Advantages of a Stepper Motor Actuator

Stepper motor actuators are among the popular types of actuators used in a variety of industries. The actuator uses a step method to perform a particular movement in an application. Unlike a linear stepper motor actuator, which moves only in a perpendicular motion, stepper motor actuators move in rotating motions, which is performed using magnets. As its function is extremely specific, you will find stepper motor actuators in varied yet particular applications such as printers, floppy drives, scanners, and even CNC machines.

Advantages of a Stepper Motor Actuator

The flexibility and efficiency of the stepper motor actuator has made it a popular option against servo motors. Here are the advantages of stepper motor actuators:

High Accuracy: As the step method is used to perform the rotary movement, there is very little chance for error. Even under open loop control, an application will have high performance accuracy.
Flexibility: These actuators have the capability to adapt to digital control applications. The reason for this is the cumulative attributes of command and motion. 
Stability: best stepper motor actuators are known to remain stable without undergoing any huge problems even after long periods of use.
Cost Saving: Thanks to the design of the actuator, there is no need for a measurement system, which can add to a higher cost. Also, the cost for the controller is economical.
A variety of industries can benefit from the design, flexibility, and accuracy of stepper motor actuators.

The Difference Bettwen Nema 17 and Nema 23 Geared Stepper Motor

Nema 17 Stepper Motor Bipolar L=48mm w/ Gear Ratio 100:1 Planetary Gearbox

This nema 17 geared stepper motor with 48mm body and 1.68A rated current, integrated a planetary gearbox of 99.05:1 gear ratio. It's a good solution to applications that with limited space but need low speed and/or high torque.

Electrical Specification
Manufacturer Part Number: 17HS19-1684S-PG100
 Motor Type: Bipolar Stepper
Step Angle: 0.018 deg
Holding Torque without Gearbox: 44Ncm(62.31oz.in)
Rated Current/phase: 1.68A
Phase Resistance: 1.65ohms
Voltage: 2.8V
Inductance: 2.8mH ± 20%(1KHz)


Nema 23 Stepper Motor Bipolar L=76mm w/ Gear Ratio 30:1 Spur Gearbox

This nema 23 geared stepper motor with 76mm body and 2.8A rated current, integrated a 60mm square spur gearbox of 30:1 gear ratio. It's a good solution to applications that with limited space but need low speed and/or high torque.

Electrical Specification
Manufacturer Part Number: 23HS30-2804S-SG30
Motor Type: Bipolar Stepper
Step Angle: 0.06 deg
Holding Torque without Gearbox: 1.89Nm(267.65oz.in)
Rated Current/phase: 2.8A
Phase Resistance: 1.13ohms
Voltage: 3.2V
Inductance: 5.4mH ± 20%(1KHz)

What exactly is a stepper motor?

Stepper motors are different from ordinary DC motors in at least four important ways.

The first difference you notice is that they have no brushes or commutator (the parts of a DC motor that reverse the electrical current and keep the rotor—the rotating part of a motor—constantly turning in the same direction). In other words, stepper motors are examples of what we call brushless motors. (You'll also find brushless motors in many electric vehicles, hidden away in the wheel hubs; used in that way, they're called hub motors.)

The second major difference is in what rotates. Remember that in a basic DC motor, there is an outer permanent magnet or magnets that stays static, known as the stator, and an inner coil or coils of wire that rotates inside it, which is the rotor. In a brushless hub-motor, the coils of wire are static in the center and the permanent magnets spin around them on the outside. A stepper motor is different again. This time, the permanent magnets are on the inside and rotate (making up the rotor), while the coils are on the outside and stay static (making up the stator).

The third big difference between an ordinary DC motor and a stepper motor is in the design of the stator and the rotor. Instead of one large magnet on the outside (the stator) and one large coil rotating inside it (the rotor), a stepper motor has an inner magnet effectively divided up into many separate sections, which look like teeth on a gear wheel. The outer coils have corresponding teeth that provide magnetic impulses, attracting, repelling, and making the teeth of the inner wheel rotate by small steps. This will become clear in a moment when we look at some pictures.

The final difference is that a stepper motor can stay still, in a certain position, once it's rotated through a particular angle. That's obviously crucially important if you want a motor to power something like a robot arm, which might have to rotate a certain amount and then remain in precisely that spot while another part of the robot does something else. This feature is sometimes called holding torque (torque is the rotary force something has, so "holding torque" simply means a stepping motor's ability to stay still).

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