Seam Welding

Seam welding forms a continuous leak-tight joint by rolling electrode wheels along overlapped sheet metal, delivering high-speed, repeatable welds on long seams.

Overview

Seam welding (resistance seam welding) joins overlapped sheet metal by passing current through rotating copper wheel electrodes while applying force. The wheels create a series of overlapping nuggets that behave like a continuous weld, making it a go-to process for long straight or gently curved seams.

Choose seam welding for high-rate production of containers, ducts, and housings where consistent strength and leak tightness matter. It runs fast, automates well, and produces uniform seams with minimal filler and low distortion compared to many arc processes.

Tradeoffs: it’s mainly a sheet-metal overlap process, not a butt-joint method. Access is required for the wheel electrodes on both sides, and part geometry must allow the wheels to track the seam. Electrode wear, surface coatings, and stack-up/fit-up variation drive weld consistency, and thick sections quickly push power and force requirements.

Common Materials

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

Tolerances

±0.010 in

Applications

  • Fuel tanks and fluid reservoirs
  • HVAC duct longitudinal seams
  • Appliance cabinet seams
  • Automotive mufflers and exhaust shells
  • Metal drums and pails
  • Hermetic enclosures and battery cases

When to Choose Seam Welding

Seam welding fits parts made from overlapped sheet metal with long seams where you need repeatable strength and good leak tightness at production volumes. It works best when both sides of the joint are accessible to wheel electrodes and the seam path is straight or smoothly contoured. Expect the best results when lap fit-up and sheet thickness are consistent across the run.

vs Spot Welding

Choose seam welding when you need a continuous or near-continuous joint for sealing, stiffness, or fatigue performance along a long seam. Spot welding is better suited to discrete attachment points; seam welding reduces the need for many spots and improves leak tightness and load distribution.

vs MIG Welding (GMAW)

Choose seam welding for high-volume sheet seams where speed, repeatability, and low heat input are priorities. MIG is more tolerant of complex 3D geometry and one-side access, but it adds filler, more thermal distortion, and more post-weld cleanup in many sheet applications.

vs TIG Welding (GTAW)

Choose seam welding when you need fast, automated joining on long seams with minimal cosmetic finishing and consistent output. TIG can produce excellent appearance and precision on short runs and intricate joints, but it is slower and more operator-dependent.

vs Laser Welding

Choose seam welding when overlap joints and robust production throughput matter more than ultra-narrow heat-affected zones or single-sided access. Laser welding excels on precise fit-up with tight gaps and can handle butt joints and complex paths, but equipment cost and process window sensitivity are higher.

Design Considerations

  • Design an overlap (lap joint) with consistent flange width so the wheel electrodes have stable tracking and contact area
  • Hold sheet thickness and stack-up variation tight at the seam; inconsistent fit-up is a primary cause of burn-through and weak nuggets
  • Provide clear, straight or smoothly radiused seam paths; avoid tight corners that the electrode wheels can’t follow
  • Keep coatings and surface condition consistent (oil, paint, heavy galvanize) and call out any plating after welding if possible
  • Add fixturing features or tabs to control part alignment and clamp force along the entire seam length
  • Specify whether the requirement is leak tightness, strength, or cosmetic appearance; this drives weld schedule, overlap, and inspection method