their cooling.

COMPENSATORS: They are used to maintain the tension over the running fabric and they work

with the help of pneumatic pressure. They maintain the tension over the fabric by charging and

discharging. Charging is defines as:

DESIZING BATH: It is tank containing desizing liquor for the removal of size so that the fabric

becomes absorbent for further processing. It consists of 8 pair of rollers so that the fabric remains

in contact with the liquor for 5 min. Squeezing rollers are provided after this tank that removesthe extra liquor from the fabric, which comes again into the tank through a tray.

SPECIFICATIONS:

Temperature of the tank: 70CCHEMICALS:

For PC: NaOH (It acts a s a surfactant)

Imrolex (It destroys the size)For Cotton: Oxalic acid

Sandozen MRN (It acts as a surfactant and wetting agent)

The capacity of this tank is 1000 liters, which is usually used to treat 3000m of fabric.

8. MACHINE UTILITIES: the machine utilities are current, water, gas and air.

GOLLER SCOURING AND BLEACHING MACHINE

SCOURING:

All natural impurities in textile fibers other than coloring matter are removed by means of

scouring. The ultimate aim of scouring is to make the material uniformly and highly absorbent ina cost-effective manner so that there are no difficulties in the later processes of dyeing, printing

and finishing.

Natural impurities include:

a. Mineral mattersOils and waxes

Leaf particles

Coloring pigments

DustPectates

a. MINERAL MATTERS:These are salts of calcium and magnesium present in soil. These are water-soluble and can be


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removed easily. If these are not removed from the fabric, spotting occurs on fabric.

b. OILS AND WAXES: There are two types of oils: Edible oil and Non edible oil- Edible oils can be removed by sponification that is, they are converted into water-soluble

component with the help of alkali.

- Non-edible or lubricating oils are dispersed into fine droplets and remain in suspension and theprocess is called emulsification. These oils can also be removed by extraction with organicsolvents.

c. COLOURING PIGMENTS: These are the nitrogen containing compounds (azo group) andthese cannot be removed in scouring but in bleaching.

d. LEAF PARTICLES: These are removed in ginning but if not removed completely they are

dissolved with the help of alkali.

e. DUST: Dust comes from atmosphere and can be removed easily. Dust must be in suspension

form otherwise the removal will not be 100% .So dust removing agents are added which makesthe sand (dust) in suspension.

f. PECTATES: These are long chain carbohydrates, insoluble in water and soluble in alkalis.

Yellowing tint is present on the fabric due to the presence of pectates and also the problem ofabsorbency occurs.

BLEACHING:Scouring removes almost all the impurities of cotton fibers except husk and natural coloring

matters that are ultimately removed by oxidizing agents. The oxidation treatment or bleaching is

necessary for producing white goods as finished products or for dyeing pastel shades. Even for

dark shades, bleaching improves the brilliance and evenness of shade. Bleaching may beOxidative or Reductive.

OXIDATIVE BLEACHING: In case of this type of bleaching the process is irreversible that is,whiteness for always. Oxidative bleaching is done with the help of following bleaching agents.

CHLORINE CONTAINING: Sodium hypovchlorite, calcium hypochlorite and sodium chlorite.

OXYGEN CONTAINING: Hydrogen peroxide, sodium peroxide and barium peroxide.Chlorine containing agents gives more whiteness as compared to oxygen containing but problem

in this is chlorine retention that is, chlorine can not be removed 100% and chlorates forms on the

fabric and yellowness appears that is why oxygen containing bleaching agents are preferred.

REDUCTIVE BLEACHING: In case of reductive bleaching the process is reversible that is the

fabric again gets yellow on exposure to air due to the oxygen present in the atmosphere.

Reductive bleaching agents are sulfur dioxide, sodium thio-sulphite and Na2S2O8.

For effective bleaching pH, temperature, time, concentration and impurities are to be controlled.For bleaching the compound must be present in unstable form that is, ionizes easily. Market form

is stable form so the bleach must be converted into unstable form for the process. It is to be

checked what is the stable form of bleach. If it is stable in acidic medium then alkali is added forinstability and vice versa.


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DIP SET#01: This is a tank like arrangement in which we apply the chemical for scouring over

the fabric, thats why it is also known as scouring chemical bath.

CONSTRUCTION OF DIP SET: It has a special arrangement for the feeding of the chemical

that consists of a narrow tray over which the feeding pipe is provided. When the tray over flow,

the chemical falls over the fast moving fabric through out the width. This is done to preventstaining of the chemical over the fabric. After impregnation of the fabric in the chemical, itpasses between the doctor rolls, they have blade like structures on two sides. This helps to

squeeze the excess liquor.

FEEDING MECHANISM OF DIP SET: The solution of chemical according to the type of fabric

is made in the main or mother tank. From there it is fed to the dip set according to the speed of

the fabric. To keep the concentration constant, the chemical from the dip set is continuously

removed and mixed with the solution in the mother tank along with fresh chemicals.

