Relations between specific grinding energy and gram depth ofcut are shown in Fig.7. Specific grinding energies increaseexponentially with decrease of the grain depth of cut. Thistendency is more remarkable when the grain depth of cuts areless than 0.02 pm. This means that high efficient grinding can berealized when grain depth of cut is greater than 0.02 urn.Fig.8 shows the effects of grain depth of cut on grinding force.Increasing the grain depth of cut induces higher grinding force.Under these experimental conditions, grinding forces increasedup to the limit of the motor capacity.This means that when wheel speed is increased, traversingspeed of workpiece or preset depth of cut also have to beincreased. Consequently, some optimum grinding conditions mayexist in the grinding of ultra high speed CBN wheel