Transformation of textile materials from fibres passing through various processes and enhancements and become a product for the end user, explained briefly


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  1. Story of Textiles

Story of Textiles

Transformation of Fibres to Fashion

The life cycle of garments begin from the making of fibre, which in turn undergoes various spinning processes and converted into yarns. Once the yarns are ready, they go through a series of processes such as weaving, knitting, tufting, felting etc. and are converted in to fabric. The fabric then is further processed known as finishing process which enhances the fabric beauty by dyeing, printing etc. These beautified fabrics are then ready to be used for garments by being designed, cut and stitched. The entire process of turning a yarn into fabric and then garment is so complex and requires lot of expertise and precision.

Textile Fibres

Fibre is a hair like strand of material. Some of which are naturally found in both plants and animals are called Natural Fibres. Some other fibres are chemically manufactured which are regenerated fibres and synthetic fibres. Regenerated fibres are made out of various minerals like asbestos, wollastine (also called as Cellulosic). Synthetic fibres are purely made out of chemicals. Synthetic fibers are stronger than regenerated fibres and thermoplastic (soften by heat).

Fibre to Yarn Formation

When the short fibres are twisted together, they take the form of yarn. Thus, yarn is a continuous filament of interconnected fibres used for making fabric. Various types of yarns can be made by different techniques of spinning. Textile fibres are converted into yarn by grouping and twisting operations used to bind them together. Although most textile fibres are processed using spinning operations, the processes leading to spinning vary depending on whether the fibres are natural, manmade, and staple or filament.

Yarn Spinning

The process of twisting together of fibres to form yarn is called spinning. The basic processes included in spinning can be listed as carding, combing, drafting, twisting and winding. When the fibres pass through these processes, they are subsequently formed into lap, sliver, roving and finally yarn. Two of the major methods of spinning are Ring Spinning and Open-End Spinning. Other methods include friction spinning, vortex spinning, air-jet spinning, etc.

Formation of Natural Fibre Yarns

Natural fibres, also known as staple include animal and plant fibres, such as cotton and wool. These fibres must go through a series of preparation steps like opening, blending, carding, combing and drafting, before they can be spun into yarn. Man-made fibres are processed into filament yarn or staple-length fibres (similar in length to natural fibres) so that they can be spun. Filament yarns are either used directly or are further shaped and texturized.

Formation of Filament Yarns

The man made filaments are produced by different methods and they can be formed directly into yarn without the use of techniques to connect fibres together to form the required lengths (spinning). These can be directly used to make fabric or can be twisted further to the desired consistency. There are many methods for making filament yarns such as wet spinning, dry spinning, melt spinning, bi-component spinning etc.

Formation of Multi-component Yarns

Integrated Multi-component Yarns are produced by combining staple and filament fibres in order to obtain certain of the characteristics of each. Integrated composite spinning and cover spun are two important methods for preparing such yarns. Blends of polyolefin and cotton, polyester and other cellulosic fibres such as rayon, and blends of polyester, cotton and wool fibres are some examples of Integrated Multi-component Yarns.

Yarns to Fabrics

Fabric is made by interlacing two set of yarns at right angles known as Weaving. This is generally done in handlooms or power-looms. Fabric may be formed by networking different types of yarns. Weaving and knitting are two of the major methods of fabric construction. Other methods like tufting, stitch-bonding, felting are also used for constructing fabrics. Nonwoven fabrics, broadly defined as sheet or web structures bonded together by entangling fibre or filaments.

Weaving of Fabrics

Weaving is the process of interlacing one set of yarns with another set oriented crosswise to form a fabric. Yarns made from both, natural fibres and man-made fibres are used for weaving textile. In the weaving operation, the length-wise yarns that form the basic structure of the fabric are called the warp and the crosswise yarns are called the filling or weft. Four major operations involved in any type of weaving are Shedding, Picking, Beating up (Battening), Taking up and letting off.

Construction of Woven Fabric

Woven fabrics are constructed (known as weave patterns) by altering the warp and weft interlacement. At times warp yarns are laid parallel and very close to each other. Some warps are lifted and others remain as such and the weft on a shuttle is then passed through them to complete the interlacement. For example alternate warps could be lifted to get a plain weave fabric. Famous weave patterns are Plain weave (Rib & Basket weave are the sub-divisions), Twill weave, and Satin weave.

Fabric Knitting

Knitting is another most frequently used method of fabric construction. Knitted fabrics are constructed by using hooked needles to interlock one or more sets of yarns through a set of loops. Knitting industry has two main divisions- One manufactures knitted goods for apparel production, sewing centres, consumers and others. The other division manufactures finished apparel such as hosiery, sweaters, slacks, underwear, rugs and other home furnishings.

