Electric resistance spot welding, commonly known as spot welding, is a widely used technique for joining thin sheets of metal. It belongs to the family of resistance welding processes and is especially popular in industries like automotive manufacturing, where quick, strong, and precise welds are essential.

How Does Spot Welding Work?

Spot welding uses the principle of electrical resistance to generate heat and join metals. The process begins by placing two or more metal sheets between two copper alloy electrodes. When a strong electric current is passed through these electrodes and the sheets, the resistance at the contact points causes localized heating. This heat melts the metal in a small, precise area, forming what is called a weld nugget.

At the same time, pressure is applied through the electrodes, pressing the sheets together to ensure a solid bond. Once the current is stopped, the molten metal quickly cools and solidifies, creating a durable weld that holds the sheets firmly together.

Advantages of Spot Welding

• Speed: Spot welding is extremely fast, often completing welds in just fractions of a second.
• No filler material: The process melts the base metals directly, eliminating the need for additional welding materials.
• Precision: The welds are localized to small areas, minimizing distortion or damage to the rest of the metal sheets.
• Cost-effective: It is an efficient method, particularly suited for mass production environments.

Common Applications

Electric resistance spot welding is predominantly used in industries where joining thin sheets of metal quickly and reliably is crucial. The automotive industry relies heavily on spot welding to assemble car bodies, doors, and other components. It is also found in the manufacture of appliances, electronics, and metal furniture.