STEAMER# 1: Fabric containing the chemical from the dip set enters into the steamer for the

completion of the reaction. Here the fabric stays for 15min and the temperature is maintainedat102C.

CONSTRUCTION OF STEAMER: It consists of two parts. The upper portion has roller

arrangement while the lower is consists of a roller bed. The fabric after passing through theroller, stay over the roller bed. Below the roller bed, sump is provided which contains water.

Super heated steam is injected in it, thus water evaporates and saturated steam passes through the

roller bed and finally over the fabric. In this way, the temperature of the steamer is maintained at102C. At the end of the roller bed, mechanical sensors are provided which is star shaped. The

function of the mechanical sensor is that, it touches the roller bed, thus stopping the feeding of

fabric in the steamer.

INTERMEDIATE WASHING: Just after scouring steamer, two intermediate washing baths are

provided to remove the scouring chemical. Here the washing is done with plane water at 98C.

DIP SET # 02: This is also a chemical tank where the chemicals for bleaching are provided. Its

construction and feeding mechanism are same as of dip set 01.

STEAMER# 02: The function is same as mentioned in steamer 01, the only difference is dwell

time i.e here the fabric remains for 30min and another difference is the type of the sensor i.e here

we use photo cell instead of mechanical sensor.

WASHING TANK: After bleaching 5 washing tanks are provided. The capacity of the4 tanks is

22m fabrics each and the washing in them is done with water at 98C. The 5th tank treats the

fabric with acid to get the neutral pH and then do the washing with plain water. Its capacity is

25m fabric. In between each washing tank, expander, squeezing roller, bowing roller andcompensator is provided and their functions are same as mentioned above.

DRYING ARRANGEMENT: 22 drums containing steam are provided in3 rows for the dryingmechanism. After passing through them, fabric comes in to J shaped tray. Just above the J


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shaped tray we have moisture meter over the roller, which is in contact with the fabric and

measures the moisture, which is usually, maintained at6%. One compensator before drying

drums and one before the J shaped tray is provided to control the speed of the fabric through themachine.

BATCH MAKING: The fabric after drying is stored over the batcher, which can then be sendingfor further processing.

IMPORTANT ASPECTS OF THIS MACHINE:

HEAT RECOVERY SYSTEM: The water in the pre wash is at 98C. It is not wasted but with the

help of the heat recovery system, it is used to increase the temperature of feeding water unto

70C. This system is consist of a drum having filler to remove the impurities and the used water

then comes in the large diameter long pipe having pipes of small diameter in it. It carries freshfeeding water & by the transfer of heat it gets the temperature of about 65-70C, where as the

used water after loosing the heat is disposed off.

WATER RECOVERY SYSTEM: The dirty water is disposed off and the fresh water is feeded to

each washing tank separately. But there is also a special arrangement by means of which the

water is transferred, if it is in the condition to be used, from 7th washing to 6th and then to 5th

and so on by piping system.

MOTOR ARRANGEMENT: There are 22 AC motors provided in the machine these are of two

types: main motors and auxiliary motors. Main motors are with chain and auxiliary motors havebelts.

RUBBER ROLLERS: Main motors drive all rubber rollers. A separate main motor drives each.

STEEL ROLLER (TOP): auxiliary motors drive these. Many steel rollers are driven by one

single motor.

STEEL ROLLER (BOTTOM): These are driven frictionally by fabric.

BED ROLLS: All are driven by one single main motor.

GOLLER BLEACH SPECIFICATIONS:

PH =7-8

ABSORBANCY: (for printing) 30-40mm.

(For dyeing) above 60mm

WHITENESS: PC (both dyeing and printing) above 70

Cotton (for printing) 65-70

Cotton (for white) 75Cotton (for dyeing) 65-70


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PROCESS: Desize to bleach wt. Reduction is 12%

SHRINKAGE: Cotton 17-19%

PC stain 4-5%

PC 7-8%

ELONGATION: Cotton 3-5%

PC 1-1.5%

MERCERIZE SHRINKAGE: cotton 2%

MACHINE UTILITIES:

1: The machine requires 5 workers during operations.

2: The length of running fabric in it is 500m

3: The time of insertion of running fabric is 8 hrs.4: For about 100000m of fabric

Water needed =275m3

Electricity=1078kwh

Steam=44tons

CHEMICALS:

For scouring: NaOH liquid 48 BeSandozin MRN (wetting agent)

For bleaching: hydrogen peroxide 50%

NaOH liquid 48 BeStablical A (stablizer)

Sandozin MRN

Sirrix 2UD (sequestering agent)

J-BOX

This machine is used for scouring and bleaching in rope forms. In J box the fabric is feeded inpiled form and stored. The J box is well insulated to retain the heat and is lined with steel. It is

used in Gul Ahmad for local dyeing.

