Typically the robot and controller, a matched welding power source and wire feeder, a positioner, the safety enclosure with interlocks and arc screening, the operator interface and the base frame that fixes all the relationships. Fixturing for the specific part is normally separate, since it is the one element that cannot be standard.

Because welding position governs deposition rate and defect rate. A positioner presents each joint flat or horizontal, where the pool is easiest to control and travel speeds are highest, instead of asking the robot to weld vertically or overhead. It also gets the torch to joints that would otherwise be unreachable without a much larger and more expensive arm.

Control of the positioner axes and the robot axes as one system, so the part turns while the torch moves and the two are solved together. It keeps travel speed and torch angle constant through a curved or circumferential seam that would otherwise need to be broken into segments with stops and restarts, each of which is a potential defect.

It removes loading from the welding cycle. While the robot welds the fixture on one side of a partition, the operator unloads and reloads the other, so the arc restarts as soon as the positioner indexes rather than waiting for a person. On short-cycle parts, where loading time rivals welding time, the gain approaches double.

Physical guarding preventing access to the working envelope, interlocked doors, presence sensing at the load station, an assessed and validated safety-rated stop, and screening against arc radiation for anyone nearby. Fume extraction is a separate duty. The safety functions are verified at commissioning and re-verified after modification, and a risk assessment supports the design.

More than the enclosure itself. Allow for the robot's full envelope plus the positioner swing, the load station's approach, cable and gas services, wire drum access, extraction ducting and maintenance clearance behind the arm. Suppliers publish footprints, but the practical figure on the drawing includes access on at least two sides.

Rarely without adjustment. Parts designed for manual welding often rely on the welder compensating for gap variation, tack sequence and distortion. Moving to a robot usually means tightening cut and form tolerances, revisiting joint design for torch access, and designing fixturing that locates positively. The design review is a normal part of the project rather than a sign of a problem.