Monday, February 28, 2022

Soft flow dyeing machine structure and working principle, Advantages of soft flow dyeing machine

Please click on the below link to read this article in Hindi:

हाई टेम्परेचर एंड हाई प्रेशर सॉफ्ट फ्लो डाइंगमशीन

High-temperature high-pressure soft flow dyeing machine:

As we know that the dyeing of the textile material is carried out by using three methods. The textile material is dyed by continuous, semi-continuous and batch dyeing methods. The batch process is the most common method used to dye textile materials. There are three general types of batch dyeing machines:

1- In which fabric is circulated

2- In which dye bath is circulated

3- In which both the bath and material are circulated.


The soft flow dyeing machine is the best example of one of the dyeing methods in which the dye bath and fabric both are circulated during the fabric dyeing process.

A soft flow dyeing machine is suitable for dyeing a wide range of knitted and woven constructions of fabric in rope form. This machine is very useful for the dyeing of lightweight woven fabrics and pile fabrics like terry towels. 

Advantages of soft flow dyeing machine:

1- The soft flow dyeing machine minimises liquor usage.

2 - The soft flow dyeing machine avoids fabric distortion, pilling and creasing. 

3 - Improved rinse efficiency results.

4 - Tensionless fabric movement helps to improve warp-wise fabric shrinkage after washing.

5 - Low dye chemical cost results in soft flow dyeing due to low material liquor ratio.

6 - The effluent treatment cost is reduced due to the low material liquor ratio.

7 - The steam cost also decreases due to the low material liquor ratio.

8 - The lightweight and loose construction are dyed in the soft flow dyeing machine without any slippage.

9 - The synthetic fabric in which the colour fixation takes place above boiling temperature can be dyed in the high-temperature high-pressure soft flow dyeing machine.  

10 - The fabric pilling properties are also improved.

11 - The shade difference between selvedge and the body of the fabric does not appear in the soft flow dyeing machine.

Types of Soft Flow Dyeing Machine:

1. Multi nozzle soft flow dyeing machine.

2. High-temperature high-pressure soft flow dyeing machine.

3. Simple soft flow dyeing machine.

Various processes involved in soft flow machine:

1. Scouring and bleaching

2. Dyeing

3. Washing and Neutralizing

4. Stripping of dyed goods

Structure and working principle of soft flow machine:

Since the fabric is circulated in the soft flow machine in the rope form therefore the soft flow dyeing is also known as the rope dyeing process.

Fabric loading  and unloading system:

The fabric is circulated in the form of an endless rope of the fabric. The pieces of the fabric are stitched together to find the continuous length of the available fabric to be dyed. A woven cotton tape having good tensile strength is passed through the fabric passage during machine commissioning. Now, the upper end of the fabric is tied with the upper end of the cotton tape. The take-up roller or drive wheel carries the fabric inside the machine. The lower end of the cotton tape is pulled out slightly during loading till the upper end of the fabric comes out of the machine. The cotton tape is removed from the fabric now. The fabric loading gets continue till the lower end of the fabric. Now, the upper and lower ends are stitched together to form an endless fabric. The fabric loading and unloading door is closed now.

When the fabric dyeing gets completed, the fabric is taken out of the machine through an unloading reel. The fabric is collected in the cloth trolley. At the end of fabric unloading, the cotton tape is inserted again in the fabric passage.

Dye autoclave or main dye vessel: 

The dye autoclave is made of high-quality corrosion-resistant stainless steel. Basically, it is a high pressure closed vessel. The dye bath is filled in this autoclave. the fabric is loaded inside this autoclave. a leak-proof fabric loading and unloading door is mounted in front of the autoclave. 

Nozzle or overflow tube and fabric transport system:

The rope of the fabric and dye liquor both move slowly in the soft flow fabric dyeing machine. The transportation of the fabric imparts a mild mechanical action. The dye liquor feeds to the nozzle at high pressure. When the fabric passes through the nozzle, the circulating fabric comes in contact with dye liquor. The dye liquor penetrates into the fabric properly due to pressurised liquor circulation.  The main dyeing vessel is a tubular vessel. The fabric coming out of the nozzle and narrow tube( delivery tube) falls into the main dye vessel. The falling fabric gets plaited continuously in the man dye vessel.

Liquor circulation pump and filter:

A high-pressure liquor circulation pump is used to feed the dye liquor into the nozzle. It takes the liquor from the main dye vessel and feeds it to the nozzle. A filter is also attached with a liquor pump that cleans the dye liquor continuously.

Heat exchanger: 

A heat exchanger is mounted between the liquor circulation pump and the nozzle of the machine. The main function of the heat exchanger is to bring down the temperature when required. When the dyeing is completed, the cooling of the dye bath is performed with the help of this heat exchanger.

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