INTRODUCTION

The art of processing of textiles today is well known to all processors. In the past the organized sector dominated the textile scene; whereas today the decentralized process houses are predominant. There is a shift in emphasis from the requirements related to finished products to environment related requirements. Requirements related to the finished product fastness & other properties of dyestuffs & chemicals, processing etc. Shift of emphasis environment related requirements, cost reduction, security, energy & water saving, toxicology, hygiene legal regulations, and competitiveness.

Reduction in costs and utilities are achieved by the trend to telescope processes. In order to be competitive processors would have to give equal if not better quality then the existing material at the same price. Considering the energy and labour costs, the only means of maintaining a competitive edge is to lay emphasis on 'Quality'. Good quality does not necessarily mean increased prices, but in fact would mean "Doing it right the first time" thereby reduce the costs.

The stages in the processing of textiles are:

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DYEING PROCESSES

Dyeing is the process of imparting colors to a textile material through a dye. Dyes are obtained from flowers, nuts, berries and other forms of vegetables and plants as well as from animal and mineral sources. These are known as natural dyes.

The other class of dyes is known as synthetic dyes. These are based on a particular type of chemical composition. Some of these dyes are- Acid ( Anionic) dyes, Basic ( Cationic) dyes, Neutral- Premetalized dyes, Sulfur dyes, Vat dyes, Reactive dyes, Pigment dyes etc.

DIIFERENT DYEING PROCESSES

1. Direct Dyeing

When a dye is applied directly to the fabric without the aid of an affixing agent, it is called direct dyeing. In this method the dyestuff is either fermented (for natural dye) or chemically reduced ( for synthetic vat and sulfur dyes) before being applied. The direct dyes, which are largely used for dyeing cotton, are water soluble and can be applied directly to the fibre from an aqueous solution. Most other classes of synthetic dye, other than vat and sulfur dyes, are also applied in this way.

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2. Yarn Dyeing

When dyeing is done after the fibre has been spun into yarn, it is called Yarn dyeing. There are many forms of yarn dyeing- Stock, Skein (Hank) Dyeing, Package Dyeing, Warp-beam Dyeing, and Space Dyeing.

Yarn dyeing is used to create interesting checks, stripes, and plaids with different-colored yarns in the weaving process. In yarn dyeing, dyestuff penetrates the fibres in the core of the yarn.

i. Stock dyeing

Stock dyeing is used to dye fibres. In this process, the staple fibres are packed into a vessel and then dye liquid is forced through them. Although the dye solution is pumped in large quantities, the dye may not penetrate completely into the fibres and some areas may be left without dyeing. However, the following blending and spinning processes mix up the fibres in such a thorough way that it results in an overall even color. Woollens are usually stock dyed. Stock dyeing the fibre is dyed even before it is spun. Stock dyeing dyes fibre using perforated tubes.

Stock dyeing is used to dye fibres. In this process, the staple fibres are packed into a vessel and then dye liquid is forced through them. Although the dye solution is pumped in large quantities, the dye may not penetrate completely into the fibres and some areas may be left without dyeing. However, the following blending and spinning processes mix up the fibres in such a thorough way that it results in an overall even color.

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ii. Skein (Hank) Dyeing

The yarns are loosely arranged in skeins or hanks/coils. These are then hung over a rung and immersed in a dyebath in a large container. In this method, the colour penetration is the best and the yarns retain a softer, loftier feel. It is mostly used for bulky acrylic and wool yarns. In skein dyeing, yarn is loosely coiled on a reel and then dyed. The coils, or skeins, are hung over a rung and immersed in a dyebath. Skein-dyed yarn is used for bulky acrylic and wool yarns. Typical capacity for package dyeing equipment is 1,210 pounds (550 kg) and for skein dyeing equipment is 220 pounds (100 kg).

iii. Package Dyeing

The yarns are wound on spools, cones or similar units and these packages of yarn are stacked on perforated rods in a rack and then immersed in a tank. In the tank, the dye is forced outward from the rods under pressure through the spools and then back to the packages towards the center to penetrate the entire yarn as thoroughly as possible.

Mostly, the carded and combed cotton which are used for knitted outerwear is dyed through this method. In package dyeing , spools of yarn are stacked on perforated rods in a rack and immersed in a tank where dye is then forced outward from the rods under pressure. The dye is then pressured back through the packages toward the center to fully penetrate the entire yarn. Most carded and combed cotton used for knitted outerwear is package-dyed.

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iv. Warp-beam Dyeing

It is similar to package dyeing but more economical. Here, yarn is wound on to a perforated warp beam, immersed in a tank and dyed under pressure.

v. Space Dyeing

In this method, the yarn is dyed at intervals along its length. For these two procedures- knit- deknit method and OPI Space-Dye Applicator- are adopted. In the first method, the yarn is knitted on either a circular or flat-bed knitting machine and the knitted cloth is then dyed and subsequently it is deknitted. Since the dye does not readily penetrate the areas of the yarn where it crosses itself, alternated dyed and undyed spaces appear. The OPI Space-Dye Applicator technique produces multi colored space- dyed yarns. The yarns are dyed intermittently as they run at high speeds of upto 1000 yards (900 m) per minute through spaced dyebaths with continuous subjection to shock waves produced by compressed air assuming supersonic velocities.

