Spot welding
What thickness can you weld with spot welding?
Quick answer
Spot welding is a sheet process: most units are happy to about 2–3 mm total combined stack thickness.
Numbers by machine/output class
| Machine class | Practical thickness |
|---|---|
| 120 A | up to ~3 mm (1.5–2 mm sweet spot) |
| 160–180 A | up to ~5–6 mm single pass |
| 200–250 A | 8–10 mm, multi-pass beyond |
Beyond single-pass
Thickness limits assume full-penetation single-pass welds. Bevelling the joint, multi-pass stacking and preheat on thick sections extend any process dramatically — that's how structural welders join 50 mm plate with the same physics. Match the machine class to the thickness you actually weld 90% of the time.