SPM leonova emerald, User Manual

Page: 114 / 170

D
D:28
Shock pulse measurement
The most important influence on the
service life of a bearing is the lubricant film
between the load carrying rolling elements
and the raceway.
By preventing or inhibiting metallic contact
between the loaded bearing parts, the
lubricant film reduces the local peak stress
in the rolling interface. The greater the
lubricant film thickness, the more even the
load distribution in the contact area, and the
better the fatigue life of the bearing.
Full
lubrication
Boundary
lubrication
LUB Ball bearing
0 Dry running
1 to 2 Boundary
lubrication
3 to 4 Full lubrication
LUB Roller bearing
0 Dry running
1 to 4 Boundary
lubrication
> 4 Full lubrication
The LUB number
Irregularities in the bearing surfaces will always cause pressure
variations in the contact area, and thus shock pulses, even when
metallic contact is prevented by a separating lubricant film. A
thinner film will result in an increase of the bearing’s HR value.
The LUB No., displayed with CODE A and B, is directly proportional
to oil film thickness. LUB No. 0 means dry running condition.
The interpretation of LUB Nos. between 1 and 4 depends on the
bearing type. For ball bearings, LUB Nos. greater than 2 mean
full lubrication (a load carrying oil film). For roller bearings, a
LUB No. greater than 4 indicates full lubrication.
The term boundary lubrication implies that part of the load
is carried by metal to metal contact. The amount of lubricant
in or supplied to the bearing is only one of the many factors
that determine lubricant film thickness. Lubricant type and the
bearing’s rpm are of great importance, but also the geometry
of bearing parts and housing, as well as the load put on the
bearing by alignment and fitting.