Time dependent behavior of alumina grains manufactured by two different routes while grinding of AISI 52100 steels

Grinding is a finishing process in which material is removed from workpiece by hard abrasives with random shape and orientation. The sharpness of abrasive grains tends to vary with grinding time which has a direct impact on material removal mechanisms and hence, the ground surface quality. This urges the researchers to continuously monitor the behavior of abrasive grains online to improve the grinding efficiency. In this paper, two different types of wheels are used: one wheel consists of 100% conventional fused alumina grains and the other wheel is made of 30% sol-gel alumina grains and remaining 70% by fused alumina grains. In case of the wheel containing sol-gel grains, attritious wear of grain occurs as the grinding proceeds which increases the contact area between abrasive grains and workpiece leading to change in dominant material removal mechanism from shearing to plowing and rubbing. The generated wear flats increase the grinding force and temperature in the grinding zone. In case of grinding wheel with 100% fused alumina grains, grit fracture occurs when the grinding force exceeds a critical value leading to self-sharpening and thus maintains the dominant mechanism to be shearing. Post-grinding microstructural characterization is also done to evaluate the materials surface integrity from the aspects of wheel grain behavior.