Ložiskové jednotky NTN-SNR

Bearing life calculation Life calculation SNR Ball Bearing Units SNR Industry 26 The inner design of bearing inserts for SNR ball bearing units are identical to deep groove ball bearings. They are manufactured out of the same material, have the same degree of precision, and are subject to the same strict production controls. The calculation of bearing life and load ratings are performed using the calculation methods in accordance with ISO 281 and ISO 76. Determining bearing sizes Before calculating the life of bearing units, the loads occurring must be determined. The required bearing size essentially depends on the load and the speed. If the load occurs mostly while the bearing rotates, this is referred to as dynamic load. However, if the load acts mainly during stand still, at very low speeds, or with slight rotating movements, this is referred to as static load. It is unimportant how the externally applied forces have their effect on the insert. The specification dynamic or static only refer to the operating condition of the bearing. Dynamic equivalent load If both radial and axial forces are applied to a bearing insert, these must be converted to an equivalent load (P) necessary for the calculation, as follows: P = X • F r + Y • F a [kN] P = dynamic equivalent load [kN] F r = actual radial load [kN] F a = actual axial load [kN] X = radial factor Y = axial factor e = limiting value C 0r = radial static load rating (see dimension tables for ball bearing units) F a Fa C 0r Fr ≤ e Fa Fr > e e X Y X Y 0.014 0.19 2.30 0.028 0.22 1.99 0.056 0.26 1.71 0.084 0.28 1.55 0.110 0.30 1 0 0.56 1.45 0.170 0.34 1.31 0.280 0.38 1.15 0.420 0.42 1.04 0.560 0.44 1.00