Datasheet
85
17
Load Carrying Capacity and Service Life
17.1 Load Carrying Capacity and Service Life
17.1 Principles
The load capacities are based on the principles of DIN 636.
In accordance with DIN in most applications a permanent overall deformation of
0.0001 times the rolling element diameter can be permitted without adversely
affecting the operating behaviour of the bearing. Consequently, the static load
capacity C
0 is set sufficiently high that the aforementioned deformation occurs
approximately when the equivalent static load corresponds to the static load
capacity. Being guided by the dynamic load capacity C is recommended so that
the aforementioned overall deformation does not occur.
The dynamic load capacity C is the load at which a nominal service life L of 100 km
of travel distance is achieved. It is important to note when calculating the service
life that not only the load, which acts vertically on the guideway, should be taken
into account but also the load spectrum of all acting forces and moments.
The service life corresponds to the total travel distance in meters which a guideway
facilitates. And this is before any noticeable material fatigue on one of the roller
guideway elements. The nominal service life is achieved when 90% of the
guideways of identical construction reach or exceed the corresponding travel
distances under normal operating conditions.
Critical for the dimensioning of the guideways are the loads occurring proportionally
with the dynamic load capacity C.
Definition of service life
As previously mentioned, the dynamic load capacity C
100 is based on a service life
of 100 km. Other manufacturers frequently indicate the load capacity C
50 for a
service life of 50 km. The resulting load capacities from this are more than 20%
higher than specified by the DIN ISO standard.
Conversion example for ball bearings
Convert C
50 load capacities to C100 in accordance with the DIN ISO standard:
C
100 = 0.79 ∙ C50
Convert C100 load capacities to C50:
C
50 = 1.26 ∙ C100
C50
C100
= dynamic load capacity C in N for 50 km of travel distance
= dynamic load capacity C in N for 100 km of travel distance, defined
in accordance with DIN ISO standard