FACULTY INFORMATION

  • Faculty of Applied Sciences
  • Department: Textile Science and Apparel Technology
  • Programme: Textile Science
  • Qualification: BSc: Textile Science
  • Qualification Code: BASTX1
  • Subject: Product Engineering 2
  • Subject Code: PROE201
  • Semester: 1, 2026

WOVEN CLOTH CONSTRUCTION

  • Impact on Physical Properties and Performance Characteristics
    • Physical properties and performance characteristics of woven fabrics are affected by the following factors:
    • (a) Characteristics of the warp and weft yarns
    • (b) Spacing and interlacing of yarns (design and construction)
    • (c) Modifications produced by finishing
(a) Characteristics of Warp and Weft Yarns
  • Fibres Influence Yarn Characteristics:
    • Fibres used to produce yarns significantly influence their characteristics, including:
    • Physical Properties:
      • Length
      • Fineness
      • Weight
      • Appearance
      • Softness
      • Texture
    • Performance Characteristics:
      • Strength
      • Moisture absorption
      • Abrasion resistance
      • Crease recovery
    • Yarn Characteristics influenced by Fibre Characteristics:
    • Yarn Strength:
      • Affected by fibre strength, fibre length, fibre fineness, and number of fibres per cross-section, as well as twist level.
    • Yarn Fineness:
      • Influenced by fibre fineness and fibre length, and level of twist.
    • Yarn Lustre:
      • Determined by fibre surface characteristics and level of twist.
    • Surface Integrity (Hairiness and Abrasion Resistance):
      • Dependent on yarn length, fineness, and twist level.
(b) Spacing and Interlacing of Yarns
  • Sett:
    • Spacing of ends and picks in woven cloth is referred to as “Sett,” expressed as threads per centimetre.
    • Number of ends/picks per cm affects:
    • Strength
    • Tear
    • Abrasion
    • Crease
    • Drape
    • Weight
    • Types of Sett:
    • Square Sett: Ends and picks per cm are approximately equal.
    • Unbalanced Sett: Significant differences between ends and picks.
    • Open Sett Structure:
      • Features voids between warp and weft yarns; affects applications such as comfort, flammability, thermal insulation efficiency, and air permeability.
    • Influences on fabric characteristics are affected by design and interlacing orders (e.g., plain weave, twills, satins).
(c) Modifications Produced by Finishing
  • Finishing Modifications:
    • Techniques include mercerisation, crease-resistant resin finish, calendering, coating, anti-static finish, and water repellency.
    • Effects of modifications:
    • Mercerisation and Calendering: Improve lustre.
    • Resin Finishes: Affect tear resistance and handle.
    • Calendering and Coating: Influence air permeability and thickness.
    • Brushing and Raising: Impact insulation properties and softness.

IMPORTANT ASPECTS IN PRODUCING WOVEN FABRIC

Fibres and Filaments
  • Basis for Fabrics:
    • Natural (e.g., cotton, wool) and synthetic fibres (e.g., polyester).
    • Fibres must be twisted into yarns for fabric production; continuous filaments do not require spinning.
Types of Yarns
  1. Continuous-Filament Yarns (C.F.):
    • Made of endless filaments; do not depend on twist for strength, but some twist is used for coherence.
    • Characteristics:
      • Smooth, lustrous, and uniform.
      • Four subgroups: flat, textured, bi-component, and film (tape or split) yarns.
(a) Flat Continuous Filament Yarns
  • Standard Filament Yarns:
    • Dull or bright, produced as monofilament or multifilament.
    • Monofilament: Diameter approx. 28 microns to 2-3 mm; high tensile strength.
    • Multifilament: Smooth surface; twisted into yarn.
(b) Textured Continuous Filament Yarns
  • Characteristics:
    • Modified to have distortions (e.g., crimps); increase bulk and differ from fancy yarns.
(c) Bicomponent Continuous Filament Yarns
  • Characteristics:
    • Made from two components with distinct characteristics (e.g., varying shrinkage ratios).
(d) Tape or Split Film Yarns
  • Production Method:
    • Polymer extruded into a thin sheet, cut into strips/ribbons, causing split film yarns.
  1. Spun Yarns:
  • Made from short fibres; relies on twist for strength.
  • Characteristics:
    • Hairy, less lustrous, more irregular compared to continuous-filament yarns.
    • Made by assembling staple fibres; can be made from chopped continuous filaments.

YARN DENSITY

  • Definition:
    • Bulk density determined by packing fraction indicating air spaces enclosed by fibres.
  • Influence on Fabric Performance:
    • High packing fraction can lead to stiffness; low packing fraction can lack bulk and surface integrity.
    • Affects comfort, dimensional stability, strength, extensibility, and air permeability.
YARN STRENGTH
  • Definition:
    • Influenced by fibre characteristics, such as strength, length, fineness, and twist level.
  • Factors Influencing Performance:
    • Breaking strength, elongation, elastic modulus, and abrasion resistance must reflect the yarn's usage or processing.
YARN FINENESS
  1. Count:
  • Yarn fineness described as yarn count or size; varies geometrically based on cross-section.
  1. Diameter:
  • Yarn fineness expressed in diameter; affects structural attributes like width and crimp.
YARN TWIST
  • Definition:
    • Spiral turns to yarn for fibre binding; described by direction (S/Z), level (turns/unit length), and twist factor.
  • Effects on Fabric:
    • Influences appearance, strength, and flexibility.
    • Twist increases up to a point enhances strength, but excessive twisting can weaken yarn.
    • Governs fabric characteristics and handle.
SURFACE INTEGRITY
  • Parameters:
    • Abrasion resistance: Wear by rubbing against other surfaces, measured by cycles to break yarn.
    • Hairiness: Defined by protruding fibres; measured by hair count and length method.
THREAD COUNT
  • Definition:
    • Refers to number of warp and weft threads per square inch; higher counts indicate better quality.
CRIMP
  • Definition:
    • Amount of bending created by yarn interlacing; calculated using ratios for length change.
  • Relation to Properties:
    • Affects fabric cover, thickness, and wear behavior.
FINISHING
  • Role:
    • Determines the suitability for various uses; includes treatments for aesthetics and protection (e.g., dyeing, anti-fungal).
CREASE RESISTANCE
  • Factors Impacting Resistance:
    • Include fibre type, bending performance, and yarn characteristics.
  • Effects of Treatments:
    • Improve comfort but might decrease tear resistance.
CALENDERING
  • Process:
    • Fabric subjected to heated rollers to produce various results such as softening and shine.
MOIRÉ
  • Production Method:
    • Results from moistening and pressing fabric layers for distinct patterns.

