Abstract: Due to the difficulty of dressing of metal-bonded diamond grinding wheel, dry electro-contact discharge dressing is employed. In order to realize dressing of fine diamond grinding wheel effectively, removal behavior of metal bond for dry and wet coolants is investigated. In experimental study, dry impulse discharge machining experiment system is established to investigate effect of open-circuit voltage and discharge polarity on impulse discharge current, discharge duration, discharge gap, discharge removal, electrode wear ratio, etc. The results show that straight polarity does not produce electrode material adhered to machined surface and the dry discharge gap is 2～3 times less than the wet, which is suitable for dressing of fine diamond grinding wheel. In addition, there exists a critical open-circuit voltage from which spark discharge aroused by insulation breakdown is transferred to arc discharge companied with an arc pillar. Although the discharge removal of spark discharge may be much less than that of arc discharge, the elec-trode wear increases greatly when open-circuit voltage is less than certain value. It is confirmed that the results of impulse discharge machining experiment may be applicable to dry electro-contact discharge dressing of fine diamond grinding wheel, resulting in good wheel topography and improving ground surface.

Key words: Arc discharge, Dressing, Impulse discharge machining, Metal-bonded diamond grinding wheel, Spark discharge