ROPE FORM: It can be1: scour bleach (in old J box)

2: solomatic (new J box)

SCOUR BLEACH (hot boiling) this is also known as boiling off or boil bleach. It includes


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scouring and bleaching of the fabric and is done in old J box. The flow of the material through

this machine is attached in flow chart.

PARTS:

GREY PITS: The fabric from Osthoff singing machine is stored in grey pits for the completionof the reaction. There are total 12 chambers in which 8000-10000m of narrow width fabric and

5000m of wider width fabric can be stored.

PRE WASHING: This is done with hot water i.e at a temperature of 70C. It consists of 6 pairs of

rollers and about 80-100m of fabric remains in it. After washing, fabric enters in to saturator by

passing through padder rollers.

SATURATOR (scouring tank): This is the portion of the machine where scouring takes place

and all the natural impurities are removed. NaOH is fed from the mother tank whose capacity is

1000m where as other chemicals are fed from a separate drum of 500lites. 3-4m of fabricremains in contact with the chemical for about 3-4 min.

STEAMER# 01: It is a 20 ft high J shaped box whose capacity is about 1200kg and the fabric

remains under 100C for about 2-2.5 hours. The maintenance of J box is done if in any casestaining occurs on the fabric. For this purpose two openings one at the top and other at the

bottom are provided and this maintenance normally takes 8 hrs. From the steamer, the fabric

enters into mid washer.

MID WASHER: This consists of two chambers one is for hot washing 70C and other is for cold

washing 30C. This is done to remove the chemicals from the fabric. The problem of dissociation

of hydrogen peroxide can arise at the temperature of 70C so cold washing is provided to keep thefabric at room temp. The capacity of this washing chamber is 102m.

SATURATOR (bleaching tank): Here the pre mixed chemicals from the mother tank by meansof motor and a pump. The fabric is impregnated in the chemicals for about 3-4min. After it, the

fabric passes through the padder roller to the steamer. The pick up of the fabric depends on the

quality but it is normally 90%.

STEAMER #02: This is the second J box and the fabric remains in it for about 1.5-2 hrs so that

the bleaching reaction completes. The capacity of this J box is about 800kg and the temp here is

100C.

FINAL WASHING: The final washing also consists of hot and cold wash. From here the fabric

is stored in white pits. There are total 9 white pits these are called as white pits because the fabric

comes here after bleaching.

SOLOMATIC PROCESS:

This is done in new J box. This process involves only bleaching of the fabric. The flow of the


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material in this process is given as:

Pre washing-------- saturator------------steamer---------- final wash-------- white pits.

PARTS:

PRE WASHING: It consists of six pairs of rollers and has the capacity of holding 120m of fabricat a time. First hot washing at 70-90C and then cold washing at 30-35C takes place. This is done

to cool down the fabric because the heated fabric is sent to the saturator then due to the increase

in temp, hydrogen peroxide dissociates so in normal practice we provide a cold wash to thefabric so that the reaction takes place at room temperature.

SATURATOR (bleaching tank): The fabric us treated with hydrogen peroxide and NaOH. 3-4m

of fabric remains in contact with the chemical for3-4min.

STEAMER: Here the fabric remains for 1.5hrs under 100C and its capacity is 2600kg. The steam

is provided from bottom, mid and top of the J box. There are 3 pressure gauges indicating thesteam pressure and also a temperature indicator, which indicates the temp of steam in the J box.

FINAL WASHING: It also consists of hot and cold washing and is done top removed the

remaining impurities or chemicals after bleaching. Their are4 hot chambers and 2 cold chambers.After this the fabric gets stored in white pits.

WATER MANGLE

Textile materials require drying after washing that is carried out in two stages. First water isremoved mechanically and then by application of heat. Evaporation of water by heat is expensive

and so maximum quantity of water is extracted by mechanical means, which are

(a). Centrifuging,


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(b) Mangling and

(c) Suction methods.

Mangling is the most economical of all the three methods of extraction and its cost is about half

of centrifuging and one third of suction method. Here in Gul Ahmad, there are 2 water mangles.

They are distinguished by:

OLD WATER MANGLES NEW WATER MANGLES

This is for narrow width this is for wider width

In this machine only batch formation is possible Pilot as well as batch can be made

The speed is about 50-70m/min its speed is usually 1/3 of the speed Of J box

In this there is no arrangement for neutralization here a trough for the acid is

of the fabric. Provided for neutralization.

The flow of the material through water mangle is attached.

WORKING:

The fabric from the white pits enters here through the guide rolls in the form of a rope. At the

beginning of the mangle there is beater rope opener arrangement that helps to open the rope bycontinuous rotations. Just after it, expanders are present which will open the fabric width wise

and remove the crease upto some extent. This whole arrangement is repeated twice. After

passing through the roller the fabric is dipped in acid then in water trough to maintain the pH.

