IAI America ISPDACR-ESD - Manual (Page 35)

27
3. Life
3. Life
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%.
Considering their moving speed, utilization ratio, etc., however, industrial equipment must have their
dynamic rated load defined based on a traveling distance of 5,000 km to 10,000 km.
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.
With the IS series, the life is designed to ensure a traveling distance of 10,000 km under a load
corresponding to the allowable load moment and at a load coefficient of 1.2.
[For the dynamic allowable load moment, refer to 2, “Performance”]
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