IAI America RCLE-GR5L - Manual (Page 32)

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10. Allowable Load Condition
10.1 Check Holding Force and Allowable Load Conditions
Follow the steps below:
Step 1: Check the necessary holding force and the weight of
the work part
Step 2: Check the allowable vertical load of the fingers and
allowable moment
Step 1: Check the necessary holding force and the weight of the
work part
In ordinary work part movement
Necessary holding force
Ÿ 10 to 20 times the weight of the work part
Work part weight
Ÿ 1/10 to 1/20 or less of the holding force
As the calculation below shows, the weight of the work part capable to hold gets bigger as the
coefficient of friction gets larger. However, for safety reasons, have the holding force 10 to 20
times more than the work part weight regardless of the coefficient of friction.
(Calculation Example) Here, figure out the necessary holding force when gripping the work part
with the friction force.
(1) In ordinary travel
F : Gripping Force [N]……Total value of the pressing force of each finger
W : Work part weight [kgf]
P : Coefficient of static friction between finger attachments and work part
m : Work part mass [kg]
g : Acceleration of gravity [
9.8m/s 2 ]
The condition when the work part is held firmly and work part would not drop is:
F P !
W
g
F
!
mg
ȝg
The necessary holding force in ordinary travel considering a recommended safety factor
of 2 is:
F
!
m
P
u 2 (Safety Margin)
Assuming the coefficient of friction
P is 0.1 to 0.2:
F
!
m
0.1 to 0.2
u 2 (10 to 20) u m
(2) When large acceleration or impact is applied during work part movement.
It will apply bigger inertial forces to the work part as well as gravity. In such a case,
consider more holding force and a larger safety factor.
When large acceleration/deceleration or impact is applied
Necessary holding force
Ÿ 30 to 50 times the weight of the work part
Work part weight
Ÿ 1/30 to 1/50 or less of the holding force
F F
W [mg]
Coefficient of
Friction [
μ]