Some Notes on Denim Washing

There are four main processes in the Denim washing

- Pretreatment

- Stone or Enzyme Wash- To adjust the surface effect

- Bleaching- To adjust the color

- Finishing- To adjust the handfeel of the garment

Pretreatment involves removal of impurities from the garments and desizing the garment. It also involves prevention of creases in the garment. Wetting Dispersing agent is used in desizing process. It should be able to rapidly wet the jeans so that it can prevent white lines of creases and prevents back staining. Back staining is the redeposition of indigo dyed short fibers, or loose indigo, removed during desizing, stone-washing or enzyme washing. Backstaining reduces the contrast of warp and undyed weft. It also stains pockets and labels and it is more prone ot ozone and yellowing. An anticrease agent is added to prevent crease formation during the washing process. 

Enzyme in garment Industry

Enzyme is a kind of protein. They help the chemical reaction but themselves do not take part in chemical reaction. The starting molecule in a reation is called substrate and the yield molecule is called substate. Enzymes and substrate work like lock-key model so only one enzyme is useful for one type of substrate. Enzymes are better than chemical catalyst because they act in mild conditions such as room temperature. They are also biodegradable. Many enzymes are used in garment washing. An enzyme called Amylase is used in removing starch in desizing. Celullase is used in breaking and removing cellulose fibers. Laccase is used in biobleaching and catalase is used as an anti peroxide. 

Stone and Enzyme Wash

Cellulase weaken the surface fibers which are then mechanically torn off during processing, taking with them indigo. However, they need mechanical action to work. Hence they are used with stones. Cellulase is also used in biopoloshing, which removes surface fibers and make the surface smooth. 

Bleach 

Laccase enzyme decolorises indigo without using bleach. It provides very good contrast and since it attacks only indigo dye and not the fiber so it gives excellent tensile strength. 

Yellowing

The discolouration of textiles, i.e. a change of shade or loss of whiteness, giving a yellow tint, is commonly known as YELLOWING.Yellowing is due to many reasons. Cotton, yellows with age. However aging cannot make severe yellowing happen. Certain lubricants used in weaving and knitting can cause yellowing. The Anti oxidants present in these oils can cause a type of yellowing called as phenolic yellowing. The anti oxidants are also present in packaging materials and silicon softeners. Also temperature of drying and curing during processing can scorch the fibers and cause yellowing. 

Indigo dyed fabrics are more prone to yellowing. Indigo when exposed to NOx or Ozone can produce yellow colored compounds. Indigo itself through simple oxidation can transform into yellow colored compounds. 

There are specialised anti-yellowing softeners available. This work by either forming a protective filem, or by reacting the pollutants to form colorless compounds.

The source of these notes this presentation. This also contains images and chemical reactions. You can also view images of various denim washes here. One more resource is here.

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What is Coated Denim

One reader has asked about coated denim.

Such jeans have a coating that feels like as if the cotton of the denim is waxed. If black in color, the jeans shines up like leather pants.

The coating is generally done using pigment, acrylic or polyurethane coating. Pigment coating provides the denim a new look and experience after every wash. Acrylic and PU, however, act as a transparent coating. This protects the fading properties. It also gives the fabric a protective breathable layer with stain resistant properties. The luster and feel of the fabric are also improved.

Resin Coating is generally done with the help of wooden handle. A rubber squeezer is used to extract resin under pressure to form leather effect on denim garment. It is a neutral ( pH 7) cream-colored paste that is miscible in cold water and resistant to heat upto 200 degree
Celcius. It is self catalysed and chlorine resistant.

The coating can be applied on the garment by screen, brush or knife edge. Machine coating is also possible.

After applying coating the fabric is dried and cured at 150 degree Celcius of 5 minutes.

Normally the coating are permanent in nature and able to sustain multiple launderings.

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Denim Produced from Your Torn Jeans

There is a patent document which claims that the denim fabric can be produced from waste denim yarn. In this fabric 40%-100% of waste fiber is used. To reclaim the waste fiber, the fabric is subjected to garnetting and low tension carding, before spinning it in the form of yarn and using it to weave fabric.

