What is arc welding, and how does it work?

Short Answer:

Arc welding is a welding method that uses an electric arc to produce intense heat for melting and joining metals. It is one of the most commonly used welding techniques in industries and workshops. A welding electrode creates an arc between itself and the metal surface, which generates heat above 3,000°C, enough to melt the metal edges and fuse them together.

Arc welding works by connecting the workpiece and electrode to a power source. When the electrode touches and then slightly separates from the metal surface, it creates an electric arc. This arc melts both the base metal and the filler material, forming a strong welded joint once cooled.

Detailed Explanation:

Arc Welding and How It Works

Arc welding is one of the most important and widely used metal joining processes in mechanical engineering. It is used to permanently join two or more metal parts by using an electric arc to generate intense heat. This heat is enough to melt the base metals and sometimes a filler electrode, which combines with the molten metal to create a solid, durable joint after cooling.

Arc welding is preferred for its simplicity, speed, low cost, and strong joints. It is commonly used in industries like construction, shipbuilding, automotive, pipelines, fabrication, and repair works.

How Arc Welding Works

The working principle of arc welding is based on electric arc generation between the metal and the electrode. Here’s how it works step-by-step in simple words:

  1. Power Supply Connection

The welding machine is connected to a power source (AC or DC). One terminal is connected to the electrode holder, and the other is connected to the metal workpiece.

  1. Striking the Arc

The welder briefly touches the electrode to the metal and then pulls it back slightly. This action creates a short circuit and generates a spark, which produces an electric arc between the electrode and the workpiece.

  1. Heat Generation

The arc produces very high temperatures (around 3,000–6,000°C), which melts the base metal and the tip of the electrode. This forms a molten weld pool at the joint.

  1. Filler Material Deposition

If a consumable electrode is used, it melts and adds filler material to the molten metal. If a non-consumable electrode is used (like in TIG welding), a separate filler rod is added manually.

  1. Shielding of the Weld

To protect the molten metal from reacting with air (oxygen and nitrogen), a shielding mechanism is used:

  • Flux-coated electrodes produce a gas shield when heated (in stick welding).
  • External shielding gas like argon or CO₂ is used in MIG and TIG welding.
  1. Solidification of the Joint

Once the arc is stopped, the molten pool cools and solidifies, creating a strong welded joint. A slag layer may form on top, which is removed after cooling.

Types of Arc Welding

  1. Shielded Metal Arc Welding (SMAW) – Also known as stick welding, uses a flux-coated electrode. Most common and low-cost.
  2. Gas Metal Arc Welding (GMAW or MIG) – Uses a wire electrode and shielding gas. Fast and clean welding.
  3. Gas Tungsten Arc Welding (GTAW or TIG) – Uses a tungsten electrode and inert gas. High precision and best finish.
  4. Submerged Arc Welding (SAW) – Arc is beneath a blanket of powdered flux. Used in heavy-duty industrial applications.

Advantages of Arc Welding

  • Strong and durable joints
  • Low cost and simple equipment
  • Works with thick and thin metals
  • Can be used indoors and outdoors
  • Suitable for a wide range of materials (steel, iron, alloys)

Limitations

  • Requires skilled operator
  • Produces heat, sparks, and fumes
  • Slower compared to automated welding
  • Needs safety gear like helmet, gloves, and apron
Conclusion

Arc welding is a popular and effective metal joining process that uses electric arc heat to melt and join metals permanently. It works by creating an arc between the electrode and the workpiece, which melts the metal to form a strong bond. Arc welding is used in many industries due to its flexibility, strength, and low cost. Understanding how it works helps in selecting the right type of arc welding for different applications.