After passing through bowing, squeezing and finally guide rollers, the fabric moves towards thedrying drums and finally wounded over the batcher or can be stored over pilot.

MERCERIZATION(GOLLER MERCERIZATION MACHINE)

Mercerization is a very important operation in the cotton wet processing industry and by virtue

of the resultant effects it may be considered both a pre treatment and a finishing process.Mercerization is the treatment of the fabric with strong caustic soda solution of about 20%

strength. The changes appear on cotton after the treatment is as follows:

1. Shrinkage in area of fabric and length of yarn.


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2. Increase in moisture absorption.

3. Great increase in dye up take.

4. Increase in chemical reactivity.5. Increase in tensile strength of the material.

TYPES OF MERCERIZATION MACHINE: These are of two types:1. Chain type2. Chainless type.

Chainless machines are normally used in all mills. The differences between the two are as

follows:

CHAIN MACHINES:

a. The chain machine gives a better tension control or better mercerization in both the warp and

weft direction and imparts a comparatively better luster to the heavier weight fabrics.b. The maintenance of the chains is high because these cannot be lubricated and so wears off

rapidly.

CHAINLESS MACHINES:

g. These have a lower capital cost per unit production

h. These machines are more efficient in use of caustic soda and there is a less possibility of

physical damage to the delicate fabrics.i. Chainless machines have also higher productivity because two or more layers of fabric can be

mercerized simultaneously by placing these side by side or by superimposing one on the other.

IMPORANT PARTS OF MACHINE:

1: CREELING: The fabric is fed in batch form that comes from continuous bleaching and

scouring machine. The fabric passes through the tension rolls and the series of bowing rollers.There are total 9 bowing rollers for straightening of the weft because the mercerization the fabric

has to swell.

2. MERCERIZATION CHAMBERS: There are three chambers for mercerization containing a

strong lye of 30 Be(299 gm/liter). Here the fabric passes between two rollers in which top one is

of rubber and bottom one is of grooved steel. NaOH softens the fabric where as grooved steelrollers straightens the fabric. There are 4 pairs of rollers in each chamber and each chamber

contains 7m of fabric .The fabric passes through these chambers in 45 seconds at room

temperature.

3.SQUEEZING ROLLERS: There are 4 squeezing rollers having 75% pick up and the pressure

applied on these rollers is 4 bars.

4.STABLIZATION CHAMBER: There are 4 stabilization chambers containing weak lye of 7-8Be and the dip time is 60 seconds. This is done for permanent straightening of the fabric. Here

also 7m of fabric are present in each chamber and the temperature of the chamber is 85C. After

this the fabric passes through squeezing rollers (5 bar pressure and pick up=80%) to the batcherand then to the washing pad steam water mangle.


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There are 2 mercerization machines in Gul Ahmed .One (new model 1999) is for wider width

(3.2m) and the other (old model 1965) is for narrow width (1.6m). The old machine also contains

the washing chambers whereas the new one does not.

LYE PREPARATION:

Strong lye (NaOH) is feeded from a mother tank (1000liters) to a bottom dip tank of 2500 litersfrom where the lye is pumped to the mercerization chamber. The concentration of caustic soda iscontrolled automatically. For filtration of caustic, a round filter is provided. To prepare weal lye

for stabilization chamber 4.5 liters/kg of water is provided before the second set of squeezing

rollers so that the concentration decreases upto 7-8 Be and then pumped by means of 16 pumpsto the stabilization chamber.

CAUSTIC RECOVERY UNIT (CRU)

During the process of mercerization we use a large amount of caustic whose initial concentrationis 30 Be and is reduced to 7-8 Be in the stabilization chamber. For reduction of concentration we

add a large amount of water i.e 4.5lit/kg. If this dilute solution is wasted directly to the sewage

then a large amount of caustic will waste. To overcome this problem we use CRU.It is a unit where caustic is recovered by a simple process of evaporation.

WORKING:

Caustic from mercerization chamber is pumped to the pre filter that is made of nylon and thenenters into buffer tank for storage. After reaching a certain level caustic passes to the heat

exchanger where it is heated by exchanging heat with hot water and then comes into evaporator.

Steam is supplied in first evaporator for evaporation. In evaporator the caustic circulates in pipeswhere as steam is in surrounding. When caustic begins to evaporate it passes to the separator

where the vapors being lighter goes up where as caustic enters into second evaporator. This

evaporator is heated by means of paper present in separator. This process is repeated one more

time so that the water separates completely. Then the required concentration of caustic isobtained i.e 30Bu (specific gravity 1.26) the caustic enters into the lye cooler above which a heat

exchanger is provided in which cold water circulates and hence the caustic cools down.

A sensor called lye measurement sensor (LMS) controls the conc. of caustic. After reaching acertain level in lye cooler caustic is stored in concentrate tank. From here the caustic again pass

to the mercerization tank.

