IAI America SSPDACR - Manual (Page 31)

3. Life
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3. Life
The mechanical life of an actuator is represented by the life of its guide that receives the largest moment load.
The “rated load” is one factor that relates to the traveling life.
There are two types of “rated load,” namely “static rated load” and “dynamic rated load.”
x “Static rated load”: Load which, when applied to a stationary actuator, leaves a minor pressure mark on
the contract surface.
x “Dynamic rated load”: Load which applies after a specified traveling distance under a load based on a
specific probability of survival at which the guide does not break
Guide manufacturers indicate the life of a guide using a dynamic rated load when the provability of survival after
50 km of traveling is 90%.
In the case of general industrial machinery, however, you must know the specific life for the purpose of
maintenance. Also, the life of a guide has a sufficient allowance relative to a radial load, and receives the greatest
impact by a moment load offset from the center of the guide.
The life of the IS series corresponds to a traveling life of 10000 km at a load factor of 1.2 (safety factor) when the
allowable load moment is applied. [For the dynamic allowable load moment, refer to 2, “Specification”]
The calculation formula for allowable load moment at a traveling life of 10,000 km is shown below:
C
IA
: Allowable load moment
f
W
: Load coefficient (= 1.2)
M
50
: Dynamic rated moment when the probability of survival after 50
km of traveling is 50%
The life at the actual moment is calculated by the formula below:
L: Traveling live (probability of survival: 90%)
C
IA
: Allowable dynamic moment
P: Actual moment