Construction of Knitted Fabric

The construction of knitted fabric is evaluated by the number of stitches or loops. Knitting is performed using either weft or warp processes. Yarns are interlocked to form the fabric, and the yarns run vertically while the connections are on the diagonal. When the interlocking loops run lengthwise, each row is called a wale. A wale can be compared with the warp in woven fabric. When the loops run across the fabric, each row is called a course. A course corresponds to the filling, or weft in weaving.

Weft and warp knitting

Weft knitting uses one continuous yarn to form courses, or rows of loops, across a fabric. Plain-knit, purl, and rib are its main stitch forms. Weft knitting machines can produce both flat and circular fabric. In warp knitting, a series of yarns form wales in the lengthwise direction of the fabric. Fabric is produced in sheet or flat form using one or more sets of warp yarns.

Tufting

Tufting is a type of textile weaving which is done by pushing extra yarns onto a ground fabric of desired weight and yarn content to create a pile of fabric. Many needles simultaneously punch the fabric at predetermined distance for extruding the fibres. The substrate fabric can range from a thin backing to heavy burlap-type material and may be woven, knitted, or web. Tufting is mainly done to manufacture rugs, carpets, blankets and upholstery.

Felting

Felting is consolidation of certain fibrous materials by the application of heat, moisture, and mechanical action, causing the interlocking, or matting of fibres properties. Wool, fur, and certain hair fibres are Felt under appropriate conditions because of their peculiar structure and high degree of crimp (waviness). Felts are used for making hats, slippers, shoes, insoles, earmuffs, table padding etc.

Nonwoven Fabrics

The nonwoven fabrics are made by bonding/interlocking of fibres through mechanical, chemical, thermal or solvent means. Various processes used in non woven fabrics are spun bond, melt blown, air-laid pulp and blends, wet laid, dry laid or stitch bonding .The methods of manufacturing differ on the basis of fibres used, techniques of laying these fibres and the bonding agents used in the process. Other methods are Resin Bonding, Latex Bonding, Gelatine Bonding, Spun bonding, Melding, and Radiation Bonding. Cotton, wood pulp, rayon, polyolefin, polyesters, nylon, acrylics, aramids are few raw-materials used.

Stitch Bonding

Stitch bonding is a process of stitching through yarns or fibres that are not connected with either sewn seams or fine warp-knitted mesh in order to join them together into a stitch bonded fabric. A stitch-bond non-woven fabric is made on a weaving machine that bonds the web, or holds the web in place, with longitudinal yarns. While other common fibre-bonding methods used in the production of non-woven fabrics-needle-punch, thermal-bond or chemical-bond-have the drawback of stiffening the texture of non-woven fabrics, the stitch-bonding method gives non-woven fabric a texture as soft as that of the original web.

Fabric Finishing Processes

Unfinished fabrics known as greige good are also called gray good or unfinished fabric. In finishing process the fabrics gets the desired appearance, durability and feel by employing various methods such as Preparatory Processes, Stabilizing Processes, and Textural Processes. Finishing process is either physical or chemical. It gives treatments like crease-proofing, water-proofing, fire-proofing, etc.

Preparatory Processes of Fabrics

Preparation, also known as pre-treatment, consists of a series of various treatment and rinsing steps critical to obtaining good results in subsequent textile finishing processes. In preparation, the mill removes natural impurities or processing chemicals that interfere with dyeing, printing, and finishing. Typical preparation treatments include desizing, scouring, and bleaching. Preparation steps can also include processes, such as singeing and mercerizing, designed to chemically or physically alter the fabric.

Fabric Stabilizing Processes

Stabilizing processes are required for improving properties such as strength, lustre, and other qualities of the fibre. Mercerization is done for improving properties such as fibre strength, shrinkage resistance, lustre, and dye affinity. Ammoniating is done for increasing lustre, affinity for dyes, abrasion resistance, smoothness etc. particularly of cotton and rayon fabrics. Shrinking is done to avoid the subsequent shrinkage of the fabric while usage. Tendering makes the fabric even for further processing. Decating improves lustre, appearance, feel as well as preshrinks the fabric.

Fabric Textural Processes

Textural processes are meant for improving the texture of the fabric such as stiffness, smoothness, weight or strength. Temporary stiffening, permanent stiffening, weighting, calendaring, glazing, embossing, moireing, cire process, beetling, raising, napping, sanding, gigging, tigering, shearing etc. are some of the processes which help in improving the texture of the fabrics.

Textile Dyeing

Dyeing operations are used at various stages of production to add colour and intricacy to textiles and increase product value. Most dyeing is performed either by the finishing division of vertically integrated textile companies, or by specialty dye houses. Textiles are dyed using a wide range of dyestuffs, techniques, and equipment. Dyes used by the textile industry are largely synthetic, typically derived from coal tar and petroleum-based intermediates.

