Seam Welding

Seam welding joins overlapping sheet metal with a continuous, leak-tight weld using rotating electrodes, delivering fast, repeatable joints on long straight or curved seams.

Overview

Seam welding is a resistance welding process that makes a continuous weld along an overlap joint using rotating wheel electrodes. It produces a near-continuous “stitch” or fully continuous seam with good repeatability, minimal filler, and low distortion versus many fusion welds. It’s commonly used on thin-gauge sheet where consistent contact and clamping can be maintained.

Choose seam welding for long, accessible seams that need strength and/or leak tightness at production volumes—tanks, housings, ducts, and formed sheet assemblies. It excels on straight seams and simple radii where the wheels can track the joint.

Tradeoffs: joint fit-up and surface condition matter; gaps, coatings, and inconsistent flange width cause skips and expulsion. Material thickness is limited by available weld current and electrode force, and the process is geometry-limited to where wheels can physically reach and roll. Expect visible wheel marks and plan for fixturing and part support to control alignment.

Common Materials

  • Low carbon steel
  • Stainless steel 304
  • Stainless steel 316
  • Galvanized steel
  • Aluminum 5052

Tolerances

±0.010"

Applications

  • Fuel tank seams
  • HVAC duct longitudinal seams
  • Stainless enclosures and instrument housings
  • Drum and can body seams
  • Automotive muffler shells
  • Battery can seams

When to Choose Seam Welding

Pick seam welding when you have overlapping sheet-metal flanges with a long, continuous seam that must be consistent and often leak resistant. It fits best for thin to moderate gauge material with predictable joint geometry and good fixturing, especially in medium to high volumes. It also works well when you want a low-heat process with minimal distortion and no filler handling.

vs Spot Welding

Choose seam welding when you need a continuous or near-continuous joint for leak tightness, EMI shielding continuity, or higher seam strength along the full length. Spot welding fits intermittent attachment points; seam welding replaces a line of spots with a controlled, repeatable weld pattern along the seam.

vs MIG Welding (GMAW)

Choose seam welding when you want a fast, highly repeatable overlap seam on thin sheet with low distortion and no filler wire. MIG is more tolerant of complex paths and access constraints, but introduces more heat, spatter/cleanup, and greater risk of warping on thin gauge.

vs TIG Welding (GTAW)

Choose seam welding when aesthetics and full manual control are less important than speed and production consistency on long seams. TIG can produce excellent cosmetic fusion welds and handle non-overlap joints, but it’s slower and typically adds more labor cost on long seams.

vs Laser Welding

Choose seam welding when you have an overlap joint and want robust production joining without tight joint-gap control or high equipment cost. Laser welding can be faster and cleaner with narrow heat input, but it demands tighter fit-up and often higher capital and process development.

vs Riveting / Self-Piercing Rivets

Choose seam welding when you need a sealed joint, lower part count, and no fastener protrusions. Riveting is useful for dissimilar materials or coated stacks where welding is problematic, but it adds hardware, can leak without sealant, and usually increases assembly thickness and weight.

Design Considerations

  • Use a consistent overlap flange width to keep the wheel electrodes centered and maintain stable current density
  • Control joint gaps with formed flanges, tabs, and fixturing; even small gaps can create skips or expulsion
  • Specify whether the seam must be fully continuous or if a stitch/seal pattern is acceptable for cost and heat control
  • Call out coating/finish constraints (galvanized, paint, plating) early; coatings affect contact resistance and weld parameters
  • Provide straight or constant-radius seam paths with adequate wheel clearance; avoid tight corners where wheels can’t track
  • Identify leak-test requirements and allowed wheel-mark cosmetics on the drawing to prevent rework and mismatched expectations