DYEING

Dye: They are the organic compounds, which produce psychological sensation when the light of

certain wavelength reaches the eye.

Dyeing: It is the process, which produces chemical or physical change in a substance so that the

reflection of light appears colored.

Dye Stuff: The substance, which produces such change in a substance, is known as dyestuff.

Basic Functions of Dyeing: There are 3 basic functions of dyeing they are:

I. Dye.II. Medium.


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III. Substrate.

Dye consists of 2 important parts. They are Chromogen and Solublising Group.

Chromogen:

The organic compound-carrying group that is chromophore is known as Chromogen. This word

is drive from a Greek words, Chroma means Color And Gen means Generating. This itselfcan be divided into two. Auxochrome and Chromophore.

Auxochrome:

It is the auxiliary of chroma. This auxiliary is one that help in brightening the color or to enhancethe color, but itself is unable to produce the color. It is also drive from Greek words Auxein

means to increase and Chroma means color. Every dye must have one auxochrome and one

chromophore. They convert a color compound into a dye that must fix permanently in a fabric.

Generally colorless chromogens become colored when an auxochrome is introduced into it. Theymay be acidic of basic, and on the basis of depth they may be Bathochomic (deepens the color)

and Hypschromic (fade the color).

Chromophore:

It is color-bearing group of dye, it is also drive from Greek word Chroma and Phore, means color

bearing. Different chromophores have different power of developing color. They can be arrange

in descending order as: C = C, C N, C = O, N = N, C = S.

The General Theory of Dyeing.

Dyeing is the process of coloring textile materials by immersing them in and aqueous solution ofdye, called dye liquor. Normally the dye liquor consists of dye, water and an auxiliary. To

improve the effectiveness of dying, heat s usually applied to the dye liquor.

The theory of aqueous dyeing is modified when an organic solvent is substituted for water.

The general theory explains the interaction between dye, fabric, water, and dye auxiliary. Morespecifically, it explains:

1. Forces of repulsion which are developed between the dye molecule and water; and2. Forces of attraction, which are developed between the dye molecule and fibers.

These forces are responsible for the dye molecules leaving the aqueous dye liquor and entering

and attaching themselves to the palymers of the fabric.DYEING MACHINARIES: (EXPORT)

PAD THERMOSOL: (Monforts thermex)

It is a continuos dyeing machine and is used for vat, disperse reactive and pigment dyeing inwhich fixation of the dye is done by means of heat. All types of shades can be dyed on this

machine but we usually dye dark shades. In Gul Alhmad this machine is used mainly for

polyester dyeing.

DYEING TROUGH:

The fabric is unfolded from batcher and with the help of guiding rolls and tension rollers enter

into the trough having 4 rollers. In trough the liqour temp is kept at low i.e 25-30C. In trough,dyes migration inhibitors alkali (to maintain ph) and wetting agents (for heavy fabric) are used.


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After trough fabric is passed through padders to remove excess of dyeing and chemical solution

by applying 1.5 bar pressure. The pick up is about 65-70% (depends on the quality of fabric).

AIRING ZONE:

There are six pairs of steel rollers in this zone fabric pass through these rollers under atmospheric

pressure and temp for the proper penetration of the dye.

INFRA RED CHAMBER:

In padding polyester and PC fabrics, the dye solution is not fully absorbed like in 100% cotton

fabrics and rubs off on coming in contact with a hot metal guide roller. The PC fabrics pickabout 50% of liquor but if moisture level could be brought down to 30%, the dye migration is

avoided. Therefore for this purpose there are two infrared zones in this machine for removing 30-

40% of moisture from the fabric. It works as a dye migration inhibitor so thats why direct drying

is avoided and prevent uneven dying. Infra red radiation has higher wavelength and lower energyand thats why they evaporates water only, dye molecules being bigger in size than water

molecules and hence are not disturbed by infrared radiation. The temp of infrared radiation is

400-500C.

The IR heaters are mounted in banks and are either heated electrically or by gas. The IR radiation

selected is of 3 micrometers wavelength as textile fibers preferentially absorb this. To monitor

moisture content and subsequently speed of padding, microwave sensors are fitted that absorbthe wave energy according to the moisture content in the fabric and alter speed of motor of the

padder. At the bottom of the heater battery, warm air is blown that travel upwards and helps in

removal of the steam away from the fabric. In case of an accidental stoppage of the fabric duringworking of the IR radiators, the fabric is protected from the intense heat by automatic cut off

system for gas or electric supply as well as by dropping a metal shutter in front of the heaters.

DRYING CHAMBERS:There are 3 chambers. First one is drying chamber having a temperature of 120C and 35m of

fabric remains in it for 1 min. The 2nd chamber is pre curing chamber here the temp=150C and

the fabric passes through it in30seconds. This chamber is for removing the moisture from thefabric completely so that no problem occurs in curing i.e to prepare the fabric for fixation.

