IAI America ISWA - Manual (Page 28)

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3. Product Life
3. Product Life
"Rated load" is one element that determines the life to drive the actuator.
In the "rated load", there are two types called "static rated load" and "dynamic rated load".
x "Static rated load" : A load that makes a tiny brinelling mark on the interfacing surface when a load is
applied while in stopped condition.
x "Dynamic rated load" : A load when it is considered the probability of the guide not being broken is
constant after driving a certain distance with a load being applied.
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of the guide not being broken is 90% after 50km driving.
But, for industrial machineries, the dynamic rated load needs to be determined under estimation of the
driving distance from 5,000km to 10,000km considering the operation speed and the operation rate.
Also, the life of guide has enough margin to the radial load, and is affected mostly by the moment load
offset from the center of the guide.
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moment and 1.2 of the load factor.
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The formula to calculate the allowable load moment when the driving life is 10,000km is shown below:
C
IA :
Allowable load moment
C
IA
=
fw
M
50
10000km
50km 3
1
˜
fw : Load factor (=1.2)
M
50 :
Dynamic moment of probability of not broken 50% when
driving 50km
The life under the applicable moment is calculated with the following formula:
L
:
Driving life (probability of not broken 90%)
L=
P
C
IA
10000km
3
˜
C
IA
: Dynamic allowable moment
P
:
Applicable moment