Cobot Cuts Plasma Cutting Cycle Time

After a manufacturer has built a robust reputation for delivering high-quality, customizable products, grappling with the high volatility and inconsistency inherent in manual cutting processes can be a risky endeavor. Tank Technology Inc. faced that scenario.

With 25% of its porcelain-lined water heaters customized to meet volume, tank diameters and application requirements, plasma cutting the heads and bases by hand generated a lot of volatility and inconsistency, said Joshua Kufahl. He’s production manager for the employee-owned Princeton, Wisconsin, company, which has about 50 people working two shifts at its 7,432-sq.-m (80,000-sq.-ft.) facility.

For its legacy line, Tank Technology built makeshift stencils, or jibs, for the handheld plasma cutter operator to create a line, such as for a circle, to cut along and try and get a decent fit, Kufahl explained. “Nothing was really round — ever.” He used the analogy of coloring and staying within the lines. “Some people could stay in the lines, some people couldn’t.”

Besides the potential for error, manual cutting is a source of physical strain, he said, noting the plasma cutter tends to feel heavier than it actually is, and the plasma leads can cause issues when trying to accurately maneuver. “You’re almost fighting yourself.”

Curved surface and custom fittings also introduce geometric complexity inherent with building custom tanks, Kufahl added, and any solution would need to handle size and structure variability. In addition, the company’s CNC machines could not accommodate the complex geometries required for their products, leading to a high rate of rework and scrap. “Speed for us at that time was the manual process.”

Tank Technology also performs welding and acquired a Cobot Welder from Hirebotics in Nashville, Tennessee, to automate the process using a collaborative robot while improving welding consistency and speed, Kufahl said. “We always had that idea that we needed a plasma cutter on a robot.”

Hirebotics had that idea as well and developed the Cobot Cutter, a cobot-operated plasma cutter, which Tank Technology purchased in December 2023. The lead time was short at two weeks, said Eric Pamenter, first shift ASME production lead for Tank Technology.

“With the Cobot Cutter, we’re seeing perfectly sized holes, perfect location every time, repeatable locations,” Pamenter said. “By hand, you can say a human is traveling at 11 to 13 inches per minute. We are traveling at anywhere from 100 to 130 inches per minute with this cobot.”