Discover the study notes BS Textile Engineering at National Textile University, Faisalabad, and unlock your potential in the dynamic textile industry! BS Textile Engineering at National Textile University in Faisalabad is a rewarding experience that will pave the way for a successful career in the dynamic and innovative textile industry. By following these study notes and tips for success, you will be well on your way to achieving academic excellence and professional growth in the field of textile engineering.

Study Notes BS Textile Engineering At National Textile University, Faisalabad.

Study Notes: Introduction to Textile Engineering (TE-1111)

 Course Overview

Introduction to Textile Engineering is a foundational course that provides a broad overview of the textile industry, from fiber production to finished garments . It is designed for first-year engineering students to understand the scope of textile engineering, the manufacturing steps involved in textile production, and the role of a textile engineer in the industry .

UNIT 1: WHAT IS TEXTILE ENGINEERING?

1.1 Definition

Textile Engineering is a branch of engineering that deals with the design, development, and manufacturing of textile products, including fibers, yarns, fabrics, and finished goods. It applies principles of chemistry, physics, and mechanics to convert raw materials into useful products .

1.2 Who is a Textile Engineer?

A textile engineer is a professional who applies engineering principles to the textile industry . Key responsibilities include:

1.3 Study Areas / Working Areas

Textile engineers can work in various sectors of the textile industry :

UNIT 2: TEXTILE MATERIALS – FIBERS

2.1 Definition of a Fiber

A fiber is the basic building block of textiles. It is defined by its high length-to-diameter ratio, flexibility, and sufficient strength to be processed into yarn or fabric .

2.2 Classification of Fibers

Textile fibers are broadly divided into Natural and Man-Made fibers .

A. Natural Fibers

These are obtained from plants, animals, or minerals .

B. Man-Made Fibers

These are produced by chemical processes .

2.3 Essential Fiber Properties

The performance of a textile is determined by the properties of its constituent fibers .

UNIT 3: YARN TECHNOLOGY (SPINNING)

3.1 What is a Yarn?

A yarn is a continuous strand of textile fibers, filaments, or material in a form suitable for knitting, weaving, or other fabric formation methods. Fibers are twisted together to provide strength and cohesion .

3.2 Yarn Manufacturing Process (for Staple Fibers)

3.3 Yarn Properties

UNIT 4: FABRIC FORMATION

Fabric is the sheet form of textile produced by interlacing, interlooping, or bonding fibers/yarns .

4.1 Methods of Fabric Construction

4.2 Introduction to Weaving Technology

• Warp: Lengthwise yarns (held under tension on the loom)

• Weft (Filling): Crosswise yarns (inserted across the warp)

• Loom: The machine used for weaving 

• Basic Weave Structures:

  • Plain Weave: Simplest, strong, used for many fabrics

  • Twill Weave: Diagonal lines (denim, chinos)

  • Satin/Sateen Weave: Smooth, lustrous surface

4.3 Introduction to Knitting Technology

• Wales: Vertical columns of loops (analogous to warp)

• Courses: Horizontal rows of loops (analogous to weft)

• Types of Knitting:

  • Weft Knitting: Yarn runs horizontally; common in sweaters, t-shirts

  • Warp Knitting: Yarn runs vertically; more stable fabrics (tricot, raschel)

4.4 Non-woven Technology

Non-wovens are fabric-like materials made directly from fibers without spinning or weaving . They are manufactured by:

• Mechanical bonding: Needle-punching, hydroentanglement

• Chemical bonding: Adhesives

• Thermal bonding: Heat to melt fibers together

UNIT 5: COLORATION AND FINISHING

5.1 What is Textile Finishing?

Finishing refers to the processes performed on fabric after it leaves the loom or knitting machine to improve its appearance, feel, or performance .

5.2 Pre-treatment Processes

Before dyeing or finishing, fabric must be prepared :

5.3 Dyeing and Printing

Stages of Dyeing:

• Fiber dyeing

• Yarn dyeing

• Fabric dyeing

• Garment dyeing

5.4 Mechanical and Chemical Finishing

UNIT 6: CLOTHING TECHNOLOGY (APPAREL MANUFACTURING)

6.1 Overview

Clothing technology involves the conversion of fabric into finished garments through cutting, sewing, and assembly processes .

6.2 Key Processes in Garment Manufacturing

UNIT 7: TECHNICAL TEXTILES

7.1 Definition

Technical Textiles are functional fabrics engineered for specific technical performance properties rather than aesthetic purposes .

7.2 Major Applications

SUMMARY: THE TEXTILE PIPELINE

FIBER → YARN (Spinning) → FABRIC (Weaving/Knitting/Non-woven) → FINISHING → CLOTHING

This production pipeline represents the complete textile manufacturing process, with quality control integrated at each stage .

KEY TERMINOLOGY GLOSSARY

SELF-TEST QUESTIONS

1. Define textile engineering. What are the primary responsibilities of a textile engineer? 

2. List five sectors in which a textile engineer can work. 

3. Distinguish between natural and man-made fibers. Give two examples of each. 

4. Name four essential fiber properties and explain why each is important. 

5. Describe the three main methods of fabric formation and give an application example for each. 

6. Explain the difference between dyeing and printing.

7. What are technical textiles? Name five technical textile sectors with their applications. 

8. List the six steps of the staple yarn manufacturing process in order (from blow room to spinning). 

REFERENCES

• Gries, T., Veit, D., & Wulfhorst, B. (2015). Textile Technology: An Introduction. Hanser Publications. 

• Sinclair, R. (Ed.). (2015). Textiles and Fashion: Materials, Design and Technology. Woodhead Publishing Limited. 

• Taylor, M.A. (1990). Technology of Textile Properties. Forbes Publications Ltd. 

• Taylor, M.A. (1999). Textile Technology. Forbes Publication Ltd

TE-1112 TEXTILE RAW MATERIALS: COMPREHENSIVE STUDY NOTES

COURSE OVERVIEW

TE-1112 Textile Raw Materials is a foundational course for textile engineering students that introduces the fundamental materials used in textile manufacturing. The course covers the classification, properties, production, and applications of natural and man-made fibers, forming the basis for understanding yarn manufacturing, fabric production, and textile processing .

