Comparative study on machining behavior of brazed CBN wheel and vitrified CBN wheel during grinding powder metallurgy superalloy

The comparative grinding test of FGH96 powder metallurgy superalloy was carried out with brazed CBN wheel and ceramic CBN wheel. The grinding performance of CBN wheel was evaluated from the dimensions of grinding force and temperature, surface roughness and wheel wear.The results showed that the grinding force of brazed CBN wheel was close to or lower than that of ceramic CBN wheel, the grinding temperature of brazed CBN wheel was similar to that of ceramic CBN wheel at lower feed speed (≤360 mm/min), and the grinding temperature of ceramic CBN wheel was significantly higher than that of brazed CBN wheel at higher feed speed (≥ 540 mm/min). Under normal grinding conditions, the surface roughness of brazed CBN grinding wheel was lower than that of ceramic CBN grinding wheel, and the surface roughness R_a was lower than 0.800 μm, the average surface roughness R_a was 0.508 μm and 0.529 μm. Material adhesion and abrasion wear occurred in the abrasive grains on the working face of brazed CBN abrasive wheel, and the grinding surface appears material smeared. While for that of vitrified CBN abrasive wheel, in addition to wear, adhesion and grinding wheel blockage, the grinding surface was easy to form deep grooves due to grain breakage and falling off, which reduced the machined surface quality. Generally, the grinding performance of brazed CBN abrasive wheel on FGH96 was better than that of vitrified CBN abrasive wheel.