Influence of the conductivity of working fluid on quality of brass surface with low melting point and low hardness was investigated by single factor experiment.Based on observation and analysis of the surface microscopic morphology and chemical composition in processing surface

the processed surface roughness and the surface layer of the brass after cutting three times by electric sparking were analyzed.The results reveal that the surface roughness of the brass has a highly significant non-linear relationship with the conductivity of working liquid.With the increase of conductivity of working liquid

brass surface roughness is decreased firstly and then increased

where the minimum value is 1.63μm.The machining surface exhibits concave

irregular drop with tiny holes

ball drop

electrolytic pinhole and micro crack

which are different distribution with different conductivity of working liquid.Because the recast layer without Mo element

the molybdenum wire presnts nearly without melting loss.Oxygen content is increased with the increase of the conductivity of working liquid.