Arc Welding: Working Principle
Definition of Welding
Welding is a metallurgical joining process in which two metal parts are fused together by localized coalescence, achieved through:
- Heating to a suitable temperature
- With or without pressure
- With or without filler material
Working Principle of Arc Welding
Arc welding works on the principle of electric arc generation between an electrode and the workpiece.
Steps:
- Circuit Setup:
- The workpiece is connected to one terminal (usually negative).
- The electrode is connected to the other terminal (usually positive).
- Arc Generation:
- When the electrode briefly touches the workpiece and then is slightly pulled back, an electric arc forms due to ionization of air between the gap.
- The arc produces intense heat (≈5000°C to 6000°C).
- Melting Process:
- This heat melts the base metal (workpiece) and electrode tip.
- The molten electrode metal acts as filler and is transferred into the weld pool.
- Shielding Action:
- The flux coating on the electrode burns and forms a protective gas shield, preventing oxidation from atmospheric gases like oxygen and nitrogen.
- Solidification:
- Once the arc is removed, the molten metal cools and solidifies, forming a strong metallurgical joint.
Components:
- Power Supply: AC or DC
- Electrode: Consumable (with flux coating)
- Workpiece: Metal parts to be joined
- Arc: Heat source
- Shielding Gas: Produced from flux to protect weld pool
Advantages of Arc Welding:
- Simple and low-cost equipment
- Portable and flexible process
- Suitable for most ferrous and non-ferrous metals
Applications:
- Construction (steel structures, bridges)
- Shipbuilding
- Pipeline welding
- Automobile and railway industries
- Repair and maintenance work