The Supply Chain of Textile Industry in Bangladesh


The Supply Chain of Textiles 


Abstract: 
A survey on the whole textile chain is presented here, starting with fiber production and its variety depending on raw material, followed by textile processing and technologies in yarn and fabric production, further finishing processing and technology, then manufacturing and merchandising, and finally consumption, use and disposal.

Introduction
Unlike value-added chains for food or building materials, textiles and apparel include a great number of process stages, carried out by different successive industry units. Along with the material fl ow, the value-added chain is modeled in the steps of fiber production, spinning, weaving/knitting, finishing, cutting and sewing, merchandising, wholesale/retail, consumption, and disposal/recycling.

Natural fibers
Today an ever-increasing variety of fiber material is applied in the production of textile fabrics. The main categories are natural fibers, gained either from plants that were once wild but are now grown in agriculture,or from domestic animals, often as a by-product of keeping them for food.

Natural fibers are gained from plants as lint or bast fibers (cotton, ramie, hemp) or from animals as hair (wool, cashmere, alpaca) or as fi laments from silk. ‘Man-made fibers’ may have a natural cellulose base (viscose, cupro) or protein base from plants or animals (polylactate), or they are derivatives of crude oil fractions (polyester, polyamide, polypropylene, polyurethane).

Man-made fibers and filament and yarns
Man-made fibers are divided into fibers based on crude oil fractions (synthetic fibers) and fibers based on regenerated cellulose (cellulosic fibers). Figure C gives an overview on the different fiber types. For a few decades, use of synthetic fibers increased only slowly due to some properties making them inferior to cellulosic fibers for apparel production. Today the most prominent fibers for apparel are polyester (PES), followed by polyamide (PA), cellulosic fibers (CV), acrylic (PAN) and others including polypropylene, elastic fibers, polyvinylchloride, polyvinylacetate, etc.
Figure C
Energy
All textile processes require a considerable amount of energy, from fiber production up to finishing. Energy is a natural resource, renewable or non-renewable, which can be converted into other forms according to the thermodynamics. Prime renewable energy sources are hydropower, wind power and solar power, generally used for electricity production, as well as wood pellets and other plants which are used in combustion. Non-renewable energy resources are crude oils, gas, brown coal, etc., prime sources that were formed on the planet over millions of years. Nuclear power takes a special position as its by-product, the hazardous nuclear waste, requires tremendous time periods to degrade. Conversion from one form of energy to another is more or less efficient, depending on the energy value, the losses by transformation to energy forms (e.g. heat) which cannot be utilized in the system.

Yarn production
Spinning processing is different for staple fibers and filaments. A staple fiber yarn is produced by twisting, entangling and embedding a certain number of fibers in order to get a longitudinal construction of a defined fineness, strength, elasticity and structure. Staple fibers are gained from all natural fibers (except silk) and from man-made filaments that are cut in staple.

Several technologies have been developed for staple spinning and filament spinning. The spinning technology sets the shape of the yarn body, which can be further influenced by individual yarn construction. The desired quality is defined in yarn quality parameters for suitable communication with fabric production.

Fabric production
Fabrics are produced as a two-dimensional arrangement of yarns or fibers. In woven fabrics two yarns are oriented at right-angles, while knitted fabrics are formed with yarn loops with an orientation in all directions. Non-woven fabrics are produced with unoriented fibers.

Woven fabrics
In weaving processes a two-dimensional fabric is produced, consisting of length-oriented yarns (warp) and cross-oriented yarns (weft or filling). The process is divided into three main sections: weaving preparation, weaving and fabric control, each consisting of different sub-processes.

Knitting and warp knitting
In machine knitting the traditional hand-knitting needles, holding all knits of a fabric, are replaced by individual needles for each loop.