The only thing remains to be seen is the techno-commercial viability of such product. Garnetted fibers produce problems in carding, drawframe and posisbly in high speed weaving. Though it is claimed that such a denim will have adequate strength, it will remain a challange. It is suggested that some virgin fiber should be added in the garnetted fiber or it is subjected to some lubrication before spinning. All this will lead to increase in process cost.

Neverthless, this is a good news for your torn denim jeans which can now be recycled into a new one without damaging the environment. Just give your jeans to the local rag picker and it will eventually find itself into a new jeans. However, if you don't want to part away with your jeans, here are the instructions what you can do with them. Of course, there are 25 other ways to make use of your old jeans.

Worldwise, concerns are growing reagarding using the denim waste. A project making the use of denim shoddy is one of such cases. It is being used in myriad ways including its use in oil filters. Successful attempts have been made to make paper out of denim wastes.

Note: Garnetting is a process by which material such as threads, rags, woven cloth scraps, and the like are broken up and returned to a substantial fluffy, fibrous condition simulating the original condition of the fiber. This is done by first chopping the material to small pieces (e.g. two to six inches) and then running the pieces through a series of high speed cylinders which can be covered with wire (e.g. saw wire), steel spikes, or the like. The treatment breaks up the material into individual fibers typically having a length of one and one-eighth inches or less.

Tsudakoma ZAX- Settings for standard Denim

Tsudakoma-ZAX Loom Settings for 14.5 Oz/Sq yd OE/OE Denim (EPI x PPI = 64 x 37) count (6s x 7s)


Back Rest- 125 mm (vertical)
-16th mark ( horizontal)

Dropper Box- 100 mm (vertical)
- 50 mm (vertical)

Shedding Amount

1st Frame- 99 mm
2nd Frame-91mm
3rd Frame- 83 mm
4th Frame- 75 mm

Heald Frame Height:

1st Frame - 43 mm
2nd Frame-41mm
3rd Frame-39mm
4th Frame- 37mm

Shed Crossing Timing- 290 deg

Leno Crossing Timing- 290 deg ( LH Side), 0 deg ( RH side)

Temple- 15 rings- Medium Type

Sub Nozzle angle- 4 deg
Sub nozzle height- 3rd Mark
Machine Pulley- 220 mm
Motor Pulley- 113 mm for 760 rpm

iboard Settings

Tension- 280 kgf
Upper Limit- 560 kgf
Lower Limit- 0 kgf
Pick Density- 37 pick
Turns/Pick- 4
Arrvial setting - 240 deg
Filling insertion timing- 80 deg
No. of Sub groups- 5

Timing

Feeler H1- 200 deg to 290 deg
H2- 200 deg to 310 deg
Forward- 350 deg
Rev (others)- 180 deg/320 d eg
(Filling)- 290 deg
WBS- 240deg-300deg

SENSOR/TROUBLE
Dropper Setting: 10 th Volume
Sensor- on
Feeler-on
Timing

Pin: 50deg-200 deg
Main: 50deg-200deg
AUX Main: 60deg-100deg
80deg

Auxiliary Nozzle- 76 deg-176 deg
1st Pick- 86 deg

Sub Nozzle

64deg-170 deg
100deg-190deg
130deg-220deg
150deg-230deg
170deg-250deg

Stretch Nozzle- 200deg-300deg

STOP MARK Data

1. F Kick ( Filling) - 0 upto 7 steps
2. F Kick (Others)- 0 upto 7 steps
3. R Kick ( Filling)- 0 upto 7 steps
4. R Kick (Others) - 0 upto 7 steps
5. Kick Back Speed- 1. Low 2, Medium 3, High On
6. Kickback order- on 1

1. Rev to Forward
2. Forward to Rev

7. Down time- 5 min
8. Fell Control-8
9. Dia Comp-48
10. Let Off Avg-2
11. F-Gain-0
12. R.Gain- 0

13. Gain -1
1. Low
2. Medium
3. High

14. Rush Torque- 1200%
15. change Picks-2
16. Change timing- 30 deg
17. 1 pick insertion- On
18. Autolevelling- On

Critical Process Parameters- Denim Manufacturing

Critical Process Parameters- Denim Manufacturing

Warping:

Machine Speed m/min= 600+-50
Tension on individual thread ( cN) 90+-30
Warping breaks ( Avg/10000m/400 ends) < = 0.2