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3. Piece Dyeing

Piece dyeing In this method, small batches of constructed natural colored fabric are dyed according to the demands for a given color.

Most dyed fabric is piece-dyed since this method gives the manufacturer maximum inventory flexibility to meet color demands as fashion changes. In terms of overall volume, the largest amount of dyeing is performed using beck and jig equipment.

Other piece dyeing methods include jet dyeing and pad dyeing.

The constructed fabrics are piece dyed for the flexibility they provide. The textile manufacturer can dye the whole fabric in batches according to the fashion demands of the time thus avoiding wastage and resultantly loss. There are several methods prevalent or piece dyeing.

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I. Beck dyeing

It is used for dyeing long yards of fabric. The fabric is passed in rope form through the dyebath. This rope of the fabric moves over a rail onto a reel which immerses it into the dye and then draws the fabric up and forward and brings it to the front of the machine. This process is repeated as long as necessary to dye the material uniformly to the desired color intensity.

Beck Dyeing (end view)

Beck dyeing is a versatile, continuous process used to dye long yards of fabric. About 1,980 pounds (900 kg) of fabric can be dyed on beck equipment at a time.

II. Jig dyeing

It is similar to the process of beck dyeing with a slight variation. The fabric in jig dyeing is held on rollers at full width rather than in rope form as it is passed through the dyebath.

Jig Dyeing (end view)

In Jig dyeing, the fabric is held on rollers at full width rather than in rope form as it is passed through the dyebath. This reduces fabric tendency to crack or crease. Jig dyeing equipment

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can handle 550 pounds (250 kg) of fabric.

III. Pad dyeing

Pad dyeing, like jig dyeing, is also done while holding the fabric at full width. The fabric is passed through a trough having dye in it. Then it is passed between two heavy rollers which force the dye into the cloth and squeeze out the excess dye. Then it is passed through a heat chamber for letting the dye to set. After that it is passed through washer, rinser and dryer for completing the process.

IV. Jet dyeing

Fabric can be jet-dyed (at up to 1,100 pounds (500 kg)) by placing it in a heated tube or column where jets of dye solution are forced through it at high pressures. The fabric too moves along the tube. The solution moves faster than the cloth while coloring it thoroughly. The dye is continually recirculated as the fabric is moved along the tube.

Jet Dyeing

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4. Solution pigmenting or dope dyeing

This is a method applied for dyeing the synthetic fibres. Dye is added to the solution before it is extruded through the spinnerets for making synthetic filaments. This gives a colorfast fibre as the pigments are used which are the fastest known colors.

5. Garment dyeing

When finished textile products such as hosiery or sweaters are dyed, it is called garment dyeing. A number of garments are packed loosely in a nylon net and put into a dyestuff filled tub with a motor driven paddle. The dye is thrown upon the garments by the moving paddles' effect. Garment dyeing Dye is applied to finished products such as apparels and garments.

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6. Top dyeing

If the top is combed wool sliver, it is wound on perforated spools and the dye solution is circulated through it. This method results in very even dyeing.

If the top is combed wool, the fibre is dyed in the stage just before the appearance of finished yarn.

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MACHINERY USED FOR DYEING

1. Package Dyeing Machine

A series of technical developments in the recent years has resulted into package dyeing being developed into a highly sophisticated as well as an economic process. Latest design Package Dyeing machines are amenable to accurate control and automation. These features would likely to lead to increases in the application of package dyeing. The term package dyeing usually denotes for dyeing of yarn that has been wound on perforated cores. This helps in forcing the dye liquor through the package. With the start of dyeing cycle, the dye liquor goes on circulating throughout the vessel and tank. This happens till all the dye is used up or fully exhausted. The dye flows through to the yarn package with the help of the deliberate perforations in the tube package. Once full exhaustion is brought about, the carrier of coloured yarn is consequently removed from the vessel. A large centrifuge removes excess water from the packages. Finally the yarn is dried using an infra red drying oven. The image shows the process working of a Package dyeing machine.

What's Latest in Package Dyeing Machine

A new high-temperature package-dyeing machine is making revolution in the world of dyeing machinery. It is offering an unprecedented liquor ratio that is as low as 1:4 this is achieved by integrated design of REV centrifugal pump, heat exchanger and unique flow-reversing system.

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Key Features:

According to test results, it can shorten total processing time needed for cotton yarn by nearly 5 hours.

Reduce water and electrical consumption by around 40% Cut down chemical costs by at least 19% as compared to conventional machines. Innovative integrated liquor circulation system results in 30% saving in area in

comparison to conventional machine arrangements. It claims to provide very good reproducibility, standardisation and energy savings.

Advantages of package dyeing machine:Package dyeing methodologies have been subjected to intensive research and development. As a result package dyeing machine has evolved into a very sophisticated apparatus. It offers a number of advantages.

