Page 56 - The Tribology Handbook

High temperature - oil oxidation limit - danger of excessive oil oxidation.
Background Industrial mineral oils can rapidly oxidize in an atmosphere containing oxygen (air). There is no precise limit;
degradation is a function of temperature and operating period. Bulk drain temperature limit in the general guide. Fig. 9.6, is
restricted to 7!i-80°C (assuming that the bulk temperatures of oil in tanks and reservoirs is of the same order).

Oil film whirl limit - danger of oil film instability.
Background Possible problem with lightly loaded bearings/rotors at high speeds.

RECOMMENDED MINIMUM DIAMETRAL CLEARANCE

E 0.6
E
w
V
5 0.5 0.02
LT
5
d 0.4 0.046
-I
a
a
L 0.3 0.012
I
a
-
D
2 0.2 0.008
3
I
-
z
p 0.1 0.004
I
0 u 1 I I I I l 1 1 I L I II11lI
mm- N g ggs g "0; N P
008 8
0 oog
0
O
0 0 000 O O
O
0 0000
8
8
SPEED, rev/rnin
Fig. 9.5. Recommended minimum clearance for steadily loaded bearings
(dashed line region - possibility of non-laminar operation)
GUIDE FOR ESTIMATING MAXIMUM CLEARANCE
Trends in bearing clearance tolerances -for bearing perjomance studies
A bearing where the housing A bearing which conforms to the
Bearing type bore tolerance has little housing bore. It has a larger
effect on bearing clearance tolerance as the wall thickness
(thickwalled or bored on and housing bore must also be
assembly). Small tolerance considered
((Bearing diieter, mm) 'I3 )
range
Typical to ( (Bearing dizeter, ~nm)'/~
tolerance (mm) on
diametral clearance

Maximum diametral clearance = Minimum recommended clearance (Fig. 9.5) + Tolerance (see trends above)

A9.3