Electrocontact discharge dressing of a resin-bonded CBN grinding wheel and its grinding performance

A conductive resin-bonded CBN grinding wheel is dressed by means of an electrocontact discharge (ECD) method, and the effects of two discharge patterns, spark discharge and arc discharge, on the grinding wheel surface topography are investigated. It is found that the CBN grains are firmly held with the resin-bond matrix with no erosion of the nickel coating which covers the CBN grains when the open-circuit voltage in the spark discharge area or a voltage lower than 20 V is applied. An alloy steel is plunge ground and the grinding performance is compared between the ECD method and the mechanical dressing method using a GC cup-wheel. When the ECD dressing is applied in spark discharge mode, the grinding force shows the same value as that obtained from the GC cup-wheel method. However, the wheel wear is only one-half of the original value and the deterioration of surface roughness is lower than those in the case of the GC cup-wheel method.