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Stepper motors

Stepper motors are brushless, synchronous electromechanical parts that convert electrical signals into mechanical shaft rotation. As the digital pulses increase in frequency, the step movement changes into continuous rotation, with the speed of rotation directly proportional to the frequency of the pulses. Every revolution of  the motor is divided into a number of steps and the motor must be send a pulse for each step from the controller. The motor’s position can be controlled without any feedback mechanism, as long as the stepper motor is appropriately dimensioned according to the application.

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Use only quality stepper motors for your application

Stepper motor drives are used in a variety of applications to position, prepare, rotate, and move various parts or equipment. We offer stepper motors from R.T.A. Group, which is a leading European company in motion control industry with 45+ years of experience. In this time they established a network of 46 distributors across 5 continents and sold more then 1 million stepper motor drivers

Their computerized testing line performs testing of each drive by two different operations, ensuring its quality. The company’s skilled engineers provide professional and fast customer assistance and support.

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Convert pulses into shaft rotation

The stepper motor converts each digital pulse into mechanical displacement. Each pulse causes the motor to rotate a precise angle. In the case of a stepper motor with typical resolution of 1.8 °, it means that the motor shaft makes 1 complete revolution after 200 pulses or steps (360 ° / 1.8 ° = 200).

The rotor of the stepper motor consists of a magnet and two toothed rotor cups, which typically have 50 teeth each. The stator of the stepper motor has 8 radially positioned poles, which are made of thin magnetic plates that are insulated from each other. There are 8 coil windings on them.

Meet the advantages of stepper motors

  • The rotation angle of the motor is proportional to the input pulse.
  • Precise positioning and repeatability of movement.
  • Easy to use (installation and start-up),
  • Versatility of use (for different applications),
  • Excellent response to starting/stopping/reversing.
  • Simple construction,
  • High reliability and robustness (suitable for demanding environments).
  • The motor has full torque at standstill (if the windings are energized) and high torque at low speeds.
  • Low price compared to other drive control systems.
  • Low maintenance costs.

Select the perfect working principle for your proccess

Full Step

The full stepper motors have 200 full steps per revolution of the motor shaft. They operate with a single phase activated at a given time or with two phases activated simultaneously, havinga 1.8° full step angle.

With the two phases on, the motor torque is 30% – 40% higher than during the one phase on.

Full Step, Single Phase

Full Step, Dual Phase

Half Step

The stepper motor is rotating at 400 steps per revolution, with one winding energized and then two windings energized alternately, causing the rotor to rotate at half the distance, or 0.9°.

Although it provides approximately 30% less torque than the full step mode, the half step mode produces a smoother motion than full step mode.


Micro Step

Here the full step (1.8°) can be divided into 256 microsteps – to smooth out the motor’s rotation at slow speeds. The stepper motor controller sends 2 voltage sine waves, 90° out of phase, to the motor windings.

Microstepping is used in applications that require accurate positioning and smooth motion at various speeds.


Just follow these simple steps

stepper motor alignment

Poles have 48 teeth, i.e., 2 less than the rotor. Alignment of the stator poles with respect to the rotor is as follows (Fig. 1): 2 poles are aligned , 2 poles are unaligned and 4 poles are half aligned with the rotor. The stator coils are two independent coil sets (Fig. 2) .

When developing an application with stepper motors, you just need to follow these simple steps:

Aligned red poles (the opposite polarity poles attract) and unaligned yellow poles (the same polarity poles repulse).

The rotor moves by tooth/4 or 1.8 °, aligning blue poles while unaligning green poles.

The rotor moves an 1.8 °, aligning orange poles while unaligning red ones.

The rotor moves by an 1.8 °, aligning green poles while unaligning blue ones.

Step 5 equals Step 1. As the rotor has 50 teeth and the tooth movement occurs with each new step (i.e., a pulse from the drive controller), the total number of  steps per full shaft rotation is 200.

Choose the right stepper motor

R.T.A. offers you a huge range of stepper motors, so you can choose the perfect solution for your application.

Choose among:

Stepper motors are inherently open-loop devices, able to make precise moves without feedback regarding motor position, i.e., without position measuring devices. Its shaft rotates by performing steps, that is, by moving by a fixed amount of degrees. This feature is obtained thanks to the internal structure of the motor, and allows to know the exact angular position of the shaft by simply counting how may steps have been performed, with no need for a sensor. Thus, the position can be precisely controlled as long as the stepper motor is properly sized to the application.

Stepper motors with encoder integrated on its shaft, leverage encoder feedback for precise control of both speed and position. The closed loop stepper motors are used if loss of position could be catastrophic to the application, yet the system requires high torque at low speed, relatively simple architecture, and relatively low cost (compared to a true servo motor system).

Stepper motors can have a brake mounted on its shaft, providing a higher holding torque when the engine is stopped.

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stepper motor alignment

Take a look at stepper motor applications

  • XY Positioning Tables,
  • Storage, Pick & Place Systems and Robots,
  • Packaging Systems and equipment for the application of labels,
  • Various Transport and Logistics Systems (internal movements, orientation),
  • Guidance and Alignment Systems (angular and linear),
  • Systems for exchanging format parts or tools,
  • Measuring and Laboratory Instruments,
  • Conveyor belts,

What machines you can develop?

  • Packaging Machines and Labeling equipment,
  • Filling Machines for liquids and powder products,
  • Cutting Machines for plastics, metals, wood, ceramics, glass, stone and leather,
  • Shaping Machines,
  • Robots,
  • Laboratory Instruments,
  • 2D & 3D Printers,

Read the latest Drives news

  • RTA ADW series drives

ADW Series Drives from R.T.A.

Take advantage of the ADW series drives from R.T.A. for easy connection to your PLC and reliable speed control of your stepper motor while saving up to 70% of space.

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