Considerable reduction in yarn handling. Compatible to automatic control, in the process leading to reproducible dyeings. Open to large batches. High temperature dyeing a possibility. Low liquor ratios, giving savings in water, effluent and energy. Uniform and High rates of liquor circulation, that leads to level application of dyes. Machinery, totally enclosed resulting in good working conditions at the dyehouse.

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2. Loose Fibre Dyeing Machine

3. Hank Dyeing Machine

Hank Dyeing Machine is designed for dyeing of loose fibers / Yarns. The heating to dye is provided and bundle of yarn is half deep and rotated at speed calculated. The rotating shaft also has veins to inject dye inner side of bundle. The machine is most suitable to avoid hazardous manual operations. The Machine can be designed with multiple shafts for higher production.

Features

Fast Process

Non Hazardous operations

For vibration free running it is provided with unique four point shock absorption system

Compact design, less floor space required.

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The machine is sturdily built and dynamically balanced to high accuracy.

Suitable for various types of yarn.

Type of Fibers / Fabric : silk, polyester, light weight cotton, wool etc

Maximum working temperature

: 100°C

Maximum working pressure

:2 kg/cm2

Heating Rate : 20°C - 130°C approx 30 min (Saturated steam pressure 7 kg/ cm2)

Cooling Rate : 130°C - 80°C approx 20 min (Cooling water at 3 kg/cm2)

MOC : SS 304 / 316

Capacity : 5kg.,10kg.,15kg., 20kg.,25kg.,30kg. & 50kg

Panel Board : Programmable Semi Automatic

Application : Packages, Bobbins, Loose Fiber, Hank Yarn, Beams, Muffs / Tops

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4. Horizontal Package Dyeing Machine

This is an alternative configuration for the vertical spindle machine. Here, the dyeing kier is mounted horizontally and the yarn carrier is introduced from a trolley. This arrangement effectively replaces the need for crane. Horizontal Spindle Machines has simplified the design of the dyehouse building.

Main Features

• Innvolite design of airpad systems.• Capacity 100 to 600 kgs per batch.• Very low liquor ratio from 1:5 to 1:7• Low ceiling height only 3 meters required.• Overhead hoist or working platform not needed.• Loading up to 30% possible.• Hydraulic door opening for utmost safety.• Large saving of water, chemical, steam and electricity.• Comfortable to load and unload yarn.• Wo. temp up to 140 0C• Wo. Pr. Up to 4 kg/cm2

Application

• Yarn Packages• Zipper Tapes• Small width Fabrics

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5. Yarn Dyeing Machine

6. Loose Stock Dyeing Machine

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7. Winch/Beck Dyeing Machine

Winch dyeing machines comes with the lucrative options of low cost design, simplicity in operation and maintenenace yet uncompromising features when it comes to versatility.

Mostly woollen fabrics are dyed by using Winch Dyeing machine. The dyeing machine derives its name "Winch" as the fabric rope gets circulated in the machine by way of a mechanical action of a horizontal rotor or reel, called as a winch or sometimes wince. The cross-section of the winch rotor may be circular or elliptical.

As shown in the diagram below, the winch dyeing machine has a front compartment, a perforated partition separates it from the main dyeing chamber. It is this front compartment where dyestuff and dyeing auxiliary additions are made. Gradually they move to main dyeing vessel from there. The process works like this first a series of fabric ropes are immersed in the dye bath. This fabric ropes must be of equal lengths. A part of each rope is then taken over two reels or over the winch itself. In the subsequent course of dyeing operation a rope of fabric is circulated through the dye bath and the winch. The dyestuff and auxiliaries are dosed manually or automatically according to the recipe method.

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8. Jet Dyeing Machine

A machine used for dyeing of fabric in rope form. Jet dyeing machines came into existence with a purpose to minimise or eliminate the drawbacks of earlier machines like winch, jigger and beam dyeing units.

Special Features and Applications1. Jet dyeing machines can be operated even at high temperatures and pressures. Jet

dyeing systems are fitted with cooling systems with the potential for reuse of the warmed water on the next dyeing cycle.

2. Jet dyeing systems operate at a low liquor ratio, or the ratio of the mass of the dye bath to the mass of the fabric in the dyeing machine. Compared to conventional dyeing, typically with a liquor ratio of 1:15 to 1:25, jet dyeing can be operated at a liquor ratio from as low as 1:3 up to 1:6. Consequently, the dyeing operation consumes less water and chemicals, and generates less effluent.

3. Since the dyeing process depends on dye concentration, the lower liquor ratio increases the dyeing rate and dye fixation.

4. Increased dyeing rate results to quicker machine drains and fills, and more rapid heating and cooling. The latter decreases energy requirements for heating the dye bath, which then leads to reduced steam and boiler use, reduced fuel consumption, and fewer emissions to the atmosphere from combustion.

