Spindle motor vs. standard motor
High-peak-torque capability combined with low rotor inertia of a high-performance
spindle motor enables higher acceleration rates to base speed than are available with a standard
ac motor. Figure 1 shows the acceleration time for a standard TENV ac motor and a high- performance ac spindle motor. Both are driving a tool load with an inertia of 0.25 lb-ft2 and are
powered at their continuous rating of 10 hp. The spindle motor, with a rotor that has 24% of the
inertia of a standard ac motor, reaches the set speed in 28% of the time required for the
standard motor. This shorter acceleration time produces faster orientation capability for tool
changing, for example.