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Modeling of Thermal Spalling During Electrical Discharge Machining of Titanium Diboride

1991; Wiley; Volume: 74; Issue: 4 Linguagem: Inglês

10.1111/j.1151-2916.1991.tb06928.x

1551-2916

Ahmed M. Gadalla, Bedri Bozkurt, Nancy Faulk,

Advanced machining processes and optimization

Erosion in electrical discharge machining has been described as occurring by melting and flushing the liquid formed. Recently, however, thermal spalling was reported as the mechanism for machining refractory materials with low thermal conductivity and high thermal expansion. The process is described, here, by a model based on a ceramic surface exposed to a constant circular heating source which supplies a constant flux over the pulse duration. The calculations were based on TiB 2 mechanical properties along a and c directions. Theoretical predictions were verified by machining hexagonal TiB 2 . Large flakes of TiB 2 with sizes close to grain size and maximum thickness close to the predicted values were collected, together with spherical particles of Cu and Zn eroded from cutting wire. The cutting surfaces consist of cleavage planes sometimes contaminated with Cu, Zn, and impurities from the dielectric fluid.