5. The lengthwise tension is less, widthwise tension is absent and fabric achieves better fullness and handle.

6. The frequent movement of fabric round the jet through the machine reduces the tenedncy of crease formation.

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Limitations of Jet Dyeing machines

1. High Initial investments and maintenance cost.2. Limited accessibility during the dyeing process.3. Foam forming substances are to be avoided.4. Any roughness of the inside surface cause damage to cloth.5. In case of cloth breakage, rethreading is complicated.

Types of Jet Dyeing MachinesAfter incestifating the dyeing results under different conditions such as development of new fiber blends, different construction fabrics, interaction position of jet, quantity of the dye liquor to be present in around the fabric and the type of impact of the dye liquor on the fabric in the jet area, the following type of jet dyeing machines were developed,

1. Fully flooded jet dyeing machines 2. Soft flow Jet dyeing machines 3. Low liqour ratio. Reel jet dyeing machines.

9. Overflow Dyeing Machine

Overflows Dyeing Machines are designed for use in delicate knitted and woven fabrics that are made up of natural as well as synthetic fibers. They are also extensively used in the production of carpets. The main difference between jet and overflows machines is that in jet machines the fabric gets transported by a bath that flows at high speed through the nozzle, while in Overflow Dyeing Machine it is the gravitational force of the liquor overflow that is responsible for fabric transportation.

Functioning of a Overflow Dyeing Machine

A typical Overflow Dyeing Machine works like this. A winch that is not motor driven usually is located in the top side of the machine where the fabric is hanged. A longer length of textile is made to hang from the exit side of the winch as compared to the inlet side. By applying the force of gravitation the longer length of textile is pulled downward more strongly than the shorter one. Consequently the fabric is soaked in the bath without any sort of tension. The following diagram well illustrates the working process.

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Advantages of Overflow Dyeing Machine

No evaporative losses- As the dyeing vessel is closed, there is no evaporative losses stemming from the dyebath. Further, depending on the situation the temperature may be raised to more than 1000oC.

No build up of steam condensate in the dyebath- The latest technology implies that the dyebath gets heated by a heat transducer which is steam driven. This technology apart from being very efficient ensures that there is no build up of steam condensate in the dyebath.

Low liquor ratios- Dyeing is conducted at relatively low liquor ratios, e.g. 10:1 and may be lesser resulting in substantial savings in water and energy.

Excellent dye liquor contact- Excellent dye liquor contact with the fabric rope results in better and more improved level dyeing.

Computer control- The machines are operated by computer and hence, operator error is eliminated.

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10. Beam Dyeing Machine

The beam dyeing machine operates with the same principle as that of package dyeing machine. It can be effectively used to dye yarn or fabric. The process works like this, fabric or yarn in open width is rolled on to a perforated beam. The beam then subsequently slid into a vessel that is closed and pressurized. The colour impregnates the fabric as the dye liquor is allowed to go on circulating through the preformations in the beam. Usually the beam machines are designed in such a manner so as to hold a single beam or multiple beams in a batch.

Features of Beam dyeing Machine

Able to adjust water level in accordance to fabric volume. Even dyeing and superior dyeing quality. Optimized circulation system along with high performance pumps.

Advantages of a Beam Dyeing Machine

The fabric is put under controlled tension, and is wound on to a perforated beam. This results in elimination of creases from the fabric. It also ensures total control of dimensions of the roll of fabric.

The fabric is not allowed to do any movement during the process of dyeing. This actually means that there is no application of mechanical action on to the fabric. As shown in the figure, there is no movement of the fabric as the hydrostatic pressure of the pump forces the dye liquor through the fabric roll.

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11. Jigger dyeing machine

Features:

Optimal, constant fabric tension and speed due to frequency controlled electric drives.

Integrated, self-cleaning filter station without maintenance intervals. Fast and tensionless unloading with frequency controlled debatching device. Frequency controlled batching rolls with digital speed indication. Entire fabric width illuminated for the supervision of the process. Two bath execution of the vat for reduction of the rinse water. Balanced expanders for crease-free winding.

Advantages

Frictionless fabric transport due to innovative drive technology. Accurate measuring of the batch length (shrinkage and extension). Enormous savings in energy costs such as water, steam and electricity. Reduced quantity of chemicals due to improved mixing and dosing function.

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12. HTHP Cabinet Hank Dyeing Machine

These are the most popular hank dyeing machines, these machines are designed to have liquor flow parallel to the yarn and they work with low liquor ratios to save substantially in consumption of thermal energy, water and chemicals. The material to be dyed in hanks is loaded on the sticks, generally two sticks are used one at the top and other at the bottom. The bottom stick is used to avoid the yarn entanglement during the liquor flow. The carriers are loaded with the sticks having hanks; the sticks are supported into slots made in the body of the carrier.

The loaded carriers are then put into the dyeing machine and door is closed. In a second variant of the machine, the machine is open at the top and career is loaded from the top, which, a rubber gasket is provided around the periphery on which the machine career rest, and vessel is sealed by the weight of the career and material, thus making closed circuit. The liquor circulation and flow remains the same as in ordinary cabinet machine.