3rd chamber is curing chamber here the temp=190C and 35m of fabric passes in 1min. This is for

fixation of the dye. Total 91m of cloth is in 3 chambers.

GOLLER PAD STEAM DYEING MACHINE:

Continuous roller steamer is used for diffusion of reactive, vat, sulphur and direct dyes into

cellulosic fibers in an atmosphere of heat and moisture that is created by saturated steam injected

into the steamer. The fabric is moved in open width around rollers in top and bottom horizontal

banks in a heat insulated steel chamber like a hot flue dryer. This is an ideal machine forReactive dyeing. Light, pale and medium shades can be dyed in this machine. Here wet on wet

dyeing is done.

PURPOSES OF THE MACHINE: It is a multi purpose m/c and serves the following purposes:


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1. It can be used as a pad batch for reactive dyeing in which batch is left for 12-18 hours for the

completion of the reaction. For time saving the fabric passes through the steamer for 1 minuteand the reaction is completed.

2. It can also be used for reduction clearance (RC) in which we treat PC fabric with caustic and

sod. Hydrosulphide to remove the disperse dye from cotton.3. Stripping of the fabric can also be done on this machine that is, colour can be removedcompletely by adding higher amount of caustic and sod.hydrosulphide.

4. It can be used for the development of Vat dyes.

5. The dyed fabric can be washed in this machine.

The flow of the fabric through different parts of machine is as follows:

CREELING=PADDING TROUGH=STEAMER=ACID TROUGH=AIRINGZONE=WASHERS=DRYERS=BATCHER

PADDING TROUGH:The fabric enters into padding trough by passing trough different tension and guide rollers. There

are 4 rolls in this trough. The trough contains the dye and other auxiliaries according to the dye

to be used. To remove the excess amount of dyeing liquor from the fabric padding rollers are

provided on which 1.5 bar pressure is applied at the center and 2.1 bar at the sides. This pressureis pneumatic and is supplied by means of compressors. The pick up on the padding rolls is

normally 75%.

STEAMER:

There are 3 chambers in the steamer in which 8 pairs of rollers are present in two chambers and 6

pairs in the third one. Sensors are provided when the fabric enters from one chamber to another

to control the speed or if the fabrics get rolled on to the rollers. The temperature of the steamer is106Cand 75m of fabric remains in it for 1 minute. Sensor is provided here indicating the steamer

temp. To maintain the temp constant throughout the steamer, small pieces of stainless steel are

placed in the roof so that they remain hot for long time and do not allow condensation of thesteam. The entrance of the steamer is known as LIP in which two pipes are provided adjacent to

each other from which steam is supplied. To avoid foaming problem steam is supplied to third

chamber and from third to second and from second to first. Steam can be provided to steamer bytwo means. First, by means of Sump (tray). Dry heated steam comes to the sump and becomes

saturated when entered to the steamer. The other way of providing steam is by means of Gatra.

WATER SEAL:The temp here is 40-45C and it serves the following purposes:

1 to cool the fabric

2 Remove excess dye from surface.

3 It condenses the steam that comes along the fabric

ACID TROUGH:

Acetic acid and HCl are added in this trough. Acetic acid is used to control pH where as HCl isused to clean NaOH i.e remove the alkaline effect.


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AIRING ZONE:

There are two portions in this zone and a ceramic sensor is present at the end of each portion thatmaintains the tension of the fabric. There are 23 pairs of rollers in this zone. The fabric is

allowed to pass these rollers under fresh air for good color fixation.

WASHING TANKS:There are 9 washing tanks. Washing #1,2, 8 and 9 contains fresh water where as the others is fed

from these tanks. The capacity of each washing tank is about 950-1300liters.

NORMAL WASH:

This wash is for printed fabrics the temp is kept at 50-60C.

MERCERIZED WASH:In this only hot washing is done. The temp in washing 1 is 50 C and from washing 28 is 98C

and last one has 70C.

DYED WASH:

This is used for dyed fabrics and in this we add soap (RSK), dispergator, Cibapon R for washing.

For light shades only soap is added where as for dark shades soda ash is also added with soap

which decreases the depth of color and improve rubbing fastness. The temp in 1st and 2nd tank isroom temp and from 3rd8th is 98C where as in the last one is 50C. The tem-p in washing tanks

is controlled by a PT temp sensor.

DRYING CYLINDERS:

There are 11 pairs of drying cylinders that are arranged horizontally and steam is injected by

means of syfon pipes. After these cylinders 2 cooling cylinders are provided for cooling the

fabric at room temp.

BATCHER:

The fabric from drying cylinders passes through some tension rolls and also from anti static rodswhich absorbs the charge from the fabric. This rod has 5 KV voltages and 1800-18000A of

current after passing through this fabric is winded on the batcher.

