Electron Beam Melting – EBM
Electron Beam Melting is similar to laser melting, but working with an electron beam instead of a laser. The machine distributes a layer of metal powder onto a build platform, which is melted by the electron beam. The build platform is then lowered and the next layer of metal powder will be coated on top. The process of coating powder and melting where needed is repated and the parts are built up layer-by-layer in the powder bed. Electron beam melting requires support structures, which anchor parts and overhanging structures to the build platform. This enables the heat transfer away from where the powder is melted. Therefore, it reduces thermal stresses and prevents wrapping. The build envelope can be filled by several parts, which are built in parallel as long as they are all attached to the build platform. Noteworthy, parts are built under vacuum.
Compared to laser melting, EBM produces less thermal stress in parts and therefore requires less support structure and builds parts relatively faster. Additionally, EBM is quite similar to Selective Laser Melting – SLM, where EBM uses an electron beam in a vacuum, SLM uses laser in a chamber of inert gas.
Some of the most reputable aerospace companies have already started adapting the use of EBM additive manufacturing. For example, Honeywell Aerospace uses EBM to work with nickel-base super alloy Inconel 718, which is ideal for intense heat and pressure situations. Because EBM operates above 1,000°C, Honeywell can produce and research parts for extreme temperature environments. Furthermore, Bradshaw believes that for aerospace, the initial adoption driver is cost reduction using additive manufacturing to redo existing parts, as in the case of the Honeywell.
In the automotive industry, weigh reduction translates directly to savings in fuel consumption. The result of using EBM additive manufacturing helps reduce feature thickness due to the dense compacting of EBM manufacturing, which results in weight saving of over 25%.
In recent years, EBM has matured as a technology for rapid manufacturing of fully dense metal parts. With EBM, it is possible to create parts with geometries too complex to be fabricated using conventional methods; such as, fine network structures, internal cavities and channels. For example, EBM technology is a cost-efficient production process for both press-fit and cemented implants. Solid and porous sections of the implant are built in the same process step, eliminating the need to apply for example plasma sprayed porous materials through expensive secondary processes.