Abstract: Metal ceramic has excellent properties both of metal and ceramic including high temperature resistance, corrosion resistance and so on, which is widely used in various types of aircraft shell, engine nozzle and other high-performance components. An environmentally-friendly and clean dry electrical discharge grinding (DEDG) process is proposed to efficiently and precisely machine metal ceramic. The relationships between the cutting depth of single grain and depth of crater and electrical discharge grinding process parameters of metal ceramic are theoretically analyzed. The mathematical model of DEDG process parameters and ground surface roughness is established. The influences of grinding process parameters including wheel speed, feed speed and grinding depth, as well as impulse discharge process parameters including open-circuit voltage, impulse width and impulse interval on the ground surface qualities of metal ceramic are systematically investigated. The results show that when the grinding depth a_p was less than the grain protrusion height h_g, the surface roughness of axial DEDG had no direct relation with grinding depth and impulse interval, but it increased with the increase of feed speed, open-circuit voltage and impulse width, and decreased with the increase of wheel speed. Compared with the measured surface roughness of DEDG, the minimum error and average error of the established mathematical model can reach 0.39% and 6.55%, respectively, which can better predict the electrical discharge ground surface roughness. When the open-circuit voltage is less than 30 V (the cutting depth of single grain f_g is greater than effective removal depth of discharge crater h_c), the surface removal form of metal ceramic materials was dominated by mechanical grain scratching. On the contrary, the material surface was mainly eroded by electrical spark discharge.

Key words: electrical discharge grinding, grinding process, surface roughness, electrical spark discharge, metal ceramic