Design and Safety Guidelines for FAG Radial Cylindrical Roller Bearings

Design and safety guidelines Load capacity and service life Bearing arrangements using FAG's ultra-precision cylindrical roller bearings are often used in applications where high load carrying capacity, high stiffness and high precision are required. In practice, fatigue failure caused by these bearings is rare. Therefore, the calculation of the rated life L10 in accordance with DIN ISO 281 to determine the working life is inaccurate. Bearing equivalent static load The equivalent static load P0 is calculated based on the axial and radial loads of the bearing.
  Ultra-precision cylindrical roller bearings can only withstand radial forces. For bearings subject to static loads, the following formula applies: P0 N bearing equivalent static load N bearing radial static load. The static load safety factor is sufficient for the static load bearing capacity. A given static load can be verified by the static load safety factor S0. S0 – Static load safety factor C0 N Basic static load rating P0 N Bearing equivalent static load. In order to use the high precision of the bearing, the static load safety factor S0 3 is necessary (S0 8 = anti-fatigue).

  Cylindrical Roller Bearing Clearance Adjustment Cylindrical roller bearings with tapered bores can be fitted with three conditions of free play, no play, or pretension, see page 126, table. For vertical lathes, 5 μm of interference has proven effective. The limit rotation nG given in the table of speed dimensions applies only to grease lubrication or to minimum oil lubrication and must not be exceeded. Cylindrical roller bearings, the rotational speed that can be achieved under movement is determined by the internal radial clearance, see table. The achievable speed dM = (d + D)/2 These values ​​are guidance values ​​when the inner and outer ring temperature difference T does not exceed 5 K. For applications with large temperature differences, consult the Schaeffler Group's Industrial Applications Division. Radially rigid radial stiffness cr is the ratio of radial load and radial displacement. Cr N/?m Radial stiffness, see dimension table Fr N Radial force r ? Radial displacement.
  Clearance or preloading up to speeds mm min–1 –5 to 0 to 0.5 n nG grease 2 10 10–5 d dM 0.5 to 0.75 n nG grease 4 10 10–5 d dM 0.75 to 1 n nG grease 1 · 10–4 · dM 1 · nG Oil bearing arrangement design In order to take full advantage of the performance of ultra-precision cylindrical roller bearings, adjacent structures must be properly designed, Figure 3. d = Nominal shaft diameter d? = Taper shaft small end diameter (= d + Deviation, see page 129, table) d1? = Taper shaft large end diameter d1? = d? + 1/12 · LL = Taper Shaft length L = 0.95 · B (bearing width) t1 = Cylindricity in accordance with DIN ISO 1101 t2 = Roundness in accordance with DIN ISO 1101 t3 = Flatness in accordance with DIN ISO 1101 t4 = Axial run in accordance with DIN ISO 1101 t5 = Conformity compliance DIN ISO 1101 ATD = taper tolerance in accordance with DIN ISO 7178 Ra = average surface roughness in accordance with DIN ISO 4768 Figure 3 Geometrical tolerances of the shaft Processing tolerances for the taper angle The taper angle tolerance ATD is measured by declining to the journal and defined as the differential diameter . If using the FAG taper MGK132, the value of the ATD in the table must be halved (inclination angle tolerance).

  For taper length tables in the table column values, the taper angle tolerance ATD can be obtained by interpolation. Taper deviation The taper angle deviation of the taper shaft mating face is used for bearings with tolerance class SP, see table. The main dimensions of the precision bearings are in accordance with the standard DIN 620-1. Dimensional tolerances and geometrical tolerances meet the tolerance class SP. Ultra-precision cylindrical roller bearings with higher tolerance class UP can also be provided by agreement. Bearings have cylindrical or tapered bores with corresponding dimensional tolerances, see figures 4 and 134, table. = Angle of inclination of the cone end = 2° 23? 9.4?2 = Taper angle of the cone end = 4° 46? 18.8?B = Inner ring width d = Nominal diameter of the bearing bore d1 = Cone large end bore diameter dmp = Single Aperture Deviation of Radial Plane Nominal Diameter Figure 4 Cone Hole Tolerance.