Discovering cobots

Plasma cutting and MIG welding cobots yield heavy-duty results for a heavy equipment maker

A UR10e MIG welding robot is mounted on a 7th axis and placed on a mobile skid to bring the robot to large workpieces. The human welder and robotic welder work side by side, leap-frogging across the side of the truck body to double output.

Carriere Industrial Supply (CIS), located in Sudbury, Canada, produces heavy equipment for harsh mining environments. Much of it – such as hauling equipment, scoops and earth movers – is used to move material from underground to the surface. Like most manufacturers, the company is adapting to a changing workforce by hiring new workers and retaining skilled talent, while strengthening its safety culture so that every employee goes home safely every day.

Automation is an ideal approach for CIS’ repeatable applications. But in a low-volume, high-mix manufacturing environment, and with many large workpieces that are difficult to move, traditional robots weren’t really a consideration.

The CIS team discovered Universal Robots (UR) at a trade show and was immediately struck by the sight of the collaborative robots (cobots) performing tasks while people interacted with them. Cobots mean bringing the robot to the work, instead of the other way around, and their easy programming empowers workers to continuously innovate to improve quality and output.

Empowering employees

The first project CIS identified for the UR application was plasma cutting large metal parts. Manual cuts require extensive cleanup due to the accumulation of dross at the bottom of the workpiece along with the jagged edges that occur when workers need to reposition themselves for long cuts. Reducing the cleanup time was an ideal area for improvement.

The truck body features large side-by-side fillet-welded ribs.

“By using a robot arm, we knew that we would get a more precise cut and there was the possibility of eliminating all of the grinding and cleanup of the joints,” says Pierre Levesque, manager of innovation and technologies, CIS.

The company chose the UR10e, which met both its reach and payload requirements, even with the weight of the plasma cutting tool and long workpieces. And despite the size and power of the robot arm, Levesque describes it as a “very approachable robotic cell” in terms of ease of use, even for operators with no robotics experience. They can place the workpiece on the table, “teach” the cobot where the part is and run the program for a clean, precise plasma cut, even on curved parts with complex geometries.

After some innovative programming, the cell became even more approachable for operators who were excited to make continual adjustments to improve quality and output.

Mason Fraser, junior software engineer at CIS, initially programmed the cutting of the most complex parts from start to finish, then built a new URCap program (a software handshake between the cobot arm and its peripherals accessible on the cobot’s teach pendant) that “puts the operator in the driver’s seat” with an easy-to-use interface. Now, operators are fully engaged in instructing the cobot on the points and speed to do the cut.

“The URCap augments the operator’s ability by automatically navigating any plate geometry imperfections and adjusting corner speeds when necessary, based on the geometry and the points they provided,” Levesque says. “You end up with the operator feeling in control, and also elevating the game to make sure that the right parameters, speeds and material being cut are all covered through the URCap. You have a very successful cut, reduced time and reduced risk for the operator, so it’s a win-win for the operation and the operator.”

Mason Fraser, junior software engineer at Carriere Industrial Supply, programs the UR plasma cutting application, using a checkerboard to calibrate the vision system.

While operators appreciate that the work is more rewarding and less physically demanding, CIS also saw significant time and cost savings. Previously, 80 percent of plasma cutting time was spent cleaning up the manual cut. For a single large truck body contract over three years, Levesque determined that the trimming process alone would be more than 50 hours for every truck. Moving to a robotic application would reduce that time to 12 hours per truck, ultimately delivering 1,000 hours and a significant cost savings on this project, exceeding CIS’ expectations.

“It’s interesting to see the operators take it even further and apply thought to their cut process,” Levesque says. “With the ease of being able to manipulate the cobot and using the free drive to position the torch in different angles, the operators take more care on applying bevels onto the final parts, which is quite impressive.”

Marc Sauve, process leader for steel processing at CIS who runs the plasma cutting robot, addresses the concern that some may have about robots and jobs. “If I had a colleague who was fearful of a UR robot coming to take their job, I would put them at ease,” he says. “Every one of those robots needs an operator, so it’s just an asset to them; it’s not a tool to remove them.”

