Grinding process applied to workpieces with different geometries interrupted using CBN wheel

Abstract

Although the fact that the interrupted cutting process is widely employed in traditional machining operations such as turning of crankshafts, engine piston ring, and helical tool sharpening, only a few number of studies in the literature approach this process. This study aims to evaluate the performance of the interrupted grinding process of workpieces with a different number of grooves (2, 6, and 12) in CBN grinding and to contribute to further findings about the integrity of interrupted surfaces and groove flanks after grinding, analyzing surface roughness and roundness deviation of workpieces after grinding process. The diametric wheel wear and grinding power were also recorded and analyzed. The performance of the interrupted grinding process was compared with the continuous grinding process, i.e., for workpieces without grooves. The AISI 4340 steel workpieces were tested under the application of flood lubri-cooling method at different feed rates (0.25, 0.50, and 0.75 mm/min). In conclusion, higher feed rate increased the surface roughness from 0.12 to 0.35 mu m for continuous grinding process, respectively at 0.25 and 075 mm/min. The interrupted grinding led to increase of surface roughness Ra values from 0.19 to 0.43 mu m (respectively 58.3% and 22.9% higher than continuous) for 2 grooves, 0.31 to 0.59 mu m (respectively 158.3% and 68.6% higher than continuous) for 6 grooves and 0.54 to 0.93 mu m (respectively 341.7% and 165.7% higher than continuous) for 12 grooves, respectively at 0.25 and 0.75 mm/min. As presented for surface roughness values, the increase of groove number resulted in higher values of roundness deviation, diametric wheel wear due to mechanical shocks caused by couplings and uncouplings of the grinding wheel. It was evidenced by SEM images of groove flanks and macro-fracture mode of abrasive grains. No microstructural damage was caused by thermal or mechanical irrespective of the experimental conditions investigated.