Monday, January 7, 2013

Selvags, Two edge of woven fabric

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Selvags
Selvage is one of the most important parts of woven fabric. It plays vital roles during weaving. Selvage could be defined as the two end of the woven fabric width or the edge of woven fabric. This is different from main fabric. Most of the selvage made with strong thread like nylon thread. It holds the woven fabric and helps to maintain the shape of fabric. It takes all the pressure of weaving machine and protect the fabric from damage.
Selvags (Selvedges) As the shuttle moves back and forth across the width of the shed, it weaves a self-edge called the selvage, or selvedge, on each side of the woven fabric. The selvage prevents the woven fabric from raveling. 
It is usually made more compact and stronger than the rest of the woven fabric by using more or heavier warp yarns or by using a stronger weave. There are different kinds of selvages. The kind of selvage used depends upon economy of production and the expected use of the woven fabric. 

Plain Selvages 
These selvages are constructed of the simple plain weave with the same size yarn as the rest of the fabric, but with the threads packed more closely together. Such selvages are fairly durable and firm. 

Tape Selvages 
The tape selvages are sometimes constructed with the plain weave but often are made of the basket weave, which makes a flatter edge. Tape selvages are made of heavier yarns or ply yarns, which provide greater strength. 

Split Selvages 
Split selvages are made by weaving a narrow width fabric twice its ordinary width with two selvages in the center. The woven fabric is then cut between the selvages, and the cut edges are finished with a chain stitch or hem. 

Fused Selvages 
These selvages are made on fabrics of thermoplastic fibers, such as nylon, by heating the edges of the fabric. The fibers melt and fuse together, sealing the edges. This technique is sometimes used to split wide fabrics into narrower widths. 

Leno Selvage 
The leno selvage is used on some shuttle less looms as well as weaving machine. The construction utilizes a narrow leno weave, which locks the cut ends along the fabric edge. A loose weave generally requires a tight leno selvage, whereas a light weave may have a leno selvage with less tension. 

Tucked Selvage 
The tucked selvage is a technique used on some shuttle less looms. A device is used to tuck and hold the cut ends into the fabric edge. The construction of the selvage is dependent upon the particular weave and a number of other factors. A formula for weaving the tucked selvage considers fiber density, the diameter of the yarns (which is also affected by twist, ply, and count variation), as well as the yarn diameter balance, or ratio of the diameter of the filling yarn to that of the warp yarn in effect, if the diameter of the filling yarn is finer than the diameter of the warp yarn, fewer fillings can be inserted in themfabric selvage, because the warp intersection requires more space between the fillings than one diameter of the filling.
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Sunday, January 6, 2013

Manufactured Fibres or Textile Fiber manufacturing

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The producer of natural fibres and the producer of manufactured fibres are engaged in two very different businesses. The farmer who raises cotton, the rancher who herds sheep or the grower of silkworms is trying to produce a maximum quantity of fibre from animal or vegetable sources. The grower may attempt to improve the quality of the seeds or breeding stock but is limited in production by natural factors. If the demand for the product increases or decreases, the grower cannot, like the manufactured fibre producer, simply increase or decrease the short-term supply of fibre.

Manufactured Fibres
The term-manufactured fibre describes a fibre produced commercially through regeneration from natural materials or synthesized from chemicals. Trade associations in the manufactured fibres industry may be industry wide or specific to particular fibres. The American Fibre Manufacturers Association, Inc. (AFMA) is the trade organization for the manufactured fibres industry, conducting many of the same kinds of promotional activities as described for the natural fibres associations.

AFMA always uses generic fibre names-such as polyester, nylon, rayon, and so on-in printed materials, while its individual fibre producing members concentrate on their trademarked fibre names, such as DuPont’s Dacron@ (polyester) or Wellman’s Fortrel@ (polyester). Producers of particular fibres may also join together to form fibre-specific trade associations. The Acrylic Council, the Polyester Council, and the American Polyolefin Association are examples of fibre-focused trade associations.

Production in the manufactured fibres industry differs from the production of natural fibres in a number of ways. While the manufactured fibres industry must depend on available supplies of the raw materials from which fibres are made, this industry is not dependent on natural forces that regulate the supply of fibre. A great many manufactured fibres are made from materials derived from petroleum, and therefore supplies and costs of raw materials may be affected by changes in the price of oil. Manufacturers can regulate production according to supply and demand. Manufacturers can also help to create demand for increased quantities of fibre products through advertising and other publicity.

Many manufactured fibre producers and firms are, or were originally, chemical companies. The fibre manufacturer generally sells the fibres produced to a firm that will make yarns and/or fabrics. These fibres may be sold as unbranded products or commodities. When fibres are sold in this way, the purchaser has no obligation to the fibre manufacturer to produce a product of any specific quality. Products must meet no minimum standards. In short, the buyers can do whatever they wish with the fibres they have purchased. Other fibres may be sold as trademarked fibres. The manufacturer owns the trademark, which is denoted by placing either the symbol @ or TM after the trademarked name. Trademarked names are always capitalized-for example, Micrell@ polyester. The owner of a trademark can bring court action to prevent unauthorized use of the trademark.

