Difference Between Spot and Seam Welding

Published: 2 Dec 2025

In this article, we will discuss the difference between spot and seam welding, how they work, their advantages, disadvantages, applications, and equipment. Both methods are widely used in manufacturing, especially in the automotive, aerospace, and sheet-metal industries. Understanding these two processes will help you choose the right welding technique for your project.

Dimension	Spot Welding	Seam Welding
Working Principle	Uses resistance heat from electric current to melt metal at a single point.	Uses resistance heat from electric current to create overlapping or continuous welds along the seam.
Electrodes	Two stationary copper electrodes press at one point at a time	Rotating wheel electrodes roll along the joint to form a continuous seam.
Weld Formation	Forms individual circular welds (nuggets) that are spaced apart.	Forms continuous or overlapping welds, making airtight and watertight joints.
Movement During Welding	Electrodes are fixed; the workpiece or robot moves to each welding location.	Electrode wheels move the workpiece forward or rotate continuously, creating long weld seams automatically.
Material Thickness	Works best on thin to medium sheet metals.	Suitable for thin sheets needing long continuous seams; thicker sheets can be welded with precise control.
Equipment Types	Rocker-arm machines, press-type machines, and portable guns.	Press-type machines with wheel electrodes; fixtures required to prevent warping; water cooling is often used.
Advantages	Low cost, simple setup, fast for individual welds, easy to automate, portable solutions are available.	Produces continuous, fluid-tight welds; strong and durable; efficient for long seams; suitable for automation.
Disadvantages	Limited to thin metals, may cause distortion, not fluid-tight, weak welds if parameters are incorrect.	Higher equipment cost, slower for short welds, requires strong fixtures and precise alignment, limited to straight or gently curved seams
Applications	Automotive body panels, electronics, battery packs, appliances, light sheet-metal parts.	Fuel tanks, radiators, mufflers, sealed containers, pipes, tubes, and any application requiring airtight or watertight seams.
Production Efficiency	Fast for individual points; ideal for high-volume production lines with robots.	Efficient for continuous welds; reduces manual handling; requires controlled speed and current for consistency.
Cost Comparison	Machines are less expensive, low consumable cost, economical for mass production of non-critical welds.	Higher initial investment, more expensive consumables, but the welds are stronger and longer-lasting.
Quality Testing	Tested using destructive tests like peel or tensile tests.	Tested using destructive tests and often leak-proof inspections for sealed products.

Conclusion

In conclusion, in this article we covered the difference between spot and seam welding in detail. These two methods are important in metalworking and help create strong joints in many industries. Hope you find this helpful