Aircraft Tooling Inc., a Dallas, Texas-based aviation repair center, has grown from a component-only repair station to include overhaul of complete landing gear and engine mount assembly and accessories. The main objective of ATI’s repair scheme is to restore high-cost parts to new standard dimensions and release for further declared life.
ATI was looking to automate some of the repair tasks involving new HVOF (High Velocity Oxygen Fuel) and plasma spray on parts. Juan Puente, an ATI thermal spray supervisor, had initially considered traditional industrial robots. But what he found did not meet ATI’s needs.
High-velocity oxygen fuel coating is a thermal spray coating process used to improve or restore a component’s surface properties or dimensions. The spraying of parts usually takes 3-4 hours, with spraying in 1- to 2-minute intervals followed by a 2-minute cool down period. The robots would need to operate reliably in dirty, harsh environments.
“The cost was outrageous, the cast iron models we looked at were too bulky, we could not easily move them between cells, they were hard to program, and all required safety guarding, which would not work in our small spray cells,” says Puente.
Choosing Universal Robots UR10 Collaborative Robot
He came across a video about Universal Robots while researching potential options. And he liked what he saw. ATI now has two UR10 collaborative robots, with a third being installed. They chose the UR10 because of its long reach (51.2 inches) and because they could hang it upside down and walk underneath it, keeping the floor clear.
The robots’ payload and speed (39.4 in./sec.) was more than sufficient for ATI. “Our spray guns are not that heavy, so payload was not an issue. Most of the speed comes from our turntables making sure that the coating is being applied at a certain velocity,” Puente said.
Using the ‘Teach Method’ to Program UR10s
It only took ATI about four hours to program the UR10s. “It was a very simply, user-friendly process as opposed to other robots with a much more complex, multi-step programming interface,” said Puente.
Programming the UR10’s spray path was done using the “teach method.” This allows the user to grab the robot arm and move it through waypoints inserted directly on the robot’s touch screen.
“We used a red laser to indicate exactly where we wanted to robot to move, once the waypoints were set, we just hit “play” and the robot moves through that trajectory,” said Puente. “We’re looking into adding a vision camera so we can have the robot perform quality inspection of coated parts, locating areas that needs an extra coating. There are so many things we can do with these robots, that we have only started to explore.”
UR10s Withstanding Harsh Environments
Puente said there was significant hesitation at ATI as to whether the UR10 would operate reliably in the spray booth’s extremely hot and dusty environment.
“We were very surprised. I actually thought the robot wouldn’t stand it. Some of these powder coatings are tungsten carbide, which is a hard metal coating. If it seeps into the bearings of the robot, we were afraid it would destroy them,” he explained.
ATI opened up the seals on the UR10 and found the bearings intact. “There were no particles in there, 3 years of operation, it doesn’t show,” said Puente, adding that recoil from the spray gun was another concern. “We were nervous that the recoil would trip the robot or interfere with the servo capabilities. We went as high as the pressures would take to make it bounce, and it wouldn’t do it. The robot simply stayed in position.”
Nick Armenta, automation engineer with Olympus Controls, the UR robot distributor working with ATI, explains that the company’s experience with the robot’s durability is common.
“We very often see the robots operate in harsh environments, taking over jobs that humans don’t want to perform,” he says. “Many think of cobots as being fragile but the opposite is true, this is an extremely durable robot; it’s sealed against dust, rated for high temperatures, and works just as well in extreme environments as in a cleanroom.”