Textile Dyes

Dyes may be classified in several ways (e.g., according to chemical constitution, application class, and end-use). The primary classification of dyes is based on the fibres to which they can be applied and the chemical nature of each dye. Reactive dyes react with fibre molecules to form chemical bonds. Direct dyes can colour fabric directly with one operation and without the aid of an affixing agent. Basic (cationic) dyes, acid (anionic) dyes, mordant dyes, vat dyes, pigment dyes are some of the commonly used dyes.

Dyeing Methods

In Batch dyeing, a certain amount of textile substrate is loaded into a dyeing machine and brought to equilibrium or near equilibrium with a solution containing the dye. Common methods of batch or exhaust dyeing include Beam, Beck, Jet, and Jig processing.Continuous dyeing processes typically consist of dye application, dye fixation with chemicals or heat, and washing. Dye fixation is a measure of the amount of the percentage of dye in a bath that will fix to the fibres of the textile material.

Yarn dyeing

Yarn dyeing is used to create interesting checks, stripes, and plaids with different-coloured yarns in the weaving process. In yarn dyeing, dyestuff penetrates the fibres in the core of the yarn. Some methods of yarn dyeing are stock, package, and skein dyeing. Stock dyeing dyes fibre using perforated tubes. In package dyeing, spools of yarn are stacked on perforated rods in a rack and immersed in a tank where dye is then forced outward from the rods under pressure. In skein dyeing, yarn is loosely coiled on a reel and then dyed.

Piece/Fabric dyeing

Piece dyeing is the dyeing of fabrics after weaving or knitting as opposed to dyeing the yarn. Most dyed fabric is piece-dyed to meet colour demands as fashion changes. Some of the common piece dyeing methods are Beck, Jig, Jet, Pad etc. Beck dyeing is a versatile, continuous process used to dye long yards of fabric. Jig dyeing uses the same procedure of beck dyeing but the fabric is held on rollers at full width rather than in rope form as it is passed through the dye bath.

Fibre and Garment Dyeing

Fibres especially wool and manmade synthetic fibres are often dyed before finishing. Finished apparels and garments are dyed with attractive colours to enhance their appearance. Pedal type garments dyeing machines are used for the woollen knit wear type garments dyeing. Rotary garments dyeing plant machine is the modified version of pedal type garments dyeing machine. Normal atmospheric pressure and High temperature are two types Rotary garment dyeing machines.

Finishing Processes for Functionality of Fibres

Finishing encompasses chemical or mechanical treatments performed on fibre, yarn, or fabric to improve appearance, texture, or performance. Mechanical finishes can involve brushing, ironing or other physical treatments used to increase the lustre and feel of textiles. The most common chemical finishes are those that ease fabric care, such as the permanent-press, soil-release, and stain-resistant finishes. Chemical finishes are usually followed by drying, curing, and cooling steps.

Printing

Fabrics are often printed with colour and patterns using a variety of techniques and machine types. The most common printing technique is rotary screen printing. Other methods, such as direct, discharge, resist, flat screen (semi continuous), Ink-Jet printing, Heat-transfer Printing and roller printing are often used. The Dyes used for printing mostly include vat, reactive, naphthol and disperse colours which have good fastness properties. Pigments are also used extensively for printing.

Classification of Printing Styles

Printing styles are classified as direct, discharge or resist. In direct printing coloured pastes are printed directly on the cloth and any design may be produced. If done on a white fabric it is called overprinting. Discharge printing refers to the fabric being the first dyed with background colour and then printed with a chemical that will destroy the colour in the designed areas. In Resist printing the cloth is first printed with a resist plate, a resinous substance that cannot be penetrated when the fabric is subsequently immersed in a dye.

Methods of Textile Printing

Block Printing - wooden blocks carved with a design are made from solid pieces of wood or metal block. Long running printing is usually done through Roller Printing. In Screen Printing print paste is poured on to the screen edge nearest the operator and is spread with a squeegee over the surface of the screen so that colour is pushed through the open parts. Other methods of printing are Heat Transfer Printing, Duplex Printing, Spray Printing, Resist Printing, Print-On-Print, Photographic Printing, Shadow Printing, Stipple Printing, and Warp Printing.

Apparel Making

Ready to wear apparel or garment manufacturing involves many processing steps, beginning with the idea or design concept and ending with a finished product. Broad categorization of apparel manufacturing process involves Product Design, Fabric Selection and Inspection, Patternmaking, Grading, Marking, Spreading, Cutting, Bundling, Sewing, Pressing or Folding, Finishing and Detailing,Dyeing and Washing, Quality Control, Ticketing and Bar-coding.