As we all know, all CNC machines are made up of various parts,of which servo motors or stepping motors are essential.
1. Performance under low speed rotation.low frequency oscillation will happen when stepping motor rotates in a low speed.such a thing would not occur to servo motor.
2. The output rotational speed of stepping motor is lower than that of servo motor. The output torque will steeply decline especially when rotation speed is high. The highest rotation speed can generally reach 300 to 600 rpm. The output torque of servo motor are constant,which ensures the output torque is rated under a certain rotary speed usually at 2000RPM or 3000ORPM. The output power is constant under a rated rotary speed.
3. Different running performance.Inside the servo motor, there is position loop and speed loop, which guarantees no steps lose or overthrow often occurring on stepping motors.
4. Generally stepping motors do not have overload capacity while servo motors have a good one.
5. Different Response Performance to Speed
It usually takes 200 to 400 milliseconds for stepping motors to return to the working speed (often several hundred rpm per minute) from the static. As for servo motors, it only need several milliseconds to reach a rated speed. The quick response to speed is needed in an occasion of urgent stop or start.
6. Different Control Accuracy.
Under the low speed(usually at 600rpm), stepping motors and servo motors have the same accuracy. But when the rotary speed reach 1200rpm, the low torque of stepping motors will lead to steps losing. So stepping motors are commonly used in the occasion of low rotary speed.
Control Method: Stepping motors use open-loop control system, so it can not get feedback. It is easier to control and only need one driver. The control system of servo motors are more complicated. The control signal from controllers will compare with motor feedback signal. If there is difference, servo motor will send alarming signals or make remedy.
Price: Stepping motors are cheaper than servo motors.