Electron beam melting (EBM) is a technique in which a machine part is manufactured by melting layer upon layer of powder to form the desired shape. This rapid manufacturing method uses an electron beam in a vacuum to produce the necessary temperature to melt the powder. Parts constructed in this manner are typically notable for having more desirable physical characteristics than parts constructed with other methods.
To build up a component through electron beam melting, the material to be worked is placed in a vacuum chamber. The size of this chamber determines the maximum possible size of the finished part. Electrons are then emitted from a filament and accelerated to approximately half the speed of light. Magnetic fields focus and direct the beam to the necessary locations. When the electrons collide with particles of powder, their kinetic energy is transformed to thermal energy thereby heating the powder.
As the beam only affects a very shallow area at the surface of the material, the part is built up layer by layer. Computers are typically used to control the location and dwell time of the beam, although an operator supervising the process will sometimes adjust it. Three-dimensional computer-aided design schematics provide the dimensional information necessary to direct the beam.
EBM is often referred to as a type of rapid manufacturing method known as additive manufacturing. Such processes deliver precise amounts of energy and material to precise locations to develop the desired structure. Rather than using a mold to define the shape of the part, additive manufacturing techniques use a three dimensional digital blueprint to specify its shape.
Metals are the most typical materials used to construct components with electron beam melting. Other materials, however, are sometimes used, such as ceramics and ceramic-metal composites. Electron beam melting is particularly suitable for use with materials that react with oxygen because fabrication takes place in a vacuum chamber.
There are a number of advantages associated with electron beam melting. Due to the high energy involved, this technology allows for high melting capacity and high productivity. EBM can produce components of extremely complex geometries. Resulting parts are generally noted for their extremely high density and lack of voids in the structure.
The extremely high temperatures typically involved in the process often produce metal parts with similar metallurgical characteristics to heat-treated components. For example, products of this method generally have higher strength and little to no residual stress compared to products of other fabrication methods. This often reduces production time by avoiding additional thermal treatment operations once the part has been built.
Components manufactured with electron beam melting are found in a wide variety of applications. Its suitability for use with reactive titanium alloys means that electron beam melting is frequently used to construct lightweight titanium components such as medical implants. Known for producing parts of high strength and good metallurgical quality, it is also frequently used to produce high-performance parts. For example, it is used to fabricate such items as turbine blades for aerospace applications and vehicle frames used in motor sports.