Non-wovens
Non-woven fabrics represent an increasing market in textile applications, e.g. for disposable wipes and baby diapers. The production can be described as follows. A web of natural and/or man-made fibers is prepared on a fl at surface, whereby the individual fibers are oriented in all directions. Different bonding technologies and processes are applied such as:
  • Creating physical tangles or tufts among fibers by stitching needles in place
  • Application of adhesives
  • Thermal fusing of fibers or fi laments to each other by fusible fibers or powders
  • Fusing the fibers by dissolving their surfaces.
Chemical treatment
Chemical treatment is by far the most diversified process in the value-added chain of textiles. Typically it is divided into three sections: pre-treatment, dyeing and finishing, of which the dyeing process traditionally is the most important. Dyeing plants are specialized in specific raw material processed as either yarn, fabric or apparel finishing. According to their specialization they have specific equipment for processing and they apply specific chemicals. The finishing processes make large contributions to waste water, energy consumption and also airborne emissions.

Manufacturing
In apparel design a three-dimensional product is constructed by assembling different fl at pieces of fabric. Fashion creates ideas about shapes and styles that could be implemented, whereby the shape does not necessarily follow the body line. If the fabric for a designed apparel is chosen, the style, cut and three-dimensional shaping is constructed by means of a sewing pattern. For every model a list of all accessories (thread, lining, stiffening material, zippers, buttons, snaps, lining pads, fixing parts, etc.) is compiled and detailed instructions for the step-by-step sewing are generated, including specifications about stitches and other machinery settings. The more complex and sophisticated these instructions are, the more expensive the apparel becomes.

In the grading process, designed with computer software, a prototype pattern is transferred into different sizes by adjusting the individual parts in appropriate dimensions. Human body size, however, shows a large variation: the differences are often not proportional, and many genetic and cultural specialties exist. The procedure is far from being standardized.

This makes the fi t of apparel so difficult. After the sized patterns are constructed, they are arranged on the fabric in such a way as to produce a minimum of waste. Fabrics with pattern require additional adjustment for the parts to be cut for matching of the parts in the final apparel. Some hairy fabrics, like velvet or ‘Manchester’, etc., show a prominent up–down orientation in the brush, or other structures infl uencing the light reflectance, which requires a consequent orientation of the pattern parts according to the fabric orientation. Marks are applied with the cutting auxiliary for assembling the different parts of an apparel.

Together with the cut parts for a piece, accessory material is assembled for further processing. On various sewing stations the apparel is produced according to sewing instructions, step by step. For correct assembly, the auxiliary marks of the pieces have to be arranged before the pieces are sewn. Some of the sewing stations carry out very simple processes, while other stations are highly specialized for specific processes like fixing a zipper, inserting pockets, sewing buttonholes, etc. The manufacture of men’s jackets may follow the most complex guidelines, while sewing a knitted T-shirt is an easy assembly with not more than 10 individual steps.

Manufacturing is the most labor-intensive stage in the production of apparel and therefore one of the most costly parts in the value-added chain. Many companies seek production sites in countries where employees work for low salaries but have good working skills. Worldwide, sewing is carried out mainly by women on traditionally lower salaries than men’s.

Consumption, use and care
Consumption, use and care patterns are different for individual cultures. Consumption of apparel has far exceeded basic needs in industrialized countries. Consumers are buying apparel no longer only for thermal protection, but for identification with a unique style to underline their individualism. Apparel is not used until its ‘technical’ end of life is achieved, but thrown away when the consumer wants new apparel, driven by the fashion market. This lifetime duration is defined as the ‘economic’ lifetime compared to the technical lifetime, which generally is significantly longer than the economic lifetime.

Care is the action in use that produces environmental impacts. It it based on consumer preferences for care properties, combined with the laundry processes for apparel.

Disposal, reuse and recycling scenarios

This section defines some strategic considerations. A representative case study on textile recycling systems will be presented and the results of two case studies will be given on material flow – for polyester and polyamide, both carried out in Switzerland.

Conclusion:
Suppliers are viewed as critical resources for the textile/apparel retailers. They have to be managed to derive the maximum potential in the supply chain, and the selection of the supplier is the most critical task in the supply management.

References:
  1. Handbook of Sustainable Textile Production by Marion I. Tobler-Rohr
  2. Greening the Supply Chain of the Textile Industry in Bangladesh – Bangladesh Textile Today
  3. Textile and apparel supply chains for the 21st century
  4. http://www.isahp.org/2007Proceedings/Papers/Working%20Sessions/Suppliers%20Selection/Supply%20Chain%20Management%20In%20The%20Textile%20Industry.pdf 
 

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