Dyeing-cum-Sizing

1. Machine Speed = 30+-2
2. Size Viscosity ( Flow seconds) = 6+-1
3. Size Add on ( %)= 6+-2
4. Breaking Force (gf) sized yarn = >=1100
5. Tenacity ( cN/tex) ( sized yarn) = >13
6. Elongation ( %) of sized yarn >= 4.5

Finishing

Quality	7 x 6	7 x 6	7 x 7	7 x 9	7 x 6
Width(cm)	151+-1	149+-1	151+-1	151+-1	151+-1
Shrinkage ( %)	15+-1	14.5+-1	15.5+-1	16+-1	14+-1
Skew ( %)	5-11	5-11	5-11	5-11	5-11

Finished Properties of some Common Denim Fabrics

New Page 1

Ideal Weight	14.5 Oz/Sq yd	13.75 oz/sq yard	12.5 oz/sq yard
Warp Count (Washed)	6.9 +-0.6	6.9+-0.5	6.9+-0.5
Weft Count (Washed)	6.0+-0.4	6.9+-0.5	9.0+-0.5
EPI ( Unwashed)	70+-2	70+-2	70+-2
PPI ( Unwashed)	43+-2	43+-2	43+-2
Wt ( Oz./ sq.Yd)	14.2	13.4	12.2
Rubbing Fastness ( Dry)	2-3	2-3	2-3
Fastness to Laundering	2	2	2

Denim of Polyester Cotton Blend

In such denims, the polyester used in warp is kept low about 20-25%, because the blend is harder to dye than cotton . Polyester can be used in much higher percentage in filling. It has the advantage of being strong, durable and even in appearance.

Receipes for different shades of Denim

Receipes For Different Shades on Denim


A) Black-on-Black
Black-on-Blue

Recipe

Liquid Sulphast Black= 200 gpl
Sodium Sulphide= 20 gpl
Sandozol HSI = 10 gpl
Soda Ash= 10 gpl

B) Blue-on- Blue

Receipe

Liquid Sulphar Navy Blue = 100 gpl
Liquid Sulphast Black= 50 gpl
Sodium Sulphide= 20 gpl
Sandozol HSI= 10 gpl
Soda Ash= 10 gpl

C) Reactive Series

Receipe

01) Ramazol Turquoise Blue G = 110 gpl
Urea= 100 gpl
Swanic 6L= 10 gpl

02) Sodium Silicate= 250 gpl
Caustic Soda = 10 gpl

Ratio of 01) and 02) = 3:1

D) Ramazol Coffee Brown G

Receipe
01) Coffee Brown G = 100gpl
Urea = 100 gpl
Swanic 6L= 10 gpl

02) Sodium Silicate = 250 gpl
Caustic Soda= 10 gpl

Ratio of 01) and 02) = 3:1

E) Ramazol Parrot Green

Receipe
01) Ramazol Turquoise Blue G = 90 gpl
Ramazol Yellow FG = 40 gpl
Urea= 100 gpl
Swanic 6L= 10 gpl

02) Sodium Silicate = 250 gpl
Caustic Soda = 10 gpl

Ratio of 01) and 02) = 3:1

F) Ramazol Blue

Receipe
01) Ramazol Black B = 70 gpl
Urea = 100 gpl
Swanic 6L = 10 gpl

02) Sodium Silicate = 250 gpl
Caustic Soda = 10 gpl

Ratio of 01) and 02) = 3:1

shrinkage norms for 14.5 oz. denim

Length wise shrinkage--> after 3rd wash---> -1.2% to -2.8%
Width wise shrinkage --> after 3rd wash--> -2.5% to -3.5%

Hard waste % in denim industry

Hard Waste % in Denim Industry

Warping--> 0.7%
Unsized Yarn--> 0.4%
Sized Yarn--> 0.6%
Fringe--> 1.7%

All these  above are percentage of Hacoba Production

Knotting + Reknotting waste --. 0.7%
Extra ends--> 0.7%

All the above are as percentage of loom shed production

Total Hard Waste= 4.8%

warp preparation for rope dyeing-1

Warp Preparation Requirements for Rope Dyeing

Ball Warping: Equipment required to form the rope of yarn. It involves creeling multiple ends of yarn ( Between 350-500 ends) and collecting them into an untwisted rope for dyeing. the rope is wound onto a long cylinder called a log on a machine called as a ball warper.

