Spot Welding

A spot-welding robot works a servo gun through dozens of resistance welds across a sheet metal panel, typically inside a body-in-white line running dozens of vehicles per hour. The gun clamps, welds, and releases at each point while the arm indexes to the next weld location.

Payload runs high, often 100 to 200 kg, because the gun itself can hit 100 kg or more before transformer weight is counted. Reach in the 2000 to 2600 mm range lets the arm keep the panel outside the swept envelope while the electrodes still reach interior weld points, which is where heavy arms like the R-2000iC/165F or ABB IRB 6700 sit.

Servo guns with integrated timers give tighter squeeze and hold control than pneumatic guns, and cooling lines have to route through the arm dress. Multiple robots often work the same panel from opposite sides, so collision zones and joint programming matter as much as the individual weld sequence.

Undersized welds usually trace to worn or misaligned tips, low current, or poor part-to-part contact. If welds start missing location, verify the tool frame after any tip dress and confirm the panel is fully seated in its fixture.

Spot welding suits overlapping sheet metal in roughly the 0.5 to 3 mm thickness range. For longer continuous joints, thicker plate, or dissimilar materials, arc welding and laser welding tend to be a better fit.

A typical underbody station runs a heavy six-axis like the Fanuc R-2000iC/165F with a servo gun and its own timer schedule. The robot controller triggers squeeze, weld, and hold through the gun controller, and cycle time is usually set by the weld sequence itself.

Tip dressing schedules and spot welding timer setup are the two levers a technician touches most. Both drift over a shift, and both show up in weld quality data before they trip an alarm.