Fundamental Investigation on EDM Characteristics of Lanthanum Hexaboride Applied for Cathode Parts

Abstract

Lanthanum hexaboride (LaB 6) is highly expected to be applied as high-performance electron emission cathode parts in place of conventional tungsten, since it has high electron emission property due to its low work function. It is considered that EDM has good potential to machine sintered LaB 6 with high hardness and brittleness. However, the EDM characteristics have not yet been made clear. In this study, the die-sinker and wire EDM characteristics of sintered LaB 6 were experimentally investigated, compared with those of alloy tool steel SKD11. Experimental results clarified that the material removal for LaB 6 was processed by material fracture in addition to material melting and boiling, and die-sinker EDM with low electrode wear was possible for LaB 6 even under finishing conditions with short pulse durations. It was also made clear that the cutting speed in wire EDM for LaB 6 is larger than that for SKD11.