Some Notes

1. Packages of yarn are preconditioned before ball warping
2. Packages are loaded into the creel ( larger lots- magine transefer creeL0 and smaller lots- swing gate or truck creel
3. Packages are placed on adapters. An adapter support the package of yarn and ensure that the package remains aligned to the tensioning devices. Wooden plug type adapter are most effective as they require least amount of exertion to remove the empty package.

Next Step is threading the tensioner located at each yarn package

1. Post and Disk tensioner. It has two posts mounted onto a flat base. two round disk are placed onto each post. The yarn is threaded between the disk and wrapped around the post. One of the parts is movable so that the angle of wrap can be varied. More tension can be added to the yarn by adding round weights onto the top disk.

Advantages are 1. Inexpnsive 2. does Marginally adequate job of maintaining yarn tension 3. Simple to thread up 4. Low maintenance requirements.

Disadvantages are 1. Yarn has a tendency to jump out from between the disks at the rear of the creel. 2. It is labour intensive- when different tension levels are required. 3. There is more frequency of cleaning up 4. It doesnt control tension well at higher speed.

2. The driven disk tensioner

It also uses twin disk arrangement, however the disks are supported from below- there are no posts. Tension is applied from above- there are weights or spring loaded.
A gear under each pair of disks is matched to another gear mounted on a continuous shaft which runs the length of the vertical tension post. This shaft is connected to a 4 rpm motor which rotates the disk.

Advantage of disk rotation are 1. Thread cutting prevention 2. Dampens out variation due to ballooning action of yarn. There is mor uniform tension 4. Less effor required to change tension levels.

Disadvantages are 1. It is more difficult to thread up, there is more maintenance due to electric motor used and at high speed the tension control is not well.

cotton Characteristics

Cotton

The botanical name of cotton is Gossypium. It has four varieties

a. G. Arboreum, G. Herbaccum- Old world cotton, native of Asia and India- Low yield - fibers are also short and coarse.

b. G. Hirsutum, G. Barbadense- America and Carribeans- High yield- fibres long and fine

Classification of Cottons

1. Primary Parmaters- Fibre length, length uniformity, fineness, maturity and bundle strength at 0 guage and 3.2 mm guage length.

2. secondary- Trash content, honey dew content and color

1.1 Fibre length and uniformity- Most important quality parameter that decides the price of cotton-Long staple cottons are used to spin finer counts and hence fetch higher prices

Uniformity ratio= (50% span length x 100)/ 2.5% span length

1.2 Fibre fineness: Indian cotton particularly long and extra long staple varities and hybrids show low micronaire values as compared to cottons of similar staple length grown in USA, Egypt and Sudan.This is due to lower maturity levels of Indian cottons.

1.3 Fibre Maturity

Maturity Coefficient = (Mature+0.6xHalf Mature+0.4xImmature)/100

Poor fibre maturity results in nappiness of the yarn and also leads to problems in even dyeing of fabric. Generally, lack of moisture and nutrients and incidence of insects and pests during cotton boll developments results in low fibre maturity

1.4 Fiber Strength

In the OE rotor system, it is fibre bundle strength, that is assigned the highest importance. Fibre bundle strength is determined by using the stelometer at zero guage. and 1/8 inch (3.2mm) guage length. It is well known that fibre strength decreases when guage length is increased. Also it is observed that yarn strength is correlated well with fibre tenacity at 3.2 mm guage length. Hence the ratio of strength at zero to that of 3.2mm is known as strength uniformity ratio.

2.1 Trash including other contaminants

Cut Seeds- during ginning
Trash and other extraneous matter. General carelessness in picking, sorting, handling and transportation of Kapas at all stages upto and including ginning.

2.2 Honey dew and Color of cotton.

Honey dew consists of sugar secreted by sucking insects that harbour on the cotton plants. Presence leads to roller lapping.
Color is more important in USA, where cotton is picked by machines and doing so gets rubbed against plant parts and thus gets contaminated.


Assessment of Spinning Performance

FQI= LSW/F

Where L= 50% span length
S= Bundle strength at 3.2 mm guage
M= maturity coefficient
F= Micronaire Value

FQI can be used to arrive at yarn CSP for a given count by using empirical equations.

