Different Textile Production Sectors in Bangladesh

The Production of Textiles:

The textile industry has seen the application of many new technologies over the centuries. However, the basic steps have remained the same. What is known as the textile industry includes all the steps necessary to transform fiber into fabric that is ready for stitching, sold either in the market or used in the RMG, or ready made garment, sector. These basic steps are spinning, weaving or knitting, and a combination of dyeing, printing and finishing.
RMG Industry in Bangladesh

The principal materials used in the spinning sub-sector are raw cotton and synthetic fibers such as viscose and polyester staple fibers. None of these materials, however, are produced in Bangladesh on a large enough scale to supply a significant part of the demand. The reasons for this are complex. 

Cotton needs to be grown in fields, and then ginned, which is the removal of seeds from cotton. At present, the cotton produced in Bangladesh is of an acceptable standard. However, the increased cultivation of cotton in this country is not feasible because the crop requires large amounts of land for a substantial yield. In overcrowded Bangladesh, farmers choose to grow rice over cotton. Locally grown cotton currently meets only 4-5% of the total requirement. The remaining 95% of the cotton needed must be imported at very high prices. The production of the synthetic/man-made fibers used in the textile industry requires fairly advanced technology and investment. 

Once the raw materials have been obtained, spinning is the first step in textile production. This is the process by which natural or synthetic fibers are cleaned and twisted into yarn. 

The raw materials first move through the blow room where all impurities are removed, for natural fibers only and the fibers are rolled into laps. The laps then go through a carding machine, where they are cleaned further and formed into slivers, thick and loosely spun yarn. In order to produce combed yarn, the fibers need to undergo further processing in the comber machine where the short strands are removed, and the remain processed into sliver. The sliver is then fed to the draw frame, and speed/roving frames where they are twisted to form what are called rovings. The rovings are finally placed in spinning frames where further twisting and drafting take place, and yarn is produced. The yarn is then spun around a bobbin or cone, using autoconers or cone winding/reeling machines, packed and marketed.

Fabric Forming :

Weaving and Knitting:

Next the yarn is made into grey, the early stage of fabric processed using looms or knitting machines. The name indicates that the material has no color at this point. These are fairly simple procedures and can even be done by hand, as they were for many centuries in cottage industries. Weaving produces cloth that has a rigid structure, such as the material used for making trousers, shirts, bed sheets, etc.

Prior to weaving the yarn is wrapped around beams and dipped in a size, an adhesive, which when dries gives the yarn a rigid and uniform structure. This yarn is then fed into the looms and called the warp. A thread of yarn, called the weft, passes between alternating warp yarn with the aid of a shuttle, air jet, or rapiers.

Knitting, however, can also be used to make grey. Instead of looms, circular knitting machines are used for knitting. These machines use needles fed with yarn that move in an up and down motion and knit interlocking arrangements of yarn. Knit fabric is much softer and more flexible than that produced on looms, and is commonly used for producing articles of casual wear such as tee shirts, and under garments.

Dyeing, Printing, Finishing:

The grey then undergoes the three steps of dyeing, printing, and finishing. I had the opportunity to learn about these processes in great depth on my various visits to textile mills. After the grey is inspected, it goes through a process called the batch method when it undergoes scouring, bleaching, and dyeing. Scouring is the treatment of grey in chemical solutions in order to remove the size, natural fats, waxes, proteins, and other impurities, and to make the fabric hydrophilic, which means it no longer repels water.

The bleaching process is next. It is essential in giving the cloth a clean white color. It is done using one of two different methods: bleaching with dilute hypochloride solution at room temperature, or by using hydrogen peroxide solution at elevated temperatures, usually 80 to 90 degrees Celsius. The latter method usually results in better and longer lasting whiteness, however is the more expensive of the two methods.

The scoured cloth is then dyed, and then printed on. Printing is done using perforated rollers that allows certain chemicals and colors to diffuse through the holes. After the printing has been completed, the fabric is washed, soaked in chemicals under elevated temperatures for color fixation, and then washed again.

Knitted fabrics are loaded on to a jigger machine, which performs the processes of scouring, bleaching, or dyeing. The fabric then moves on to a machine called either de-watering or de-twisting machine, which removes water from the fabric. The fabric then goes through a shrinkage tensionless drier which is designed for drying, shrinking, and relaxing the knitted fabrics.

The final process before the fabric is ready for stitching is compacting. During this step the fabric is steamed and ironed between a roller assembly. The fabric is then folded and is ready for marketing. 


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