Not Ready for Robots (in High-Stress Structures)

Robots may soon dominate the service industry. But heavy industry still requires welding skills only humans possess.

“Robots weld. They don’t think.” Wärtsilä Inspection Manager Raimo Mäki-Reini succinctly delivers his verdict when asked how quickly the robots will begin welding structures for his company.

How soon robot overlords will put humans out of jobs has never been a more popular topic in the mainstream media. In the service industry, it’s predicted that by year 2030 between thirty and forty-seven percent of humans will be replaced by robots. But welding is a different story.

Robot flaws
Steel base plates which house Wärtsilä ship engines and generators can weigh 32 tons. Add an engine and they weigh over hundreds of tons. This is not yet a job to entrust to robots. “I was amazed in the visual inspection,” says Mäki-Reini of the times he’s inspected robot work. “What beautiful welds! But when I broke them open they were terrible. Robots don’t notice air gaps.”

Tolerances are tight in Wärtsilä’s business. Material tolerances for welded plates are +/- 0.5 millimeters; cutting tolerances +/- 2.0mm; assembly +/- 2.0mm; and expansion tolerance +/- 5 mm. “A robot can’t handle all of these,” says Mäki-Reini. “I’ve inspected nine suppliers who use robots and I’ve rejected all but one. The one I accepted made assembly planning, and they welded only the clear areas with a robot — only about half of the total welding job.”

“Manual welding, like Fortaco does it, is the only possible way of working to get the quality level Wärtsilä requires with the highest stress structures,” says Mäki-Reini. “However, Fortaco does use robots to do small parts of the larger job in areas where a robot can excel.”

A robot future?
Mäki-Reini does not totally dismiss robots but believes if they’re to have a future working for Wärtsilä, then good communication will be part of that solution.

“If you want to use robots, then step one is better defining where a robot can weld and where it can’t,” says Mäki-Reini. “Step two: program it so well that the robot can weld tough parts like the corners. Step three is better cutting control.

Perhaps the tolerance should be +/- 0.5mm and not 2 mm.” But tightening tolerances is not only tough — it also causes increased costs.

Whether robot welders will ever replace humans in large part depends on the development of a machine eye. “If we can give it clear requirements for what it must see, then it can determine what’s okay and what’s not okay. After that, however, you need an adaptive system. And then after that you need control, checking the work. You need a robot to do the control if possible. There is no equipment for that today.”

Wärtsilä is currently working with a company in Germany which makes machine eyes for automotive manufacturing. “But our situation is more complicated,” Mäki-Reini says. “Automotive robot welding tolerances are in centimeters. Ours are in fractions of millimeters.”

Humans rule (for now)
For the foreseeable future humans will rule the shop floor. “We have great manual welders and Fortaco is one of them,” says Mäki-Reini. “The secret to great welding is good routines to control process and clear requirements to the floor. When that’s done right the result is satisfactory. The result is the most important part.”

Mäki-Reini says if there’s one human challenge to address it’s creating welders themselves. “Young people don’t want to weld anymore” – he makes a gesture of typing on a keyboard to show the type of jobs the young prefer. “We could lose all our welders in 20 years, so our challenge is to improve robots to the point they can weld high-stress structures.”