Bearing Materials

In general it can be said that a good bearing material should posses following characteristics :

a.    It should be strong enough to sustain bearing load.
b.    It should not heat rapidly.
c.    It should show a small coefficient of friction.
d.    It should wear less, having long service life.
e.    It should work in foundary.

Generally it is expected that the journal and bearing would be made of dissimilar materials although there are examples where same materials for journals and bearings have been used. When the two parts are made in the same material the friction and hence the wear is high.

Cast iron has been used as bearing material with steel shafts in several solutions. However, the various non-ferrous bearing alloys are now being used largely as bearing material because they satisfy the conditions outlined above more satisfactory.

Bronzes, babbitts and copper-lead alloys are the important bearing materials that are widely used in service. Certain copper zinc alloys, that is brasses, have been used as bearing materials, but only to limited extent. Since brass in general is chapter, it has replaced bronze in several light duty bearings.