Increasing use of silicon nitride rollers in recent years has led to the development of ASTM F2094/F2094M, Specification for Silicon Nitride Bearing Balls. It was developed by ASTM Subcommittee F34.01, which is under the jurisdiction of Committee F34 on Rolling Element Bearings.

Examples of where hybrid roller bearings are found include high-speed machine tool spindles and high-pressure turbopumps that move liquid hydrogen in a space shuttle. End users of bearings, bearing manufacturers and roller manufacturers will use the standard to procure finished bearings to ensure they're made with sufficient material. Bearing companies can use the new standard to acquire finished silicon nitride rollers from the manufacturers, who will use the standard to ensure that unfinished roller blanks meet the material capability they need.

ASTM F2730/F2730M complements ASTM F2094/F2094M, Specification for Silicon Nitride Bearing Balls, according to William Mandler, general manager of Enceratec Inc. and task group chairman for the group responsible for developing the standard. "ASTM F2730, like ASTM F2094, provides a specification for the material used to make the roller-three levels of capability are included, so the material can be specified for the severity of the intended application," Mandler says. "The specification also provides dimensional specifications for form and surface condition of the finished roller."