PART ONE: INTRODUCTION TO TEXTILE FIBERS

1.1 What is a Textile Fiber?

Definition: A textile fiber is a fundamental unit of textile materials characterized by:

• High length-to-width ratio (at least 100:1)

• Flexibility and cohesiveness

• Sufficient strength to withstand processing

• Uniformity and consistency

1.2 General Classification of Textile Fibers

TEXTILE FIBERS
├── NATURAL FIBERS
│   ├── Vegetable (Cellulosic) Fibers
│   │   ├── Seed fibers (Cotton, Coir, Kapok)
│   │   ├── Bast fibers (Flax, Jute, Hemp, Ramie)
│   │   ├── Leaf fibers (Sisal, Abaca, Pineapple)
│   │   └── Fruit fibers (Coir)
│   ├── Animal (Protein) Fibers
│   │   ├── Wool (Sheep, Lamb)
│   │   ├── Specialty hair fibers (Cashmere, Mohair, Alpaca, Camel)
│   │   └── Silk (Mulberry, Tussah, Muga, Eri)
│   └── Mineral Fibers
│       └── Asbestos
│
└── MAN-MADE FIBERS
    ├── Regenerated Fibers (Natural Polymers)
    │   ├── Cellulosic (Viscose Rayon, Lyocell, Acetate, Triacetate)
    │   └── Protein (Azlon, Casein, Soybean)
    └── Synthetic Fibers (Synthesized Polymers)
        ├── Polyester (PET)
        ├── Polyamide (Nylon 6, Nylon 6,6)
        ├── Polyacrylic (Acrylic, Modacrylic)
        ├── Polyolefin (Polypropylene, Polyethylene)
        ├── Elastomeric (Spandex, Rubber)
        └── High-performance (Aramid, Carbon, Glass)

1.3 Fiber Terminology

PART TWO: NATURAL FIBERS

Natural fibers are provided by nature in ready-made form and need only to be extracted from their source. They are classified as cellulosic (plant-based), protein (animal-based), or mineral fibers .

2.1 CELLULOSIC (VEGETABLE) FIBERS

2.1.1 Cotton

Origin: Cotton fibers are seed hairs (trichomes) from the seed bolls of plants of the genus Gossypium, family Malvaceae. The fiber is almost pure cellulose .

Cultivation: Cotton grows in tropical and subtropical regions. Major producers: China, India, United States, Pakistan, Brazil, Uzbekistan.

Fiber Structure:

• Cuticle: Outermost waxy layer

• Primary wall: Thin outer layer with cellulose in a random network

• Secondary wall: Thick inner layer with cellulose arranged in concentric layers

• Lumen: Central hollow canal that collapses when fiber dries

Physical Properties:

Chemical Properties:

• Cellulose content: 88-96% (highly pure)

• Other components: Waxes (0.5-1.0%), pectins (0.5-1.0%), proteins (1.0-1.5%), ash (0.5-1.0%)

• Effect of acids: Strong acids destroy cellulose

• Effect of alkalis: Resistant to alkalis (mercerization uses caustic soda)

• Effect of light: Turns yellow and degrades with prolonged exposure

Cotton Varieties:

Mercerization:

• Treatment with caustic soda under tension

• Causes fiber to swell, straighten, and become more cylindrical

• Increases luster, dyeability, and strength (10-20%)

Applications: Apparel (shirts, denim, underwear), home textiles (sheets, towels), medical (bandages, gauze), industrial (threads, canvas).

2.1.2 Flax (Linen)

Origin: Flax fibers are bast fibers obtained from the stem of the plant Linum usitatissimum. After processing into threads and fabrics, it is called linen .

Fiber Structure:

• Multicellular fiber with bundled fibrils

• Contains cellulose, lignin, pectin, fat, and wax

• Nodes (joints) visible along the fiber length

Physical Properties:

Processing:

1. Retting: Microbial decomposition to separate fibers from stem

   • Water retting (immersion in water)

   • Dew retting (exposed to dew on grass)

   • Chemical retting (using chemicals)

2. Scutching: Beating to remove woody matter

3. Hackling: Combing to align and clean fibers

Applications: Apparel (summer clothing, suits), home textiles (tablecloths, napkins, bed sheets), industrial (canvas, twine, upholstery).

2.1.3 Jute

Origin: Jute is a bast fiber obtained from the stems of plants of the genus Corchorus (species C. capsularis and C. olitorius).

Physical Properties:

Applications: Packaging (hessian, sacking, gunny bags), carpet backing, wall coverings, geotextiles.

2.1.4 Hemp

Origin: Hemp is a bast fiber from the stem of Cannabis sativa.

Physical Properties:

Applications: Rope, canvas, geotextiles, apparel (increasingly popular), paper.

2.1.5 Other Cellulosic Fibers

2.2 ANIMAL (PROTEIN) FIBERS

2.2.1 Wool

Origin: Wool is the protective hair covering of sheep (genus Ovis). The principal fiber comes from domesticated sheep .

Fiber Structure:

• Cuticle (Epicuticle): Outer scaly layer

  • Scales overlap like roof tiles

  • Important for felting and fiber identification

• Cortex: Main body of the fiber

  • Ortho-cortex (one side) and para-cortex (other side)

  • Differential swelling creates crimp

• Medulla: Hollow central canal (absent in fine wools)

Physical Properties:

Chemical Properties:

• Composition: Keratin protein (containing sulfur)

• Amino acids: 18 types including cystine (forms disulfide bonds)

• Effect of acids: Good resistance to dilute acids

• Effect of alkalis: Damaged by weak alkalis (soap), destroyed by strong alkalis

• Effect of light: Turns yellow and degrades with prolonged exposure

Wool Grades (Bradford System):

Specialty Animal Hair Fibers:

Felting:

• Unique property of wool due to scales

• Under heat, moisture, and friction, scales interlock

• Causes irreversible matting and shrinkage

• Used to create felt fabrics intentionally

Applications: Apparel (suits, sweaters, coats, socks), home textiles (blankets, carpets, upholstery), industrial (felts, insulation).

2.2.2 Silk

Origin: Silk is a continuous protein filament produced by the silkworm (primarily Bombyx mori) when forming its cocoon .

Sericulture (Silk Production):

1. Egg stage: Female moth lays 400-500 eggs

2. Larva (caterpillar) stage: Hatched silkworms eat mulberry leaves

3. Cocoon stage: Silkworm spins cocoon (2-3 days), producing 1,000-1,500 meters of filament

4. Pupa stage: Transformation inside cocoon

5. Moth stage: Emerges if not killed

Reeling Process:

• Silkworms killed by heat before emerging (prevents filament breakage)

• Cocoons softened in hot water

• Filaments from 4-8 cocoons combined to form silk thread

Fiber Structure:

• Fibroin: The protein core (70-80% of fiber)

• Sericin: The gum coating (20-30% of fiber)

  • Removed during degumming process

  • Accounts for silk’s natural luster

Physical Properties:

Chemical Properties:

• Composition: Fibroin protein (containing amino acids: glycine, alanine, serine)

• Effect of acids: Damaged by mineral acids; organic acids have little effect

• Effect of alkalis: Damaged by strong alkalis

• Effect of light: Particularly sensitive to UV radiation (degrades rapidly)

Silk Varieties:

Weighted Silk:

• Treated with metallic salts (tin chloride) to compensate weight lost during degumming

• More vulnerable to deterioration from light and pollutants

Applications: Luxury apparel (dresses, ties, scarves), home textiles (bed sheets, pillowcases), medical (sutures), industrial (parachutes, bicycle tires).

