Robotic Welding – Rail Freight Wagons

CLIENT : Transnet Rail Engineering, South Africa

PROBLEM : The manufacture of rail freight wagons (for transporting coal and iron ore) is slow and arduous work for manual welding staff at the client’s Wagon Build factory. Very long, consistent and durable welds are required along each 7 tonne steel chassis. Despite this, they deliver up to 500 of these wagons a year, to local and international markets.

However, facing the additional challenge of a shortage in local skilled welding labour and a determination to become more globally competitive, the client chose again to explore an automated solution. While this followed three other successful MOTOMAN robotic welding cell installations in the client’s other production areas, the size of these wagon parts brought an unprecedented scope to the project.

Railways Robotic Welding SA
The MOTOMAN welding cell – largest gantry robot system in the Southern Hemisphere.

SOLUTION :  Measuring 37.5 metres long by eight metres in width and height, the latest cell is said to be the largest gantry robot system in the Southern hemisphere. The system has 20 synchronised servo axes, two of them controlling a pair of 20 tonne capacity, rotating positioners and tailstocks. They are capable of manipulating a 7-tonne steel chassis for a rail wagon through 360 degrees, while two suspended HP6 Motoman robots complete the welding cycle.

The robots work independently and simultaneously, carried on slides that provide three additional degrees of freedom. The system also includes automated seam-finding and tracking functions to allow for some variance in the parts’ shapes and surfaces.

Wagon assemblies are first tack-welded and then loaded onto one of two workstations in the gantry system, allowing automated arc welding to start immediately while the previous fabrication is unloaded – providing an uninterrupted work-flow. Each unit is now produced with higher quality, consistency and speed, while actually costing less – all of which is essential to global competitiveness.

Railways Robotic Welding SA 2
A CAD model showing the twin workstation configuration for uninterrupted production.


  • 2 x MOTOMAN HP6 Robots 
  • 2 x MOTOMAN Positioner / Rotators – 20 tonne capacity
  • 2 x TOUGHGUN torch
  • GMAW digital pulse inverter and peripherals
  • Gantry construction, fencing and safety features


  • Improved productivity, quality & consistency
  • Improved staff safety
  • Lower production costs
  • Reduced labour costs, injury claims & lost production time