Module 5-Welding

Vellore Institute of Technology

  • Name: Vellore Institute of Technology

  • Status: Deemed to be University under section 3 of UGC Act, 1956

  • Course: Manufacturing Processes (BMHA202)

  • Module: 5: Welding/Joining Process

  • Instructor: Dr. Manoj Kumar R

  • Contact: r.manojkumar@vit.ac.in

  • Mobile: 9121989787

Module Overview

  • Duration: 8 hours

  • Main Topics:

    • Classification of welding processes

    • Fusion welding: Oxy-fuel gas welding, Arc welding, Beam welding

    • Solid State welding

    • Brazing, Soldering, and adhesive bonding

Classification of Welding Processes

Fusion Welding

  • Oxy-fuel gas welding: Types of flames and uses

  • Arc welding:

    • Power sources

    • Methods of arc initiation and maintenance

    • Metal transfer modes

    • Types:

      • Non-consumable electrodes: GTAW, PAW, AHW

      • Consumable electrodes: SMAW, SAW, GMAW, FCAW, EGW, ESW

  • Beam Welding: EBW and LBW.

Solid State Welding

  • Types include:

    • Cold welding

    • Roll bonding

    • Ultrasonic welding

    • Friction welding and Friction stir welding

    • Resistance welding

    • Explosion welding

    • Diffusion welding

    • Thermit welding

Brazing, Soldering, and Adhesive Bonding

  • Principles: Joining methods, advantages, limitations, and applications.

Casting and Forming Processes

  • Definition: Zero processes involving shifting of metal using heat/pressure.

  • Main Manufacturing Processes:

    • Casting, Forming, Machining, Welding.

  • Classification: Positive, negative, or zero processes.

Selection of Joining Process

  • Types of Joining Methods:

    • Mechanical joining (nuts/bolts, clamps, rivets)

    • Adhesive joining (e.g., epoxy)

    • Welding (welding, brazing, soldering)

  • Considerations for Selecting Joints:

    • Type of joint (temporary/permanent)

    • Similarity of materials

    • Physical/chemical/metallurgical properties

    • Service requirements (temperature, corrosion, reliability)

    • Loading conditions (static/dynamic)

    • Cost-effectiveness.

Welding Process Overview

  • Definition: Joining of similar/dissimilar metals via heat with/without pressure, filler, or flux.

  • Characteristics of Welding:

    • Creation of molten weld area, filled with or without filler material.

  • Types of Welding Processes:

    • Resistance welding: Automotive applications

    • Thermotic welding: Rail joints

    • Gas welding: Metal joining sensitive to gases.

Advantages Disadvantages of Welding

Advantages:

  • Joins diverse materials

  • Strong and durable joints

  • Design flexibility

  • Cost-efficient and portable equipment

Disadvantages:

  • Residual stresses and distortions

  • Metallurgical changes in structure

  • Requirement of skilled labor

Applications of Welding

  • Industries: Essential across construction, automotive, aerospace, and manufacturing.

  • Uses: Structural members, pressure vessels, pipelines, and reinforcement.

Fundamental Concepts in Welding

Welding Types and Mechanisms

  • Types: Autogenous, Homogeneous, Heterogeneous.

    • Autogenous: Base metal corresponds only to itself without filler

    • Homogeneous: Filler matches base metal.

    • Heterogeneous: Different filler for welded joints.

Energy Source Classification

  • Energy forms: Based on chemical, mechanical, electrical, and radiation sources for providing necessary heat to achieve fusion.

Conclusion

  • Understanding welding processes is crucial for engineering applications. Factors like power density, heat transfer efficiency, and joint design significantly influence and dictate the choice of the welding technique.