COMPLEX YARNS

  • Definition:
    • Yarns with uneven sizes, color variations, or irregularities.
  • Types and Characteristics:
    • Single Novelty Yarns: Include slubs or knots.
    • Complex Ply Yarns: Include a base, effect, and tie yarn.
    • Yarns used primarily for aesthetic value.
  1. Slub Yarns:
  • Made by uneven twisting, creating bulky areas of varying spacing.
  • Used in fabrics such as shantung.
  1. Thick-and-Thin Yarns:
  • Composed of filament-length fibres; thickness varies due to extrusion pressure.
  1. Flock Yarns:
  • Incorporate small tufts at irregular intervals for texture.
  1. Bouclé Yarns:
  • Characterized by loops with a 3-ply structure, create a rough surface.
  1. Ratiné and Gimp Yarns:
  • Similar to bouclé, with tighter loops and distinct twist directions.
  1. Nub and Knot Yarns:
  • Made by wrapping effect yarn to form a nub; minor differences in definitions.
  1. Spiral or Corkscrew Yarns:
  • Include two yarns of differing sizes; allow for greater elongation.
  1. Chenille Yarns:
  • Resemble a hairy caterpillar; formed into narrow strips for unique surface effects.
USE OF COMPLEX YARNS
  • Design Purpose:
    • Add texture and aesthetic appeal to fabrics.
  • Comfort and Maintenance Considerations:
    • Some complex yarns may snag easily or cause abrasion damage leading to wear.

COMPOUND YARNS

  • Definition:
    • Composed of at least two strands; includes covered and core spun yarns.
COVERED YARNS
  • Construction Process:
    • Filament or yarn at the core, wrapped to provide protection and aesthetics.
CORE-SPUN YARNS
  • Composition:
    • Centre axis with different fibres; types include filament and staple fibre wraps.
  • Advantages:
    • Improve balance properties and reduce costs through elimination of twist.

YARN DOUBLING

  • Definition:
    • Twisting multiple yarns together to improve regularity, strength, and extension.
  • Production Methods:
    • Primarily through ring twisting or two-for-one twisting methods.
TWIST DIRECTION AND FACTORS
  • Twist Measurement:
    • Defined as turns per inch and can be in S/Z directions.
  • Importance of Twist Factors & Strength Relationship:
    • Strength increases with twist until a certain threshold.

TEXTURISING

  • Definition:
    • Processing to introduce durable coils and crimp; improves warmth and comfort of fabrics.
  • Different Methods of Texturing:
    • Include false twist, stuffer box, airjet, knit-deknit treatments, etc.

YARNS AND THEIR CHARACTERISTICS

CONTINUOUS-FILAMENT AND SPUN YARNS COMPARISON
  • Physical Properties:
    • Depend on warp and weft characteristics, spacing/interlacing, finishing modifications.
    • Smoothness and lustre are generally higher for continuous-filament yarns.
    • Resistance to flattening and yarn strength varies based on structure and characteristics.
  • Yarn Strength Relationships:
    • Spun yarns typically weaker due to structural variations and load-bearing capacities.
FIBRE DENSITY AND SHAPE
  • Density:
    • Varies among fibres (e.g., Polyamide: 1.14-1.17 g/cm³, Polyester: ~1.38 g/cm³).
  • Effects on Bulkiness:
    • Low density fibers provide bulkier yarns; shape influences packing.
BULKED AND TEXTURED YARNS
  • Increasing Yarn Bulk:
    • Achieved through heat-setting and crimping methods.

CALCULATIONS

  • Yarn Count:
    • Weight per unit length vs length per unit weight; includes direct (denier, tex) and indirect systems (cotton, worsted).
  • Yarn Diameter Calculations:
    • Methods depend on counting/fiber density; formulas derived from direct/indirect systems.
EXAMPLES OF YARN DIAMETER CALCULATIONS
  1. Use Peirce's formula:
    • d=128extsqrt(N)d = \frac{1}{28} ext{sqrt}{(N)}
  2. Example with worsted and cotton counts and corresponding relationships.

TWIST IN YARNS

  • Effects on Properties:
    • Twist affects strength, compactness, and lustre; relationships with angle of twist and yarn characteristics.

WOVEN FABRIC CONSTRUCTION

  • Representation:
    • Uses graph paper to symbolize weaves with black squares for warp and white for weft.
  • Types of Weave: (1) Plain Weave
    • Simplest form; maximum binding interactions yielding stronger fabric. Classifications:
    • (1) Balanced (similar warp/weft counts).
    • (2) Warp-faced (warp predominates, larger crimp).
    • (3) Weft-faced (weft predominates).