Why should axial seating against a shaft shoulder be checked after thermal mounting?

LILY Bearing | 2026-10-28

Best answer

Thermal assembly includes an axial seating requirement

A heated ring may move readily into place while expanded, but the completed assembly still needs the intended relationship with its shoulder or locating face.

NSK's hot-mounting guidance includes measures to avoid a gap as the bearing cools. The general principle is to verify the final seating condition under the specified method, not to assume that the first apparent contact remains adequate throughout temperature equalisation. The geometry of the shoulder and bearing corner also matters. An unexplained gap can reflect a different issue from insufficient movement during assembly, so its cause must be established before more force or a changed fastening method is proposed.

Record the condition at the specified inspection stage

Identify the axial locating face, bearing orientation and the seating checks required by the approved mounting procedure.

Record when the observation was made relative to heating and cooling, and any subsequent specified verification. If a gap remains, retain its location and measured evidence along with the bearing and shaft drawing identifiers. Do not hide the observation by reporting only that the bearing was heated and installed. Compare the actual interface and mounting sequence before deciding on corrective action. The record should demonstrate how the intended final location was verified; it should not invent a universal holding time, impact method or locknut torque from a general description.