A Bigger Build
- Published: February 10, 2017
A limited build area has been one of the major challenges in developing additive manufacturing’s practical potential. Powder bed fusion technology is currently limited to about one cubic foot, with two
cubic feet the likely limit for some time to come.
But that could change with the blending of multiple additive manufacturing technologies–and the addition of robotics. At least that’s the hope of Lincoln Electric, whose wholly owned subsidiary Wolf Robotics specializes in robotic welding and cutting systems. Lincoln showcased its latest work in medium and large scale robotic metal AM technology at the 2016 International Manufacturing Technology Show (IMTS) in Chicago last September, and again in November at FABTECH 2016 in Las Vegas.
“Lincoln Electric, together with its Wolf Robotics automation division, is currently developing medium and large scale robotic metal AM systems, incorporating Lincoln electric arc and laser hot wire welding technologies,” says Jason Flamm, project manager, Wolf Robotics. “These systems will enable a high deposition rate, near net printing of metal parts at speeds more than ten times greater than typical powder bed printers.”
The multi-feedstock systems utilize both wire and powder feedstock or print material, which enables a wide range of available print resolution. The wire feedstock can be printed at higher deposition rates to a near net shape; at that point the powder feed stock can be used, which has a lower deposition rate, but achieves a better surface finish.
“Current efforts are focused on printing large titanium and steel parts,” Flamm says, “though the system will also be capable of processing nickel alloys, aluminum, and others.”
Flamm says the new systems are being developed to deliver on three fronts. First, they are pushing the current powder bed build envelope. The new systems, says Flamm, can print small, medium and large scale parts “and are easily scalable with the addition of tracks or multi-axis gantry systems to extend the robot build envelope.” Sizes exceeding one metre in any given direction are possible. Flamm says a seven-foot stick will be printed for ConExpo next March in Las Vegas as part of the AEM Tech Experience booth.
Second, most current metal AM systems utilize three axis positioning systems that limit them to printing two-dimensional layers. Lincoln’s new systems use six-axis robotic arms and positioning equipment, which enables multi-planar printing. This will minimize the need for support material and “allow for more robust build/print strategies,” Flamm says. He adds it will also “improve part strength by controlling or eliminating layered sheer planes, and better control heat inputs to reduce and eliminate distortion.”
Third, the print path programming is fully automated, with a CAD-to-path workflow optimized for six-axis industrial robots. The lack of such a
product on the market has been a major obstacle up to this point, Flamm says.
Applications include high-mix, low-volume production parts, on-demand printing of spares, tool and die work, part repair and an alternative option for low-volume forging and casting. Flamm says potential customers in aerospace, shipbuilding, oil and gas, and general industry have shown interest.