Seam Welding

Seam welding creates continuous, often leak-tight welds along sheet metal joints using rotating electrodes, ideal for long straight seams at production volumes.

Overview

Seam welding is a resistance welding process that uses rotating wheel electrodes to create a continuous or overlapping series of weld nuggets along a sheet metal joint. It excels at producing consistent, leak-tight seams on thin sheet, often in lap joints or cylindrical forms like tubes and tanks. Heat is generated by electrical resistance at the faying surfaces, while pressure from the wheels forges the weld.

Use seam welding when you need long, straight or smoothly curved welds with uniform quality, especially in sealed assemblies and high-volume production. It delivers fast cycle times and repeatable weld spacing but requires good joint fit-up, consistent material thickness, and access for the wheels. Distortion and burn-through can be issues on very thin or poorly clamped material, and setup is less flexible than manual processes for complex geometries or short runs. Expect strong, clean seams with minimal post-processing when the part is designed around the process.

Common Materials

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

Tolerances

±0.010" to ±0.020" on weld location and seam straightness; weld size per AWS resistance welding standards

Applications

  • Fuel and hydraulic tanks
  • Automotive mufflers and exhaust shells
  • HVAC ducts and plenums
  • Battery and electronic enclosures
  • Metal containers requiring leak-tight seams
  • Radiator and heat-exchanger shells

When to Choose Seam Welding

Choose seam welding for long, continuous or closely spaced welds on thin sheet where consistency and potential leak-tightness matter. It suits medium to high production volumes with repeatable joint geometry and good access for straight or smoothly curved seams.

vs Spot Welding

Choose seam welding when you need a continuous or near-continuous joint, especially for liquid or gas containment and structural seams along long flanges. It provides more uniform load distribution and better sealing than discrete spots, at the cost of more specialized fixturing and setup.

vs MIG Welding

Choose seam welding for thin-gauge sheet where you want fast, automated, low-spatter welds and minimal filler metal. It is typically faster and more consistent for long, straight seams than manual MIG, assuming the joint is accessible to wheels and the production volume justifies tooling.

vs TIG Welding

Choose seam welding instead of TIG when you need production-rate welding on simple seams and can sacrifice some cosmetic finish for speed and automation. Seam welding avoids filler wire handling, reduces operator skill dependency, and delivers highly repeatable welds on compatible sheet thicknesses.

vs Laser Welding

Choose seam welding when you’re working with common steel or aluminum sheet thicknesses and want lower equipment cost and simpler setup than laser. It tolerates slightly less precise fit-up and joint positioning, though it cannot match laser’s minimal heat input or ability to access very tight joint geometries.

vs Manual Arc Welding (Stick)

Choose seam welding over stick welding for any repetitive sheet metal seams where quality and speed matter. Seam welding delivers much higher throughput, less distortion, and more consistent weld quality, provided the part geometry suits automated wheel access.

Design Considerations

  • Keep total sheet stack thickness within the welder’s qualified range and specify material thicknesses clearly on the print
  • Provide sufficient overlap width (typically 3–4x sheet thickness) for lap seams so electrodes can form a robust weld without edge burn-through
  • Maintain straight, consistent flanges and avoid abrupt thickness transitions along the seam path to stabilize weld heat and pressure
  • Ensure clear access and straight-line travel for the weld wheels; avoid obstructions, tight corners, or features too close to the seam path
  • Call out whether the seam must be leak-tight and specify any test methods (e.g., pressure or dye penetrant) so parameters can be tuned accordingly
  • Keep coatings, platings, and sealants away from the weld area or specify weld-through materials that are compatible with resistance welding