A numerical investigation on material removal mechanism of electro discharge machining of non-conductive ceramics

Although Ceramics are well known for some of their excellent properties such as high hardness, thermal and chemical resistance, wear resistance and high strength, they are also limited in terms of machining due to hardness. Electro discharge machining has its upper hand when it comes to ceramics machining due to its noncontact and no force nature machining. However, for any materials to qualify for the electro-discharge machining, there is minimum requirement of electrical conductivity. Ceramics doped with conductive particles can be machined using EDM, whereas nonconductive ceramics needs assistive electrode EDM. While, material removal mechanism of conductive materials is predominately melting and evaporation, for non-conductive ceramics mechanism are mostly thermal spalling, melting, and evaporation This study aims to model the material removal rate and surface roughness associated with electro discharge machining of non-conductive machining. Proposed model is based on removal due to melting in multi discharge manner. Although model only considers removal due to melting, it is shown that it is agreeable to experimental results in a reasonable margin.