Shaft and housing tolerances

The fit is determined by the ISO tolerances for shafts and housings (ISO 286) in conjunction with the tolerances Δdmp for the bore and ΔDmp for the outside diameter of the bearings (DIN 620).

Tolerance zones

The ISO tolerances are defined in the form of tolerance zones. They are determined by their position relative to the zero line (= tolerance position) and their size (= tolerance grade, see ISO 286). The tolerance position is indicated by letters (upper case for housings, lower case for shafts). For a schematic representation of the most common rolling bearing fits.

Fits for rolling bearings
Fits for rolling bearings
(1)Zero line
(2)Nominal diameter
(3)Medias/00016412_mei_in_0k_0k.gif Loose fit
(4)Transition fit
(5)Tight fit
(6)Shaft diameter
(7)Housing bore
ΔDmp = tolerance for bearing outside diameter
Δdmp = tolerance for bearing bore

Reference to tables of shaft and housing tolerances

The tables as below contain recommendations for the selection of shaft and housing tolerances that are valid for normal fitting and operating conditions.

Deviations are possible if particular requirements apply, for example in relation to running accuracy, smooth running or operating temperature. Increased running accuracies thus require closer tolerances such as tolerance grade 5 instead of 6. If the inner ring is warmer than the shaft during operation, the seating may loosen to an impermissible extent. A tighter fit must then be selected, for example m6 instead of k6.

In such cases, the question of fits can only be resolved by a compromise. The individual requirements must be weighed against each other and those fulfilled that give the best overall solution.

Shaft tolerances for radial bearings with cylindrical bore

Condition of rotation Bearing type Shaft diameter
mm
Displacement facility
Load
Tolerance zone
Point load on inner ring Ball bearings, roller bearings All sizes Inner ring easily displaced g6 (g5)
Inner ring not easily displaced, angular contact ball bearings and tapered roller bearings with adjusted inner ring h6 (j6)
Needle roller bearings All sizes Non-locating bearing h6 (g6)1) 
Circum‑ ferential load on inner ring or indeter-
minate load direction
Ball bearings up to 50 Normal loads2)  j6 (j5)
50 to 100 Low loads3)  j6 (j5)
Normal and high loads4)  k6 (k5)
100 to 200 Low loads2)  k6 (m6)
Normal and high loads5)  m6 (m5)
over 200 Low loads m6 (m5)
Normal and high loads n6 (n5)
Roller bearings up to 60 Low loads j6 (j5)
Normal and high loads k6 (k5)
60 to 200 Low loads k6 (k5)
Normal loads m6 (m5)
High loads n6 (n5)
200 to 500 Normal loads m6 (n6)
High loads, shocks p6
over 500 Normal loads n6 (p6)
High loads p6
Needle roller bearings up to 50 Low loads k6
Normal and high loads m6
50 to 120 Low loads m6
Normal and high loads n6
120 to 250 Low loads n6
Normal and high loads p6
250 to 400 Low loads p6
Normal and high loads r6
400 to 500 Low loads r6
Normal and high loads s6
over 500 Low loads r6
Normal and high loads s6
  1. For easier fitting.
  2. C/P > 10
  3. C/P > 12
  4. C/P < 12
  5. C/P < 10

Shaft tolerances for axial bearings

Load Bearing type Shaft diameter Operating conditions Tolerance zone
Axial load Axial deep groove ball bearings All sizes - j6
Axial deep groove ball bearings, double direction - k6
Axial cylindrical roller bearings with shaft locating washer - h6 (j6)
Axial cylindrical roller and cage assemblies - h8
Combined load Axial spherical roller bearings All sizes Point load on shaft locating washer j6
up to 200 mm Circumferential load on shaft locating washer j6 (k6)
over 200 mm k6 (m6)

Housing tolerances radial bearings

Condition of rotation Displacement facility Load Operating conditions Tolerance zone
Point load on outer ring Outer ring easily displaced, housing unsplit The tolerance grade is determined by the running accuracy required H7 (H6)1)
Outer ring easily displaced, housing split H8 (H7)
Outer ring not easily displaced, housing unsplit High running accuracy required H6 (J6)
Outer ring not easily displaced, angular contact ball bearings and tapered roller bearings with adjusted outer ring Housing split Normal running accuracy H7 (J7)
Outer ring easily displaced Heat input via shaft G72) 
Circum‑ ferential load on outer ring or indeter-minate load direction Low loads, outer ring cannot be displaced For high running accuracy requirements: K6, M6, N6 and P6 K7 (K6)
Normal loads, shocks, outer ring cannot be displaced M7 (M6)
High loads, shocks (C/P < 6), outer ring cannot be displaced N7 (N6)
High loads, severe shocks, thin-walled housing, outer ring cannot be displaced P7 (P6)

1, G7 for housings made from flake graphite cast iron GG, if bearing outside diameter D > 250 mm and temperature difference between outer ring and housing > 10 K.

2, F7 for housings made from flake graphite cast iron GG, if bearing outside diameter D > 250 mm and temperature difference between outer ring and housing > 10 K.

Housing tolerances for axial bearings

Load Bearing type Operating conditions Tolerance zone
Axial load Axial deep groove ball bearings Normal running accuracy High running accuracy E8
H6
Axial cylindrical roller bearings with housing locating washer - H7 (K7)
Axial cylindrical roller and cage assemblies - H10
Axial spherical roller bearings Normal loads High loads E8
G7
Combined loads Point load on housing locating washer Axial spherical roller bearings - H7
Combined loads Circumferential load on housing locating washer Axial spherical roller bearings - K7

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