3M High Performance Vitrified Grinding Wheel 91VA is a vitrified bonded grinding wheels with a blend of white aluminum oxide and very low concentration of 3M Precision-Shaped Grain, featuring geometrically defined cutting edges. They’re ideal for economical single rib profile grinding of small gear parts.3M High Performance Vitrified Grinding Wheel 91VA provides an increased in-feed and feed rate while reducing the number of grinding passes to improve grinding operation cycle times, helping to reduce costs and increase productivity without sacrificing quality. Vitrified bonds are manufactured primarily of synthetic, technical glasses referred to as low-temperature bonds. Wheels made with these bonds are insensitive to chemicals and can be stored indefinitely. High Performance Series 3M High Performance Series balances advantages of a very low concentration of 3M Precision-Shaped Grain and low-temperature bond 601 and 901. The result is an economic grinding solution which lasts long, cuts fast and runs cool. These wheels feature a very low concentration of 3M Precision-Shaped Grain that makes them an economical solution for single rib gear grinding operations.