Loads

There are no standardized calculation methods internationally for calculating basic load ratings for polymer ball bearings. According to the current state of technology, a bearing rating life calculation is not possible.
For low speeds (n < 25 r/min), the static load limit is to be used.
Dynamic
load limit
The dynamic load limit is an indication of the operational load that the bearing can accommodate in the majority of applications under standard conditions. The dynamic load limit depends on the operating conditions and needs to be adjusted under the following conditions:
  • operating temperature T > 50 °C (120 °F)
  • rotational speed n > 20% of the limiting speed nlim (→ product table)
The adjusted dynamic load limit can be estimated by using
Clima = fT fn C

Calculation example
Bearing 6301/HR11TN, n = 650 r/min, T = 90 °C (195 °F)

From the product table:
  • Clim = 0,31 kN
  • nlim = 1 300 r/min
From diagram 1:
  • with T = 90 °C (195 °F) and rings made of POM
    → fT ≈ 0,87
  • with n/nlim: (650/1 300) x 100 = 50%
    → fn ≈ 0,85

Clima = 0,87 x 0,85 x 0,31 = 0,229 kN
Static
load limit

The static load limit is the maximum load that a bearing can accommodate at standstill without sustaining damage to the balls or raceways. It depends on the operating temperature and needs to be adjusted at operating temperatures T > 50 °C (120 °F).

The adjusted static load limit can be estimated by using
C0lima = fT C0

Symbols


Climdynamic load limit [kN] (→ product table)
Climaadjusted dynamic load limit [kN]
C0limstatic load limit [kN] (→ product table)
C0limaadjusted static load limit [kN]
fnadjustment factor for speed (diagram 1)
fTadjustment factor for operating temperature (diagram 1)
n
rotational speed [r/min]
nlim
limiting speed [r/min] (→ product table)
T
operating temperature [°C (°F)]

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