Lou Kren Lou Kren
Senior Editor

More Lasers Promise Greater Productivity Despite the Complexity

February 5, 2021


The march continues toward metal 3D printing technology that provides volume industrial production. Case in point: Formnext. Looking through the new technologies forwarded at Formnext 2020, a sizable number involve the addition of lasers to laser powder-bed metal-additive manufacturing (-AM) machines.

3D Metal Printing’s Formnext review highlights these advancements. As AM further travels into the realm of production quantities, the addition of laser power and multiple-laser arrays offers a means to significantly boost the output of AM machines. For example, SLM Solutions’ NXG XII 600 system features 12 1000-W lasers, and reportedly produces at speeds five times faster than a quad-laser unit—printing as much as 1000 cm3/hr.

3D Systems for its part reports the first test print completed on a nine-laser AM machine for the U.S. Army’s Combat Capabilities Development Command Army Research Laboratory (ARL). The 3D printer, with a huge 1 m by 1 m by 600-mm build chamber, is expected to help propel supply chains associated with long-range munitions, next-generation combat vehicles, helicopters, and air- and missile-defense capabilities. 

And, Velo3D has debuted its Sapphire XC large-format 3D metal printer, boasting eight 1000-W lasers and reportedly enabling increased throughput to five times and with a 75-percent-reduced cost per part as compared to the existing two-1000-W-laser Sapphire system. 

Powerful software and hardware upgrades, as hinted at above, enable the productive use of these laser arrays. More processing power allows software and machine controls to reliably position lasers and parse out the work to optimize overlaps and laser utilization while in-situ monitoring assures quality control. Of course, mentioning powerful software and hardware glosses over just how tricky multiple-laser implementation can be.

“When making parts for aeronautics, medical devices and other complex applications, quality is fundamental…any gains in output that compromise the safety or utility of the part aren’t gains at all,” explains Dr. Zach Murphree, Velo3D vice president, in a blog that discusses the technical hurdles in jumping from one to two lasers in a metal-AM build. In building a single large aerospace part, for example, scan-field alignment presents a particular concern in a multiple-laser setup, whereas for small medical parts, the lasers can be tasked with each building separate parts.

“With larger parts that take up most of the build plate, the lasers must work in concert, and, like circus performers catching each other in mid-air, a slight misalignment can have big consequences,” he offers in the blog. “In engineering terms, this means that each scanning system has to be aligned to the other with less than 50-micron (1/20th of a millimeter,―thinner than a human hair) difference everywhere on the build plate.

“The thermal state of the system also becomes an important variable,” he adds, introducing another complication. 

Even a 15 C change in the chamber temperature can change the distance between the scan head and build plane by more than 100 microns.

“Depending on the angle of incidence in the overlap region,” Murphree writes, “this temperature change, by itself, can invalidate the calibration.” 

Murphree sees laser scheduling and pathing as solutions here, and also as critical to realizing the benefits of multi-laser systems. ”But,” he cautions, “engineers also must examine how the laser soot effects the scheduling and how well the lasers coordinate their efforts on contour and core for larger parts.”

And the complexities grow from here. So much to think about…but it seems that the newest technology is putting such thinking into action.

Industry-Related Terms: Build plate, Overlap
View Glossary of 3D Metal Printing Terms

 

See also: SLM Solutions NA, Inc.

Technologies: Powder-Bed Systems

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