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 qs 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 Q’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 etotal were derived from grinding, pump, and machine base load. F120 wheels showed no systematic dependence of Q’w, crit on qs, whereas for coarser F80 and F60 wheels, decreasing qs from 1.0 to 0.6 increased Q’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, qs = 0.6) required 152.8 J/mm3, the least efficient (F120, 60 m/s, qs = 0.8) 333.1 J/mm3. Because CO2 emissions scale with etotal, the relative differences in energy directly indicate relative differences in CO2 output. An illustrative case study shows that adjusting qs 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 qs on grinding efficiency and process energy demand.