When the fibre manufacturer’s trademarked name is carried by the finished product, the fibre manufacturer has some control over the quality of the fabric, although it is still possible that a poorly made garment could be constructed from the fabric. One advantage to the fabric and garment manufacturers of buying a trademarked fibre is that they can capitalize on the publicity and promotional materials distributed by the fibre manufacturer. Licensed trademarked fibres are sold only to those manufacturers whose fabrics meet the standards established by the fibre manufacturer. Standards may be set in regard to the construction of fabrics, the manufacture of apparel or other products, and, in blends or combinations of two or more fibres, the appropriate proportion of fibres to be combined. As an alternative to trade marking, some fibre companies assign certification mark names to yarns or fabrics made from their fibres. Such designations require that the items identified with the certification mark meet criteria established by the fibre manufacturer.

Not only do the fabric and garment manufacturers benefit from customer familiarity with the brand name of the fibre, but the fibre manufacturer often shares the costs of advertising or mounts intensive publicity campaigns to promote the fabric, the final product, and even retail outlets where the products are sold.

The interest of manufactured fibre producers in their products does not end when the fibre is sold. Because techniques for spinning and fabricating manufactured fibres may not be uniform for all fibres, the fibre producer provides technical assistance to the fabric manufacturer. Technical bulletins are published that recommend the most effective ways of processing fibres. Consultants from the fibre companies provide information about new developments in textile machinery and finishing. Research and development in fibre-producing companies is often focused on more effective ways of handling manufactured fibres during fabrication.

Fibre producers assist manufacturers of fabrics, garments, or other products to locate sources of yarns and fabrics. The marketing department of a fibre-producing company also maintains a library of fabrics that can be used by manufacturers and their designers.

A wide variety of other services is offered to the direct customers of the fibre companies and to the general public. Exhibits of current products are presented, often at trade and professional meetings. Educational materials for schools, retailers, and consumers are prepared and distributed. Retail stores may be assisted in promoting trademarked products through fashion shows, publicity materials, or cooperative advertising in which the fibre producer pays some part of the advertising costs. Fashion consultants may be available to assist the designers of fabrics, clothes, and furnishings.

Many of these activities are part of an organized advertising and public relations program. In addition to the services offered that result indirectly in publicity and goodwill for the company, direct advertising is also utilized. Besides advertising cooperatively with manufactures of retail products and retail stores, fibre companies also advertise in publications ranging from those for the trade to general magazines. Research and development (often abbreviated as R & D) is an important function in most large textile fibre companies.

Researchers are constantly looking for new fibres, fibre modifications, and improvements in processing at all steps of manufacture. The whole synthetic fibres industry might be said to have grown out of the research and development program at the chemical company Dupont, for it was in this program that W. H. Caruthers first synthesized nylon.
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Industrial Textiles; The Major Textile Production Segments

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Industrial Textiles 
Most consumers are not aware of the segment of the textile industry known as industrial textiles, even though they encounter these products every day. Industrial textiles is the most commonly used name for textile applications in agriculture, air and water filtration, architecture, automobiles, banners and flags, casual furniture, environmental protection, earth stabilization, medical products, recreational products, and transportation vehicles. Apparel items in this category are those in which performance is paramount: clean room garments, protective gloves and clothing for industry and farming, industry garments that don’t develop electrostatic charges (World of Industrial Fabrics n.d.) 

Other descriptive terms applied to this segment of the industry are industrial fabrics, technical textiles, engineered fabrics, and technical fabrics. Industrial textiles may be woven, knitted, or nonwoven, often of manufactured fibers. Fashion is not a factor in industrial textiles, but instead such functional characteristics as strength, stability, chemical resistance, and weight are likely to be important. Examples of industrial textiles range from small products such as filters and auto safety belts to enormous structures such as roofs, tents, and storage tanks. Roofs and other building structures encompass the field of textile architecture, a growing area of interest that combines engineering and art design. Consumers of industrial products include the construction, mining, sanitation, and transportation industries; medicine; and the military. 

The industrial fabric segment of the textile field has grown rapidly in recent years. Some of the more dramatic examples of progress in textile technology have come in this area, particularly fiber-reinforced composites for the aerospace industry and geotextiles. Geotextiles are textiles used in soil and soil-based structures such as roads, dams, and erosion-control products. 

The Major Textile Production Segments 
The textile industry is segmented into three large groupings: Apparel, the textiles used in clothing; interior furnishings (also called home fashions) the textiles used in furniture, bath, kitchen and bed; and industrial, the textiles used in such items as luggage, flags, boat sails, gauze bandages, dust filters, and so on. The market is divided into approximately 40 percent apparel, 40 percent interior furnishings, and 20 percent industrial and miscellaneous consumer-type products. 

The textile industry uses many different raw materials and many steps in the process of manufacturing a finished textile material. Each segment in the pipeline is not only involved with production, but also with buying the product of a previous producer. Thus, the entire process from fiber to consumer (or other ultimate buyer) involves the coordinated activities of many firms and many individuals within each firm. The following sections describe the major production segments, each of which is discussed in much more detail later in this book. 

It takes almost a year from the time a fiber supplier starts delivering fibers for yarn manufacturing until the completed garment is ready for sale in the retail store. The fiber shipments stop about four months before the start of the retail season. The yarn manufacturers begin delivering their yarns to the mills about nine months before the garments are to be sold in the retail stores and stop about two months before. The finished fabrics start to be shipped to the garment manufacture about six moths before and continue to be sold into the retail-selling season. 



Some apparel manufactures start cutting fabrics four months before the season and many continue to cut after the season has begun. There are two main retail-selling seasons for apparel. They are fall and spring. The former starts about August first and the latter begin about February first. The other seasons include summer and Holiday.
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