Versatility and mobility

After the success of the plasma cutting robot, CIS knew it could leverage the programming to MIG welding projects, even though that is a more difficult application.

Marc Sauve, process leader for steel processing at Carriere Industrial Supply, operates the plasma cutting robot with no prior robotics experience.

“The MIG welding UR10e is doing similar profiles to what the plasma cutting robot is doing in the sense that it is following curvatures and following profiles,” Fraser says. “It’s just welding them instead of cutting them.”

Levesque knew MIG welding would pay dividends based on the large volume of welding work the company does. The challenge was to find repeatable parts in its low-volume, high-mix environment. One application stood out: the production of truck bodies with seven large side-by-side fillet-welded ribs, spaced 3 ft. to 4 ft. apart.

“We envisioned the welder working on one of the ribs while the cobot works on the next rib in coordination, and then you just index them over,” Levesque says.

Fraser adds, “There’s a ton of welding on those, so we try to save time for the welders. They can work alongside the cobot and split the work in half.”

Because of the length of the welds, the manual work raises critical ergonomic challenges to consider for welders.

“The cobot doesn’t care about ergonomics,” Fraser notes, “so the operator can set it up and go work on other stuff that’s more productive and easier to do. Some of the more productive work they can do is clean up the welds and make them look nice. The more we can free them up to do that kind of work, the better.”

Comparison of a part manually plasma cut (left) and one robotically plasma cut (right) shows elimination of dross and jagged edges that no longer need to be cleaned up.

The MIG welding process is applied to massive parts weighing more than 15 tons on the bodies of heavy-duty mining trucks; these workpieces can’t be fixtured inside a traditional robotic cell. This requires CIS to bring the robot to the workpiece, rather than the other way around. Unable to find a standard solution, the CIS team developed a custom welding skid that can be moved with a forklift to wherever the welding robot is needed. The robot is mounted on a lift to create a 7th axis to reach the entire weld on the side of a truck body. The relatively light weight of the UR cobot arm allowed CIS to develop this innovative approach.

Contributing to success

Industrial robots typically use proprietary code that requires special software for development and test. In contrast, the open platform and ease of programming of the UR cobots was a significant advantage.

“In traditional industrial robot applications, you have to do all the programming in the cell, at a reduced speed, and then leave the cell, press the button and hope for the best,” Fraser says. “Universal Robots was a refreshing change from this because all the scripting and programmability in it was open, and it can interface with any software, program and simulation tool. You’re not limited.”

As Fraser started the project, he was able to easily find the resources he needed on the UR website. “The UR Academy has great examples and tutorials on programming the cobot. It actually gives you a full simulation of how a program would look and how to write it, without having to download any software. It’s all purely online, so that was extremely helpful.”

Fraser says his team developed their own URCap in-house, noting, “A lot of the tools available to us online, such as the UR+ Developer Forum, had a ton of resources and answers that I needed to get through the project. All in all, it ended up being a pretty great experience.”

Fraser also discovered the value of UR and its partner’s simulation tools to save time and effort. The UR Sim is an offline simulator for the UR pendant. It let him test the URCaps he developed without having to upload them to the cobot and test them on the production floor.

“The big benefit of being able to upload to a simulator rather than the actual cobot was a major reduction in cycle times,” Fraser explains. “We didn’t have to go back and forth to the cobot to test it. I could test everything right on my computer.”

He also discovered the UR-certified RoboDK offline simulation software on the UR+ website. RoboDK is an offline simulation tool where Fraser could load 3-D parts data and program an entire path. The uploading and reading UR script into RoboDK made testing very quick.

Now that CIS has experience with UR, they have confidence for future initiatives and application, such as machine tending in manufacturing assembly. Fraser is also considering adding vision capabilities to the MIG welding robots similar to the approach used for plasma cutting. Another option is implementing more complex cuts with the plasma cutting robots such as coping for steel beams or standard part cuts the robot could do quickly while minimizing disruption to production.

“UR is definitely a platform with which we’re going to continue to work,” Levesque says. “The ease of use and approachability of the platform is definitely appealing for the company.”

Carriere Industrial Supply

Universal Robots

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