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INTRODUCTION TO DIFFERENT DYEING MACHINES
There are several dyeing machines used for dyeing of fibre, yarn, fabric and garments.
Some of the important of them are
(1) Jigger Dyeing Machine
(5) Package Dyeing Machine
(6) High Pressure High Temperature Dyeing Machine. (Beam Dyeing Machine)
Jigger Dyeing Machine
Jigger dyeing machine is the most commonly used for dyeing all kinds of cotton fabric. There are mainly two types of jigger dyeing machine. One is open jigger dyeing machine and other is closed jigger dyeing machine. The open jigger dyeing machine is shown in the figure. This machine consists of V shaped stainless steel vessel. Two rollers are fitted above the vessel called as cloth rollers. These rollers are rotated by power. Out of these two rollers one roller is driven by a motor which is called take up roller and the other roller from which the cloth is delivered is called let off roller. When all the cloth is passed from the let off roller to the take up roller, it is called as one end or one turn. The number of ends or turns depends upon the type of the fabric and also the percentage of the shade. Initially, a large length of (50 kg) cloth is wound on the let off roller and take up roller is then driven by the power. After one end is taken, the take up becomes let off roller. These backward and forward movements of cloth through the dye liquor absorb more and more dye. The capacity of the jigger is 100 to 150 gallons. In the modern jigger, automatic devices are fitted along with the timing switch by using reversing will take place automatically. When dyeing all the dye liquor should not be added at one time. The dye liquor should be added in batch wise, in order to get even shade on the cloth. In the present scenario, closed types of jiggers are used. The main advantage is to prevent heat loss and chemical loses by evaporation. This type of jigger is very important for dyeing vat, Sulphur etc.
Advantages of Jigger Dyeing Machine
1. The cloth can be dyed in open width form of full width form.
2. Chemical and heat loses are less when compared to winch dyeing machine
3. The material to liquor ratio is 1:3 (or) 1:4 which saves considerable amount of
chemical cost and steam cost.
Disadvantages of Jigger Dyeing Machine
It exerts lot of tension in the warp direction and because of this normally woolen, knitted
fabrics, silk etc are not dyed in jigger dyeing machine.
Winch Dyeing Machine
Winch dyeing machine is normally used for dyeing light weight fabrics like knitted fabrics as well as woven, silk etc. The winch dyeing machine is different in construction from the jigger. The machine consists of elliptical winch (or) circular winch which is driven by hand or motor. Elliptical winches are most widely used. It has a perforated portion dividing the machine in to two compartments. One is small and the other one is bigger in size. Dye- liquor pipe, steam pipe, water inlet are provided in small compartment. Dyeing is carried out in the larger compartment. During working, one end of the fabric is passed over the guide rollers and winch and under the dye liquor and passed in between the pegs. After the sufficient amount of cloth is fed the ends are stitched and making a long continuous loop formation. Many such loops run together separately by a series of pegs, to avoid entanglements. The loops are drawn in and out of the bath by rotating the winch. After dyeing is over the pieces are separated. The winch is made up of stainless steel. Now-a-days closed type of winch is also used to prevent the temperature loss and pressure loss.
Thin and light weight fabrics like knitted fabrics, voile cloth etc, can be dyed successfully in winch dyeing machine without exerting any tension. Embroidery fabrics may be dyed in winch dyeing machine without affecting the embroidery designs.
Fabrics are dyed in rope form, so there are more chances for uneven dyeing. Therefore, we will get even dyeing only when retarding / leveling agent is added to the dye liquor. The material to liquor ratio is very high i.e. 1:30 or 1:40. Therefore the heat and the additional chemicals are provided more when compared to jigger. Heat and chemical losses are more because of the wider open tank.
Continuous dyeing methods depend upon the impregnation with the padding mangles. The padding mangles are equipped with two, three or even four mangles. The rollers are arranged one above the other. Three bowl padding mangle are usually prepared for dyeing of cloth. The padding mangle consists of two ebonite rollers and one rubber covered roller. To reduce the material to liquor ratio, low capacity troughs are generally used with the different shapes. Some of the machines are provided with jacket troughs for maintaining the temperature of pad liquor. An over head tank is connected to the mangle for feeding the stock solution through the perforated pipe. The supply of the dye-liquor is controlled automati
cally to maintain a constant level. The pressure on the padding mangle is applied by hydraulic or pneumatic system which enables heavier and uniform pressure. The trough is fitted with dye-liquor and the cloth passes through the dye solution, which is heated by steam. After that the cloth is passed between the ebonite and rubber covered roller to give uniform pressure throughout the fabric. The pressure can be altered depends upon the type of the fabric. The speed is 200 yards/minute. It is used for dyeing vat, Sulphur, Naphthol etc. The solution used in the trough is divided in two equal portions to avoid uneven dyeing. The padding mangles may also be used for desizing purposes.
This is the most modern machine used for the dyeing of polyester using disperse dyes. In this machine the cloth is dyed in rope form which is the main disadvantage of the machine. In this machine, the dye tank contains disperse dye, dispersing agent, leveling agent and acetic acid. The solution is filled up in the dye tank and it reaches the heat exchanger where the solution will be heated which then passed on to the centrifugal pump and then to the filter chamber. The solution will be filtered and reaches the tubular chamber. Here the material to be dyed will be loaded and the winch is rotated, so that the material is also rotated. Again the dye liquor reaches the heat exchanger and the operation is repeated for 20 to 30 minutes at 135o C. Then the dye bath is cooled down, after the material is taken out. Metering wheel is also fixed on winch by external electronic unit. Its purpose is to record the speed of the fabric. The thermometer, pressure gauge is also fixed in the side of the machine to note the temperature and pressure under working. A simple device is also fixed to note the shade under working.
Ï Dyeing time is short compared to beam dyeing.
Ï Material to liquor ratio is 1:5 (or) 1:6
Ï Production is high compared to beam dyeing machine.
Ï Cloth is dyed in rope form
Ï Chance for crease formation.
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 applicati
on 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.
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.
Ï Considerable reduction in yarn handling.
Ï Compatible to automatic control, in the process leading to reproducible dyeing.s.
Ï High temperature dyeing a possibility.
Ï Low liquor ratios, giving savings in water, effluent and energy.
Ï Uniform and High rates of liquor circulation, that leads to level application of
Ï Machinery totally enclosed resulting in good working conditions at the dye-house.
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 perforations 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
Ï Able to adjust water level in accordance to fabric volume.
Ï Even dyeing and superior dyeing quality.
Ï Optimized circulation system along with high performance pumps.
Advantages of Beam Dyeing machine
Ï 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.
Ï 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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