Case Studies / Arc Welding / Heavy Vehicle Axle Housings

System is up to 20 percent faster than requirement for 175-part/shift average for mix of heavy and light parts. Achieved 175 part/shift for heavy parts, and 210 parts/shift for light parts. System produces welds with required part penetration that meet visual inspection criteria and CPK requirements

Project Challenges

  • Weld 18 different part numbers in both runs, with manual changeover between fixture setups.
  • Fit-up and part length vary from one manually pre-tacked part to the next. Gap ranges from 0-1.016 mm (0"-0.040"), offset ranges from 0-1.524 mm (0"-0.060"), and part length varies from 0-6.35 mm (0-0.25").
  • Achieve minimum of 55% weld penetration near inboard with 100% penetration for last 152.4 mm (6") of each weld on both sides of the part (from transition to end).
  • Meet SPC requirements of 1.67 CPK on weld penetration.
  • Meet AWS welding criteria for visual inspection.
  • Weld a minimum of 175 parts per 7.6-hour shift (2-3 shifts per day). Required rate is an average, assuming a mix of heavy and light parts. Heaviest parts are 7 mm (0.67") thick mild steel weighing up to 107 kg (236 lbs.) each. Light parts are 9 mm (0.35") thick and weigh approximately 36-41 kg (80-90 lbs) each. Each part gets four heavy-deposition welds.

Motoman Robotics Solution

Motoman Robotics provided a flexible material handling and heavy deposition welding system, including:

  • Motoman SK150 robot with air-conditioned MRC controller.
  • Custom pneumatic end-of-arm tooling (gripper) with five sets of gripper fingers.
  • Four Motoman SK6 robots with air-conditioned DR2C MRC controllers. (Two robots per positioner.) MRCs have expanded memory and MARIO boards.
  • Four Tough Gun™ 650-amp water-cooled welding packages (one per SK6 robot).
  • Four Banner laser height detection units for seam-finding.
  • Four Miller Deltaweld™ 652 power sources with Robotic II interfaces.
  • Start-up kits, 1/16" solid-core steel wire. Customer will add bulk wire feeders on-site.
  • Four Tregaskiss nozzle reamers with anti-spatter sprayers.
  • Four Motoman ToolSight® torch alignment packages.
  • Two 3,000-lb capacity, heavy-duty Koike-Aronson headstock/tailstock positioners with 1,500-lb capacity per HS/TS (3,000-lb total capacity).
  • Custom steel robot risers and base and spanners for positioners and robots.
  • 5.2-m (17-ft) over/under palletized conveyor with pneumatic part elevators at both ends. Includes powered chain-driven infeed conveyor and gravity pallet return conveyor with part-present sensors.
  • Custom pallet fixtures.
  • Custom fixtures on headstock/tailstock positioners with automatic hydraulic clamping.
  • Four copper/tungsten alloy welding back-up bars, located by eight pneumatic cylinders.
  • Two hydraulic pumps, plus hydraulic intensifiers for welding fixtures.
  • Two intermediate part stands and one outfeed stand.
  • Allen-Bradley SLC/503 PLC with Remote I/O.
  • Allen-Bradley PanelView™ 600 operator interface.
  • Integrated safety package, including light curtains and photo eyes at operator load station, arc curtains, elevator guarding, wire safety fence with arc screens and three safety interlocked gates.
Ref: ACS-030
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