Jet Dyeing Machine:
Jet dyeing machine is the most modern machine used for the dyeing of polyester fabric with disperse dyes. In these machines, both the fabric and the dye liquor are in motion, thereby facilitating a faster and more uniform dyeing. In jet dyeing machine, there is no fabric drive reel to move the fabric. The fabric movement by only force of water. It is economical, because of low liquor ratio. It is users friendly because comparison with long tube dyeing machine, to control the fabric movement four valves required. In jet dyeing machines and fabric dyeing machine, there is only one valve. Absent of reel, reduce connecting electric power, maintenance of two mechanical seal and breakdown time, if jet pressure and reel speed not synchronized.
In jet dyeing machines a strong jet of dye liquor is pumped out from an annular ring through which a rope of fabric passes in a tube called a venturi. This venturi tube has a constriction, so the force of the dye liquor passing through it pulls the fabric with it from the front to the back of the machine. Thereafter the fabric rope moves slowly in folds round the machine and then passes through the jet again, a cycle similar to that of a winch dyeing machine. The jet has a dual purpose in that it provides both a gentle transport system for a fabric and also to fully immerse the fabric in liquor as it passes through it.
In all types of jet machines there are two principle phases of operation:
- The active phase in which the fabric moves at speed, passing through the jet and picking up fresh dye liquor
- The passive phase in which the fabric moves slowly around the system back to the feed‐in to the jets
Jet dyeing machines are unique because both the dye and the fabric are in motion, whereas in other types of machine either the fabric moves in stationary dye liquor, or fabric is stationary and the dye liquor moves through it.
The design of the jet dyeing machine with its venturi means that very effective agitation between the fabric rope and the dye liquor is maintained, giving a fast rate of dyeing and good levelness. Although this design can create creases longitudinally in the fabric, the high degree of turbulence causes the fabric to balloon out and the creases disappear after the fabric leaves the jet. However, the rapid flow of the dye liquor can lead to a high degree of foaming when the machines are not fully flooded. The machines operate at low liquor ratios of about 10 : 1, so as with beam dyeing, exhaustion is good and water and energy consumption efficient.
Jet dyeing machines were initially designed specifically for dyeing knitted textured polyester, and indeed they were originally designed to operate at high temperature for this purpose. Jet dyeing machines through their various designs and transportation systems provide a great amount of versatility and are used for many woven and knitted fabrics. Below figure shows a jet dyeing machine being unloaded after the dyeing cycle has completed.
The strong liquor flow in early machines gave somewhat rough treatment to fabrics, so they were not suited for dyeing delicate fabrics. The development of fully flooded machines, in which the rope is always kept fully immersed in dye liquor, overcame this issue. After the fabric passes through the venturi, it passes to a much wider storage tube, where the speed is much slower. Thereafter it is drawn through a narrow tube back towards the venturi. In this machine the cloth is dyed in rope form which is the main disadvantage of the machine.
Features of Jet Dyeing Machine:
In the case of a jet dyeing machine, the dyebath is circulated through a nozzle that transports the goods. Features and technical specifications of jet dyeing machine are given below.
- Capacity: 200–250 kg (single tube)
- Typical liquor ratios are between 1:5 and 1:20;
- Dye: 30–450 g/m2 fabrics (polyester, polyester blends, woven and knitted fabrics)
- High temperature: Up to 140°C
- A jet dyeing machine operates at a material velocity of up to 200–500 m/min,
- Machine body and wetted parts made of ss 316/316L for corrosion resistance.
- Winch reel of larger diameter offers lower surface tension with the fabric.
- Heavy-duty ss centrifugal pump that provides high fl ow rate to complement the high fabric speed.
- Reversing nozzle that ejects the fabric rope back to automatically release any tangling.
- Highly efficient heat exchanger for fast heating and cooling.
- Color kitchen with accessories.
Types of Jet Dyeing Machine:
In deciding the types of textile dyeing machines the following features are generally taken into consideration for differentiating. They are the following. Shape of the area where the fabric is stored i.e. long shaped machine or J-box compact machine. Type of the nozzle along with its specific positioning i.e. above or below the bath level. Depending more or less in these criteria for differentiation following types of Jet Machines can be said to be as developments of the conventional jet dyeing machine. There are three types of jet dyeing machine. They are,
- Overflow Dyeing Machine
- Soft Flow Dyeing Machine
- Airflow Dyeing Machine
Main Parts of Jet Dyeing Machine:
- Main Vessel or Chamber
- Winch roller or Reel
- Heat Exchanger
- Reserve Tank
- Chemical dosing tank
- Controlling unit or Processor
- Fabric Plaiter
- Different types of motors and Valves Main Pump
- Utility lines i.e. water line, drain line, steam inlet etc.
Working Principle of Jet Dyeing Machine:
In this machine, the dye tank contains disperse dyes, 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 135oC. 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.
Advantages of Jet Dyeing Machine:
The jet dyeing machine offers the following striking advantages that make them suitable for fabrics like polyesters.
- Dyeing time is short compared to beam dyeing.
- Material to liquor ratio is 1:5 (or) 1:6
- Production is high compared to beam dyeing machine.
- Low consumption of water which provides savings in energy and faster heating and cooling.
- Short dyeing time
- High fabric transport speed by adjusting nozzle valve to cause level dyeing.
- Can be easily operated at high temperatures and pressure
- Vigorous circulation of liquor and material causes quicker dyeing.
- Less dye at the surface resulting in quicker washing with marginally better fastness properties.
- Fabrics are handled carefully and gently
Limitations / Disadvantages of Jet Dyeing Machine:
- Cloth is dyed in rope form.
- Risk of entanglement.
- Chance for crease formation.
- The force of the jet may damage delicate fabrics.
- Sampling of the dyed fabric during dyeing is difficult.
- Fabrics from spun yarns of staple fibers may tend to become quite hairy in appearance because of abrasion.
- Internal cleaning is difficult as the machine is completely enclosed.
- High initial investment and maintenance cost is high.
- Textile Dyeing by Dr. N. N. Mahapatra
- An Introduction to Textile Coloration: Principles and Practice by Roger H. Wardman
- Handbook of textile and industrial dyeing, Volume 1 Edited by M. Clark
- Textile Chemistry by Thomas Bechtold, Tung Pham
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Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.