2.3 MINERAL FIBERS

Asbestos:

• Natural mineral fiber with excellent heat and chemical resistance

• Highly resistant to acids, alkalis, and burning

• Health hazard: Carcinogenic (causes asbestosis, mesothelioma)

• No longer used in textiles in most countries

PART THREE: MAN-MADE FIBERS

Man-made fibers are produced through industrial processes. They are classified into regenerated fibers (from natural polymers) and synthetic fibers (from chemically synthesized polymers) .

3.1 REGENERATED FIBERS

These fibers are manufactured using raw materials available in nature (cellulose or protein) that are chemically processed, dissolved, and regenerated into fiber form .

3.1.1 Viscose Rayon

Production Process:

1. Cellulose (from wood pulp or cotton linters) treated with caustic soda → alkali cellulose

2. Reacted with carbon disulfide → cellulose xanthate

3. Dissolved in dilute caustic soda → viscose solution

4. Extruded through spinneret into acid bath → fibers regenerated

Physical Properties:

Advantages: Good drape, absorbent, inexpensive, can imitate silk, cotton, linen

Disadvantages: Low wet strength, shrinks, prone to wrinkling

Applications: Apparel (dresses, linings, blouses), home textiles (bedspreads, draperies), industrial (tire cord).

3.1.2 Lyocell (Tencel)

Production: Cellulose dissolved in N-methylmorpholine N-oxide (NMMO) – organic solvent process; no chemical reaction, only dissolution

Properties:

• High wet strength

• Excellent drape and luster

• Biodegradable

• Environmentally friendly process

Applications: High-quality apparel, eco-friendly textiles, industrial fabrics.

3.1.3 Acetate and Triacetate

Applications: Linings, evening wear, cigarette filters, sportswear.

3.1.4 Regenerated Protein Fibers

3.2 SYNTHETIC FIBERS

Synthetic fibers are chemically synthesized from monomeric units (primarily petroleum-based) .

3.2.1 Polyester (PET – Polyethylene Terephthalate)

Production:

• Polymerization of ethylene glycol and terephthalic acid

• Melt spinning (extruded through spinneret as molten polymer)

Physical Properties:

Advantages:

• Strong and durable

• Wrinkle-resistant

• Quick-drying

• Resistant to most chemicals

• Good abrasion resistance

Disadvantages:

• Low moisture absorbency (can feel clammy)

• Subject to mildew

• Can pill (form small fiber balls on surface)

• Can melt (heat-sensitive for ironing)

Applications: Apparel (shirts, pants, jackets, sportswear), home textiles (sheets, curtains, carpets), industrial (seat belts, tire cord, ropes), technical (fill for pillows, insulation).

3.2.2 Polyamide (Nylon)

Production:

• Nylon 6,6: Condensation polymerization of hexamethylenediamine + adipic acid (DuPont, 1938)

• Nylon 6: Ring-opening polymerization of caprolactam

Physical Properties:

Advantages:

• Very high strength

• Excellent elasticity and recovery

• Abrasion-resistant

• Lightweight

Disadvantages:

• Low moisture absorbency

• Poor resistance to light (degrades)

• Generates static electricity

• Low melting point (for heat-setting applications)

Applications: Apparel (hosiery, lingerie, swimwear, activewear), carpets, industrial (ropes, seat belts, airbags, fishing nets), technical (parachutes, tire cord).

3.2.3 Acrylic

Production: Polymerization of acrylonitrile (at least 85% acrylonitrile content)

Physical Properties:

Advantages:

• Wool-like feel (often called “artificial wool”)

• Warm and lightweight

• Resistant to moths, mildew, chemicals

• Good color retention

Disadvantages:

• Pills easily

• Low moisture absorbency

• Static electricity buildup

Applications: Apparel (sweaters, fleece, socks, gloves), home textiles (blankets, carpets, upholstery), industrial (awnings, outdoor fabrics).

Modacrylic: Modified acrylic with 35-85% acrylonitrile; flame-resistant properties.

3.2.4 Polyolefin (Polypropylene – PP)

Production: Polymerization of propylene; melt spinning

Physical Properties:

Advantages:

• Very lightweight (floats on water)

• Excellent wicking (transports moisture)

• Chemical resistance

• Low cost

Disadvantages:

• Low melting point (cannot iron)

• Poor UV resistance

• Difficult to dye

Applications: Apparel (thermal underwear, sportswear, socks), carpets, geotextiles, industrial (ropes, filters, diapers).

3.2.5 Elastomeric Fibers (Spandex/Elastane, Rubber)

Spandex (Elastane) – Segmented Polyurethane:

Applications: Swimwear, sportswear, undergarments, hosiery, medical (compression garments).

3.3 HIGH-PERFORMANCE FIBERS

These fibers are produced for specific technical and performance properties rather than aesthetics .

PART FOUR: FIBER PROPERTIES COMPARISON

4.1 Physical Properties Comparison Table

4.2 Chemical Properties Comparison

PART FIVE: FIBER IDENTIFICATION

5.1 Microscopic Identification

5.2 Burning Test

5.3 Solubility Test

PART SIX: INDUSTRIAL APPLICATIONS

6.1 Fiber Selection Criteria

PART SEVEN: REVIEW QUESTIONS

Sample Theoretical Questions

1. Classify textile fibers with examples of each category.

2. Describe the physical and chemical properties of cotton fiber.

3. Explain the structure of wool fiber and how it relates to its unique properties.

4. Compare and contrast silk and wool as protein fibers.

5. What is mercerization? Describe its effects on cotton fiber.

6. Differentiate between regenerated and synthetic fibers with examples.

7. List the properties and applications of polyester fiber.

8. Explain the production process of viscose rayon.

9. Discuss the advantages and limitations of synthetic fibers compared to natural fibers.

10. How can you identify different fibers using microscopy and burning tests?

RECOMMENDED RESOURCES

Textbooks

• Kadolph, S.J. Textiles. Pearson Education.

• Tortora, P.G. Understanding Textiles. Pearson.

• Cook, J.G. Handbook of Textile Fibres (Volumes I & II). Woodhead Publishing.

Standards

• ASTM D123 – Standard Terminology Relating to Textiles

• ISO 2076 – Textiles – Man-made fibres – Generic names

Online Resources

• Textile Learner (textilelearner.net) – Fiber properties and processing

• Textile World (textileworld.com) – Industry news and applications

PE-2102: Polymer Engineering Fundamentals – Detailed Study Notes

Unit 1: Introduction to Polymers

1.1 What Are Polymers?

• Definition: Polymers are materials of very high molecular weight, consisting of several structural units (monomers) bound together by covalent bonds.

