Caster Bearing Fit and Clearance

Work out the axial clearance a caster bearing has when new, and what differential expansion of the axle and hub leaves once the caster is running hot.

A bearing that turns freely when cold can pinch its own clearance away once the caster runs warm, because the axle and the hub do not expand at the same rate. Enter the bore, the outside diameter, the initial clearance, and the service temperature rise, and the calculator returns the expansion of each component and the clearance left.

A negative remaining clearance is reported rather than clamped, because a bearing that has lost its clearance is the answer a seized caster needs explaining. The result is a screening model for the thermal side of fit only.

Result

Clearance lost to thermal expansion (µin)

0.14

Clearance remaining as a fraction

0.999

Clearance when new (µin)

125.00

Clearance when hot (µin)

124.86

Verdict

The bearing keeps working clearance at this temperature, so heat will not bind it. The remaining clearance also leaves room for the small amount of dirt and wear a caster picks up in service.

Bearing note

A deep groove ball bearing carries radial load in both directions and is the usual choice in a caster. It needs a grease fitting or a sealed variant, because a ball bearing that runs dry will brinell and fail quickly.

What to check

Enter the temperature rise of the bearing itself where it can be measured, not the ambient room rise.
Check the initial clearance against the bearing maker's class, not a catalogue average.
Treat a passing result as a thermal check only and confirm the press fit separately.