Servo Motor vs Stepper Motor

Servo Motor vs Stepper Motor; what are the similarities?

Both servo and stepper motors can provide reliable power for a highly effective system. They both have the following features:

• High positional accuracy
• Compact mechanical assembly
• Reduced machine parts count
• Very smooth velocity
• Quiet operation

Servo Motor vs Stepper Motor; what are the differences?

One of the main differences between a servo motor and a stepper motor is the overall pole count, as well as how they are controlled. Typically, stepper motors use 50 to 100 pole brushless motors, while servo motors have four to 12 poles.

Stepper motors step between their poles to set positions. They do not require an encoder since they can accurately move between their many poles. A servo motor has fewer poles and use an encoder for position measurement, meaning it can be very accurately positioned anywhere between poles. Stepper motors move incrementally using pulses, while servo systems read the difference between the motor’s encoder and the commanded position, then adjusts accordingly.

Stepper control is simpler open-loop and makes system setup easier. Stepper motors have many advantages over servo systems:

• Lower cost
• Standard nema flange mounts
• Lower torque options
• Require simpler cabling

Servo motors are well suited to precision velocity and positioning applications. They offer far more accurate control of speed, position and torque. Benefits of a servo motor include:

• Higher torque at higher speeds than stepper motors
• Better suited to higher rpm applications

Speed/Torque Comparison: Servo Motor vs Stepper Motor

The speed/torque chart below demonstrates that for similar sized stepper and servo motors, the stepper motor has higher torque at low speeds, but the servo motor can run at high torque at higher speeds. Please note this is a generalisation.

Servo Motor vs Stepper Motor; the verdict

When properly applied, both stepper motors and servo motors can provide reliable power for a highly effective system. There are many things to consider, with the most important being cost, torque, efficiency, speed and circuitry.

For applications with constant load and relatively low accuracy requirement, stepper motors would be better suited. Stepper motors also tend to be more compact and inexpensive compared to servo motors.

For systems requiring high speed and high acceleration, and for applications with varying loads, servo motors are the more suitable option. They are designed for continuous duty applications in production facilities.

If you’re application is on a budget, consider a stepper motor. However, if performance is a more important aspect and cost isn’t an issue, choose a servo motor. 

Advantages of Servo Motors:

• Higher efficiency
• Higher output power
• Closed loop control
• Quieter
• More reliable
• Higher acceleration
• Better high-speed performance
• Torque control
• Smoother running
• Higher accuracy
• Better for varying load applications

Advantages of Stepper Motors:

• Lower cost
• Higher holding torque (powered)
• Detent torque when no power
• Higher low speed torque
• No tuning required
• Low maintenance
• Easier setup and installation
• Constant torque
• Good repeatability
• No damage from mechanical overload
• Good for constant load applications

Servo and Stepper Motors from Heason Technology

Servo and stepper motors can be used across a range of different industries including robotic systems, medical systems, laser sighting, cryogenic cooling pumps and semiconductor processing equipment.

Our motors product portfolio offers a huge variety of different size and package types. We also have a wide range of servo and stepper drives which are compatible with the motors. This enables us to fulfill the most demanding application requirements, ensuring machines are built faster and to a higher quality.

Browse our full range of Servo and Stepper motors.  If you would like to find out more information on our motors, please contact us on +44 (0) 1403 792 300 or email sales@heason.com.