ITT MODULE 4

ITT MODULE IV

Fabric Formation

• Methods of Fabric Construction:

  • Weaving

  • Knitting

  • Non-woven

  • Braided

  • Nets

  • Laces

• Main Construction Methods:

  • Woven

  • Knitted

  • Bonded (non-wovens)

  • Felted (non-wovens)

• Factors affecting fabrics:

  • Construction method impacts properties, appearance, and end use of fabrics.

Woven Fabric Formation (Weaving)

• Definition:

  • Weaving is an intersection of warp and weft yarns at right angles.

• Components:

  • Warp Yarns: Lengthwise yarns (strongest grain).

  • Weft Yarns: Widthwise yarns.

  • Selvedge: Non-fraying edge of the fabric.

• Characteristics of Woven Fabrics:

  • Firm fabric structure caused by interlacing.

Details of the Loom

• Types of Looms:

  • Backstrap loom

  • Pit-looms

  • Hand loom

  • Power loom

  • Automatic loom

• Loom Components:

  • Warp Beam: Holds the warp threads.

  • Heddles: Separate the warp threads.

  • Harnesses: Frames holding heddles.

  • Shuttle: Holds the weft yarn.

  • Beater and Reed: Presses weft against woven fabric.

  • Breast Beam & Cloth Beam: Tensions and rolls the cloth.

Weaving Operations

• Primary Motions:

  • Shedding: Separating warp yarns to create space.

  • Picking: Passing the shuttle carrying weft yarn.

  • Beating-up: Pushing weft yarn against the fabric.

• Secondary Motions:

  • Taking-up: Winding woven fabric onto the cloth beam.

  • Let-off: Regulating warp yarn release.

• Stop Motions: Stop loom on thread breaks.

Types of Weaves

• Basic Weaves:

  • Plain weave

  • Twills

  • Sateen

• Material Divergence:

  • Woven fabrics are durable, maintain shapes, but may ravel easily.

  • Fabric count (warp & weft yarn number) affects durability.

Loom Preparation

• Yarn Processing: Yarn must be prepared before entering loom.

• Essential Processes:

  • Winding: Creating long yarn lengths on larger packages.

  • Warping: Preparing yarns into parallel sheets for weaving.

  • Sizing: Coating threads for strength and reduce hairiness.

Types of Warping

• Direct Warping: Fast method for smaller beams.

• Sectional Warping: Used for striped materials, maintaining yarn order.

Sizing Process

• Purpose: Improve weavability and fabric quality.

• Ingredients: Adhesives, lubricants, solvents, and appearance agents.

• Sizing Machine Parts: Creel, size box, drying zone, and headstock.

Looming-in Process

• Drawing-in: Inserting warp threads through drop wires.

• Denting-in: Feeding threads through reed dents.

• Tying-in: Connecting new warp to exhausted warp.

Pirn Winding

• Definition: Yarn wound on pirn for weft insertion in the loom.

• Automatic Systems: Facilitate replacement and start-stop operations.

Types of Looms

• Handlooms: Non-electric, manually operated looms.

• Power Looms: Mechanized, high output, employs steam/electricity.

• Modern Looms: Classifications based on fabric production style, e.g., flat looms and shuttleless looms.

Jacquard and Dobby Looms

• Jacquard Looms: Capable of intricate designs, individually controls threads.

• Dobby Looms: Faster than tappet looms but with design limitations.

Knitting

• Definition: Fabric formed by intermeshing loops of yarn.

• Types:

  • Weft Knitting: Horizontal loop formation, elastic and warm.

  • Warp Knitting: Vertical loop formation, parallel sheet structure.

Comparison of Woven and Knitted Fabrics

• Knitted Fabric Characteristics: Elastic, breathable, wrinkle-resistant.

• Woven Fabric Characteristics: More durable, complex designs, requires finishing.

Non-Woven Fabrics

• Definition: Structure bonded without traditional weaving techniques.

• Method Types:

  • Mechanical (entangling)

  • Thermal (heat bonding)

  • Chemical (using binders)

Manufacture of Non-Wovens

• Process Steps:

  1. Forming a fibrous web.

  2. Bonding the fibers.

  3. Finishing and converting the fabric.

• Common Uses: Medical materials, filtration textiles, coatings.

Felting**

• Definition: Non-woven fabric made by compressing fibers using heat and moisture.

• Applications: Padding, lining, crafts, and industrial uses.