Setting Of Rotation Time; Moment Of Inertia - SMC Networks C(D)RB1 50F Series Operation Manual

5. Setting of Rotation Time

Even if the torque - required by the load in the rotation movement is small, the shaft and/or internal
parts could become damaged depending on the inertia of the load. Therefore, select an appropriate
model for your application by taking the load's moment of inertia, kinetic energy, and rotation time into
consideration.

Moment of inertia

(1) Moment of inertia is the tendency of a stationery object to resist rotation, or, conversely, the
tendency
of a rotating object to resist stopping.
When the actuator moves an object (load), inertia (kinetic energy) is generated in the object.
The actuator stops at the rotation end, but due to inertia, a large shock (kinetic energy) is applied to the
rotary actuator.
The kinetic energy can be calculated using the formula below.
E = 1/2 x I x ω
(2) There is a threshold of kinetic energy that a rotary actuator allows. Therefore, by finding the
moment of inertia, it is possible to find the threshold value of the rotation time.
The basic formula for finding the moment of inertia is shown below.
Moment of inertia can be found with the basic formula shown below.
2
I = m x r
This represents the moment of inertia for a shaft with mass M, which is located at distance r
from the shaft.
2
E：Kinetic energy
I：Moment of inertia
ω：Angular speed
m:：Weight (kg)
(J)
2
(kg/m )
(rad/s)
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