Robotic Arc Welding of Steel Structures
Robotic arc welding pays for itself in two places: consistent penetration on repeated seams, and the ability to weld downhand on parts that a manual welder has to reach around. The second is usually worth more than the first, and it depends less on the robot than on how the part is held.
Manual welding of a fabricated frame is mostly positioning: the welder stops, walks around, re-clamps, and welds the next seam at whatever angle is available. A robot welding the same frame on a positioner welds every seam in the flat position and never stops. Arc-on time in a well-designed cell is several times what a manual station achieves, which is where the payback comes from — not from welding faster.
Which parts suit it
Steel structures and frames, agricultural and construction machinery, trailer and truck bodies, pressure vessels and pipe spools, gearbox and machinery housings, furniture and shopfitting, exhaust and tube assemblies. The common condition is repeatability: the same part more than a few dozen times, with fit-up consistent enough that the seam is where the program expects it.
Choosing the robot
Payload on a welding robot is the torch package, not the part: torch, wire feeder, cable assembly, and any seam-tracking or laser sensor. A standard MIG torch fits comfortably within 6 kg. Add a through-arm cable package, a heavier air-cooled torch or a tracking sensor and 10 kg is the safer rating.
- RH14-06-W — 6 kg, 1468 mm, and RH14-10-W — 10 kg, 1440 mm. Small and medium frames, brackets, tube assemblies.
- RH18-06-W — 1850 mm, RH20-06-W — 2012 mm, RH21-06-W — 2093 mm. Larger weldments and parts on a two-station positioner.
- RA32-20-W — 20 kg, 3160 mm. Long structures, chassis and beams.
- PRO versions of the RH14-10-W and RH20-06-W carry reinforced wrists for heavier torch packages.
The hollow wrist matters more than it sounds. Routing the cable package inside the arm stops it snagging and dragging on long seams and rotating parts, and it is the difference between a cell that runs unattended and one that needs watching.
The positioner decides the cell
Specify the positioner before the robot, not after. It determines what the robot has to reach, and a good positioner frequently allows a smaller and cheaper arm than the part dimensions suggest.
- Single-axis — one rotation. Right for anything cylindrical or symmetrical: pipe spools, flanges, wheels, shafts, vessel shells. Sixteen models from 150 kg to 3 tonnes, including movable and idle tailstock versions, roller supports for thin-wall vessels, and a linear track that moves the robot along parts too long to rotate.
- Two-axis — rotation plus tilt, so seams on several planes all come flat. Eight models, 250 to 500 kg. This is the default for frames, brackets and housings.
- Three-axis — adds indexing between two stations, so the operator loads one while the robot welds the other. On short-cycle parts it roughly doubles throughput.
Capacity figures include the fixture, and on a welded assembly the fixture is often as heavy as the part.
What else the cell needs
Welding power source and wire feed, fixture and clamping, torch cleaning and wire cutting station, fume extraction, welding screens and interlocked fencing, and — for parts with variable fit-up — seam tracking. Offline programming is worth considering above roughly twenty part variants.
Get a quotation
Send a drawing or photograph of the part with material, thickness, weld lengths and annual volume. We will propose a robot, a positioner and a cell layout.
