FABRIC CONSTRUCTION

Woven Fabrics

Fabrics can be constructed in a variety of ways, ranging from the matting together of fibrous materials to the intricate interlacing of complex yarn systems. The major classifications of fabric constructions are -

Woven Fabrics. Weaving of fabrics consist of interlacing systems of yarn. By varying the interlacing, a wide variety of different fabric constructions can be made.

Knitted Fabrics. Fabrics can be constructed from one or more continuous yarns by the formation of a series of interconnected loops. Knitting tough a complex form, is one type of looping construction, Crochet is another.

Non Woven. Masses of fibers can be held together into a fabric by interlocking of fibers by mechanical action or by fusing fibers together with heat, adhesive or chemicals. Examples of a few fabrics constructed by these means include felt, bark cloth, spun lace, spun bonded and needle-punched fabrics and bonded webs.

Knotted Fabrics. Some fabrics are created by knotting yarns together. Lace, nets, macramé and tatting are produce by knotting.

Braided Fabrics. Fabrics may be created by plaiting together yarns or strips of fabrics. The components are interlaced in a diagonal pattern over under one another to form a flat or tubular fabric of relatively narrow width.

Films. Since films are not considered to be true textiles. They are sometimes laminated to textiles. They are sometimes laminated to textiles and therefore may be part of the structure of some textile products. They are synthetic polymers extruded in the form of sheets rather than as fibers. In some cases, these films are eventually made into fibrous form by a process called fibrillation or by cutting the sheet into fibers.

Stitch-Through Fabrics. Stitch through or stitch bonding is a relatively new technique for constructing fabrics in which two sets of yarns or masses of fibers are stitched together into a fabric structure by another set of yarns.

Textile Composites. These materials generally consist of one or more textile components impregnated with or embedded in a resin matrix. Textile composites are generally used for high technology products for industry, the military and aerospace.

Woven Fabrics- Oldest & widely used method of construction- Made with two or more sets of yarns interlaced at right angles to each other.

Yarns in lengthwise direction: warp/ends, yarns in crosswise direction: filling/weft/picks

- Selvage: self-edge of fabric on both sides along the length of the fabric. Made with more closely placed warp yarns, width:1/4th inch. The selvedge prevents the fabric from raveling. It usually made more compact and stronger than the rest of the fabric. Plain, split, fringe, fused, leno & tucked selvage.

- Grain: indicates warp & weft positions in fabric. Lengthwise grain Crosswise grain Bias & True bias - Identification of grain: selvage parallel to lengthwise grain, less stretch along

warp yarns, warp yarns lie straighter & more stronger, more twist in warp yarns, single yarn is used.

- Fabric lengths & widths: length – 40 – 100 yards or more, width – 20 – 60 inches (handwovens:27 – 36 inches, Power loom: 40 – 60 inches)

- Done on a machine called handloom or power loom

GRAIN: Position of warp yarns relative to filling yarns in fabric.On-grain: Warp yarns lie parallel to each other (lengthwise) & weft yarns lie parallel to each other (crosswise). Warp & weft yarns lie perpendicular to each other.Off-grain: Lowers fabric quality, fabric does not drape properly, Printed designs are not straight.Skewed fabric: Filling yarn is at an angle other than 900 to warp yarns.Bowed fabric: Filling yarns dip in the centre of fabric.

FABRIC COUNT/THREAD COUNT: No. of warp & weft yarns per square inch. Denotes closeness or compactness of fabric.

Higher the count, better the quality of fabric, higher strength.E.g. 80 X 76 (80 warp yarns & 76 weft yarns in 1 inch)

Fabric weight is measured in Grams per square meter (gsm).

BALANCE: Ratio of warp yarns to filling yarns in a fabric.BALANCED FABRIC: Will have a ratio of warp to weft yarns as 1:1. E.g. Fabric count of a balanced fabric: 78 X 78 or 64 X 60. This fabric is more durable.

UNBALANCED FABRIC: Will have a ratio of warp to weft yarns as 2:1. E.g. Fabric count of a unbalanced fabric: 144 X 76 or 100 X 60. It exhibits rib like structure.

Weaves are represented on graph paper or point paper. Each square of the paper represents the yarn that appears on the top.

WEAVING PROCESS

Weaving is the process of making cloth with two components, a warp and a weft, and can be done by very simple techniques on complicated loom.

