
B–65142E/04
4. SELECTING A MOTORDESCRIPTIONS FOR THE α series
33
The load inertia has a great effect on the controllability of the motor as
well as the time for acceleration/deceleration in rapid traverse. When the
load inertia is increased, the following two problems may occur: When
a command is changed, it takes more time for the motor to reach the speed
specified by the new command. When a machine tool is moved along two
axes at a high speed to cut an arc or curve, a larger error occurs.
When the load inertia is smaller than or equal to the rotor inertia of the
motor, those problems will not occur. When the load inertia is up to three
times the rotor inertia, the controllability may have to be lowered a little.
Actually, this will not adversely affect the operation of an ordinary metal
cutting machine. If a router for woodworking or a machine to cut a curve
at a high speed is used, it is recommended that the load inertia be smaller
than or equal to the rotor inertia.
When the load inertia is greater than the rotor inertia by a factor of more
than 3 to 5, the controllability of the motor will be adversely affected. If
the load inertia much larger than three times the rotor inertia, an
adjustment in the normal range may be insufficient. Avoid using a
machine with such a great load inertia.
D Note Limitations on
load inertia