“Manual pedestal welding is kind of a dying breed,” he continues, “mainly due to the ergonomics—lifting heavy parts, standing all day trying to move these parts and fixture them for welding. A cobot welding machine can do all of that while freeing up the technician to perform other productive duties.”
Rapid ROI
A cobot spot-welding machine is a long-time partner with potential quick payback, Hamilton explains. For example, he cites a unit in the field surpassing 600,000 welds and still running strong. That machine, installed at Lewis Welding in Grand Rapids, MI, tackles a product line that the full-service sheet metal-fabrication and powder-coating company brought on last year.
The machine runs about 9000 welds/day, according to Jake Buchholz, Lewis Welding inside sales engineer, with a 6-mo. return on investment for the fabricator on that product-line project. In the video, Buchholz lauds the safety and ergonomic aspects of the cobot-spot-welding setup, negating the need for protective caging and saving personnel from awkward bending and other movements with parts.
“The training did not take long,” says Buchholz, referencing the technology’s implementation at Lewis Welding. “The operators like it and we like it because we can place different operators on the machine and they don’t have to be experienced in spot welding.”
Simulation Eases Implementation
To help fabricators determine how a cobot-led spot-welding machine will perform on the shop floor, simulation proves effective. In the case of Lewis Welding, “Pro Spot helped us design a simulation model … that showed how it would help us spot-weld our parts,” Buchholz says.
With a solid model of the product to be welded in hand, Pro Spot fed it into its simulator.
“In creating a SolidWorks simulation that displayed exactly how the weld head would interface with the parts. It also provided estimates on cycle time, and let us see if the application would require any special tooling or custom elements,” says Hamilton.
Via simulation, Pro Spot found that the application needed a custom electrode and the cobot arm had to be slightly taller to reach around fins on the parts. Simulation can assist in other ways, too, such as exploring options for fixturing, according to Hamilton.
Sweet Spots for Cobot Spot Welding
In many applications, cobot-led spot welding means more welding time vs. handling time. Specifically, such a setup makes sense for “medium- or even lower-volume, high-mix jobs,” Hamilton says, “and for awkward-to-handle parts. Unique about cobot spot welding: It brings the welding head to the part instead of trying to bring the part to the pedestal welder. That’s beneficial when dealing with awkward parts that are difficult to hold together and to transport by a person or even a robot.”
Of course come the oft-stated advantages of cobots over traditional industrial robots: easier to install and program, minimal guarding required in many cases, the ability to function in close proximity to humans, lightweight and portable, etc.
As for portability and flexibility, “we’ve placed our cobot spot welder on wheels,” Hamilton says. “In a high-mix environment, fabricators can run a job in one area of the plant and then simply roll it over to another area—it’s self-contained.”
Precision Not a Problem
Fabricators may wonder about the precision of a cobot-led spot-welding machine.
“It hits spots within 1 to 2 mm of the programmed location—more than adequate for spot welding,” says Hamilton. “Of course, the fixturing is important so as to hold the parts in the same location repeatedly. Fabricators on the road to employing this technology should consider how parts are presented, as the fixturing will make the process work effectively.
“Spot welding is more forgiving than gas-metal-arc welding (GMAW), and allows some tolerance to work with,” he continues. “Cobot spot welding can do some things that GMAW can’t. For example, when welding flanges, the process squeezes together a couple pieces of work material with a gap between them and holds them in place, with the current brought in to perform the weld. GMAW can’t do that. And, spot welding results in a very small heat-affected zone with no after-welding work such as grinding. Design engineers sometimes neglect these advantages—every day we try to educate fabricators on these benefits.”
With decades of experience in designing equipment to repair automobiles after accidents in order to transport people safely, Pro Spot knows the importance and value of good welds, and that knowhow has been transferred to cobot-led spot-welding technology.
“We check 60 to 80 different parameters on a weld in collision repair, and have applied that sophisticated technology in fabrication shops,” says Hamilton.
The company also shrunk its i5s spot-welding head used in collision repair for mounting on a cobot arm, and various Universal Robots cobot models can be used in the spot-welding setup depending on reach and load requirements.
Another feature now available for cobot spot welding: wireless capabilities.
“This allows for sending updates to the machine,” Hamilton says, “and distributing weld logs to whomever needs them.
“For 40 yr., spot welding has been performed with manual pedestal-welding setups, and cobot-led spot welding breaks the mold,” Hamilton concludes. “This technology is disruptive in the industry, and is a no-brainer for many fabrication-shop applications.” MF
Industry-Related Terms: Bending,
Case,
Fixture,
Forming,
Grinding,
Model,
Run,
Tolerance,
Forming,
Forming,
Spot Welding,
WeldingView Glossary of Metalforming Terms
See also: Pro Spot International Inc., Universal Robots
Technologies: Pressroom Automation, Welding and Joining
Pro Spot since then has advanced this technology, and we met recently with Bob Hamilton, chief technology officer at Pro Spot and the technology’s inventor, to provide a good overview on cobot-led spot-welding applications and their sweet spots for job volume and part types.