• Etymology: “Poly” (many) + “meros” (parts)

• Example: Polyethylene is represented as -[CH₂-CH₂]-n where n represents the chain length and -CH₂-CH₂- is the repeat unit.

1.2 Key Terminology

1.3 Unique Properties of Polymers

• High strength-to-weight ratio

• Glass transition temperature (Tg)

• Rubber elasticity

• High viscosity as melts and solutions

1.4 Classification of Polymers

By Origin:

• Natural polymers: Cellulose, silk, wool, cotton, proteins, DNA

• Synthetic polymers: Polyethylene, nylon, polyester, epoxy resins

By Polymerization Mechanism:

• Addition (Chain-Growth) Polymers: Formed by chain reactions of unsaturated monomers (e.g., polyethylene, polystyrene, PVC)

• Condensation (Step-Growth) Polymers: Formed by stepwise reactions between functional groups with small molecule byproducts (e.g., nylon, polyester)

By Thermal Behavior:

By Chain Structure:

• Linear polymers: Chains are straight; thermoplastic behavior

• Branched polymers: Side chains attached to main chain; lower density

• Cross-linked polymers: Chains connected by covalent bonds; thermoset behavior

1.5 Common Commercial Polymers

Unit 2: Polymer Additives and Blends

2.1 Why Additives?

Few polymers are used in pure form. Additives are incorporated to:

• Improve properties

• Facilitate processing

• Modify physical, chemical, or electrical properties

• Reduce cost

2.2 Types of Additives

2.3 Polymer Blends

• Definition: Physical mixtures of two or more polymers without significant chemical bonding between them

• Objective: Achieve commercially viable products with unique properties or lower cost

• Types:

  • Miscible blends: Single-phase system at molecular scale

  • Immiscible blends: Multi-phase system (most common)

Examples:

• HIPS (High Impact Polystyrene): Polystyrene + polybutadiene rubber

• ABS (Acrylonitrile Butadiene Styrene): Acrylonitrile + butadiene + styrene

• PC/ABS blend: Polycarbonate + ABS (automotive interior parts)

2.4 Compatibilizers

• Substances added to immiscible polymer blends to improve interfacial adhesion

• Result in better mechanical properties and more stable morphology

Unit 3: Polymer Rheology

3.1 What is Rheology?

• Definition: The study of flow and deformation of materials

• Origin: Greek “rheo” (to flow) + “ology” (study of)

• Importance in Polymers: Provides relationship between properties, structure, and processing behavior

3.2 Viscosity

• Definition: Resistance of a fluid to flow or deformation at a given rate

• Newton’s Law of Flow: τ = η γ̇

  • τ = shear stress

  • η = viscosity

  • γ̇ = shear rate

Factors Affecting Viscosity:

3.3 Newtonian vs. Non-Newtonian Fluids

Key Insight for Polymers: Most polymer melts exhibit pseudoplastic (shear-thinning) behavior – viscosity decreases as shear rate increases. This is crucial for processing, as high shear rates during injection molding or extrusion make the material flow more easily.

3.4 Viscoelasticity

• Definition: Combined behavior of viscous (liquid-like) and elastic (solid-like) properties

• Elastic behavior: Instantaneous deformation; returns to original shape when stress removed (spring-like)

• Viscous behavior: Time-dependent deformation; permanent change (dashpot-like)

• Polymers are viscoelastic because long chains can both stretch (elastic) and slide past each other (viscous)

Viscoelastic Phenomena:

3.5 Measurement of Rheological Properties

Unit 4: Polymer Processing Techniques

4.1 General Processing Phases

1. Heating: Soften or melt the polymer

2. Shaping/forming: Under constraint using a mold or die

3. Cooling: Retain the shape

4.2 Major Processing Methods

4.3 Extrusion

• Principle: Polymer granules are fed from hopper onto a rotating screw; material is conveyed, heated, melted, and forced through a die

• Screw Geometry:

  • Feed zone: Conveys solid polymer

  • Compression zone: Melts and compresses material

  • Metering zone: Pumps melt through die

• Applications: Pipes, tubing, sheets, films, wire coating

4.4 Injection Molding

• Principle:

  1. Polymer fed from hopper into barrel

  2. Heated and melted by rotating screw

  3. Screw moves forward (reciprocating action) to inject melt into closed mold

  4. Polymer solidifies in mold

  5. Mold opens, part ejected

• Reciprocating Screw: Performs dual role – rotates for melting, moves like plunger for injection

• Key Terminology:

  • Shot size: Quantity of melt injected per cycle

  • Cycle time: Time per complete molding cycle

  • Clamping unit: Holds mold closed during injection

4.5 Blow Molding

• Principle: Three steps – melt resin, form preform tube (parison), blow into shape using compressed air

• Applications: Hollow, thin-walled parts – bottles, containers, fuel tanks

• Common materials: HDPE, LDPE, PP, PVC, PET

• Blow ratio: Mold diameter / parison diameter (typically 1.5–3.0)

4.6 Compression Molding

• Principle: Preheated polymer placed in open mold cavity; mold closed with pressure; material flows and cures under heat and pressure

• Parameters:

  • Pressure: 2000–3000 psi (13.8–20.7 MPa)

  • Temperature: 149°C–191°C (300°F–375°F)

• Advantages: Low cost, uniform density, minimal warping

• Disadvantages: Long curing time, scrap cannot be reprocessed

Unit 5: Polymer Composites

5.1 Definition

• Composite material: Solid material composed of two or more distinct phases, combining properties of both for superior performance

• Two phases:

  • Matrix phase: Surrounds and binds reinforcements

  • Reinforcement/dispersed phase: Harder, stiffer component (fibers, particles)

5.2 Functions of the Matrix Phase

1. Binds fibers together, transmits applied stress to fibers

2. Protects fibers from surface damage (abrasion, chemical reactions)

3. Separates fibers, preventing crack propagation

4. Provides barrier to environmental degradation

5.3 Types of Polymer Matrix Composites

5.4 Fiber-Matrix Interface

• Critical for mechanical properties

• Strong interface: High strength and stiffness

• Weak interface: Lower strength, but may improve toughness

• Bonding mechanisms: Adsorption/wetting, interdiffusion, electrostatic attraction, chemical bonding, mechanical adhesion

5.5 Why Composites Over Metals?

• Higher specific modulus (stiffness-to-weight ratio)

• Higher specific strength (strength-to-weight ratio)

• Weight reduction leads to greater efficiency and energy savings

Unit 6: Testing and Characterization of Polymers

6.1 Common Polymer Tests

6.2 Molecular Weight Determination

• Gel Permeation Chromatography (GPC): Size-exclusion chromatography to determine molecular weight distribution

