Resistance Welding

Resistance welding joins sheet and wire by clamping parts and passing current to generate heat at the interface, enabling fast, repeatable production welds.

Overview

Resistance welding (RSW) forms a weld by squeezing parts between electrodes and driving electrical current through the joint. The electrical resistance at the faying surfaces generates localized heat, creating a weld nugget with little to no filler metal. Common sub-processes include spot welding for discrete joints and seam welding for continuous, leak-tight seams.

Choose resistance welding for high-volume assemblies of thin to moderate-gauge metals where cycle time, repeatability, and automation matter. It works best with lap joints, good electrode access from both sides, and consistent material/coating conditions.

Tradeoffs: joints are geometry-limited (mostly lap joints), cosmetic electrode marks are typical, and quality depends heavily on surface condition, fit-up, and parameter control. Equipment and tooling can be capital-intensive, and thick sections or highly conductive materials can require high current and robust fixturing.

Common Materials

  • Low carbon steel
  • Stainless steel 304
  • Galvanized steel
  • Aluminum 5052
  • Nickel alloys

Tolerances

±0.010"

Applications

  • Automotive body-in-white spot welds
  • Appliance sheet metal housings
  • Battery tab-to-busbar welds
  • Wire mesh and grating fabrication
  • Fuel tank and radiator seam welds
  • Metal office furniture frames

When to Choose Resistance Welding

Resistance welding fits production work where you need fast, consistent joints in sheet or formed components. It’s strongest when the design allows lap joints with electrode access from both sides and the build can be fixtured for repeatable fit-up. It scales well from moderate to very high volumes because cycle time is short and automation is straightforward.

vs MIG (GMAW)

Choose resistance welding when the joint can be made as a lap weld and you want seconds-level cycle time with minimal consumables and post-weld cleanup. It’s a strong fit for repetitive sheet metal assemblies where fixture-driven consistency beats operator-dependent bead quality.

vs TIG (GTAW)

Choose resistance welding when appearance of a continuous bead isn’t required and you need high throughput on thin materials. It avoids filler and shielding gas, and it’s easier to automate for large counts of identical welds.

vs Stick (SMAW)

Choose resistance welding for indoor, production sheet metal work where you can clamp the parts and control the process tightly. It’s not suited to field repair, heavy sections, or situations where you can only access one side of the joint.

vs Laser Welding

Choose resistance welding when lap joints and electrode access are available and you want lower part-specific programming complexity and very high repeatability at scale. It tolerates minor surface variation better than many precision beam processes, but needs physical access for electrodes.

vs Brazing & Soldering

Choose resistance welding when you need a true fusion joint with higher strength and temperature capability, and you want to avoid flux, filler management, and cleaning. It’s also better when you need short cycle time and straightforward in-line automation.

Design Considerations

  • Design joints as lap joints with clear, flat electrode landing pads on both sides
  • Control stack-up thickness and keep it consistent across the weld pattern to reduce parameter spread
  • Specify coatings and surface condition (oil, plating, galvanize) because they drive current/force requirements and electrode life
  • Keep flanges wide enough for electrode access and spacing; call out minimum edge distance and pitch targets on the print
  • Provide a weld schedule target (nugget size, number of spots, locations) and quality criteria so the shop can quote and validate consistently
  • Plan for electrode witness marks or define cosmetic zones where marking is acceptable