ABSTRACT
Additive thermal techniques involving EBM, LBM, and arc machining are covered in Chapter 9.
Among thermal methods, electrical discharge machining (EDM), using electrical sparks for cutting, is one of the oldest. In an “uncontrolled” fashion, EDM has existed ever since the first thunderstorm. The first widespread “controlled” application for shaping some of the toughest metals was developed during World War II. Although the EDM principle was discovered during the early 1940s, it was not until the early 1950s that the first practical EDM machine was designed. In the United States, during the 1960s, EDM machining was used to create features in the 75-µm range; even more precise EDM, using rotating spindles, was pioneered in Japan in the late 1980s (5-µm size range). There are two major types of EDM: wire EDM and sinker EDM. Sinker EDM is the older of the two. Wire EDM was introduced as a machining process in 1969. EDM, until 10 years ago, found limited application in micromachining1; given its very good accuracy, the method is now being investigated for a wide variety of miniaturization problems. Electron beam machining (EBM) and laser beam machining (LBM), two other examples of thermal techniques, were developed in the 1960s and 1980s, respectively. In EBM, high velocity electrons are used instead of sparks, and in LBM intense photon pulses are used. Some authors group EBM, LBM, and ion-beam machining together as high-energy beam machining. Ion-beam machining is a mechanical removing technique and as such is covered in Chapter 6 on mechanical energy-based removing techniques. We only touch briefly on plasma arc cutting because the method has only limited utility in miniaturization science.
