Typical load inertia equations
Mechanism Equation Mechanism Equation
Axis of rotation on center
W: Mass (kg)
a: Length (m)
b: Width (m)
Axis of rotation on center
W: Mass (kg)
D
1
: External diameter (m)
D
2
: Internal diame
ter (m)
Axis of rotation o cent
er
W: Mass (kg)
a: Length (m)
b: Width (m)
R: Rot
ational diameter (m)
Axis of rotation o center
W: Mass (kg)
D: Workpiece diameter (m)
R: Ro
tational diameter (m)
Conveyor
W: Mass (kg)
D: Pulley wheel diameter (m)
Ball screw
W: Mass (kg)
P: Lead (m)
J
b
: Ball screw inertia (kg·m
2
)
Object hung with pulley
W: Mass (kg)
D: Pulley wheel diameter (m)
J
p
: Pulley iner
tia (kg·m
2
)
Reducer
W: Mass (kg)
n
1
/n
2
: Speed of each motor
(rpm)
J
1
/J
2
: Inertia of eac
h motor
(kg·m
2
)
A.5.2 Selection examples
Descr
ip
tion
This section uses a ball scr
e
w mec
hanism as an example to illustrate the motor selection
procedure.
Exemplary data
The following table lists the data related to the ball screw mechanism and operation pattern.
Workpiece weight W 40 kg
Material density of the ball screw ρ 7.9 × 10
3
kg/m
3
Appendix
A.5Motor selection
SINAMICS S200 pulse train servo drive system with SIMOTICS S-1FL2
756 Operating Instructions, 11/2023, FW V6.3, A5E51646767B AA