Among its most recent capital-equipment investments, to maintain pace with its growing customer base: a new robotic-welding cell, added in 2019 to take over for its aging workhorse. “We still use that old robotic welding workcell occasionally,” Reiker says, “but only out of necessity as demand requires it.”

The new welding cell on the block: an OTC Daihen Eco-Arc 200, with OTC Daihen’s exclusive Synchro-feed welding package designed to provide ultra-low spatter, and ideal for the wide mix of material thicknesses at Haake, especially thin-gauge parts with outside corner welds. Anchoring the cell is a model FD-B6 six-axis arc welding robot—6-kg payload capacity, 1445-mm reach and built-in wrist motors to avoid interference with jigs and workpieces. It also boasts built-in cables to avoid weld-conduit interference and improve torch reach. And, OTC Daihen touts a seamless, high-speed digital connection to the welding power supply and a built-in mechanical shock sensor as part of the package.

Aluminum Welding Shines

“Researching our robotic-welding options in 2019, we really appreciated the ability of the OTC Daihen cell to shine when welding aluminum,” Rieker says, also noting that the cell’s flexible tilt-turntable positioner allows it to complete complex weldments without requiring the robot to perform acrobatic maneuvers.

“We have one job, for example, welding an aluminum tube to a bracket for an assembly used in the sign industry, which requires a convoluted circular weld path,” he explains. “We can use the tilt-turntable to maneuver and spin the part under the stationary welding torch to maintain the proper torch orientation to the weld joint.”

The OTC Eco-Arc production robotic arc welding systems are two-station, two-table configurations that allow an operator to unload a finished weldment and reload parts into a fixture on one worktable, all while the robot welds on the second table. OTC offers the systems in several configurations—as a cobot production cell, a compact cell, a cell with fencing that anchors to the floor, a cell with the fencing mounted to a common base and large cells featuring long-reach robots and larger weld tables.

Haake’s system employs the OTC Daihen Synchro-feed gas-metal-arc-welding setup—500-A inverter-based pulsed power supply (OTC Daihen model WB-P500L) and weld-wire delivery system—that, OTC Daihen officials say, virtually eliminate weld spatter. Via a welding process called PulseDip, the setup incorporates a servo-driven wire feeder within the torch body that advances the welding wire forward to create the arc, and then precisely retracts the wire while synchronizing with a weld-current waveform that extinguishes the arc. The result: consistent droplet transfer into the weld joint with minimal if any spatter. 

The WB-500L power supply employs OTC Daihen’s Wave Pulse process that delivers high-speed waveform control, for spatter control as well as to minimize undercut during high-speed welding. OTC Daihen also touts the power supply for eliminating the need for expensive helium-based shielding-gas mixtures, enabling instead the use of 100-percent argon on aluminum, and argon-CO₂ mixtures when welding stainless steel.

Simpler to Program and Run

“Compared to our older robotic welding cell, we’ve found the Eco-Arc much simpler to program and operate,” Rieker says, noting that his programmer can develop new robotic welding routines in 1 to 2 hr. using a teach pendant at the cell.  

“And, while previously the operator tending our older cell required a lot of expertise in welding to avoid quality issues,” he adds, “when that operator left the company, we were able to replace him with a cell operator who knew how to program robots but lacked that higher level of welding expertise. That’s because the OTC Daihen welding system is so intuitive and forgiving; the operator does not need to have a lot of welding skill or knowledge. This new cell really does make it much easier for fabricators to adopt robotic welding.”

Faster and more intuitive to program helps make for an easily adaptable and productive piece of automation, but when weld quality and repeatability also improve, then you’re on to something, and that’s precisely the case at Haake. “We experience little to no spatter,” Rieker confirms, “and part-to-part results are very consistent. We never have to worry about wasting time manually touching up welds or wire-brushing to remove spatter. 

“Overall, we’ve experienced a 20-percent improvement in throughput compared to the older cell,” he adds, “and gained probably at least another 10 percent in overall productivity when you include the improvement in weld quality.”

As An Example

…Rieker describes an assembly it runs regularly through the robotic arc welding cell: thin-gauge stainless-steel weldments for a wastewater-treatment application. Here, the robotic arc welder joins a 10-gauge base plate to a 22-gauge wrapper.

“Throughput on that job has increased by nearly 20 percent,” Rieker says.

One final key to success when it comes to robotic welding in a relatively low-volume, high-mix environment such as Haake’s: quick changeovers, and here Rieker identifies a couple of enablers.

“First, the robot carries a multifunction welding torch that makes the changeover from welding stainless or carbon steel to aluminum quick and simple,” he says. “We don’t have to change out the entire torch, only the gun liner, which takes less than 30 min. Second, we design and build our weld fixtures to use common base plates where possible, with tooling inserts so that each fixture can handle multiple part families. We try to not over-engineer the fixtures, so they’re easily modified. Of the 50 or so fixtures we’ve built only 15 or 20 are regularly used.” MF

See also: OTC-Daihen, Inc., TRUMPF Inc., Aida-America Corp.

Technologies: Welding and Joining

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