Beam Deposition Processes
Beam deposition (BD) processes enable the creation of parts by melting and deposition of material from powder or wire feedstock. Although this basic approach can work for polymers, ceramics, and metal matrix composites, it is predominantly used for metal
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Beam Deposition Processes
9.1
Introduction
Beam deposition (BD) processes enable the creation of parts by melting and deposition of material from powder or wire feedstock. Although this basic approach can work for polymers, ceramics, and metal matrix composites, it is predominantly used for metal powders. Thus, this technology is often referred to as “metal deposition” technology. To avoid limiting the readers’ understanding to just metal build materials, however, we will refer to this category of processes as beam deposition processes. BD processes use some form of energy focused into a narrow region (a beam), which is used to heat a material that is being deposited. Unlike the powder bed fusion techniques discussed in Chap. 5, BD processes are NOT used to melt a material that is pre-laid in a powder bed but are used to melt materials as they are being deposited. BD processes use a focused heat source (such as a laser, electron beam or plasma arc) to melt the feedstock material and build up 3-dimensional objects in a manner similar to the extrusion-based processes from Chap. 6. Each pass of the BD head creates a track of solidified material, and adjacent lines of material make up layers. Complex 3-dimensional geometry requires either support material or a multiaxis deposition head. A schematic representation of a BD process using powder feedstock material and laser is shown in Fig. 9.1. Most commercialized BD processes enable complete melting of powders using a focused high-power laser beam as the heat source. Research variants include using an electron beam or plasma source in place of the laser beam or the use of a thin metal wire instead of powder as the build material. In many ways, BD techniques can be used in an identical manner to laser cladding and plasma welding machines. For the purposes of this chapter, however, BD machines are considered as those which are designed to create depositions of complex 3D shapes directly from CAD files, rather than the traditional welding and cladding technologies, which were designed for repair, joining, or to apply coatings and do not typically use 3D CAD data as an input format.
I. Gibson, D.W. Rosen, and B. Stucker, Additive Manufacturing Technologies, DOI 10.1007/978-1-4419-1120-9_9, # Springer ScienceþBusiness Media, LLC 2010
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9 Beam Deposition Processes
Fig. 9.1 Schematic of a typical beam deposition process
Laser beam
Power Feed Nozzles Powder stream Layer thickness
Motion Track width
Fig. 9.2 LENS-deposited Ti/TiC metal matrix composite structure (4 layers on top of a Ti substrate)
A number of organizations have developed BD machines using lasers and powder feeders. These machines have been referred to as Laser Engineered Net Shaping (LENS) [1], Directed Light Fabrication (DLF) [2], Direct Metal Deposition (DMD), 3D Laser Cladding, Laser Generation, Laser-Based Metal Deposition (LBMD), Laser Freeform Fabrication (LFF), Laser Direct Casting, LaserCast [3], Laser Consolidation, LasForm and others. Although the general approach is the same, differ
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