Stepper Vs. Servo Motors Characteristics Servo Motor (DC Brushed Stepper (Hybrid)
| Cost | The cost for a servo motor and servo motor system is higher than that of a stepper motor system with equal power rating. | This feature would have to go to
stepper motors. Steppers are generally cheaper than servo motors that
have the same power rating. | |
| Versatility | Servo motors are very versatile in their use for automation and CNC applications. | Stepper motors are also very
versatile in their use for automation and CNC applications. Because of
their simplicity stepper motors may be found on anything from printers
to clocks. | |
| Reliability | This is a toss up because it depends on the environment and how well the motor is protected. | The stepper takes this category only because it does not require an encoder which may fail. | |
| Frame Sizes | Servo motors are availible in a
wide variety of frame sizes, from small to large motors capable of
running huge machines. Many of the motors come in NEMA standard sized. | Stepper motors do not have as many size selections
as servo motors in the large sizes. However stepper motors may still be
found in a variety of NEMA frame sizes. | |
| Setup Complexity | Servo motors require tuning of the (PID) closed loop variable circuit to obtain correct motor function. | Stepper motors are almost plug-and-play. They require only the motor wires to be wired to the stepper motor driver. | |
| Motor Life | The brushes on servo motors must be replaced every 2000 hours of operation. Also encoders may need replacing. | The bearing on stepper motors are the only wearing parts. That gives stepper motors a slight edge on life. | |
| Low Speed High Torque | Servo motors will do fine with low speed applications given low friction and the correct gear ratio | Stepper motors provide most torque at low speed (RPM). | |
| High speed High Torque | Servo motors maintain their rated torque to about 90% of their no load RPM. | Stepper motors lose up to 80% of their maximum torque at 90% of their maximum RPM. | |
| Repeatability | Servo motors can have very good repeatability if setup correctly. The encoder quality can also play into repeatability. | Because of the way stepper motors
are constructed and operate they have very good repeatability with
little or no tuning required. | |
| Overload Safety | Servo motors may malfunction if overloaded mechanically. | Stepper motors are unlikely to be damages by mechanical overload. | |
| Power to Weight/Size ratio | Servo motors have an excellent power to weight ratio given their efficiency. | Stepper motors are less efficient than servo motors which usually means a smaller power to weight/size ratio. | |
| Efficiency | Servo motors are very efficient. Yielding 80-90% efficiency given light loads. | Stepper motors consume a lot of power given their
output, much of which is converted to heat. Stepper motors are usually
about 70% efficient but this has some to do with the stepper driver. | |
| Flexibility in motor resolution | Since the encoder on a servo motor determines the motor resolution servos have a wide range of resolutions available. | Stepper motors usually have 1.8 or 0.9 degree
resolution. However thanks to micro-stepping steppers can obtain higher
resolutions. This is up to the driver and not the motor. | |
| Torque to Inertia Ratio | Servo motors are very capable of accelerating loads. | Stepper motors are also capable of accelerating
loads but not as well as servo motors. Stepper motors may stall and skip
steps if the motor is not powerful enough. | |
| Least Heat production | Since the current draw of a servo motor is proportional to the load applied, heat production is very low. | Stepper motors draw excess current regardless of load. The excess power is dissipated as heat. | |
| Reserve Power and Torque | A servo motor can supply about 200% of the continuous power for short periods. | Stepper motors do not have reserve power. However stepper motors can brake very well. | |
| Noise | Servo motors produce very little noise. | Stepper motors produce a slight hum due to the control process. However a high quality driver will decrease the noise level. | |
| Resonance and Vibration | Servo motors do not vibrate or have resonance issues. | Stepper motors vibrate slightly and have some resonance issues because of how the stepper motor operates. | |
| Availability | Servo motors are not as readily available to the masses as are stepper motors. | Stepper motors are far easier to find than quality servo motors. | |
| Motor Simplicity | Servo motors are more mechanically complex due to their internal parts and the external encoders. | Stepper motors are very simple in design with no designed consumable parts. | |
| Direct Drive Capability | Servo motors usually require more gearing ratios due
to their high RPM. It is very rare to see a direct drive servo motor
setup. | Stepper motors will work fine in
direct drive mode. Many people simple use a motor couple and attach the
motor shaft directly to the leadscrew or ballscrew. | |
| Power Range | Because servo motors are available in DC and AC servo motors have a very wide power availability range. | The power availability range for stepper motors is not that of servo motors. | |
Stepper vs Servo Motors 
