16 Oct 3D Manufacturing’s Holy Grail Aerospace America
Great article from America Aerospace about the success of the implementation of EBAM technology from Sciaky, Inc. at the Lockheed Martin company.
Extract from the article:
Slade Gardner, a Lockheed Martin fellow focusing on advanced manufacturing and materials, refers to the powder bed method as “small metal,” because it typically is used to make such parts as mounting brackets for communications antennas. He calls the alternative wire-fusing process “big metal,” and his company hopes to someday make tanks that way for Orion and other spacecraft.
At Lockheed Martin, the big metal construction gear consists of a large vacuum chamber containing a robotic arm from Chicago-based Sciaky, Inc. It has an attached feeder containing a 100-pound spool of titanium wire and an electron gun. A vacuum is necessary for the electron gun to fuse the wire into shape. The arm moves along ceiling-mounted slides that allow it to move back and forth, left to right in what resembles a very large version of a desktop fabrication device, Gardner explains. The working chamber also contains a table that can tilt and move side to side, permitting the arm to build complex shapes. When the electron gun fuses the titanium wire, it creates a bead of metal. As layers of wire are put down, the resulting surface is rough and much thicker than the target width of what will be a lightweight structure. A second robotic arm trims away the excess metal and machines the walls down to their proper thickness. “Inherently it’s still a welding process. If you imagine the way that really beautiful weld beads look, they have some flow to them. We cannot achieve smooth wall surfaces using this deposition process,” Gardner says. To build a propellant tank, a satellite or rocket, the Sciaky wire-deposition gear builds two domes and a central “barrel” section. A grinder mounted on a robotic arm then machines the three parts to remove excess material and to achieve the desired thickness of .02 to .04 inch before they are welded together. So far, Lockheed Martin has built a 16- inch diameter prototype propellant tank, as well as parts for a 33-inch diameter tank. The prototype tanks are built to the requirements of the company’s A2100 communications satellite frames. It takes about 15 hours to get a tank to its basic shape, with each dome and barrel requiring roughly three hours to construct. The entire process from construction to machining, welding, and final testing takes roughly a month, Gardner says. This is a great improvement over the traditional method of making a tank, which required forging a mushroom-shaped dome of titanium and machining it down to size.