Working Process of Roller Hank Dyeing Machines

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 have the filling and draining facility of dye liquor. The dyes and chemicals are added directly into the dye vat.

Roller Hank Dyeing Machine
Operation of the Machine:
The hanks to be dyed are loaded onto the rollers bars by avoiding overlapping of hanks, in lifted position. The dye bath is kept ready with proper liquor level ,and mixed homogenously ,preferably with an external circulation pump .The hanks are lowered into the dye bath and movement is started , approximately 40-50% part of the hanks remain the liquor and rest is exposed to atmosphere . The material is lifted up for addition of colors ,chemicals ,salt, alkali etc or for raising the temperature of dye bath(in case of direct steam injection). In case of indirect heating the dye bath temperature may be increased at set rate of heating ,but in case of direct heating the temperature rise is step by step. The sample may be drawn at the completion of dye cycle and checked for shade, without stopping the machine. All operations can be done in the same machine

hank dyeing
Roller hank dyeing machines

Advantages and disadvantages of Roller Hank Dyeing machines

  1. Roller dyeing machines are simple in design and operation
  2. Cost of the machine is not very high
  3. Almost all type of dye classes such as direct, reactive, vat, naphthols, 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.
  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. Liqour ratio is high ,generally 1:15 to 1:20, therefore chemicals, steam and water consumption is comparatively high.
  10. The yarn entanglements takes place during running which reduce 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.
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Mazharul Islam Kiron is a textile consultant and researcher on online business promotion. He is working with one European textile machinery company as a country agent. He is also a contributor of Wikipedia.

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