Spot welding uses resistive heat to form weld nuggets at sheet metal lap joints, requiring no filler wire or shielding gas. It is highly suitable for rapid lapping of thin sheets. Electrode pressure ensures a strong weld, with deformation concentrated around the weld nugget. This makes it the most economical joining method for thin-walled enclosures, electrical cabinet interior panels, and ventilation duct components.
Process Overview
During spot welding, two electrodes clamp the sheet metal from both sides and apply high current. The resistive heat at the interface locally melts the metal, which solidifies under pressure after current cutoff to form the weld nugget. We are equipped with medium-frequency spot welding machines and electrode grinders. Welding time, current, and pressure are digitally settable, ensuring consistent strength for batch weld nuggets. Regular electrode dressing maintains uniform contact surface condition.
Capability Parameters
- Applicable Sheet Thickness: 0.5 – 3.0 mm (single layer)
- Weld Strength: Suitable for general structural joining
- Characteristics: High speed, no auxiliary materials required, suitable for automation
- Weldable Combinations: Steel + Steel, Steel + Galvanized Steel, Aluminum + Aluminum (process review required)
- Weld Spacing: Typically 8 – 12 times the sheet thickness
Technical Points
Spot welding quality depends on the matching of current, time, and pressure, as well as electrode condition: Excessive current causes spatter and excessive indentation, while insufficient current results in incomplete fusion. We establish parameter libraries based on material combinations and perform periodic sampling tests for weld nugget strength (peel tests). When spot welding galvanized steel, we use steep current pulses to first melt the coating before forming the weld nugget, preventing cold shuts. Aluminum spot welding requires higher current due to high conductivity; we schedule a specialized process review before production.
Typical Applications
Lapping of thin-walled enclosures, fixing of electrical cabinet interior panels, and lock-forming connections for ventilation ducts. When the joint is primarily lapped, speed and low cost are prioritized, and there are no aesthetic requirements for the weld seam, spot welding is the preferred choice. For components requiring weld seam sealing or aesthetics, we recommend TIG or MAG welding.
FAQ
How strong are spot welds?
Single-weld strength correlates with base material thickness; multi-point arrangements satisfy general structural joining requirements. We design the number and layout of weld nuggets based on load conditions and perform peel or shear sampling tests on critical components.
Will spot welding leave marks?
Electrodes leave circular indentations on the sheet surface, which is controllable. For visible surfaces, we use large flat electrodes or adjust parameters to reduce indentation; for surfaces with extremely high aesthetic requirements, we recommend traceless solutions such as clinching or threaded fastening.
Can you weld aluminum?
Yes, but aluminum has high electrical and thermal conductivity, requiring medium-frequency high current and specialized electrode matching. We arrange a process review to confirm parameters before batch production.
Have a thin sheet lapping requirement? Please provide the material combination and weld specifications; we will evaluate spot welding applicability and provide a quotation.