The dye liquor in these machines moves while the material remains stationary. The flow direction is reversed frequently to ensure level dyeing.

Main features of the cabinet dyeing machines are:

1. These machines are most researched, developed and technically advanced, and these are most preferred choice for the dyeing of all types yarn in hank form.

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2. Modern machines are more flexible and capable of partial or half loading, without changing the M:L, by using either dummies or by using special loaders , which can be easily adjusted in the machines. The new machines are equipped with continuous variable volume control and monitoring system, which maintains the M:L even at reduced load .

3. Machine capacities available with same material to liquor ratios, from lab scale to 1000 kgs for bigger lot size. Coupling of similar capacity machines is also possible to get even bigger lots.

4. All features such as inverter controlled pumps, dosing and automatic color kitchen and fully automatic dyeing controllers, same as package dyeing machines are available in these machines.

5. These machines are suitable for dyeing of various sizes of hanks ( from 48” to 90 “) in different qualities such as cotton, viscose, cotton blends, acrylic, wool and its blends and nylon etc. without any problem.

6. The liquor ratio of machines varies between 1:10 to 1:15, depending upon the machine and quality of material to be processed.

7. In the machines with air pad technology, the air pad acts as a air cushion to take care of expanded dye liquor and it is possible to work with higher pressure and temperature The machines with air pad are capable of working up to a maximum temperature of 135 0 C and there is no need of an extra heat exchanger to cool down the expanded dye liquor. Since the machine works in a closed circuit mode, therefore the entire dye liquor participate in the dyeing.

8. The machines may be having a preparation tank with a quick transfer pump for faster liquor transfer from and to the machine without losing time and reducing the overall dyeing cycle. New machines are equipped with automatic color kitchen, multiple feeding and drainage points for more efficient and cleaner working.

9. The machines are equipped with an internal or external sampling device, which allows the inspection of samples at any point of dyeing cycle ,without disrupting the actual dyeing process.

10. The machines with interchangeable extra careers offer mach more flexibility in terms of saving in loading /unloading time as well as automation of loading and unloading.

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13. Roller Hank Dyeing Machine

These machines are based on Hussong type of hank dyeing machines in design .These machines are very simple in design and operation. In the basic design of machine there is rectangular SS tank with proper heating mechanism (either a heating coil or direct steam injection through a perforated steam pipe) and have a false bottom above the heating coil.The tank is fitted with a temperature indicator and control sensor. There is an array of SS rollers/poles which are fitted on a suitable frame .The rollers can rotate in clockwise or anticlockwise directions with the gears arrangement. The machine is fitted with a stop /start system to control the roller movement.The hanks loaded on rollers can be lowered in the tank or lifted out by lifting or lowering the frame with the help of hydraulic system. The speed (RPM) of rollers can be varied by changing the gears and rotation cycles are controlled by timers which change the direction of movement of motors.The dyeing vat has the filling and draining facility of dye liquor. The dyes and chemicals are added directly into the dye vat.

Advantages and disadvantages of Roller Hank dyeing machines

1. Roller dyeing machines are simple in design and operation2. Cost of the machine is not very high3. Almost all type of dye classes such as direct, reactive, vat, naphtha’s, pigments, soluble vats

can be applied to cotton, mercerized cotton or rayon filaments.4. All types of yarns can be processed such as cotton, mercerized cotton; viscose filament or

even silk can be processed. The machines with simple modifications can be used to produce tie and dye effects in bigger lots particularly in cellulosic substrates.

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5. The machine capacity depends upon the number of rollers, which could be from 1 to even 10 rollers, and each roller can handle from 2 to 4 kg of yarn.

6. Only 40-50% of yarn takes part in dyeing and rest is exposed to atmosphere, therefore hydrosulphite consumption is high in these machines.

7. The machines are open type, therefore maximum dyeing temperature is 95-98 0C .8. The liquor ratio increases with heating in case of direct injection of steam.9. Liquor ratio is high, generally 1:15 to 1:20, therefore chemicals, steam and water

consumption is comparatively high.10. The yarn entanglements take place during running which reduces the hank to cone winding

efficiency.11. Only limited automation is possible.12. The dyeing is carried out under atmospheric pressure and there is no liquor pressure,

therefore the color penetration in hard twisted material is poor.

14. Top Loading Cabinet Hank Dyeing Machine

15. Spray Dyeing Machine

Main features of spray dyeing machines are:

1. The machines are specially built for processing of delicate yarns such as wool, wool blends, silk and viscose yarns.

2. The yarn is treated very gently, and has minimum mechanical abrasion, the impact of dye liquor turbulence on the yarn is also minimum, thus minimum entanglement and mechanical damage during processing.

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3. The liquor is fed through an inverted controlled centrifugal pump, so the liquor circulation in liters / min/ kg can be adjusted as per requirement as well as when the machines are used at a reduced capacity.

4. Total liquor volume of the machines can be adjusted as per loading or number of arms in the use.

5. The entire dyeing cycle can be carried out in fully automatic mode with the help of with the help of microprocessor based programmer.

