Britannica Sources used in this answer

How are spot welding and seam welding used to join sheet metal?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Welder in a blue uniform and protective helmet using shielded metal arc welding to join metal pieces, with bright sparks and smoke visible at the welding point. — welding Shielded metal arc welding.

Spot welding and seam welding are resistance welding processes used to join sheet metal by generating heat through the electrical resistance of the joint. Both methods utilize a low-voltage, high-current power source and apply force via electrodes on either side of the material.1

Spot Welding: This process creates welds at regular, isolated intervals on overlapping sheet metal. The strength of the resulting joint is determined by the specific number and size of these individual welds.1
Seam Welding: This is a continuous process used when spot welding is insufficient, such as in the fabrication of containers or specialized structures. During this process, electric current is pulsed into the joint in succession to form a series of overlapping spots, effectively creating a continuous, sealed seam.1

Both techniques are highly efficient, capable of supporting high production rates with integrated quality control systems to ensure structural integrity.1