Sizing a sintered self-lubricating bushing

Correct sizing of a sintered self-lubricating bushing increases product life and reduces the risk of failure.

Used under ideal conditions, a Metafram ring can last for tens of years.

The strength and life of a self-lubricating bushing depend on 4 major factors:

  • The speed of the shaft
  • The load on the bearing during operation, it is important to define and calculate it
  • The shaft material
  • The material of the Metafram sintered bushing

You can find all this information in our brochure

Determination of the shaft speed

Speed is a determining factor in the sizing of a Metafram bushing. In order to be able to determine this speed at the point of contact between the bearing and the shaft, it is important to have the following information:

  • N : The speed of rotation of the shaft in revolutions / minute (rpm)
  • Ø : The shaft diameter in meters (m)
formule_design_vitesse_coussinet

Material

BG10

BP25 / BP22 / BP15 / BP10

BG22 / BG20

BPV30

BPV50 / BPV60

FP18 / SO16 / TR16

FP20

Speed max

0,5 m/s

6 m/s

6 m/s

6 m/s

8 m/s

0,5 m/s

4 m/s

Speed min

NA

0,5 m/s

0,5 m/s

0,5 m/s

0,5 m/s

NA

0,5 m/s

Determination of the load on the shaft

The load on the shaft is the second element to be determined for the correct sizing of a Metafram bushing. For this you need to know your application and the force that is applied to the bearing.

On the side of the sinterted bushing, it is important to determine the force exerted on it. To do this, it is necessary to have the following 3 pieces of information:

  • F : The load of the shaft on the bearing (daN)
  • Ø int. : the internal diameter of the self-lubricating bushing (cm)
  • Long. : the length of the self-lubricating bushing (cm)
formule_design_charge_coussinet

Material

BG10 / BG22

BP25 / BP22 / BG20 / BPV30 / BPV50

BP15 / BPV60

BP10

FP20

FP18

SO16

TR16

Load max

75 daN/cm²

100 daN/cm²

175 daN/cm²

175 daN/cm²

225 daN/cm²

500 daN/cm²

600 daN/cm²

750 daN/cm²

Determination of the PV

Speed and load multiplication is essential for a sintered self-lubricating bushing. The higher the load, the lower the speed must be to preserve the Metafram ring and vice versa.

This multiplication is calculated very easily with the product of the speed and the load:

formule_design_couple_PV_coussinet

In the table below the max PV for the materials of the Metafram range:

Material

BG10

BG22

BP25 / BP22

BG20

BP15

BP10 / BPV30

BPV50

BPV60

FP18 / SO16 / TR16

FP20

PV max

8

15

18

20

25

30

50

60

9

18

Find the shaft that matches the sintered bearing

The last parameter to consider when choosing the sintered self-lubricating bushing is the shaft. While respecting the operating clearances stated in the brochure, the shaft must have a defined roughness and hardness depending on the material of the Metafram bearing.

A shaft that is too hard, with a high roughness, will prematurely deteriorate the bearing. Conversely, a shaft that is not hard enough will wear out on contact with the bushing, it is generally better to wear out the bearing rather than the shaft because it is easier to replace.

Below are the characteristics of the recommended shaft :

Metarial

BPV50 / BPV60

BP25 /  BP22 / BP15 / BP10

BG22 / BG20 / BG10

BPV30

FP20

SO16

FP18

TR16

Roughness max. (µm)

0,3

0,6

0,6

0,6

0,2

0,2

0,4

0,3

Hardness min (HB)

225

250

250

250

350

350

350

375

Make the right choice for your Metafram self-lubricating sintered bearing

Ultimately, for a good use of the bushing, all the conditions listed above must correspond with the specifications. Speed, load, PV, shaft, all of these contribute to the proper functioning of the Metafram bushing.

If in doubt, it is always best to contact the Metafram design office for sizing according to your application.