Page 126 - The Tribology Handbook

Rolling bearing installation A22

Seatings
1 The fits intdicated in Table 22.2 should be used to avoid load-induced creep of the bearing rings on their seatings.

Table 22.2 Selection of seating fit

Rotatin,? member Radial load Shaft seating Homing seating
Shaft Constant direction Interference fit Sliding or transition fit
Shaft Rotating Clearance fit Interference fit
Shaft M housing Combined constant Interference fit Interference fit
direction and
rotating
~___
Housing Constant direction Clearance fit Interference fit
~~
Housing Rotating Interference fit Sliding or transition fit
2 Bearings taking purely axial loads may be made a sliding fit on both rings as there is no applied creep-inducing load.
3 Select the shaft and housing seating limits from Tables 22.3 and 22.4, respectively, these having been established to suit
the external dimensions, and internal clearances, of standard metric series bearings.
4 Where a free sliding fit is required to allow for differential expansion of the shaft and housing use H7.

Table 22.3 Shaft seating limits for metric bearings (values in micro-metres)

Shaft over - 6 10 18 30 50 80 120 150 180 250 315
mm -
incl. 6 10 la 30 50 80 120 150 180 250 315 400
~~
ht. grade j5 j5 j5 j5 j5 k5 k5 k5 m5 m5 n6 n6
Pt -
limits +3 +4 +5 +5 +6 +I5 +I8 +21 +33 +37 +66 +73
-2 -2 -3 -4 -5 +2 +3 +3 +I5 +I7 +34 +37
Sliding grade g6 g6 g6 g6 g6 96 g6 g6 g6 96 g6 g6
ft
limits -4 -5 -6 -7 -9 -10 -12 -144 -14 -155 -17 -18
-12 -14 -17 -20 -25 -29 -34 -39 -39 -44 -49 -54

EXAMPLE
Interference fit shaft 35 mm dia. tolerance from table = +6/-5pm. Therefore, shaft limit = 35.006/34.995 mm.

Table 22.4 Housing seating limits for metric bearings (values in micro-metres)
~~~
prsg over - 6 10 18 30 50 80 120 180 250 315 400 500 630
mm -- ---__
incl. 6 10 18 30 50 80 120 180 250 315 400 500 630 800
Int. grade M6 M6 M6 It46 M6 M6 M6 M6 M6 M6 MG M6 M6 M6
P __---___ ____--__---
limits -I -3 -4 -4 -4 -5 -6 -8 -8 -9 -IO -IO -26 -30
-9 -12 -15 -17 '-20 -24 -28 -33 --37 -41 -46 -50 -70 -80
Transition grade J6 J6 J6 J6 J6 J6 J6 56 J6 J6 J6 56 H6 H6
fit -_-___-
limits +5 +5 +6 +8 +I0 +I3 +I6 +I8 +22 +25 +29 +33 +44 +50
-3 -4 -5 -5 -6 -6 -6 -7 -7 -7 -7 -7 -0 -0

EX A M PL E
Transition fit housing 72 mm dia. tolerance from table = +13/-6km. Therefore, housing limit = 72.013/71.994 mm.
A22.2