Design and layout of bearing assembly bearing clearance, press fit

Theoretical bearing clearance

Bushes made from KS PERMAGLIDE® P1 and P2 are pressed into the housing and fixed in place radially and axially. No further measures are required. For rigid housings and shafts, the fitting tolerances from Table 1 result in the following:

  • The press fit
  • The bearing clearance as per Table 6

The theoretical bearing clearance is calculated as follows:

[12] Δsmax = dGmax – 2 · s3min – dWmin
[13] Δsmin = dGmin – 2 · s3max – dWmax

Δsmax [mm] Maximum bearing clearance
Δsmin [mm] Minimum bearing clearance
dGmax [mm] Maximum diameter of housing bore
dGmin [mm] Minimum diameter of housing bore
dWmax [mm] Maximum shaft diameter
dWmin [mm] Minimum shaft diameter
s3max [mm] Maximum wall thickness
s3min [mm] Minimum wall thickness (see Tab. 4)

Attention:

Widening the housing bore is not taken into consideration in the bearing clearance calculation.
For calculating the press-fit U, the tolerances of the housing bore are stated in Table 1 and the dimensions of the bush outside diameter DO are stated in Table 2.

Press fit and bearing clearance

The bearing clearance and press fit can be influenced by the measures shown in Tab. 7:

  • At high ambient temperatures
  • Depending on the housing material
  • Depending on the housing wall thickness.

Smaller clearance tolerances require narrower tolerances for the shaft and bore.

Attention:

When using shafts with tolerance zone position h, the bearing clearance for 5≤dW<80 (P10, P14, P147) and dW<80 (P 11) must be verified using equations [12] for Δsmax and [13] for Δsmin.

  • Tab. 1: Recommended fitting tolerances

    Diameter range

    P10, P14, P147*

    P11

    P20, P200

    Shaft

       

    dW <5

    h6f7h8

    5≤ dW <80

    f7f7h8

    80≤ dW

    h8h8h8

    Housing bore

       

    dG ≤5.5

    H6--

    5.5< dG

    H7H7H7
  • Tab. 2 - Dimensions for outside diameter Do

    Außendurchmesser der Buchse Do

    Abmaße (Prüfung A nach DIN ISO 3547-2)

     

    P10, P14, P147*, P20, P200

    P 11

     

    oberes

    unteres

    oberes

    unteres

    Do ≤ 10

    +0.055

    +0.025

    +0.075

    +0.045

    10 < Do ≤ 18

    +0.065

    +0.030

    +0.080

    +0.050

    18 < Do ≤ 30

    +0.075

    +0.035

    +0.095

    +0.055

    30 < Do ≤ 50

    +0.085

    +0.045

    +0.110

    +0.065

    50 < Do ≤ 80

    +0.100

    +0.055

    +0.125

    +0.075

    80 < Do ≤ 120

    +0.120

    +0.070

    +0.140

    +0.090

    120 < Do ≤ 180

    +0.170

    +0.100

    +0.190

    +0.120

    180 < Do ≤ 250

    +0.210

    +0.130

    +0.230

    +0.150

    250 < Do ≤ 305

    +0.260

    +0.170

    +0.280

    +0.190

  • Tab. 3 - Wall thickness s3 for P1 bushes and flange bushes

    Inside diameter of bush D1

    Wall thickness s3

    Dimensions to DIN ISO 3 547-1, Table 3, row B

      

    P10, P14, P147*

    P 11

      

    Upper

    Lower

    Upper

    Lower

    D1 ≤ 5

    0.75

    0

    -0.020

    --

     

    1--

    +0.005

    -0.020

    5 ≤ D< 20

    1+0.005

    -0.020

    +0.005

    -0.020

    20 ≤ D1 < 28

    1.5+0.005

    -0.025

    +0.005

    -0.025

    28 ≤ D1 < 45

    2+0.005

    -0.030

    +0.005

    -0.030

    45 ≤ D1 < 80

    2.5+0.005

    -0.040

    +0.005

    -0.040

    80 ≤ D< 120

    2.5

    -0.010

    -0.060

    -0.010

    -0.060

    120 ≤ D1

    2.5

    -0.035

    -0.085

    -0.035

    -0.085

  • Tab. 4 - Wall thickness s3 for bushes made from KS PERMAGLIDE® P20/P200

    Inside diameter D1

    Wall thickness

    Dimensions to DIN ISO 3 547-1, Table 3, row D, P20, P200

     

    s3

    Upper

    Lower

    8 ≤ Di < 20

    1

    -0.020

    -0.045

    20 ≤ Di < 28

    1.5

    -0.025

    -0.055

    28 ≤ Di < 45

    2

    -0.030

    -0.065

    45 ≤ Di < 80

    2.5

    -0.040

    -0.085

    80 ≤Di

    2.5

    -0.050

    -0.115

  • Tab. 5 - Outside bevel Co and inside bevel Ci (Fig. 2) for bushes with metric dimensions to DIN ISO 3 547-1, Table 2

    Wall thickness s3

    Outside bevel, without cutting Co

    Inside bevel Ci

     

     

    Min.

