Mobile robot colleagues on wheels

Located outside Nashville in Fairview, Tenn., Scott Fetzer Electrical Group (SFEG) is a manufacturer of a range of electrical motors and components. As a high-mix, low-volume producer, the company was challenged to automate lines that are not always running. As an alternative to more costly, fixed industrial robots, the company deployed a fleet of collaborative mobile robots to automate monotonous and repetitive tasks.

“We wanted to build a mobile, flexible robot workforce,” says Matthew Bush, director of operations at SFEG. “The only way we would accomplish this was with a collaborative robot. It’s got the speed and precision of a standard industrial robot with the ability to move around and work next to humans.”

SFEG placed the robots (Universal Robots, universal-robots.com) on pedestals with wheels and is now using them throughout the sheet metal department, integrating them in the entire production cycle from cutting the initial blank on the blanking press to forming, folding and final assembly of the electrical components. Additional robots are planned to help tend the turret presses and press brakes.

“One day it would be bending sheet metal, the next day it would be performing pick-and-place tasks, and the third day we would take it to Manufacturing Day at the local high school,” Bush says. “Before we had the robots on our transformer line, we averaged about 10 parts per person per hour, that’s up to 12 parts per person per hour now, so about a 20% increase.”

One robot is placed at the end of the line right next to an employee, who hands the robot a motor field part. The robot puts it in a holder, picks up a wire cutter to trim the wires, and then places the part for another robot to pick up and place on a conveyor for final assembly. The two robots work in tandem and communicate their position to each other through Modbus socket connections.

“It’s a potential carpal tunnel syndrome application cutting about 16,000 wires a day by hand,” Bush says. “So we thought that was a great place to put robots—let them get carpal tunnel.”

Bush is currently estimating a payback period between 12 and 14 months on the robots.

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