Safety
Safety tests the hazards specific to a robotic arc cell and the standards that control them. The governing documents are AWS Z49.1 for welding safety, ANSI/RIA R15.06 with ISO 10218 parts 1 and 2 for robots, NFPA 51B for hot work, and OSHA 1910.252 for welding in general industry.
Robot-specific controls
- The cell is safeguarded by a perimeter fence with an interlocked gate, plus light curtains or area scanners where access is required. Opening the gate initiates a protective stop.
- Teaching happens in manual reduced speed mode at no more than 250 mm/s, using a three-position enabling device that stops motion when released or squeezed.
- A single point of control prevents anyone else from starting the robot while a programmer is at the pendant.
- Emergency stop per ISO 13850 is separate from the protective stop; recovery from either needs a deliberate reset and a check that no one is inside the cell.
- Safety-rated soft limits and monitored standstill are configuration settings, not teaching aids.
Welding hazards
- Electric shock: open circuit voltage, wet gloves, damaged torch cables, and welding on a robot arm or positioner bearing that carries current.
- Fume: manganese and hexavalent chromium from stainless and hardfacing work; local exhaust at the arc is the primary control, with respiratory protection where assessment requires it.
- Radiation: UV and IR from the arc. Filter shade depends on current, typically 10 to 12 in the robotic GMAW range, plus flash screens and flame-resistant clothing.
- Fire: NFPA 51B calls for combustibles moved at least 35 ft away or protected, with a fire watch where required.
- Compressed gas: cylinders secured upright, acetylene limited to 15 psi, no oil on oxygen fittings.
Worked example
A programmer wants to jog the robot to a new weld start with the gate open, in automatic mode at full override, because the motion is easier to see. With the gate open the safety circuit cannot be bypassed; the correct state is manual reduced speed mode with the enabling device held and the pendant in control. Full-speed motion with an open gate is a safeguarding failure no matter who is watching.