Layered fabrication now growing solid metal parts
March 6, 2006 A new rapid manufacturing and prototyping system that makes 100 percent solid metal parts has been introduced to the market - the ARCAM EBM S400. Employing a patented CAD-to-Metal process, which is based on Electron-Beam Melting (EBM), the highly efficient system produces parts from titanium powder and does so between three and five times faster than other additive fabrication methods. In contrast to laser sintering (SLS), the electron beam fully melts the metal particles to produce a void-free part. The process occurs in a high vacuum, which ensures the part is completely solid, without imperfections caused by oxidation.
The EBM process is ideal for applications where high strength or high temperatures are required. Medical product manufacturers can benefit from the parts' high flexural strength for bone implants requiring cycle life exceeding 10 million cycles (or movements). Automobile makers can build strong parts for high temperature testing, including under-the-hood applications. Aerospace engineers will be interested in the combination of a high strength yet light weight titanium part. And because the EBM process produces a homogenous solid, parts can be flight-certified.
All additive-fabrication processes build parts in layers following a tool path defined by CAD geometry. In the EBM process, each layer is formed when an electron beam, following the tool path, is directed onto a bed of metal powder. The beam liquefies the powder in fine paths, forming the required shape. The process uses a high power electron beam that is 95 percent efficient -- 5 to 10 times more so than a laser beam. This efficiency results in the creation of parts 3 to 5 times faster than other metal additive-fabrication methods, and it uses only seven kW of average power. With laser-based systems, like sintering, 95 percent of the light energy is reflected by the powder rather than absorbed, significantly reducing efficiency.
"The high speed electron beam system is the next generation of additive fabrication technology for rapid manufacturing of titanium parts," says Crump. "The machine creates parts comparable to wrought titanium and better than cast titanium, with a 95 percent powder recovery yield, which is unheard of in our industry."
Two variations of titanium "six four" alloy are available for the EBM S400: Ti6AL4V and Ti6AL4V ELI. Titanium parts created on the system are accurate near-net shape and are HIP heat treatable. The system builds parts up to approximately 8 x 8 x 7 in. (200 x 200 x 180 mm), with a layer thickness range of 0.002 to 0.008 in. (0.05 - 0.2 mm).