6. The arms can be removed and replaced easily, therefore it is also possible to keep a lot ready on a spare set of arms, which can be easily replaced after the completion of a dyeing cycle. The machines can be used at reduced capacity by reducing the number of arms in operation and more flexible.

7. The machines are available with air pad facility to run the machine at higher temperature and pressure and also keeping the constant liquor ratio when used at reduced loading.

8. Similar machines can be coupled together for dyeing of bigger lots in the same shade.9. The machines are equipped with a single addition tank ,which is used for injection of dyes

and chemicals through a separate pump. Fully automatic machines can be connected with automatic color kitchen also.

10. The machines are equipped with a sampling device to draw a sample for shade inspection without interrupting the dyeing operation

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16. Air Jet Dyeing Machine

Air jet dyeing machine is designed on the basis of aerodynamics principles. High-speed air jet is pumped into the nozzle; dyeing liquor is pumped into the nozzle from another pipeline. The vaporous particle of air jet and dyeing liquor mixture will realize a homogenous dyeing effect. Compared with the traditional dyeing machine, the air jet dyeing machines are outstanding in that water is used as the carrier of the dyestuff and the fabric driving force is air jet. It thus can reach a super lower liquor ratio. This is a revolutionary improvement in terms of saving heating time, saving energy and reducing the contamination discharge. Another outstanding factor to be noted is that there will be no crease marks on the fabrics because the fabric can open and move freely after entering into the nozzle.

Features：

Super-low and stable liquor ratio High repeatability Homogenous dyeing effect Crease marks free Spraying ringing

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17. Garment Dyeing Machine

This machine can be widely used for the pre and after treatment and dyeing of woolen sweater, clothes, acrylic fiber clothing, silk clothing, gloves, socks and other ready fabrics. Equipped with stepless speed regulator, the plate speed can be adjusted according to requirement of different fabrics. Dyeing cycle is shortened while dyeing effect is guaranteed.

18. HT Hank Dyeing Machine

Hank dyeing machines are mainly used to dye high temperature hanks, such as terylene-cotton, terylene, terylene-wool, acrylic fiber, cotton fiber, artificial silk, mercerized cotton, nylon, and blended yarns etc.

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Structure Features: Water flow can be regulated during dyeing process. Dam-type spraying tube can spray liquor, turn-over and move yarns. This designing can avoid twisting, knotting problems and minimize dyeing waste.

19. Atmospheric Soft flow Dyeing Machine (Fabric, piece dyeing)

Features:

Totally tangle free operation with help of angular design nozzle & fully floatable square pipe.

Dye 30 to 500g./mtr. Sq. Fabrics (Polyester, Cotton, Woven & Knitted fabrics). Excellent & even Dyeing with low tension & perfect rinsing system. Stirrer mechanism

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QUALITY CONTROL PARAMETERS

Fastness:

Washing fastness, perspiration fastness, rubbing fastness, scrubbing fastness, light fastness, seawater fastness, pool water fastness, Sublimation fastness, Hot press fastness, fastness to saliva, Chlorine fastness, Gas fading etc are different fastness test for color. Color change is measure by grey scale method. Staining is measured by adjacent fabric.

10-4 cm sample dyed or printed is sandwiched between two adjacent fabric which are undyed or unprinted with the same material. For blended fabric predominant blend is taken for sandwiching or multifilament fabrics are used for sandwiching. The sample must be 3mm smaller from all the 4 sides.

All 4 sides are stitched on stitching machine and then the suitable test is performed. For change in the color, after opening the sample it is dried in shadow and carried out the color change without washing. For staining adjacent fabrics are dried in shadow without washing and used for staining scale.The viewing condition for both the samples is in color cabinet and the observer must be at 450 angle and the light source used is D65.

Evaluation of staining:

Fastness to washing:

In case of IS (Indian Standard) five different method are there.Test Name Concentration Temp and MLR Time in Mins RemarksIS 1 5gpl Soap Test is carried

out at 450C with MLR 1:40

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IS 2 5gpl Soap 1:50 at 50oC 45IS 3 5gpl Non ionic

neutral soap,free from OBA+ 2gpl soda

600C 30

IS 4 5gpl soap +2gpl soda

950C 30 Add 10stainless steelballs having1.5gm weight,in the vessel.

IS 5 5gpl soap +2gpl soda

950C 4 Hrs 10 stainlesssteel ball asabove.

Fastness to perspiration:

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There are two type of human perspiration i.e. Acidic and Basic. Perspiration is prepared by using

L,hystadine monohydrochloride, monohydrate at concentration of 0.5 gpl + Sodium chloride 5gpl.

For acidic perspiration Disodium hydrogen orthophosphate dodecahydrate is taken at 5gp and pH is adjusted to 5.5 with acetic acid.

For basic perspiration Sodium dihydrogen orthophosphate dehydrate is taken at 2.2 gpl. pH is adjusted with 0.1N NaOH.