PAD BATCH KUSTER PADDER (BLIND DYEING)

It is a semi continuous method of dyeing & is used incase of reactive dyes only.

DYE PADDER:

The padding operation consists of two parts: first immersion of the fabric in dye liquor in a

trough and second passing the fabric b/w two rollers to force dye liquor in and to squeeze excessliquor back to trough. Padder is the most sensitive component of the continuous dyeing system


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and any fault developed at the padding stage will not be corrected later. Padder may have 2 or 3

rolls: the latter having 2 dips and 2 nips. Normally the 2-roll padder is preferred for most types of

fabrics and the 3 roll one is used only for heavy weight fabrics.Both the rollers should have exactly the same hardness otherwise there will be a color difference

in the face and backsides of the fabric. The material of the rubber should be chemically resistant

to dye liquor and auxiliary products. Speed of this m/c is 50m/min and 6-7 m of fabric is presentin this m/c at a time.

PADDING TROUGH:

The padding trough is generally considered to be just a container for the dye liquor and itsimportance in obtaining constant shade and dye economy is not fully realized by the dyers. The

trough is placed below and in front of the padder and consists of a u or v shaped box with one or

more free running guide rollers of about 10 cm dia. Dye liquor is fed in through a perforated pipe

running across the entire length of tank with perforations pointing away from fabric.Ideally a trough should contain a minimum quantity of dye liquor consistent with adequate pick

up so as to reduce wastage of un-used dye at the end of the process and more importantly to have

a high liquor replacement value. Small liquor volume and minimum distance b/w top of troughand nip of pad rolls are necessary to reduce the effect of preferential pick up of dye or water by

fabric and thus minimize tailing effect.

The troughs are double walled so that hot or cold water could be circulated through the jacket to

maintain dye liquor at constant and optimum temperature. To ensure constancy of fabricimmersion time through out its running in trough the dye liquor is kept at same level by

automatic controls.

COLOR MIXING:

The colors and chemicals i.e. alkalis are put in separate tank and are mixed by a diaphragm at a

ratio of 4:1. The diaphragm feed these mixed chemicals to the trough by means of pipes.

WORKING:

The fabric is feeded in this machine in the form of batcher, which after passing through certain

tension rollers and guide rollers enters into the dyeing trough. In this trough the dyes andchemicals are showered on the fabric. There is a tube attached with the trough indicating the

level of mixture in the trough. Padders are provided after trough having the pressure of 2 bars

and pick up of 75%, they squeeze the excess liquor. Finally the fabric passes through somerollers and winded on a batcher. The batcher should rotate continuously for about 12-18 hrs for

fixation of the color. From this m/c fabric goes to washing m/c and then to the drying cylinders.

HOT FLUE: 1976

This m/c is used for local dyeing (exhaust process). This is a semi thermosol m/c but do not have

curing chamber like thermosol. When vat dyeing is done in this machine then only padding and

drying is done. After this the pad is taken to the jigger for development.

WORKING:

The fabric after mercerization is feeded by means of tension and guide rolls to the paddingtrough. In this trough there are 3 rollers and dye and leveling agents are added. Hydraulic


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pressure of 2.5 bar in center and 1.6 bars at side is applied on padder rollers.

COMPENSATOR:

The compensator in this m/c is mechanical based; it controls the speed of m/c. It is connected

through a chain to a sensor (rod). When the speed increases the tension applied on compensatorincreases due to which it moves up and hence the chain also moves as a result of this movementthe sensor rod moves downward since it is connected with the opposite side of chain. Electric

sensors provide the limit if the rod touches it the m/c stops automatically.

DRYING CHAMBERS:

There are 2 drawing chambers where drying is done with the help of steam. In each chamber

there are 7 pairs of rollers. The top rollers are driven by means of rope, which gets drive by achain from main motor, and bottom rollers are frictionally driven by fabric i.e. they are free

running. In first dryer the temp is 140 C & in second dryer is 150C. The length of fabric from

padded and drying chamber is 75m. The exhaust of moist air and fluff is through a duct at thetop. After drying the fabric is winded either on batcher or it is piled.

LOCAL DYEING MACHINARIES:

PAD STEAM CONTINUOUS DYEING MACHINE

This machine is used for dyeing narrow width fabric. It can also be used only for washing. The

speed of this machine is about 40m/minand about 180m of fabric is present on the machine at a

time. The flow of the material through different parts of machine is as follows:

CREEL=DYEINGTROUGH=STEAMER=ACIDTROUGH=AIRING=WASHER=DRYE

RS=BATCHER

IMPORTANT PARTS OF MACHINE:

DYEING TROUGH:

The dye is prepared in a tank of 500 liters and pumped to another tank from where it is feeded to

the dyeing trough. The dyeing trough has the capacity of 25 liters and about 80m of fabric (lawn)

can be dyed by this. After this the fabric passes through 3 padders that has the pick up of 68-70%and 1-2 bar pressure is applied.