Preparing the Wrap Yarns for Weaving

Before their use on the loom, wrap and filling yarns must be prepared for weaving.In preparation for weaving, each wrap end (yarn) must be threaded through its own drop wire, heddle eye, and reed dent. The Drop wire is a device that will stop the loom if an end should break, the heddle eye is the opening in a heddle that carries the yarn, and the reed comb like device that will push each filling yarn close against the completed fabric.Placing the wrap yarns on the loom is done either by drawing-in or by tying-in.Heddle wires are held in frames called harnesses. The number of harnesses required for the loom is determined by the weave.

Preparing the Filling Yarns for WeavingYarn that is to be used for filling must be packaged in some from that allows it to be unwound easily for transport through the shed is called a shuttle and is made up of a wooden carrier into which a quill or pirn is placed.

Basic Weaving Operation – 4 basic steps – Primary Motions

Once the filling yarns have been prepared and the wrap beam containing the sized yarns is placed at the back of the loom. The warp yarns are conveyed to a cylinder called the cloth beam which is in front.The loom goes through a series of motionShedding: raising and lowering of warp yarns by means of harness to form shed, opening between warp yarns through which weft yarn passesPicking: inserting of weft yarn by the shuttle through the shedBeating up: packing the weft yarn into the cloth to make it compactTaking up: winding newly formed cloth onto the cloth beam, Letting off: releasing yarn from warp beam

Classification of Woven Fabrics 1. Basic/Simple Weaves2. Compound/Complex/Novelty Weaves

Basic/Simple Weaves: 3 basic weaves

a) Plain Weaveb) Twill Weavec) Satin Weave

Compound/Complex/Novelty Weavesa) Dobby Weaveb) Jacquard Weavec) Double Cloth & Double Weaved) Piquee) Pile Fabrics f) Surface Figure Weaves

Plain Weave

Simplest weave requiring a 2 harness loom, formed by yarns at right angles whereby each warp yarn interlaces with each weft yarnProperties: least expensive to produce, reversible unless surface design, wrinkles more, firm & wears well, less absorbent, abrasion resistant, used as background for printing/embroidery

Rib Weave fabricsrib effect is produced by using heavy yarns in the filling direction or by more warp than filling yarns per inch. Eg Bengaline, ottoman, faille, poplin, broadcloth, taffeta

Basket Weave fabricsBasket weave is made by treating two or more yarns as one in either the warp or weft or both the directions and interlacing them in plain weave. It is not as firm as plain weave, have more yarn slippage, shrinks easily. Eg 2X1, 2X2, 2X4, 3X2, 4X4. Oxford cloth is 2X1 & monk cloth is 4X4. Flat duck, hopsacking, panama are other examples.

Twill Weave

Each warp or weft yarn floats across two or more weft or warp yarns with a progression of interlacing by one to the right or to the left, forming a distinct diagonal line or wale. Direction of diagonal may be formed from right to left, from left to right or a combination of both. Soil resistant, softer & pliable, good wrinkle recovery, durable & wears well. The direction of the twill on the back of the cloth is opposite to the twill line on the face. 3 harness are required for twill weave.

Right Hand Twill - diagonals run upwards to the right

Left Hand Twill - diagonals run upwards to the left.

Balanced Twill – same number of warp pass over filling yarns. It is reversible. 2X2, 4X4

Unbalanced Twill – have uneven number of warp or filling yarn. It has a right or wrong. Denim

Broken Twill – combines right or left hand twills

Herringbone Twill – a series of inverted V’s are formed resembling the backbone of the herringbone fish. Most commonly used in suiting fabrics.

Twill Angles – according to the angles of the diagonal line, Regular twill - 45 , Reclining twill – with smaller angles, Steep twill – with larger angles.

E.g.: denim, herringbone, hound’s-tooth

Satin Weave

Each warp/ filling yarn floats over 4 filling/ warp yarns & interlaces with 5 th filling/ warp yarn, with progression of interlacing by 2 to right or left (warp faced/ weft faced). Luster (long floats), firm, durable (yarns packed closely together), pliable, wrinkle resistant, yarn slippage. Satin is warp faced. Sateen is weft faced. 5 harness are required for satin weave.

