| dc.description.abstract | Material removal in electrical discharge machining, EDM is by thermal erosion.
Therefore, information on thermal phenomena of the process is required for further
analyses of the process. Currently, demands on micro components increase the
applications of EDM for micro machining significantly. This leads to the development
of EDM with comparatively lower discharge energy than that of conventional EDM. In
this work, for convenience the conventional and newly developed EDM is called macro
and micro EDM, respectively. Although there is no difference in principle and
mechanism of material removal between both processes, the micro EDM is capable of
producing micro components with higher accuracy beyond the capability of macro
EDM. However, unlike macro EDM, researches on the micro EDM thermal phenomena
are limited due to the small spatiotemporal scale of the process, which makes both
observation and analysis of the gap phenomena significantly difficult. Therefore, in this
work thermal phenomena of micro EDM were obtained including energy distribution
ratios, plasma diameter, power density and removal mechanism. These parameters were
compared with those of macro EDM, and their influence on micro and macro EDM
efficiencies were discussed. In this work, the efficiencies are represented by ratio of
removal with respect to molten area volume or removal efficiency, Re and ratio of
energy consumed for material removal with respect to energy distributed into workpiece
or energy efficiency, Ee. Both Re and Ee of micro EDM were greater than those of macro
EDM because the power density at micro EDM workpiece was found significantly
higher than that of macro EDM. These results also explain differences in their
performances such as the formation of white layer and residual stress. At the end of this
work, to show the importance of the obtained results, an example application that
describes deformation of micro fin machined by micro EDM due to thermal stress was
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