Here sample is sandwiched in the adjacent fabric, there it is clipped into the glass plates, and keeping under weight of 4.5kg for 4 hours, 380C +- 10C is the temperature, maintained.

Fastness to hot pressing:

It is carried out in two ways. Hot pressing and wet pressing. In case of wet pressing, sample and adjacent fabric is dipped into water and it is kept in filter paper to remove excess water from fabric and a test is carried out. Pressure given on the fabric is 30gm/cm2. Test is carried out at 1000C+-20C, 1500 +-20C and

2000 C + -20C. For every test time allotted is 15 sec. All three samples are heated from top. One side is electric heated and adjacent fabric is kept to the opposite side of the sample. Sample is analyzed for the change in color and staining on the adjacent fabric. Some times for the adjacent fabric multifilament fabric are taken whenever the blend is present.

Fastness to Sublimation:

This test is mainly carried out for polyester and its blend for disperse dyes particularly to check the tendency of migration. The test is carried out in scorch tester. It is similar as hot pressing but slight change with heating with both the side of the fabric, where both the plates are electrically heated.

Fabric is sandwiched in same kind of undyed blend fabric or 100% polyester, and kept in the sublimation tester and treatment is carried out for 30 seconds at temperature 1500C, 1800C and 2100C. The sample is checked for the color change and the adjacent fabric for staining change.

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Rubbing Fastness Test:

Rubbing test is generally carried out in Pigment, vat, reactive, acid dye etc. The fabric is clamped on the rubbing fastness tester. The white fabric approx 5cm is clamped on the finger of tester. The probe is moving against the specimen in 10cm distance for 10 times to & fro with one to & fro stroke at speed of 1 sec. Probe is having a 900gm load. Then rubbing fastness is calculated by staining scale method by checking the fabric clamped on the finger. In case of the wet rubbing test the fabric on the probe is wetted and same procedure as above is followed.

Fastness to wet scrubbing:

This test is only for pigment dyed fabric. The sample is same as the rubbing fastness test. Instead of rubbing device there is a scrubbing device (metallic wire brush with 250 wires/sq inch area with length 5mm. Weight is 100gms, which is fitted with a brush. The specimen is dipped in the 5gpl soap and 2gpl soda ash at 600C and then generally 100 Strokes are given. After 50 strokes the sample is again dipped in the soap and soda solution and again it is scrubbed. Then the sample is washed and dried in shade and change in color and change in depth is evaluated.

Light Fastness:

Fastness for light is generally carried out for all types of dyed and printed fabrics. The artificial lamps which have same intensity of Sunlight are selected. Mainly Xenon lamp is used. This test is carried out from scale 1 to 8. For this purpose 1-8 different wool samples which are called as know blue wool standards, having known light fastness properties. During the exposure the precaution is taken to maintain temperature in and around the sample 300C. For that water cooling systems are used to maintain temperature and humidity in fadometer. All blue wool samples are exposed along with specimen. Time of exposure is from 24hrs – 72 hrs. After the exposure time, complete change in the color of specimen is compared with change in the blue wool sample. E.g. If 5 number blue wool sample color change is equivalent to the specimen sample then light fastness rating is 5.

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PROCESS CONTROL IN DYEING

YARN DYEING:

Winding density should be even. Package density is checked before loading the package.

First take circumference, then measure height and deduct the center portion of cone that is hollow. Then weigh it so you will get the density. For cotton the package density is taken as 0.3 gram/cc.

Shape of the Cheese:

Shape and size of the cheese should be same. Prior to process checking is done visually.

Checking the angle of the winding:

Angel should be 30-450. As the angle increases the density decreases.

Perforation of the spindles:

Perforation of the spindles prior to mounting the spindle. It is visually assessed.

STANDARD: No perforation mark.

NECESSARY ACTION: Wound butter paper or non woven textile. Polycarbide, and polyethylene spindles are only wound. Spring type are not wound..

MLR:

MLR for conventional machine is 1:10. Fongs has reduced the MLR to 1:4.

STANDARD: MLR varies from 1:6 to 1:12 and necessary action is adjusting the MLR as per the requirement.

Pump pressure:

Modern machine gives upto 6-7 Psi and old machines used to give 4psi.

Take necessary action for smooth reversal flow of the liquor.

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Recipe Colour and chemical:

Prior to dyeing ensure confirmatory of standard recipe.

Colour Dissolution:

Prior to dyeing check colour dissolution. Method of checking is spotting on filter paper.

STANDARD: Complete dissolution of colour, if partly colour is getting dissolved then strain the solution prior to dyeing.

pH:

Check with pH paper or pH meter.

STANDARD: No standard it varies as per the dye class.

NECESSARY ACTION: By addition of acid or alkali.

Temperature:

Check with thermometer and adjust steam supply.

STANDARD: No standard, it varies as per the class of dye.

Time:

During process, the method of checking is dyeing record.

Entrap air:

Entrapped air is checked prior to built up of the pressure. Method is by checking air vent valve.

STANDARD: No entrap air and ensure complete air removal.

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Steam leakages:

During process visual checking is done for no leakage in the pump and circulating valve.

