What factors affect spot weld quality and how is it monitored?

Spot weld quality factors: Current (too low = cold weld, too high = expulsion), weld time, electrode force (affects contact resistance and heat generation), electrode condition (wear affects current density), surface condition (coatings, contamination), material stack-up (thickness combinations), and shunting from adjacent welds. Monitoring methods include: Destructive testing (peel, chisel, tensile tests), ultrasonic testing (non-destructive nugget measurement), dynamic resistance monitoring (correlates to nugget formation), and visual inspection. Adaptive welding systems adjust parameters in real-time based on resistance feedback. Documentation requirements include weld schedules, validation testing, and ongoing process control.