Preparatory Process in Weaving

Introduction

The preparatory processes in weaving play a vital role in ensuring smooth, efficient, and high-quality fabric production. This book focuses on the key steps of winding, warping, and sizing, which prepare yarns for the weaving loom.

Winding

Winding is the process of transferring yarn from one type of package to another to facilitate further processing, especially weaving or warping. It ensures that the yarn is in a suitable form, free from defects, and ready for the next operation.

Objectives of Winding

• To prepare yarn packages suitable for warping or weft insertion.

• To remove yarn faults such as slubs, neps, and thin/thick places.

• To improve yarn tension and regularity.

• To splice or knot broken yarn ends for continuity.

• To increase productivity in subsequent processes.

Classification of Winding Packages

Winding packages can be classified based on shape and end use:

• Based on Shape:

  • Cone

  • Cheese

  • Flanged bobbin

  • Pirn

  • Cop

• Based on Purpose:

  • Warp packages – For warping (e.g., cones, cheeses).

  • Weft packages – For insertion into shuttle or projectile looms (e.g., pirns, cops).

Warp and Weft Packages

• Warp Packages: Cones and cheeses are preferred due to their large size and stability for warping.

• Weft Packages: Pirns, cops, and spools are ideal for shuttle looms and automatic insertion systems.

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Warping

Flow Chart of Warp Yarn Preparation

Yarn Package (Cones/Cheeses)
        ↓
      Winding
        ↓
      Warping
        ↓
      Sizing
        ↓
   Drawing-in / Leasing
        ↓
   Weaving Preparation Complete

Definition and Classification of Warping

Warping is the process of arranging yarns parallel to each other in sheet form to form a warp beam, ready for sizing or direct weaving.

Classification of Warping:

1. Sectional Warping:

   • Suitable for short runs and colored warp.

   • Uses drum and section-wise yarn laying.

2. Beam Warping (High-Speed Warping):

   • Suitable for long runs and uniform warp.

   • Involves simultaneous winding of all warp ends.

Objectives of Warping

• To convert cone yarns into a warp beam suitable for weaving.

• To maintain uniform tension and length among yarns.

• To prepare warp ends in proper sequence and order.

• To facilitate coloring and design (in sectional warping).

• To improve efficiency of the sizing and weaving processes.

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Sizing

Definition of Sizing

Sizing is the process of applying a protective adhesive coating (size paste) to the warp yarns to increase their strength and smoothness, and reduce breakage during weaving.

Purposes of Sizing

• To increase yarn strength and abrasion resistance.

• To reduce hairiness and improve yarn surface.

• To decrease yarn breakage and improve loom efficiency.

• To reduce friction between yarns and loom parts.

• To ensure better fabric quality and fewer weaving defects.

Sizing Ingredients and Their Functions

Ingredient	Function
Starch	Film-forming agent; provides strength and stiffness.
Polyvinyl Alcohol (PVA)	Synthetic substitute for starch; improves elasticity and adhesion.
Carboxymethyl Cellulose (CMC)	Increases film flexibility and improves cohesion.
Softener (e.g., wax, tallow)	Reduces friction and increases smoothness.
Antimicrobials	Prevents microbial growth in size paste.
Preservatives	Extends shelf life of the size mixture.
Lubricants (e.g., oils)	Reduce yarn-to-metal friction and wear.
Antifoaming Agents	Control foam formation during mixing.