Denim Specification Sheet

Effluent treatment in denim industry

Denim Effluent
Characteristics
-Dark Blue Indigo color
-High Dissolved Solids ( Decomposed products of hydro)
-High Chemical Oxygen Demand (COD)
-High pH
-Chlorides and Sulphates of Suspended matter

Characteristics of Effluent
Appearance: Dark Blue
pH: 9-10
Suspended Solids: 250ppm
Dissolved Solids: 3500-5000 ppm
Oil/Grease: Traces
BOD ( 5 days, 20 deg C): 160-350 ppm
COD: 570-1100 ppm
Alkalinity (pH): 400 ppm
,,,,,,,,,,,,,,,,,(MO): 1700 ppm
Total Hardness: 220 ppm
Chlorides: 210-480 ppm
Sulphates ( SO4): 1200 ppm
Calcium: 15 ppm
Magnesium: 45 ppm
Ammonical Nitrogen: 2.5 ppm
Color (pt.Co): 250

Effluent is characterized by “high strength low volume”, as most of the most contaminated (“high strength”) effluent come from comparatively small quantity ( “low volume”) of wash waters used for rinse after yarn dyeing with indigo. Major contaminant is Indigo.

Permissible Limits for Cotton/ Synthetic Textile Industry (India) Effluent
pH= 5.5-9.0
Suspended Solids= 100 ppm
Oil and Grease= 10 ppm
BOD= 30 ppm
COD= 100 ppm
Hexavalent chromium: 0.1 ppm
Total Chromium= 2.0 ppm
Phenolic Compunds= 5 ppm
Sodium absorption ratio= 26
Sulphides= 2.0 ppm
color ( pt.Co.Scale) = 100
Bioassay test= 90% survival of fish after 9 hours in 100% effluent.


Effluent Treatment Scheme

1. Equalization
Equalization tank in two compartments. Retention time of at least 7-8 hours.

2. Flash Mixing
Equalisation Tank flash mixer ( to adjust pH) clarifloculator Unit ( Alum/Poly Aluminium Chloride) for coagulation/segmentation

3. flocculation
( it is a physico chemical process with 35-40% COD removal, 25-30% BOD and 70-80% color removal, also >95% color removal is possible if PAC and polymer dosage increased) overflow rate at CFU < 20 m^3/day
The sludge withdrawal should not be too less or too large ( can take place in lamella unit also )

4. Aeration
Effluent after CFU aeration process ( time > 18 hours) ( New recent aerators use injectors which produce very fine bubble resulting in a large air/water interface. Waste water is used as pressure water fro the operations of injection. Water +air stream are subjected at the bottom of the tower to prevent any possible sedimentation. Gas bubble rise to full height of the tower long resident time. Good utilization of oxygen upto 80% is possible.

5. Clarification
Effluent from aeration  clarifier ( resident time 3-4 hours)  activated sludge recalculated from clarifier to aeration tank sludge thickened  centrifugal decanter filtrate is then discharged to another tank.

Dissolving Oxygen
Clarified Effluent deficient in dissolved oxyen (DO)( for bioassay parameters) DO make uptank ( 2 hours resident time) – the output is expected to meet the criteria.

6. Ultrafilteration
Process for filtration of particles >5 n meters, from feed water made to flow at low pressure through membrane having pore size of 4-5 nm.
Useful for elimination of high molecular weight organic compounds. By using this ( the original indigo concentration in rinse water is 0.05%) fully usable 5% dispersion of indigo dye is obtained.
There are two types of membranes available. 1. Organic 2. Mineral – resistant to pH 0-14, resistant to mechanical and thermal conditions and are unaffected by solvents.

7. Incineration
Burning of waste
Major threat to possible health
Destruction of resources
Expensive
Generate toxins

8. Sludge Disposal
 85% of the waste is biodegradable. Can be used for compost. Lime sludge has agricultural value as it is free from pathogenic microorganisms
Bugs convert dyes into colorless substances
Microorganisms ( Geotrichum Candidum  filament fungus isolated from soil) can decompose 18 different kinds of dyes in to colorless substances. Preferred pH for them is 4-7 at a temperature of 20-30 deg C. Can destroy dye in two days ( at a concentration of 12 g/lit). They can eat indigo also.

