Investigations on the Effect of Fluid Jet to Wheel Speed Ratio on Specific Grinding Energy

The use of metalworking fluid (MWF) in surface grinding is essential, but its supply contributes notably to the process energy demand. This study investigates the effect of the fluid jet to wheel speed ratio <i>q</i>_s on specific grinding energy and associated CO₂ emissions. Experiments with grinding wheels of different grit sizes (F60–F120) were conducted at cutting speeds of 35 and 60 m/s. Critical specific material removal rates <i>Q</i>’_{w, crit} were determined by taper grinding, with the onset of grinding burn identified by Barkhausen noise analysis. Based on these values and the grinding wheel width, specific process energies <i>e</i>_total were derived from grinding, pump, and machine base load. F120 wheels showed no systematic dependence of <i>Q</i>’_{w, crit} on <i>q</i>_s, whereas for coarser F80 and F60 wheels, decreasing <i>q</i>_s from 1.0 to 0.6 increased <i>Q</i>’_{w, crit} by 13–27% at 35 m/s and decreased it by 33–35% at 60 m/s. The most efficient process (F60, 35 m/s, <i>q</i>_s = 0.6) required 152.8 J/mm³, the least efficient (F120, 60 m/s, <i>q</i>_s = 0.8) 333.1 J/mm³. Because CO₂ emissions scale with <i>e</i>_total, the relative differences in energy directly indicate relative differences in CO₂ output. An illustrative case study shows that adjusting <i>q</i>_s alone (F80, 35 m/s) lowers annual emissions from 0.284 t to 0.206 t, a reduction of approximately 27%. These findings highlight the influence of <i>q</i>_s on grinding efficiency and process energy demand.