Spot Welding
Resistance spot welding joins overlapping sheet metal by passing a high current through two electrodes that squeeze the sheets, fusing them at small spots in a fraction of a second. It is fast, clean and needs no filler, ideal for sheet metal assemblies.
What it is
The resistance of the metal to the current generates heat at the interface, forming a weld nugget while the electrodes apply pressure. Parameters of current, time and force are set for the material and thickness.
Spot welding is used extensively in automotive bodies, enclosures and appliances, and can be automated easily.
Typical applications
- Enclosures and cabinets
- Automotive and two-wheeler sheet parts
- Brackets and reinforcements
- Appliance and HVAC parts
- Wire mesh and guards
Suitable materials
- CRCA mild steel
- Galvanised steel
- Stainless steel
- Aluminium (special equipment)
Points to consider
- Both sides of the joint must be reachable by the electrodes.
- Galvanised and aluminium sheets need adjusted parameters and electrode care.
- Spot spacing and edge distance affect joint strength.
- Spot welds leave small marks; plan cosmetic faces accordingly.
Frequently asked questions
What thickness can be spot welded?
Typically sheets around 0.5–3 mm each; thicker needs larger machines.
Does spot welding need filler wire?
No. The overlapping sheets fuse together under the welding current and electrode pressure, so no filler wire or rod is used.
Can galvanised steel be spot welded?
Yes, with adjusted current and electrode maintenance because of the zinc coating.