Necessary action: Trap or plug all leakages.

Variation in Package density during process:

In case of cotton carry out pre-treatment process with low alkali. In case of polyester texturised yarn due to boiling treatment yarn shrinks, to avoid that either hold the batch at low temperature for longer time i.e 45-60min or adjusting density during winding i.e Wind at lower density so the density increases or become optimum after shrinking

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Remnants of fabrics can be dyed a single colorway, making them ideal for a quilt or patchwork project. Over dyeing a range of fabrics with a single color will present a wide selection of different colors, but all with a similar tone. Lighter colors, of course, will pick up the color of the new dye more readily than darker colors. This is a handy technique to use when looking to recycle and repurpose garments and fabrics.

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DYEING TECHNIQUES

Different dyeing techniques can create some wonderful and extremely unusual effects on fabric.

Finished garments can be dyed, and this can present an extremely good way to create some unique garments relatively cheaply. For instance a whole summer wardrobe could be created from a few yards of undyed cotton, and dyed afterwards in a range of complimentary colors.

Some of the Dyeing Styles are :

1. Tie dyeing

Tie-dye is a process of resist dyeing textiles or clothing which is made from knit or woven fabric, usually cotton; typically using bright colors. It is a modern version of traditional dyeing methods used in many cultures throughout the world. "Tie-dye" can also describe the resulting pattern or an item which features this pattern.

Tie-dyeing is accomplished by folding the material into a pattern, and binding it with string or rubber bands. Dye is then applied to only parts of the material. The ties prevent the entire material from being dyed. Designs are formed by applying different colors of dyes to different sections of the wet fabric. A wet t-shirt is much easier to use rather than just dyeing on a dry t-shirt. Once complete, the material is rinsed, and the dye is set.

Common modern tie-dyeing folds and patterns include: Spiral, V, Random and Random circles.

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2. Shibori

Shibori is a Japanese term for several methods of dyeing cloth with a pattern by binding, stitching, folding, twisting, compressing it, or capping. Some of these methods are known in the West as tie-dye.

Each method is used to achieve a certain result, but each method is also used to work in harmony with the type of cloth used. Therefore, the technique used in shibori depends not only on the desired pattern, but the characteristics of the cloth being dyed. Also, different techniques can be used in conjunction with one another to achieve even more elaborate results.

Ne-maki shibori

Kanoko shibori

Kanoko shibori is what is commonly thought of in the West as tie-dye. It involves binding certain sections of the cloth to achieve the desired pattern. The pattern achieved depends on how tightly the cloth is bound and where the cloth is bound.

Miura shibori

Miura shibori is also known as looped binding. It involves taking a hooked needle and plucking sections of the cloth. Then a thread is looped around each section twice. The thread is not knotted; tension is the only thing that holds the sections in place. The resulting dyed cloth is a water-like design. Because no knot is used, miurea shibori is very easy to bind and unbind.

Kumo shibori

Kumo shibori is a pleated and bound resist. This technique involves pleating sections of the cloth very finely and evenly. Then the cloth is bound in very close sections. The result is a very specific spider-like design. This technique is very precise to produce this specific design.

Nui shibori

Nui shibori includes stitched shibori. A simple running stitch is used on the cloth then pulled tight to gather the cloth. The thread must be pulled very tight to work, and a wooden dowel

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must often be used to pull it tight enough. Each thread is secured by knotting before being dyed. This technique allows for greater control of the pattern and greater variety of pattern, but it is much more time consuming.

Arashi shibori

Arashi shibori is also known as pole-wrapping shibori. The cloth is wrapped on a diagonal around a pole. Then the cloth is very tightly bound by wrapping thread up and down the pole. Next, the cloth is scrunched on the pole. The result is a pleated cloth with a design on a diagonal. "Arashi" is the Japanese word for storm.

Itajime shibori

Itajime shibori is a shaped-resist technique. Traditionally, the cloth is sandwiched between two pieces of wood, which are held in place with string. More modern textile artists can be found using shapes cut from acrylic or plexiglass and holding the shapes with C-clamps. The shapes prevent the dye from penetrating the fabric they cover.

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3. Batik

Batik is a cloth that traditionally uses a manual wax-resist dyeing technique.

Batik or fabrics with the traditional batik patterns are found in Indonesia, Malaysia, japan, China, Azerbaijan, India, Sri Lanka, Egypt, Nigeria, Senegal, and Singapore.

Javanese traditional batik, especially from Yogyakarta and Surakarta, has notable meanings rooted to the Javanese conceptualization of the universe. Traditional colours include indigo, dark brown, and white, which represent the three major Hindu Gods (Brahmā, Visnu, and Śiva). This is related to the fact that natural dyes are most commonly available in indigo and brown. Certain patterns can only be worn by nobility; traditionally, wider stripes or wavy lines of greater width indicated higher rank. Consequently, during Javanese ceremonies, one could determine the royal lineage of a person by the cloth he or she was wearing.

Javanese batik with bird and floral motifs

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