Printing metal? There are several ways to do this, mostly involving mixing fine metal powder with a sticky medium, then firing it to fuse the metal together and burn of the sticky stuff. But now we've run across a completely different way to print metal.
Optomec's LENS technology (Laser Engineered Net Shaping) focuses a very high power laser (up to 4kW, ouch!) that fuses metal powder directly as it is deposited. Otherwise the same XYZ platform movements gradually build up the metal object. Will we see this appear inside inexpensive home 3D printers soon? Perhaps not:
The LENS process is housed in a hermetically-sealed chamber which is purged with argon so that the oxygen and moisture levels stay below 10 parts per million. This keeps the part clean, preventing oxidation. The metal powder feedstock is delivered to the deposition head by Optomec's proprietary powder-feed system, which is able to precisely regulate mass flow. Once a single layer has been deposited, the deposition head moves on to the next layer. By building up successive layers, the whole part is constructed. When complete, the component is removed and can be heat-treated, Hot-Isostatic-Pressed, machined, or finished in any customary manner.