Process Control for Effluent
Usually 10% of the applied indigo is washed off in rinses. Indigo fixation of yarn could be improved by:
-Slightly lower pH- can reduce indigo consumption for a given visual depth of shade
-Use of pre reduced indigo and indigo dyeing under nitrogen blanket. Can cut hydro consumption
-Use of prereduced sulpher dye and maintain reduction potential with hydrol ( glucose + other oligomeric reducing agent) instead of sod. Sulphide.

Effluent volume can be reduced through water conservation
-Washing in counter current type
-Decrease size of wash tanks
-Use Na2CO3 (Sod. Bicarbonate) in first rinse tank
-Use Co2 for neutralization of alkali
-Use as many nips as possible during washing to squeeze out alkali to maximum ( squeezed liquor should not drop back into bath)
-Relying more on spray rather than immersion into the bath
-Create enough stir in wash tank for best washing efficiency.

Integrated Finishing for Denim- my Notes

Preshrinking of Textile Fabrics- or compressive shrinkage

Shrinkage can be
- Natural Wash shrinkage- When the fibres swell in the presence of water and tensions induced during Spinning, weaving and processing of fabrics
- Compressive or Mechanical Shrinkage

It can be compared to the action of press. The effectiveness of ironing depends upon:
Temperature of the press
Amount of Moisture present in the fabrics
Amount of Physical Pressure Applied
Time duration of application of press.

In case of pressing, the new memory is set by drying, in compressive shrinking, it is the palmer unit which dries the fabric, thereby setting its new memory

Amount of preshrinkage left in the fabric is adjusted by varying the relative speed of the palmer to that of the rubber belt unit.

Temperature

The temperature affects in the following way the various components of the palmer/ compressive shrinkage unit

- Rubber Belt Cylinder
o Lower Temperature- Fabric appearance is affected- Sharp crease
o Higher temperature- rubber belt life is shortened
- Palmer Cylinder
o If lower temperature: No dry Stuff; Elongation of preshrunk fabric- also stretching of inspection and rolling operation.
o The purpose of palmer cylinder is to dry a fabric to a level of about 4% relative humidity. If there is higher temperature, there is elongation with natural moisture regain.
- Temperature of fabric as it enters rubber belt unit
If properly controlled, then high production. Most fabrics will shrink more easily if heated before entering the rubber belt unit.
Moisture

- 100% cotton denim may require as much as 14% moisture to permit effective pre shrinkage
- Moisture must be uniform thoroughout the length, width, and depth of fabric

How to ensure moisture uniformity
- Use of heated cans
- Apply needed moisture of fabric vial cooling water applied to rubber belt surface. But it also depends upon the condition of the rubber belt. Freshly grinded rubber belt carry more water à water removal roll of the rubber belt unit

Penetration of moisture applied to the fabric is very important. If insufficient moistureà Innermost dry layers of yarn will act like spring and cause the fabric to elongate.

Pressure

Maximum amount of rubber belt compression should not be greater than 25% of the actual belt thickness.

More heavy the fabric, more potential, more compression will it need

d. Duration

If above three factors are maintained and we have a sufficiently large palmer unit, we can compress durably a fabric to its ‘zero’ potential.

Its important to use cooling cans at the exit of the palmer

Fabric Scray: Use of exit scray allows additional time for fabric cooling as it is impossible to roll fabrics without the use of lengthwise tension.

Guider: The function of the guider is to keep the fabric to its full width.

Skyer: It is a sort of time delay device allowing time for moisture to penetrate into the fabric without the need to increase the machine length.

Heated Can: purpose: it is to drive the surface moisture into the fabric and to preheat the fabric.

