After entering data from design software into this 3-D printer, engineer Chris Turner watches as it forms the hinge layer by layer. A layer of fine metal particles is spread on the printing surface, and the machine uses a beam of electrons to fuse them into solid shapes in the designated areas.The electron beam sketches the outline of a cross-section of the part onto a thin layer of a powdered titanium alloy.
The beam completes its sweep, filling in the outline to form one layer of the part. The table supporting the fused metal then descends by 70 micrometers, and another layer of metal powder is spread on top. This process repeats until the entire part has been built.When printing is complete, finished parts are embedded within a block of powdered metal. Only the tops of the parts are visible. An engineer removes the leftover powder from around the printed parts. The machine shown here is a second type of 3-D printer that fuses the powder using lasers rather than electron beams. Components begin to emerge from the block. Because the leftover powder can be reused to build more parts, the technique results in up to 95 percent less waste than machining processes. The finished components correspond exactly to an original computer model. The parts on the left are shaped like a conventional component. The ones on the right are the same component optimized to reduce weight. The size of the parts that can be made is currently limited by the size of the cavity inside the 3-D printer. Scaling up the process to print large parts could involve a printing head mounted on a crane that would deposit powder and melt it at the same time, using a laser or an electron beam.