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rollers that will be difficult to wash off, therefore are not suitable for sulphur dyeing. This

problem is not present in Jiggers.

The quality produced by jigger is better than that of pad steam.

JIGGER

For batch processing of cotton cloth in open width, jigger or jig is the oldest and still frequently

used dyeing machine. In the past, jiggers were mainly used for dyeing medium and heavy weightfabrics b/c of excessive longitudinal tension imposed on the fabric. However, modern versions

cause very little tension and so light weight fabrics may also dye now. A jigger consists of a V

shaped trough or vat containing dye solution through which fabric, batched as a roll, moves andis wound on another roller. After the second roll is full, movement of cloth is reversed. Each

batching on a roller is called a pass or an end.

MAIN PURPOSES:

Jigger is a multi-purpose m/c and it serves as follows;

1- Vat developing2- Reactive dyeing

3- Bleaching

To ensure even dyeing there are 2 rounds of fabric in cold water.


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CHEMICALS:

Incase of reactive dyes fixation, salt and NaHCO3 are used. For development of vat dyes (local),

sodium hydro sulphide Na2S2O4 is added in small portions for even fixation and caustic (liquid)

38be is used. Caustic either increases depth of color or decreases. As we dont want to decreasecolor so we add dye in cold water and the fabric is allowed to complete 2 rounds. Then thechemicals are added in hot water (65C). If water is not heated then the chemical will burst the

dye molecule and not even color results. In order to avoid oxidation by air we keep fabric in

center by a lever. Incase of bleaching in jigger, a squeezer roll is provided which is adjusted by ahandle. So that the roller presses fabric and squeezes the bleaching chemicals. In development of

vat dyes & bleaching we provide direct steam through holes provided in beneath of trough. But

for reactive dyeing we provide indirect steam i.e. the steel pipes provided in trough are heated by

circulating steam in coils of pipes.

As only a few meters of fabric are immersed in dye bath at a time, a very low liquor ratio of 4 to

5 can be achieved. Normal size jiggers store about 700 to 1000m of fabric and fabric generallymoves at a rate of 60 to 100 m/min depending upon its unit weight. After 4 rounds of chemical

the fabric takes 1 round of hot wash with soap MRN and in case of development of vat soda ash

is also added to remove H2O2, Acetic acid etc and than 1 round of cold water. For unloading of

fabric from jigger a steel rod is provided and fabric is unwound from batcher and winded on thisroll.

From here the fabric is to water mangle where initially 2 washing tanks are provided and finallydried and piled.

WINCH

The winch m/c is one of the oldest dyeing m/c (for reactive and direct dyeing) & is still popular

b/c of low capital cost, simplicity in operation and versatility in use for different types of fabrics& operations. Principle of winch is to circulate a no. of fabric loops that are lying in a dye bath

but are continuously pulled out & returned to it with the help of a circular or elliptical winch.

Compared to the jigger, the winch dyeing causes less lengthwise tension in fabric. As thewinches are suffering from deficiencies of long liquor ratio, non-uniform temp of dye bath,

formation of creases in fabric and excessive mans power requirements. So jets are replacing

winches.

In Gull Ahmed, the winches are used only for washing purpose. For washing of printed fabrics

like lawn having dark shades. Linen which is 100% viscose is preferred washed in rope form

otherwise due o a little elongation it deteriorates.


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WASHING METHOD:

Usually 1000 liters of water is taken in the stainless steel vat having a depth of 2.5m, height of1m and length varying b/w 2 to 4 m. The backside of vat is not vertical but it is sloping at an

angle of 45 so as to facilitate the sliding of ropes and also to reduce volume of processing

liquor. To avoid entanglement, a peg rail fitted below a jockey roller in front of m/c, separatesthe fabric ropes. The fabric rotates at a speed of 60 to 70 m/min. A salting box is provided infront of m/c by interposing a perforated steel sheet at a distance of 30cm from the front of dye

bath. Water & steam pipes and a drain valve are also provided in this compartment. Fabric pieces

are loaded manually but are unloaded with the help of a mobile set of squeeze rollers after tyingtogether different ropes of fabric into a continuous length. The liquor goods ratio of winches

varies from 12 to 20.

In 1000lit of water, soap and soda ash are added at a temp of 100C. Firstly, fabric is given acold wash for 15mins then with chemicals fabric is washed for 45mins. Washing of reactive dyes

are done only in winch.

JET DYEING MACHINE

This m/c is mainly used for dyeing (Disperse) Polyester fabric since polyester dyeing requires

very high temp about 130C in the acidic medium of ph 3-5 otherwise the dye will not fix in

fabric. Dyeing at this temperature yields rapid, better penetrated and more level dyein

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Grey Departmen & Weaving Finishingt