A stepper motor moves in discrete increments called "steps," achieved by sequentially energizing the stator coils. It can operate without an encoder or feedback system, meaning it runs in open-loop mode with reliable performance—as long as the load is predictable. Nowadays, more stepper motors come with closed-loop control, featuring multiturn absolute encoders for feedback and improved accuracy.
Servo motors, or brushless synchronous motors with permanent magnets, operate in closed-loop control. Coupled with a drive and encoder, they provide precise control of torque, position, and speed. This allows for fast, accurate, and adaptive movements—even under varying load conditions.
The choice between a stepper motor and a servo motor depends on your application requirements, budget, and performance needs. Here’s a quick comparison table to help you decide:
The traditional distinctions between servo and stepper motors are becoming less clear as new technologies emerge. Innovations in motor design, control methods, and system integration are enabling stepper motors to achieve servo-like performance and making servo systems more compact and flexible. These advancements open up new possibilities for industrial automation, allowing you to select the most optimal motor technology tailored to your specific application needs.
Stepper motors have long been valued for their simplicity and cost-effectiveness but were limited by open-loop control and speed constraints. Today, full servo systems based on stepper technology are revolutionizing this landscape. For instance, Festo’s EMMT-ST motor combines the best of both worlds by integrating:
This hybrid solution allows stepper motors to deliver higher speeds and dynamic responses, making them suitable for applications that previously required more expensive servo systems—offering a compelling balance of performance and cost.
Modern motor drives are designed to be technology-neutral and PLC-agnostic, supporting multiple industrial communication protocols such as PROFINET, EtherCAT, and Modbus TCP. This multi-protocol capability ensures:
Such open connectivity is crucial for complex machines with mixed motor technologies, enabling smooth coordination between servo and stepper motors within the same system.
Selecting the right motor and drive combination can be complex, especially with the growing variety of technologies and application requirements. Innovations in software tools now allow engineers to:
Festo’s Electric Motion Sizing Tool is a prime example, available online with real-time updates and no downloads required. This tool helps reduce technical risks, shorten design cycles, and ensure the selected motor technology—whether servo or stepper—is truly optimal for the application.
Advanced closed-loop steppers can serve many applications traditionally reserved for servos, especially where cost is critical. However, for high-speed, high-precision, or heavy-load tasks, servo motors remain superior.
Steppers are easier to control with simple pulse inputs. Servos require more sophisticated drives and tuning but offer unmatched performance. Decentralized drives and single-cable solutions are simplifying servo integration.
Servos generally consume less energy due to closed-loop control and optimized torque delivery. Steppers may generate more heat and consume more power under continuous load.
Steppers have fewer wear points but risk missed steps. Servos require periodic encoder and drive maintenance but benefit from advanced diagnostics.
Servo and stepper motors are complementary technologies tailored to different industrial needs:
Emerging technologies like closed-loop steppers and decentralized servo drives expand your options, enabling optimized performance, cost, and integration.
By leveraging modern sizing tools and understanding each motor’s strengths and limitations, you can confidently select the best motor technology—maximizing productivity and minimizing total cost of ownership.