Palmer

Function

Dry the fabric and set shrinkage
Adjust the shrinkage
To compare incoming and outgoing fabric tension and determine fabric shrinkage

Less dense the felt, greater is the drying capacity

Exit Scary
- To relax and cool;
- To prevent hot stop marks. It increases the rubber belt life
- To facilitate shrink environment
Why Wet Finishing for Denim

- Moisture doesn’t penetrate in the core- in foam finishing
- Its better to shrink fabric with a low moisture content than those which are bone dried

In integrated Machine

Padder- wetting
- squeezing the moisture
- application of heat

Once it is shrunk the fabric is thoroughly dried by palmer

- Hand can be adjusted in padder use of starch, lubricant
- Width can be controlled by adjusting tension between the padder and dry can
- Higher speed
- Even ness of the moisture content- Residual moisture after leaving palmer should be 4%

Drying depends upon the pressure of the steam, m/c speed, size of palmer , construction of felt

Rubber Belts: 36-40 deg. Shore

Harder- crack and lesser shrinkage capacity
Softer- require replacement frequently
Thickness- 67mm

Thicker- more grinding
- cracking
- more wear and tear to machine parts
- energy consumption

Rubber belt: Inside circumference- 3.962m
- Rubber surface width should exceed fabric width by at least 6” and preferably 8”

How to increase the life of the Rubber belt

- Nip pressure used on rubber belt should be optimum
- Over tension in the rubber belt should be avoided
- Belt should be run with sufficient cooling water in its interior and exterior surface
- Belt should be run with lowest possible operating temperature 115 deg- 140deg
- Frequency of grinding of the rubber belt should be optimum ie should be enough and at sufficient depth.
- Grind when density of belt surface has varied by 10% of its original hardness
- Water removal roll pressure adjustment is very important to insure max. belt life. Water acts not only to cool the rubber, but is also a lubricant
- Product machine stops or “hot stops” should be avoided to the maximum extent possible. One of the best ways to eliminate is to install scrays at the entrance and exit of the shrinking machine.
- Foreign objects should be avoided. Knot size for joining fabrics should be smaller.
- Regular cleaning and inspection of rubber belt.
- Use correct belt width
- Be careful during installation and maintenance of rubber belt, avoid use of chemicals.

Function of Felt Palmer

- It is required to maintain the preshrunk fabrics in intimate uniform contact with the surface of the heated cylinder in order to ensure uniform smooth drying of the fabricà new dimensionally stable memory.
- Fabric drying depends upon, palmer cylinder temperature, shrinking machine speed and permeability of the drying felt.
- It helps in precise fabric shrinking adjustment. It acts as a fabric puller to precisely control tension on the fabric
- Provides a pressing and calendaring effect on the preshrunk fabric

Balancing of a spinning line for denim Manufacturing

Critical Consumable Item List in Denim Industry

1. Vat Indigo dye
2. NaoH--> flake, lye
3. Na2SO4
4. Dispersing Agent
5. Wetting Agent
6. Potessium persulphate
7. Thin boiling Starch
8. PVA
9. Mutton Tallow- or equivalent
10. Acrylic Polymer
11. Hessian Cloth- a. 45"width, 10 oz./linear yard, b. 45"width, 14 oz. per linear yard
12. High Molecular high density polyethylene: 65" guage x 44 "width, 65" guage x 50" width
13. Spiral Built Paper a. 51mm ID x 60-60.5 mm OD x 60" long

Vendor Rating for Yarn Supplier for Denim

For 7s count

Evaluated at the end of 6 months

Weightage



Quality=50%,Price=30%,Delivery= 20%


I. Quality

CSP
>1900=4, 1800-1899=3, 1700-1799=2, 1600-1699=1, <1599=0>Count CV
0-2.5=2, >2.5=0,

Imperfections( /1000m)

a. Thin places
0-2=5, 3-10=2, >10=0

b. Thick Places
<10=5, 40="2,">40=0

c. Neps
0-2=5, 3-6=2, >6=0

Classimate Results

a. Analysis for total faults

<10=4, 30="2," 50="1,">50=0

b. Analysis for Objectionable Faults(A4, B4, C3, C4, D3, D4)

0-2=4, 3-4=2, >4 =0

Weightage in Quality

CSP=20%, Count CV=20%, Imperfections( Thin=10%, Thick=10%, Neps=10%), Classimate ( Total Faults=10%, Objectionable Faults=20%)

II. Delivery Schedule

100% Compliance=5, 90-99%=4, 80-89%=3, 70-79%=2, 60-69%==1, <60%=0

III. Prices

They are determined on a 5-point basis.

Total

>3.8--> Excellent, 3.0-3.8-->Good, 2.0-3.0-->Average, <2-->Poor