How to use stepper motors and servo motors? What is the difference between them in terms of motor structure and areas of specialization?

I see. This is a good opportunity, so let's organize it. First, let me briefly explain about the structure of each motors.
Both stepper motors and servo motors are composed by the components called stator and rotor. These two parts are the same in that they attract each other to determine their position, but the structure of the parts is different.
Take a look at the illustration below. I’d like you to pay special attention to the rotor. The stepper motor has small teeth engraved on the outer circumference of the rotor, and each of the small teeth and the stator attract each other little by little to achieve precise positioning. For more information, watch our Basic Stepper Motor Seminar.
On the other hand, servo motors do not use a mechanical structure to improve positioning accuracy, but instead it use feedback information from a position sensor (encoder) to determine position.

I see.

Next, let us review the basic features. Can you think of any differences in characteristics?

Well... I wonder if gain adjustment is necessary...

Gain adjustment too, but there's a more obvious difference. I'm sure you'll find some clues when you look at the torque characteristics.

Torque characteristics?

That’s right. The stepper motor output guidelines and torque characteristics diagram are listed on the website, so let's take a look at them together.

This characteristic comparison is easy to understand! Stepper motors have more torque in the medium and low speed range, while servo motors have more torque in the high speed range.

What can be said from the trend of this torque characteristic diagram?

Mmm... Does it mean that stepper motors are suitable for use in the middle and low speed range, while servo motors are suitable for high speed range?

That's right. By the way, what are some applications that use the middle and low speed range?

Applications that do not require high speeds, it may be used for pitch feeding of an index table with a small amount of movement.

That's right! If the movement during positioning operation is small, such as a pitch feed, the required rotation speed is often less than 1000 r/min.

I see. Conversely, servo motors do not lose torque at high speeds, which means they are suitable for long strokes to be raised to high speeds. For example, a ball screw mechanism!

A stepper motor is sufficient for fine inching operations even with a ball screw, so it would be better to use a stepper motor for short strokes and a servo motor for long strokes.

I've got it now! I will first try to explain to the customer about the different structures and areas of specialization.
Are there any other points to distinguish between stepper motors and servo motors? I would like to learn more.

This time we explained the areas each motor is good at, but I also want you to know the differences in performance. We'll get to that next time.

I’m looking forward to it.