• Viscosity methods: Measure intrinsic viscosity; relate to molecular weight via Mark-Houwink equation

Unit 7: Polymer Recycling and Ecology

7.1 Recycling Categories

7.2 Challenges in Polymer Recycling

• Contamination (food residues, labels)

• Polymer sorting (different types not compatible)

• Degradation during reprocessing (reduced properties)

• Economic viability

7.3 Biodegradable and Bio-based Polymers

• PLA (Polylactic acid): From corn starch; compostable

• PHA (Polyhydroxyalkanoates): Produced by bacteria

• Starch blends: Partially biodegradable

Unit 8: Key Equations and Relationships

8.1 Number Average Molecular Weight (Mₙ)

Mn=∑NiMi∑NiMn​=∑Ni​∑Ni​Mi​​
where Nᵢ = number of molecules of molecular weight Mᵢ

8.2 Weight Average Molecular Weight (M_w)

Mw=∑wiMi∑wi=∑NiMi2∑NiMiMw​=∑wi​∑wi​Mi​​=∑Ni​Mi​∑Ni​Mi2​​

• Polydispersity Index (PDI) = M_w / M_n (typically 1.5–5 for synthetic polymers)

8.3 Viscosity Relationships

• Newtonian: τ = η γ̇

• Power Law (Ostwald-de Waele) : η = K γ̇⁽ⁿ⁻¹⁾

  • n = 1 → Newtonian

  • n < 1 → Shear-thinning (pseudoplastic)

  • n > 1 → Shear-thickening (dilatant)

8.4 Arrhenius Equation for Viscosity

η=Ae(Ea/RT)η=Ae(Ea/RT)

• η = viscosity

• Ea = activation energy for flow

• R = gas constant

• T = absolute temperature

Final Exam Tips for PE-2102

1. Understand the structure-property-processing triangle: These three aspects are interconnected – changes in one affect the others.

2. Know the difference between thermoplastics and thermosets: This dictates appropriate processing methods.

3. Memorize the four major processing methods and which materials they work best with.

4. Rheology is critical: Understand why polymer melts behave differently from simple liquids (shear-thinning, viscoelasticity).

5. Be able to identify common polymers by their repeat units and typical applications.

6. Know the functions of major additives – fillers vs. plasticizers vs. stabilizers.

7. For composites: Remember the role of matrix and reinforcement, and why fiber length matters.

Recommended Resources

ME-2122: MECHANICAL ENGINEERING FUNDAMENTALS

1. Course Overview & Core Tools

Mechanical engineering fundamentals introduce the core concepts and practical tools used throughout the field. A key component is learning how engineers communicate designs and solve complex problems.

Engineering Graphics & CAD (Computer-Aided Design)

Engineers use drawings and 3D models to visualize, communicate, and analyze designs before anything is built .

• Freehand Sketching: Quick, rough drawings to capture initial ideas.

• 2D CAD: Creating precise flat drawings (like blueprints) showing top, front, and side views.

• 3D Solid Modeling: Building virtual 3D objects. Software calculates properties like volume, weight, and center of gravity automatically.

• Standard Drawing Views:

  • Orthographic Projection: Showing multiple 2D views (front, top, side) of a 3D object.

  • Section Views: A “cutaway” view showing internal features.

  • Detail Views: Enlarged views of a complex small area.

Dimensioning & Tolerancing

• Dimensioning: Specifying the exact size and location of every feature on a drawing.

• Tolerance: The acceptable amount of variation in a dimension. No part can be made exactly to a number, so tolerances define the range (e.g., 25.0 mm ± 0.1 mm) .

Computer-Aided Engineering (CAE) Tools

Engineers use software to solve complex math problems, like simulating stress on a bridge or fluid flow through a pipe, which is impossible to do by hand efficiently .

2. Foundational Mechanics

These are the core physical principles that explain how forces affect objects at rest (Statics) and in motion (Dynamics).

Statics: Analyzing Objects at Rest

Statics is the study of forces on stationary objects. The key principle is that all forces are balanced, meaning the object will not move or rotate.

• Newton’s First Law: An object at rest stays at rest unless acted on by an unbalanced force.

• Key Concepts:

  • Force (F): A push or pull (measured in Newtons, N).

  • Moment (M) / Torque: The rotational effect of a force. Calculated as Force × Perpendicular Distance from a pivot point.

• Free Body Diagram (FBD): The single most important tool in statics. It’s a simplified sketch of a single object, isolated from everything else, with all forces acting on it drawn as arrows. Drawing a correct FBD is the first step to solving almost any mechanics problem.

Dynamics: Analyzing Objects in Motion

Dynamics explains why and how things move. It is governed by two other laws from Newton.

• Newton’s Second Law (F = m × a): The acceleration of an object depends on the net force acting on it and its mass.

  • Force (N) = Mass (kg) × Acceleration (m/s²)

  • This is the fundamental equation connecting force and motion.

• Newton’s Third Law: For every action, there is an equal and opposite reaction.

Kinematics vs. Kinetics

• Kinematics: Describing motion (velocity, acceleration) without caring about the forces that cause it. *Question: If a car goes from 0 to 60 km/h in 5 seconds, what is its acceleration?*

• Kinetics: Linking the forces on an object to its motion using F = m × a. Question: What force must the engine produce to give the car that acceleration?

Mechanical Systems in Motion

• Linear Motion: Motion along a straight line (e.g., a train on a track).

• Rotational Motion: Spinning motion around an axis (e.g., a wheel, a turbine).

3. Properties of Engineering Materials

Engineers must select the right material for the job. This requires understanding how materials behave under different conditions.

Stress and Strain

These concepts describe how a material deforms when a force is applied .

• Stress (σ – sigma): The intensity of the internal force inside a material.

  • Formula: σ = F / A (Force divided by cross-sectional area)

  • Units: Pascals (Pa) or N/m².

• Strain (ε – epsilon): The amount of deformation, expressed as a fraction of the original length.

  • Formula: ε = ΔL / L₀ (Change in length divided by original length)

The Stress-Strain Curve

This graph is a material’s “fingerprint.” By pulling a sample until it breaks, engineers get a curve that reveals key properties:

• Elastic Region: If you stretch it, it returns to its original shape when released. (Like a rubber band).

  • Hooke’s Law: In this region, stress is proportional to strain.

  • Young’s Modulus (E): The slope of this line. It measures stiffness. A high E means the material is hard to stretch.

• Yield Point: The point where permanent deformation begins. The material won’t fully return to its original shape.

• Plastic Region: Beyond the yield point, the material is permanently stretched. It behaves more like clay than a rubber band.

• Ultimate Tensile Strength (UTS): The highest point on the curve—the maximum stress the material can withstand.

• Fracture Point: Where the material finally breaks.

Material Types & Properties

4. Key Concepts in Thermal & Fluid Systems

These areas deal with energy, heat, and the behavior of liquids and gases.

