Electron Beam Melting

Electron Beam Melting (EBM) is a type of rapid prototyping for metal parts. It is often classified as a rapid manufacturing method. The technology manufactures parts by melting metal powder layer per layer with an electron beam in a high vacuum. Unlike some metal Sintering techniques, the parts are fully solid, void-free, and extremely strong. Electron Beam Melting is also referred to as Electron Beam Machining.

High speed electrons .5-.8 times the speed of light are bombarded on the surface of the work material generating enough heat to melt the surface of the part and cause the material to locally vaporize. EBM does require a vacuum, meaning that the workpiece is limited in size to the vacuum used. The surface finish on the part is much better than that of other manufacturing processes. EBM can be used on metals, non-metals, ceramics, and composites.

The benefits of the EBM is its ability to make very small and accurate cuts. It can drill holes on the order of a few nanometers. EBM offers a good alternative to LBM because of its better surface quality and the fact that it does not have as great of a heat affected zone. EBM offers a narrow kerf width for more accuracy than other machining methods. Because EBM requires a vacuum in which to operate, the size of the workpiece is limited; this is the main limitation on the process. Geometry of the workpiece is a nonissue.

Technology

This solid freeform fabrication method produces solid metal pieces directly from metal powder with characteristics of the target material. The EBM machine reads data from a 3D CAD model and lays down successive layers of powdered material. In this way it builds up the model. These layers are fused together utilizing a computer controlled electron beam.

The melted material is from a pure alloy in powder form of the final material to be fabricated (no filler). For that reason the electron beam technology doesn't require additional thermal treatment to obtain the full mechanical properties of the parts. That aspect allows classification of EBM with LSM where competing technologies like SLS and DMLS require thermal treatment after fabrication. Comparatively to SLS and DMLS, EBM has a generally superior build rate because of its higher energy density and scanning method.

Minimum layer thickness: 0.05 mm

This technology was developed by Arcam AB in Sweden. [http://wohlersassociates.com/NovDec02TCT.htm “A Year Filled With Promising R&D”] . Wohlers Associates, Inc. November/December 2002]

Market

Titanium alloys are widely used with this technology which makes it a suitable choice for the medical implant market.

The CE-certified Fixa Ti-Por acetabular cup from the orthopaedic implant manufacturer [http://www.alaortho.com Adler Ortho] is produced with EBM. The cup is manufactured with an integrated lattice structure for enhanced osseointegration.

Aerospace and other highly demanding mechanical applications are also targeted. The tolerance capability of this technology is around +/-0.4 mm.

References

2.Manufacturing Engineering and Technology Fifth Edition. Serope Kalpakjian.

3.www.eng.ku.edu

External links

* [http://www.arcam.com/index.asp Arcam AB]
* [http://www.alaortho.com Adler Ortho Group]
* [http://www.rapidprototypinghomepage.com The Rapid Prototyping Home Page]
* [http://www.engineershandbook.com/RapidPrototyping/ebm.htm Engineer's Handbook]
* [http://www.automotivedesignline.com/howto/chassisandsuspension/198702147 Automotive DesignLine]
* [http://www.eod.gvsu.edu/eod/manufact/manufact-284.html Manufacturing Engineer On A Disk]
* [http://composite.about.com/library/glossary/e/bldef-e1937.htm About.com]