1 6 A D V A N C E D M A T E R I A L S & P R O C E S S E S | J U L Y / A U G U S T 2 0 2 2 DED processes allow for complex curvature component shapes to be built with nonsymmetric features such as those in Fig. 4b. In the powder-based DED processes, various nozzles can be used as illustrated in Fig. 5. They range from a coaxial configuration to multi-jet nozzles to vectored nozzles for internal cladding (Figs. 5a-c). Inert carrier gas is used to propel powder through the various nozzle configurations into the melt pool, creating the deposited bead. Figure 6a provides a schematic overview of the LP-DED system showing the powder feeders or hoppers. Use of multiple hoppers facilitates the build of bimetallic and functionally graded parts by varying the types of powder as well as the mixture ratios. Powder flow paths are illustrated in Fig. 6b for a coaxial nozzle and Fig. 6c for a vectored nozzle. Research is also being conducted using central wire or powder feed deposition nozzles with an annular laser beam or series of off-axis laser beams around the center axis[15]. Several of the processes that use wire feedstock are illustrated in Fig. 7. For these, the fusion source uses standard welding-based processes including metal inert gas (MIG), gas tungsten arc (TIG), laser beam (LW-DED), and electron beam (EBW-DED). In contrast to fusion welding, the arc and beam sources melt the wire into a free-form structure of the desired part geometry. trunnion table is often integrated within DED platforms adding tilt and rotational axes. These aspects of the MAM of axes and the size of the component as either the robot or part, or both, can be mounted on a moveable platform. A Fig. 5 — Various powder nozzles: (a) coaxial (continuous annulus); (b) multi-jet; and (c) vectored nozzle capable of depositing inside a 57-mm ID to a depth of 610 mm. Courtesy of RPM Innovations Inc. Fig. 6 — (a) LP-DED systemwith multiple powder feeders or hoppers[5]; (b) coaxial nozzle powder flow path; and (c) vectored nozzle powder flow path. (c) (b) (c) (a) (a) (b)
RkJQdWJsaXNoZXIy MTYyMzk3NQ==