Thermodynamics: The Science of Energy

It focuses on heat, work, and the conversion of energy from one form to another (e.g., an engine converting fuel’s chemical energy into motion).

• System: The specific object or region we are studying (e.g., the gas inside an engine cylinder).

• Surroundings: Everything outside the system.

• Key Properties:

  • Pressure (P): Force per unit area exerted by a fluid.

  • Temperature (T): A measure of the average kinetic energy of particles.

  • Volume (V): The space the substance occupies.

• The First Law (Conservation of Energy): Energy cannot be created or destroyed, only converted from one form to another. The change in a system’s internal energy equals the heat added minus the work done by the system.

Fluid Mechanics: The Behavior of Fluids

Fluids include both liquids and gases.

• Viscosity (μ – mu): A measure of a fluid’s resistance to flow.

  • High Viscosity: Flows slowly (e.g., honey, motor oil).

  • Low Viscosity: Flows easily (e.g., water, gasoline) .

• Pressure: Fluids exert pressure equally in all directions. This is why hydraulic systems work so well.

• Key Principles:

  • Continuity Equation: For an incompressible fluid, the flow rate is constant. A fluid flows faster through a narrower pipe.

  • Bernoulli’s Principle: Faster-moving fluid exerts less pressure. This is the principle that gives lift to airplane wings.

Study Tips for ME-2122

1. Master the Free Body Diagram (FBD): Almost every Statics or Dynamics problem starts with a correct FBD. Practice drawing them until it becomes second nature.

2. Understand the Stress-Strain Curve: Memorize the shape, the 5 key points (Yield, UTS, Fracture), and the meaning of the slope (Young’s Modulus = Stiffness).

3. Know Your Units: Mechanical Engineering is unforgiving with unit errors. Memorize the base units: kg for mass, m for distance, s for time. Force is a derived unit: 1 N = 1 kg·m/s².

4. Practice, Practice, Practice: Engineering is an applied science. Work through sample problems for Kinematics, Statics, and Stress analysis. You can’t learn it just by reading.

5. Think Visually: Sketch the problem, draw the graph, label the forces. A good diagram is worth 50% of the solution.

TE-2111 Introduction to Yarn Manufacturing – Comprehensive Study Notes

These notes provide a detailed introduction to the principles, processes, and technologies involved in converting textile fibers into yarn. The content is organized to follow a standard university syllabus and is suitable for undergraduate students in textile engineering.

Part 1: Foundations of Yarn Manufacturing

1.1 What is Yarn?

Yarn is defined as a linear assemblage of fibers twisted together. Yarns are the basic building blocks used to produce textile products such as fabrics, garments, and home textiles .

Key Yarn Properties:

1.2 What is Spinning?

Spinning is the process of drawing out fibers from a mass and twisting them together to form a continuous thread or yarn . The so-called “spun yarns” are yarns made from staple fibers (natural fibers like cotton, wool, and cut man-made fibers). In man-made fiber production, the name “spinning” is also applied to the extrusion of a solution to form a filament .

With the exception of silk, all natural fibers are obtained as staple fibers characterized by a specific average length. In the spinning process, fibers are entangled by rotation to increase friction between individual fibers, thereby building a cohesive staple fiber yarn .

1.3 Types of Spinning Systems

1.4 The Cotton (Ring) Spinning Process – Overview

Ring spinning is the most common spinning method worldwide, suitable for all fiber types with lengths up to 40 mm. It is highly flexible in terms of yarn properties and applications . Yarns manufactured by ring spinning are processed into woven fabrics, hosiery, knits, and braidings for apparel, home textiles, and technical textiles .

Complete Machine Flow Chart (Ring Spinning):

┌─────────────────────────────────────────────────────────────────────────────┐
│                    COTTON YARN MANUFACTURING PROCESS FLOW                    │
├─────────────────────────────────────────────────────────────────────────────┤
│                                                                             │
│   BALE OPENING ──→ MIXING/BLENDING ──→ BLOW ROOM ──→ CARDING                │
│        │                 │                 │              │                  │
│   (Loosening)       (Uniformity)     (Cleaning)      (Individualization)    │
│                                                                             │
│         ↓                                                                    │
│                                                                             │
│   CARDING ──→ DRAWING ──→ COMBING (optional) ──→ DRAWING ──→ SIMPLEX        │
│                │                                        │                    │
│         (Parallelization)                            (Roving)               │
│                                                                             │
│         ↓                                                                    │
│                                                                             │
│   SIMPLEX ──→ RING FRAME (Spinning) ──→ WINDING (Autoconer) ──→ YARN        │
│                              │                         │                     │
│                       (Twisting & Drafting)      (Package & Clearing)       │
│                                                                             │
└─────────────────────────────────────────────────────────────────────────────┘

Part 2: Blow Room Operations

2.1 Bale Opening (Bale Breaking)

Cotton arrives at the mill in highly compressed bales. The first operation is to loosen these matted fibers using rotating spiked rollers of the bale opener . The cotton tufts are opened and loosened in this process.

Key Principles of Bale Opening:

• Fibers are plucked from bales in thin, even layers

• Mechanical bale pickers pluck from multiple bales in sequence for uniformity

• The opened material passes to subsequent opening machines for further processing

2.2 Mixing and Blending

After bale opening, mixing and blending are performed .

Objectives of Mixing :

• Decrease irregularities in bales of different origins

• Enable economic processing

• Allow recycling of comber waste and other offal

• Improve final product properties

• Reduce raw material costs

2.3 Opening

Opening is the process of breaking up the fiber mass into small tufts. The main objectives are the further separation of fiber flocks and the removal of contamination particles and dust .

Key Opening Equipment:

• Porcupine beater: Revolves at high speed (approx. 1000 RPM); blades take off small tufts and loosen the mass

• Screen rolls: Air suction through screens removes dirt and trash while condensing cotton

• Opener cylinders: Cylinders with protruding fingers open the fiber limp and free trash

Critical Considerations in Opening:
Increase in opening/cleaning intensity increases waste removal but also leads to fiber damage, fiber loss, and an increase in neps level. Choice of beaters and sequence of opening depend on the nature of fiber and process requirements .

Good, gentle opening ensures:

• Maximum retention of fiber strength

• Minimization of fiber rupture

• Reduction in neps level

• Effective trash removal

• Minimal amounts of microdust and lint

2.4 Blow Room Functions

The blow room is the first stage in the spinning line where raw cotton is prepared for carding. The blow room line consists of a series of machines performing opening, cleaning, and blending operations.

Output of Blow Room:
The blow room produces either lap (for conventional carding) or directly feeds chute to the card.

Part 3: Carding

3.1 The Heart of Spinning

Carding is considered the heart of the spinning process . It is a crucial step that prepares raw fibers for further processing and spinning into yarn .

