11.2.3 Conversions Between Engineering Units And Si Units - YASKAWA E Series Product Manual

11.2 Reference Information for Servomotor Capacity Selection

11.2.3 Conversions between Engineering Units and SI Units

General Formula When
Rotary Shaft Is outside
Rotating Body
Information
11.2.3 Conversions between Engineering Units and SI Units
The following table provides the conversion rates between engineering units and SI units for
typical physical quantities required for capacity selection.
Quantity
Force or load
Weight
Mass
Torque
Inertia (moment of
inertia)
2
GD
11-6
General formula for diameter of rotation when rotary shaft Is
outside rotating body
2 2 2
=
D D + 4 d
2 1
: Diameter of rotation when shaft that is parallel to rotary shaft and
D
1
runs through center of gravity virtually operates as a rotary shaft
= Weight × (Diameter of rotation)
2
GD
Engineering Unit
kgf
kgf
2
kgfs /m
kgfm
2
gfcms
2
kgfm
2
SI Unit
N 1 kgf = 9.80665 N
– The numerical values are the same for mass in
the traditional unit and the SI unit.
(The mass SI unit Wkg is used for objects in
kg
the Wkgf traditional unit.)
Nm 1 kgfm = 9.80665 Nm
= 0.980665 × 10
2 2
kgm 1 gfcms
Relationship between GD
moment of inertia
2
kgm
2
GD
=
J J
4
Continued from previous page.
Center of gravity
Rotary shaft
d
Conversion Factor
-4 2
kgm
2 (kgf·m 2 ) and
2
J (kg·m )