Electron Beam Melting - EBM Rapid Prototyping (original) (raw)

Rapid Prototyping -- Electron Beam Melting - EBM

Metal Part made by Arcam's EBM Process

With Arcam's Electron Beam Melting method a 100% solid metallic object is produced directly from metal powder. The part, which is to be produced, is designed in a three-dimensional CAD program. The model is sliced into thin layers, approximately a tenth of a millimeter thick. From a magazine of powder, an equally thin layer of powder is scraped onto a vertically adjustable surface. The first layer’s geometry is then created through the layer of powder melting together at those points directed from the CAD file, with a computer controlled electron beam. Thereafter, the building surface is lowered just as much as the layer of powder is thick, and the next layer of powder is placed on top of the previous. The procedure is then repeated so that the object from the CAD model is shaped, layer by layer by layer, until a finished metal part is complete.

The usage of a highly efficient computer controlled electron beam in vacuum provides high precision and quality. EBM makes possible the fabrication of homogeneous metal components such as complex tooling for spray-forming and injection molding tools and functional prototypes in a very short time. The production process is fast in comparison with conventional manufacturing methods. The highly efficient system produces parts from titanium powder and does so between three and five times faster than other additive fabrication methods. One other advantage is that reworking of the part is minimized. 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. The machine creates parts comparable to wrought titanium and better than cast titanium, with a 95 percent powder recovery yield. 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.

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.

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).

EBM systems are manufactured by Arcam AB and distributed in North America by Stratasys. Outside North America, the system is available from Arcam as the EBM S12.