3.2 Functions of Carding

3.3 Carding Machine Operation

Basic Carding Machine Sequence:

Feed Roll → Licker-in → Cylinder → Flats → Doffer → Condenser → Coiler → Card Sliver in Can

Component Functions :

3.4 Card Output

The card produces card sliver – a continuous, untwisted rope of parallelized fibers. Card sliver is used to produce carded yarns, which are serviceable for inexpensive cotton fabrics .

Sliver from carding may be:

1. Passed directly to drawing (for carded yarns)

2. Passed to combing (for combed yarns – finer quality)

Part 4: Drawing

4.1 Purpose of Drawing

Drawing refers to the attenuation (lengthening) and straightening of slivers. The drawing process also removes fibers with hooked ends from the carded sliver .

4.2 Draw Frame Operation

Key Features of the Draw Frame:

4.3 Blending at Drawing

The drawing process is where cotton is usually blended with man-made fibers . Blending at this stage ensures:

• Uniform fiber distribution in the blend

• Consistent yarn quality

• Enhanced yarn performance

4.4 Number of Drawing Passages

4.5 Drawing Output

The sliver from drawing is more uniform, with fibers much more nearly parallel. The sliver is coiled into cans and ready for the roving frame .

Part 5: Combing

5.1 What is Combing?

Combing is an optional step in yarn production used when a smoother, finer, higher-quality yarn is required .

5.2 Functions of Combing

5.3 Comber Waste

The combing process removes up to 25% of the original card sliver as waste (noils). This means almost one-fourth of the raw cotton becomes waste . This waste is a necessary cost for producing high-quality yarns.

5.4 Combed vs. Carded Yarn

Long-staple yarns produce stronger, smoother, and more serviceable fabrics. Quality cotton goods often carry labels indicating they are made from combed yarns .

Part 6: Simplex (Roving Frame)

6.1 Purpose of Roving

Roving is an intermediate step in textile spinning that follows the drawing process and precedes the final spinning of fibers into yarn . The drawn sliver is too thick to be fed directly into the ring frame, so it must be attenuated further.

6.2 Roving Frame Operations

6.3 Purpose of Twist in Roving

The slight twist in roving serves two purposes :

1. Improves cohesion of the strand

2. Condenses the strand so it can be handled effectively in the subsequent spinning process

The roving is now ready for the ring spinning frame.

Part 7: Ring Spinning

7.1 The Spinning Process

Spinning is the final step of yarn manufacturing. The roving on bobbins is placed in the ring spinning frame, where it passes through several sets of rollers running at successively higher speeds and is finally drawn out to yarn of the desired size .

7.2 Key Components of Ring Frame

7.3 Ring Frame Operations

The Drafting Process:
The roving passes through drafting rollers where it is attenuated to the required fineness. The drafting arrangement typically consists of three or more roller sets, each running at a progressively faster speed.

The Twisting Process:
As fibers exit the drafting system, the spindle rotates, inserting twist into the yarn. Twist binds the fibers together, giving the yarn strength.

The Winding Process:
The ring and traveler mechanism winds the twisted yarn onto the bobbin.

7.4 Drafting and Twist

7.5 Types of Spinning Machines

The ring frame is more suitable for the manufacture of cotton yarns in mass production, with hundreds of spindles whirling at thousands of revolutions per minute .

Part 8: Winding (Autoconer)

8.1 Purpose of Winding

Winding is the final stage in yarn manufacturing. All yarns produced on ring frames are wound into larger, more convenient packages on winding machines .

8.2 Winding Functions

8.3 Winding Machine Types

8.4 Winding Output

Winding produces:

• Cone packages – for knitting and weaving (most common)

• Cheese packages – for dyeing

• Flanged bobbins – for specific applications

Part 9: Alternative Spinning Technologies

9.1 Rotor (Open-End) Spinning

Principle: Fibers are fed into a rapidly spinning rotor where they are collected, twisted, and withdrawn.

Applications: Denim, towels, industrial fabrics, lower-cost yarns.

9.2 Air-Jet Spinning

Principle: High-speed air jets create a vortex that wraps surface fibers around a core of parallel fibers.

Applications: Polyester/cotton blends, sheeting, uniform fabrics.

9.3 Friction Spinning

Principle: Fibers are collected between two rotating friction drums that twist the yarn.

Applications: Industrial yarns, protective fabrics, low-quality bulk yarns.

9.4 Comparison of Spinning Technologies

Part 10: Exam Preparation Summary

10.1 Key Terminology

10.2 Process Summary Table

10.3 Sample Exam Questions

Short Answer (4-6 marks):

1. Define spinning. Name three common industrial spinning techniques.

   • (Answer: Spinning is the process of drawing out fibers and twisting them into a continuous yarn . Three common techniques: ring spinning, open-end (rotor) spinning, and air-jet spinning .)

2. Why is carding considered the “heart of the spinning process”?

   • (Answer: Carding is crucial because it individualizes fibers, removes remaining impurities, straightens and aligns fibers, and forms the first continuous sliver. The quality of carding directly affects all subsequent processes and final yarn quality .)

3. Differentiate between mixing and blending in blow room operations.

   • (Answer: Mixing combines fibers of the same type from different bales/origins to improve uniformity. Blending combines fibers of different types (e.g., cotton + polyester) to achieve desired properties and cost effectiveness .)

4. What is the purpose of winding (autoconer) after ring spinning?

   • (Answer: Winding creates larger packages (cones) for easy unwinding in subsequent processes, removes yarn faults using yarn clearers, and splices ends without knots .)

5. List the six main steps in the cotton yarn manufacturing process (ring spinning).

   • (Answer: Bale opening → Blow room (mixing/cleaning) → Carding → Drawing → Simplex (roving) → Ring spinning → Winding.)

6. What is the difference between carded yarn and combed yarn?

   • (Answer: Combed yarn has short fibers removed, producing a smoother, stronger, finer, and more lustrous yarn. Carded yarn retains short fibers, is coarser, and less expensive, suitable for standard applications .)

Long Answer/Essay (10-15 marks):

7. Draw and explain the complete process flow chart of cotton yarn manufacturing using the ring spinning system.

   • (Answer: Should include all stages from bale opening to winding with descriptions of each stage’s functions. See Section 1.4 for flow chart and descriptions.)

8. Explain the functions of carding in detail. Describe the basic operation of a carding machine.

   • (Answer: Should cover individualization, cleaning, parallelization, web formation, and sliver formation. Machine operation should describe licker-in, cylinder, flats, doffer, coiler, etc. .)

9. Compare and contrast ring spinning with rotor (open-end) spinning in terms of process, yarn properties, and applications.

   • (Answer: See Section 9.4 for comparison table. Ring: high quality, versatile, slower, uses roving. Rotor: faster, direct from sliver, lower quality, suitable for denim/towels.)

