Page 28 - 3D Metal Printing Winter 2020

3D AM Benefits from More Powerful Process Simulation
BeAM’s directed energy deposition process combines a three-axis laser head with a tilt- rotary table to provide five-axis control of the AM process. The work requires powerful software to correctly define and execute tool paths. Resulting accurate modeling eliminates collisions and resulting tool damage during builds.
of power, five separate material hoppers and a maximum build volume of 1200 by 800 by 800 mm.
“Think of our machine as a five-axis machining center, with the spindle replaced by a laser-deposition head,” explains BeAM’s business development manager Zeke Sudbury. “Since its intro- duction to the U.S. market in 2016, it’s become popular with the aerospace, ener- gy and defense industries, and is begin- ning to move into the automotive market for use with tooling repairs.”
Robust Oversight Required for Complex AM Process
Because of this widespread interest, and to prevent the crash experience detailed above, BeAM has entered into an informal partnership with Irvine, CA-based CGTech Inc., provider of Vericut tool path simulation and verification software.
Vericut verifies laser activity, power, material feed and gas flow; detects collisions between machinery and an AM part; and identifies errors, voids and misplaced mate- rial during part construction, according to
ance of ±0.002 in., and attain a great sur- face finish,” Kron explains.
The DED advantage extends to post- processing. Unlike powder-bed printers, which require elaborate structures to sup- port the workpiece during the build process, BeAM’s DED machines rotate the part in any needed direction to prevent molten metal from drooping or curling. This greatly reduces post-secondary machining time and its associated fixture costs, and lets us generate otherwise unachievable shapes.
The machines also can combine mul- tiple materials such as stainless steel and titanium or copper and steel in a single workpiece, opening the door to enhanced electrical, thermal and mechanical prop- erties. And, users can add material to exist- ing parts—repairing damaged turbine blades, perhaps, or adding features to pre- viously machined products—or simply build those same parts from scratch. The result is increased flexibility for designers and end-users alike.
Similar in concept to laser cladding, DED works by injecting metal powder― roughly the consistency of bread flour― into a stream of argon gas. The entrained material then is directed through a nozzle and into the path of a high-power fiber laser, which creates a melt pool on the
surface of the burgeoning workpiece. For maximum material deposition, a second stream of gas can be applied, as can addi- tional laser power. For example, BeAM’s flagship model, the Magic 800, supports dual fiber lasers providing as much as 2 kW
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This crashed AM part resulted from incorrect machine programming, wasting not only material but hours of build time. In some cases, tool damage also results.