    Max.

    0.75

    0.5 ± 0.3

    0.1

    0.4

    1

    0.6 ± 0.4

    0.1

    0.5

    1.5

    0.6 ± 0.4

    0.1

    0.7

    2

    1.0 ± 0.4

    0.1

    0.7

    2.5

    1.2 ± 0.4

    0.2

    1.0

  • Tab. 6: Theoretical bearing clearance after press-fitting bushes or flange bushes with metric dimensions, without consideration of possible widening of the bore

    Bush diameter

    Bearing clearance Δs

    P10, P11, P14, P147*

    P20, P200

    Di (mm)

    Do (mm)

    Δsmin (mm)

    Δsmax (mm)Δsmin (mm)

    Δsmax (mm)

    2

    3.5

    0

    0.054

    --
    3

    4.5

    0

    0.054

    --
    4

    5.5

    0

    0.056

    --
    570

    0.077

    --
    680

    0.077

    --
    79

    0.003

    0.083

    --
    810

    0.003

    0.086

    0.040

    0.127

    1012

    0.003

    0.092

    0.040

    0.130

    1214

    0.006

    0.092

    0.040

    0.135

    1315

    0.006

    0.092

    --
    1416

    0.006

    0.092

    0.040

    0.135

    1517

    0.006

    0.092

    0.040

    0.135

    1618

    0.006

    0.092

    0.040

    0.135

    1820

    0.006

    0.095

    0.040

    0.138

    2023

    0.010

    0.112

    0.050

    0.164

    2225

    0.010

    0.112

    0.050

    0.164

    2427

    0.010

    0.112

    0.050

    0.164

    2528

    0.010

    0.112

    0.050

    0.164

    2832

    0.010

    0.126

    0.060

    0.188

    3034

    0.010

    0.126

    0.060

    0.188

    3236

    0.015

    0.135

    0.060

    0.194

    3539

    0.015

    0.135

    0.060

    0.194

    4044

    0.015

    0.135

    0.060

    0.194

    4550

    0.015

    0.155

    0.080

    0.234

    5055

    0.015

    0.160

    0.080

    0.239

    5560

    0.020

    0.170

    0.080

    0.246

    6065

    0.020

    0.170

    0.080

    0.246

    6570

    0.020

    0.170

    --
    7075

    0.020

    0.170

    0.080

    0.246

    7580

    0.020

    0.170

    0.080

    0.246

    8085

    0.020

    0.201

    0.100

    0.311

    8590

    0.020

    0.209

    --
    9095

    0.020

    0.209

    0.100

    0.319

    95100

    0.020

    0.209

    --
    100105

    0.020

    0.209

    0.100

    0.319

    105110

    0.020

    0.209

    --
    110115

    0.020

    0.209

    --
    115120

    0.020

    0.209

    --
    120125

    0.070

    0.264

    --
    125130

    0.070

    0.273

    --
    130135

    0.070

    0.273

    --
    135140

    0.070

    0.273

    --
    140145

    0.070

    0.273

    --
    150155

    0.070

    0.273

    --
    160165

    0.070

    0.273

    --
    180185

    0.070

    0.279

    --
    200205

    0.070

    0.288

    --
    220225

    0.070

    0.288

    --
    250255

    0.070

    0.294

    --
    300305

    0.070

    0.303

    --
  • Tab. 7 - Errors, consequences and measures in relation to press fit and bearing clearance at high ambient temperatures, with special housing materials or housing wall thicknesses

    Design and environmental influences

    Consequence

    Measure

    Note

    Alloy or thin-walled housing

    Extensive widening
    Excessive clearance

    Reduce housing bore dG

    The housing is under greater strain; the permitted housing tension must not be exceeded.

    Steel or cast iron housing at high ambient temperatures

    Smaller clearance

    Reduce shaft diameter dW by 0.008 mm per 100°C above room temperature

     

    Bronze or copper alloy housing at high ambient temperatures

    Poor press fit

    Reduce housing bore dG, recommended change to diameter per 100°C above room temperature: dG -0.05%

    Reduce shaft diameter dW by the same value, in order to retain the same bearing clearance.

    Aluminium alloy housing at high ambient temperatures

    Poor press fit

    Reduce housing bore dG, recommended change to diameter per 100°C above room temperature: dG -0.1%

    Reduce shaft diameter dW by the same value, in order to retain the same bearing clearance. The housing is under greater strain at temperatures below 0°C; the permitted housing tension must not be exceeded.

    Bushes with thicker layer of corrosion protection

    Outside diameter Do
    too large
    Insufficient clearance

    Enlarge housing bore dG
    Example:
    Layer thickness 0.015 ± 0.003 mm producing dG +0.03 mm

    The bush and housing are subject to greater strain unless appropriate measures are taken.


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