Grease Service Life - Bosch Rexroth MAD Project Planning Manual

MAD / MAF Asynchronous Housing Motors
9.16

Grease service life

Reduction factors
Designation
Influence of dust and moisture on
the functional surfaces of the bear‐
ing
Influence of abrupt loads, vibrations
and oscillations
Influence of an increased bearing
temperature
Influence of a high load
Influence of air currents through the
bearing
If there is a centrifugal effect or if
the shaft is vertical depending on
the sealing
Calculation
The grease service life (t
bearing is started until it fails as a result of lubrication failure. Unfavorable
operating and ambient conditions reduce the grease service life. When the
grease service life to be expected (t
necessary that certain reduction factors for unfavorable operating and ambi‐
ent conditions be taken into account for each single case of application. The
following table specifies the reduction factors, which refer to publication no.
WL 81 115/4 DA by FAG Kugelfischer AG.
Designa‐ Influence
tion
Moderate
Strong
f
1
Very strong
Moderate
f
2
Strong
Very strong
Moderate (up to
75 °C)
strong (75 ...
f
3
85 °C)
very strong
(85 ... 120 °C)
P/C=0.1 ... 0.15
P/C=0.15 ... 0.25 0.7 ... 0.4
f
4
P/C=0.25 ... 0.35 0.4 ... 0.1
Minor currents
f
5
Strong currents
f
Vertical
6
Tab. 9-22: Grease service life reduction factors
Fig. 9-26: Reduction factors for calculating the grease service life to be expec‐
ted
) is defined as the time from the point when the
f
is determined, it is therefore absolutely
fq)
Factor Notes
0.9 ... 0.7 Rexroth offers the "radial shaft sealing
ring" as an option for this environment.
0.7 ... 0.4
If this option is used
0.4 ... 0.1
⇨ f = 1
1
e.g., with machine tools and printing
0.9 ... 0.7
presses
e.g., with materials handling equipment
0.7 ... 0.4
(portals)
0.4 ... 0.1 e.g., with punches, presses
The bearing temperature depends on the
0.9 ... 0.6
degree of capacity utilization of the motor.
If a special high-temperature grease is
0.6 ... 0.3
used: Utilization 0 ... 70%
⇨ f = 1
3
0.3 ... 0.1
Utilization 71 ... 100% ⇒ f
1.0 ... 0.7 Loading the shaft/bearing corresponding‐
ly in accordance with the respective shaft
load diagram results in the following for
MAD/MAF motors: Utilization 0 ... 70% ⇨
f = 1
4
Utilization 71 ... 100% ⇨ f
0.7 ... 0.5 There is no influencing air current in the
motor if it is operated properly
0.5 ... 0.1
⇨ f = 1
5
If the motor is installed horizontally
0.7 ... 0.5
⇨ f = 1
6
R911295781_Edition 11 Bosch Rexroth AG
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Application notes
= 0.99 ... 0.7
3
= 0.99 ... 0.7
4