10. What is combing and why is it performed? Describe the combing process and its effect on yarn and fabric quality.

    • (Answer: Combing removes short fibers (noils), neps, and impurities. It produces finer, smoother, stronger yarns with higher luster. Combed yarns produce premium fabrics .)

11. Trace the changes in fiber form from bale to finished yarn, naming each intermediate stage (e.g., tufts → lap → sliver → roving → yarn).

    • (Answer: Bale → opened tufts → lap or tufts → card sliver → drawn sliver → roving → yarn on bobbin → yarn on cone.)

12. Explain the purpose of the drawing process. Why is doubling important at this stage?

    • (Answer: Drawing attenuates and straightens slivers. Doubling (combining multiple slivers) reduces irregularities by averaging thickness variations across slivers, improving yarn evenness .)

13. Describe the operation of the ring spinning frame including drafting, twisting, and winding functions.

    • (Answer: Drafting rollers attenuate roving to required fineness; spindle rotation inserts twist; ring and traveler wind twisted yarn onto bobbin .)

End of Notes – These notes provide a comprehensive foundation for understanding yarn manufacturing, focusing on the ring spinning process as the most common spinning method worldwide . Success in TE-2111 requires understanding both the sequence of processes and the principles behind each stage: fiber individualization (carding), parallelization (drawing), optional quality improvement (combing), preparation (roving), final formation (ring spinning), and packaging (winding). Review flow charts, machine diagrams, and the specific functions of each process for exam preparation.

TE-2112: INTRODUCTION TO FABRIC MANUFACTURING – Detailed Study Notes

Module 1: Introduction to Fabric Manufacturing

1.1 Definition and Scope

1.2 Classification of Fabrics

Module 2: Woven Fabric Manufacturing – Overview

2.1 Flow Chart of Woven Fabric Manufacturing

Yarn (from spinning)
        ↓
   WINDING (cone to cone/package)
        ↓
   WARPING (parallel winding of warp yarns on beam)
        ↓
   SIZING (applying size to warp yarns for strength)
        ↓
   DRAWING-IN / TYING-IN (thread warp yarns through heald eyes and reed)
        ↓
   WEAVING (interlacing warp and weft on loom)
        ↓
   GREY FABRIC (unfinished)
        ↓
   INSPECTION / QUALITY CONTROL
        ↓
   (to chemical processing – desizing, scouring, bleaching, dyeing, printing, finishing)

2.2 Basic Terminology of Woven Fabrics

Module 3: Preparation for Weaving

3.1 Winding

Types of winding:

Key components of winding machine:

• Yarn clearer (optical or capacitive) – detects and removes thick/thin places

• Splicer (air or mechanical) – joins broken ends without knot (smaller than knot)

• Automatic doffing – changes full packages automatically

Winding defects: Ribboning (yarn layers aligned), package hardness variation, sloughing (layers slipping off)

3.2 Warping

Types of warping:

Creel types:

• Magazine creel – Yarn packages in rows and columns (V-shape)

• Truck creel – Movable trucks (easy loading/unloading)

Warping parameters: Creel capacity (number of cones), warping speed (300-1200 m/min), beam size (flange diameter)

Warping defects: End breakage, uneven tension, missing ends, crossed ends

3.3 Sizing

Why sizing is needed:

• Warp yarns undergo high abrasion during weaving (from heald eyes, reed, friction with other warp/weft)

• Unsized yarns (especially cotton) have protruding fibers that cause entanglement (sizing lays down fibers)

Size ingredients:

Sizing machine (slasher) components:

Size pick-up: Percentage of size add-on (usually 6-12% on weight of yarn for cotton)

Desizing (after weaving): Removal of size from fabric (enzymatic for starch, hot water for PVA)

3.4 Drawing-in and Tying-in

Drawing-in steps:

1. Heald frames arranged according to weave plan

2. Ends drawn through heald eye (manually or semi-automatic)

3. Ends drawn through reed dents (reed count – number of dents per inch)

Equipment:

• Manual drawing-in – Hook, slow, labor-intensive

• Semi-automatic – Machine assists drawing-in

• Automatic drawing-in – Fully automatic (high cost, fast)

Module 4: Weaving Mechanisms (Primary)

4.1 Shedding

Shedding mechanisms:

Tappet shedding:

• Cams (tappets) rotate, push levers to lift heald frames

• Positive tappets (both raising and lowering controlled) vs. negative tappets (springs return)

• Suitable for plain, twill, satin weaves (up to 8 shafts)

Dobby shedding:

• Mechanism selects which heald frames to lift (pattern on chain of bars or electronic)

• Double-lift dobby (one frame lifts while another lowers) – higher speed

Jacquard shedding:

• Each warp end individually controlled by hook and needle

• Pattern stored on punched cards (mechanical) or computer file (electronic)

• Creates intricate patterns (brocade, damask, carpet, upholstery)

4.2 Picking (Weft Insertion)

Types of picking systems:

Comparison of weft insertion systems:

4.3 Beat-up

Beat-up parameters:

• Beating force – Determines fabric density (ends/picks per inch)

• Reed number – Dents per inch (e.g., 72 reed means 72 dents per 2 inches or 36 per inch in some systems)

4.4 Take-up and Let-off

Take-up types:

• Positive take-up – Precision gearing; picks per inch fixed by gear ratio (most common)

• Negative take-up – Friction driven; less accurate

Let-off types:

• Negative let-off – Warp released by rotation of beam due to tension (dead weight or spring)

• Positive let-off – Motor-driven warp release controlled by tension sensor (modern looms, constant tension)

Module 5: Weave (Basic Weaves)

5.1 Weave Notation

Weave representation: Raising heald frame → warp up → weft under; warp float on top

5.2 Basic Weaves

A. Plain Weave (1/1)

B. Twill Weave

Notation: 2/1, 3/1, 2/2, 4/4, etc. (first number = warp float count, second = weft float count; sum = repeat size)

Types of twill:

• Warp-faced twill (3/1) – Warp floats dominant (diagonal lines of warp)

• Weft-faced twill (1/3) – Weft floats dominant

• Equal twill (2/2) – Equal warp and weft floats (denim, gabardine)

• Z-twill – Diagonal runs from lower left to upper right (left-hand twill)

• S-twill – Diagonal runs from lower right to upper left (right-hand twill)

• Herringbone twill – Diagonal reverses direction periodically

Examples: Denim (jeans), gabardine, drill, khaki, tweed

C. Satin and Sateen Weaves

Characteristics: Very smooth, lustrous, drapes well, poor abrasion resistance (long floats snag), less durable

Examples: Satin fabric (bridal, lingerie), sateen bedsheets, charmeuse

5.3 Woven Fabric Density and Calculation