Bearing fit and clearance

Check each measurement convention

Use the diametral fit values and clearance convention requested by the fields. Do not mix radial interference with diametral interference. Fit-transfer factors depend on the assembly; they are not universal constants for all rings, shafts, and housings.

A negative result needs further investigation

The estimate can indicate clearance loss under the assumed conditions, but it does not calculate rolling-element contact loads or a valid preload setting. Confirm the bearing's clearance class, tolerances, fits, and operating temperatures using the manufacturer's application guidance.

Checking the least favorable clearance condition

Start with the bearing's relevant initial clearance, then apply the entered reductions from the shaft and housing fits. Temperature terms account for the modeled relative growth of the rings. A warm inner ring can reduce clearance relative to a cooler outer ring, but the overall result depends on the dimensions and temperatures represented. The worksheet does not infer ring temperatures from machine ambient temperature.

Evaluate a range when fits, initial clearance, or operating temperature are uncertain. Combining only nominal values can conceal a condition that loses clearance at an allowed tolerance extreme. Make sure the fit-transfer factors correspond to the geometry and support conditions; a thin housing can respond differently from a massive one. If the output becomes negative, it indicates a modeled interference or preload condition, not a calculated preload force. The relationship between internal clearance and rolling-element load requires additional bearing geometry and stiffness information. Use manufacturer selection guidance to decide whether the resulting operating condition is appropriate for the bearing type and application.

Formula

Operating clearance = initial clearance − fit reductions − inner growth + outer growth.