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NTN bearing internal clearance is how to choose.

NOVEMBER 02, 2022
NTN bearing internal clearance is how to choose.

The internal clearance of a bearing under operating

Criteria for selecting bearing internal clearance
A bearing's life is theoretically maximum when operating clearance is slightly negative at steady operation. In reality it is however difficult to constantly maintain this optimal condition. If the negative clearance becomes larger by fluctuating operating conditions, heat will be produced and life will decrease severely. Under ordinary circumstances study must be needed to have a clearance slightly larger than zero.
For ordinary operating conditions, use fitting for ordinary loads. If rotational speed and operating temperature are ordinary, selecting normal clearance enables you to obtain the proper operating clearance Table 8.2 gives examples applying internal clearances other than CN (normal) clearance.

NTN bearing internal clearance is how to choose.

Calculation of operating clearance.
Operating clearance of a bearing possible calculated from initial bearing internal clearance decrease in internal clearance thanks interference and decrease in internal clearance due to difference in temperature of the inner and outer rings.
δeff = δo − ( δf + δt ) ... ... ...... ( 8.1 ).
δeff: Effective internal clearance, mm.
δo: Bearing internal clearance, mm.
δf: Reduced amount of clearance thanks to.
interference, mm.

Adjustment of radial internal clearance based on.

conditions (effective clearance) is usually smaller than the initial clearance before being installed and operated. This is because of several factors including bearing fit, the difference in temperature between the inner and outer rings, etc. As a bearing's operating clearance has an effect on bearing life, heat generation, vibration, noise, etc.; care must be taken in selecting the most suitable operating clearance.