Electron beam machining (EBM) is a metallurgy term that describes a process in which the concentrated heat from an electron beam is used for melting metal. The process usually takes place inside a vacuum, thus protecting the metal from the outside atmosphere as a flux does in traditional welding processes. The process is used in a variety of applications, including welding, annealing, and metal removal.
Due to the complexity and expense of the equipment, as compared to laser beam machining equipment, this type of machining has not become a keystone of industry and manufacturing. While the electron beam processes produce a smoother surface finish and more precise results than other machining processes, the need for specially trained operators and the inherent limitations of the equipment make electron beam machining unsuitable for most industries. This equipment is primarily used in the electronics industry, which uses the technology to etch the circuits of microprocessor units and other miniaturized technology.
EBM can cut many different types of metal and metal alloys. The electron beam is highly focused, and thus produces a thinner kerf or cut area than many other thermal methods. The process also produces a smoother surface on cut faces that requires little, if any, surface finishing for the end product.
Typically, the welding application of this process produces a highly concentrated heat within a vacuum chamber. This vacuum serves as a flux to protect the joint as the heat of the beam machining process melts the two pieces of metal and any filler metal, allowing these pieces to be joined together. The welding process of electron beam machining in this way is limited by the size of the vacuum chamber. To work around this limitation, this type of machining is sometimes used in an open air form, called non-vacuum EBM, but this greatly reduces the power of the process and the thickness of the metals that can be effectively worked.
A third application of electron beam machining is annealing of metal and metal alloys through the use of heat. The metal parts to be processed are placed inside the vacuum chamber and then bombarded with high velocity electrons. As these electrons reach the metal, the part is heated to its melting point and then allowed to cool. This heating and cooling process softens the metal to prepare it for further metalworking.