High precision ball bearings - Spekuma Kullager AB

www.gmn.deBearing calculationThe service life calculation assesses a bearing solution withconsideration for bearing material fatigue under defined operatingconditions.Calculation methods per DIN ISO 76 (static load rating) and DIN ISO281 (dynamic load rating and service life)GMN offers an option for performingthese calculations by running the GLOBUSball bearing calculation program on acomputer; this permits selection of variousservice life solution options from thecomprehensive product line.1. Extended service life L nmL nm = a 1 · f t · a ISO · L 10a 1 : Factor for the probability of failuref t : Factor for operating temperaturea ISO : Life adjustment factor Û 7.L 10 : Nominal service life [h] Û 2.Failureprobability( )10L 10 =C––––– –– [h]60 · n ·3Pn : Speed [1/min]C : Dynamic load rating [N] Û 3.P : Equivalent bearing load [N] Û 5.10% 5% 4% 3% 2% 1%Factor a 1 1 0.64 0.55 0.47 0.37 0.25Maximum150°C 200°C 250°C 300°Coperating temperatureFactor f t 1 0.73 0.42 0.222. Nominal service life L 10GLOBUS bearing calculation program from GMNBearing service life calculation3. Dynamic load rating Cfor two or more spindle bearingsin X, O or Tandem arrangement:C = i 0.7 · C single [N]i: Number of bearingsC single : Load rating of single bearing [N]4. Axial loading F aF a = K a [N] (if K a > 3 · F V )F a = F V + 0.67 · K a [N] (if K a ≤ 3 · F V )K a : External axial force [N]F V : Preload [N]5. Equivalent bearing load PP = X · F r + Y · F a [N]F r F a : Radial load, axial load [N] Û 4.X, Y : Radial factor, axial factor Û 6.Equivalent bearing load is an auxiliary quantity. It serves to account for andstandardize various operating conditions and load relationships.6. X and Y factorsRelative axial loadSingle bearingBearing pairTandem arrangementin X or O arrangementi · F a / C 0e F a / F r ≤ e F a / F r > e F a / F r ≤ e F a / F r > eX Y X Y X Y X YSpindle bearingContact angle 15° 0.015 0.38 1.47 1.65 2.390.029 0.40 1.40 1.57 2.280.058 0.43 1.30 1.46 2.110.087 0.46 1.23 1.38 2.000.120 0.47 1 0 0,44 1.19 1 1.34 0.72 1.930.170 0.50 1.12 1.26 1.820.290 0.55 1.02 1.14 1.660.440 0.56 1.00 1.12 1.630.580 0.56 1.00 1.12 1.63Contact angle 20° 0.57 1 0 0.43 1.00 1 1.09 0.7 1.63Contact angle 25° 0.68 1 0 0.41 0.87 1 0.92 0.67 1.41Deep groove ball bearingsNormal internal clearance 0.014 0.23 2.30 2.78 3.740.028 0.26 1.99 2.40 3.230.056 0.30 1.71 2.07 2.780.085 0.34 1.55 1.87 2.520.110 0.36 1 0 0,56 1.45 1 1.75 0.78 2.360.170 0.40 1.31 1.58 2.130.280 0.45 1.15 1.39 1.870.420 0.50 1.04 1.26 1.690.560 0.52 1.00 1.21 1.63C 3 internal clearance 0.014 0.29 1.88 2.18 3.060.029 0.32 1.71 1.98 2.780.057 0.36 1.52 1.76 2.470.086 0.38 1.41 1.63 2.290.110 0.40 1 0 0,46 1.34 1 1.55 0.75 2.180.170 0.44 1.23 1.42 2.000.290 0.49 1.10 1.27 1.790.430 0.54 1.01 1.17 1.640.570 0.54 1.00 1.16 1.63C 0 : static load rating [N]e : Loading ratio: radial/axial loadFor Tandem arrangement: i = 1; C 0 and F a : Use single bearing valuesF r F a : Radial load, axial load [N]X , Y : Radial factor, axial factor86 87