title = "Resistance Spot Welding for Sheet Metal"

content = """
Resistance spot welding (RSW) joins two or more overlapping sheet metal layers by passing a high electrical current through the joint while applying clamping force between copper alloy electrodes. At Ridgecrest Metalworks, spot welding is used extensively for sheet steel assemblies, enclosures, brackets, and thin-wall fabrications where lap joints are acceptable.

The spot welding process works by the resistance heating principle: the electrical resistance of the metal interface between the sheets is much higher than the resistance of the copper electrodes or the sheet metal itself, so heat is generated preferentially at the faying (mating) surfaces. As the material melts, a lens-shaped nugget of molten metal forms. The electrode force maintains contact and constrains the nugget shape; upon current cessation, the nugget solidifies under continued electrode pressure, forming a weld that is essentially a small cast metal cylinder.

Key parameters that govern spot weld quality are: current (amperes), weld time (cycles at 60 Hz), electrode force (pounds or kN), and electrode face diameter. These parameters interact: higher current with shorter time, or lower current with longer time, can produce similar heat input. The combination must be selected to produce a nugget of the specified minimum diameter (typically 4√t where t is the sheet thickness in millimeters) without expulsion (ejection of molten metal from the joint, indicating excessive heat or insufficient force).

Electrode material is typically Class 2 copper-chromium-zirconium alloy—copper's high conductivity keeps the electrode cool while the alloying elements provide hardness to resist face deformation under repeated high-force cycling. Electrode face geometry (dome, flat, truncated cone, offset) is selected by joint accessibility. Electrodes wear with use, changing face diameter and increasing contact area, which reduces current density and weld quality. Electrode life (measured in welds per dress cycle) is tracked and electrodes are tip-dressed (re-machined to restore the correct face geometry) on a scheduled basis.

Spot weld quality verification includes peel tests (destructive, to expose nugget diameter), cross-section metallographic examination, and ultrasonic testing (non-destructive). Weld schedule qualification establishes the acceptable parameter window for each material and thickness combination per AWS D8.1 or customer specifications.
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version = "0.0.1"
