4.2 Metallic materials

Powder-bed systems are designed to be used with metallic materials. Figure 19 shows a powder-bed system. Powder is added to the workpiece in a thin layer using a roller or rake. The layer is then consolidated. A metal is usually fully melted but sometimes it is only sintered (compacted and heated). Lasers are the most common choice for an energy source because of the powers and wavelengths available, but electron beams have also been used. Electron beams require a high vacuum though and are therefore less popular.

Figure 19 Powder-bed system

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Figure is a sketch showing a laser and scanner forming a component in a powder bed.

Figure 19 Powder-bed system

The powder-feed system shown in Figures 20 and 21 delivers material through a powder nozzle directing a stream of powder into the path of a laser or electron beam. A wire can be used instead of the powder stream.

Figure 20 Powder-feed system

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Figure is a sketch showing a laser and beam guidance system forming a component from deposited material delibered by deposition heads.

Figure 20 Powder-feed system

Figure 21 A powder-feed system in operation. The powdered metal feedstream, confined and protected against oxidation with a surrounding jet of inert shielding gas, is fused by a laser focused through a central bore in the head.

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This figure shows the laser for a powder feed system

Figure 21 A powder-feed system in operation. The powdered metal feedstream, confined and protected against oxidation with a surrounding ...

Both powder-bed and powder-feed systems have benefits and drawbacks (Table 1).