Timken Super Precision Bearings for Machine Tool Applications

ENGINEERING
A
SHAFT AND HOUSING TOLERANCES
Shaft Geometry Requirements
t3
A
t3
B
A
Ra
Ra
B
t2
d
d
t2
t1
t1
Shaft Tolerances
t4
A
Description
Symbol
Tolerance
value
MV
ABEC 7 (ISO P4)
MMV/MM
ABEC 7/9 (ISO P4S)
MMX
ABEC 9 (ISO P2)
Roundness t1 IT2 IT1 IT0
Parallelism //
t2 IT2 IT1 IT0
Squareness t3 IT2 IT1 IT0
Concentricity t4 IT3 IT2 IT2
Surface Finish Ra 16 (μin.) or 0.4 μm
Shaft journal diameter
(d)
mm
Units – micrometer (μm)
Shaft journal diameter
(d)
mm
Units – microinches (μin.)
> ≤ IT0 IT1 IT2 IT3 > ≤ IT0 IT1 IT2 IT3
— 10 0.6 1.0 1.5 2.5 — 10 20 40 60 100
10 18 0.8 1.2 2.0 3.0 10 18 30 50 80 120
18 30 1.0 1.5 2.5 4.0 18 30 40 60 100 160
30 50 1.0 1.5 2.5 4.0 30 50 40 60 100 160
50 80 1.2 2.0 3.0 5.0 50 80 50 80 120 200
80 120 1.5 2.5 4.0 6.0 80 120 60 100 160 240
120 180 2.0 3.5 5.0 8.0 120 180 80 140 200 310
180 250 3.0 4.5 7.0 10.0 180 250 120 180 280 390
250 315 — 6.0 8.0 12.0 250 315 — 240 310 470
Reference ISO 286.
90 TIMKEN MACHINE TOOL CATALOG