Compound/Complex/Novelty Weaves/ Figure/ Decorative weave

Dobby WeaveSmall figured designs (floral or geometrical) woven repeatedly throughout the fabric, produced by a combination of two or more basic weaves, using a dobby attachment on the loom. Weaving pattern controlled by a plastic tape with punched holes that control the raising & lowering of warp yarns. It uses up to 32 harness.

Jacquard WeaveCharacteristics: highly intricate large designs using coloured yarns and multi-weaves produced on loom with jacquard attachment. Incorporates all 3 basic weaves & their combination. Each warp yarn is controlled separately by punched cards that are laced together in a continuous strip. Are more expensive. Used for home furnishing, apparel, elaborate & decorative fabrics.Eg Brocade, Damask, tapestry, brocatelle, matelasse

Surface Figure /Extra Yarn WeavesExtra warp or weft yarn introduced in fabric to produce designs at regular intervals. Between 2 motifs, extra yarn floats across back of fabricClipped / unclipped Spot – embroidery like design are achieved through either extra warp or weft yarn. Long floats on the back when cut is called Clipped Spot & when uncut – Unclipped Spot.Swivel - contains extra filling yarns. In these weave the extra yarn is interlaced with the background at different places to avoid pulling. These are more stronger than Spot weave.Lappet – contains extra warp yarns.

PiqueLightweight to heavyweight cotton fabric with a raised woven design. Lengthwise wales or cords on the face of fabric (formed by extra warp yarns) that are held in place by

crosswise weft floats on the back of fabric. Extra warp yarns (stuffer yarns) do not show on face of fabric. They are not interwoven but laid under the cords to emphasize quilted effect. Made on dobby or jacquard loom.Eg waffle, huck toweling, granite, honeycomb, bedcord, pique

Double ClothThey are made with 3, 4 or 5 sets of yarn. Two fabrics are woven together on the same loom, one above the other & laced together with an extra set of warp or weft yarns called binder yarns (5 sets of yarns). Pile fabrics are commonly prepared by this method. Produces a variety of fabrics, reversible, stable, may have different color or design on the two sides. Used for upholstery, drapery and heavy apparels.

Other Special Weaves

Crepe WeaveCrinkled or pebbly surface. Irregular, indistinct pattern utilizing both plain and satin weave using dobby attachment are made. Few crepe weave fabric are available.Other crepe fabrics are created using crepe yarn which are highly twisted (up to 65 tpi). Textured yarns, bicomponent yarns (uneven shrinkage), embossing, stamping crepe like effect are being used. In all these plain weave, synthetic fibers and thermoplastic property is used,

Leno WeaveThe warp yarns are paired. With a special leno or doup attachment warp yarns are crossed/ twisted over each other in pairs around each pick, firmly holding the filling yarn in the figure – 8 loops formed. Leno fabrics are open and gauge like. Leno weave is useful in reducing yarn slippage, greater firmness & strength than plain weave. Uses- curtain, gauge, marquisette, grenadine, fruit sacks, rice net, mosquito net, mesh.

Woven Pile Fabrics3-dimensional fabrics, utilizing 3 sets of yarns, warp & weft to form base fabric & extra set of warp or weft yarns to form pile or loop surface. Extra set of yarns forming the pile may be cut to produce an erect pile on the face of fabric – Cut Pile – velvet or left uncut to form loops on one or both sides of fabric- Uncut pile – terry.Warp pile fabric- velvet, plushes, terry, velour.Weft pile fabric – velveteen, corduroy

Colour & Weave Effect Pattern produced in a fabric by using a certain weave and a certain arrangement of differently coloured yarns in both warp and filling. Hound’s tooth – 2 up, 2 down, 45 left hand twill, and group of 4 yarns of one colour are arranged in both warp & filling followed by the other colour.

Triaxial Fabric

Triaxail fabrics have 3 set of yarns, 2 warp & 1 filling. The warp yarns are placed diagonal to each other by special attachments, through which the filling yarn is interlaced. It is an ancient weave used in basket weaving. Stability against stretching in all direction even bias, strong resistance, resistance to shear forces & raveling. Lighter, longer life & less material required than biaxial fabrics. Three major weaves – basic triaxial weave, basic basket triaxial weave & biplane weave.Uses – aerospace, industrial fabrics, sail cloth, balloon, truck covers, uniforms & outerwear.