In this article, we have prepared some content about the industrial stepper motor, also known as the industrial step motor, for you. Be sure to stay with us until the end.
As always, we first turn to a definition of the industrial stepper motor.
What is an Industrial Stepper Motor?
A stepper motor, or industrial step motor, is a DC electric motor that divides one complete revolution (360 degrees) into a number of equal steps or steps.
Stepper motors have multiple coil wires divided into groups called “phases.” By energizing each phase in sequence, the motor rotates one step at a time. With computer-controlled step, speed, torque, and position can be precisely controlled.
For this reason, the industrial stepper motor is very precise for many motion control applications. Stepper motors come in different sizes and types, with various electrical characteristics. Switched reluctance stepper motors are very large stepper motors with reduced pole count and are generally closed-loop commutated.
Types of Industrial Stepper Motors
Stepper motors come in a wide variety of types, some of which are highly specialized. Generally, we examine types of stepper motors that can operate with standard drivers. These stepper motors include permanent magnet or hybrid stepper motors, two-phase bipolar, or four-phase unipolar motors.
Industrial Stepper Motor Sizes
One of the first considerations is the tasks an industrial stepper motor must perform. Larger stepper motors are capable of providing more power. The size of an industrial stepper motor can range from smaller than a ground nut to NEMA 57. The torque rating of an industrial stepper motor determines what tasks it can perform.
NEMA 17 is a common size used in smaller 3D printers and CNC factories. Smaller stepper motors find applications in many robotics and animatronics programs. Larger NEMA frames are typically used in CNC machines and industrial applications.
NEMA numbers define standard mounting face dimensions for stepper motors, but they do not specify other motor characteristics. Two different NEMA 17 stepper motors may have completely different electrical or mechanical specifications and may not necessarily be interchangeable.
Step Count in Industrial Stepper Motors
The next issue to consider is the accuracy of industrial stepper motors in positioning. The number of steps per revolution ranges from 4 to 400. Common step counts are typically available in 24, 48, and 200. The resolution of steps is often expressed in degrees per step. A 1.8-degree stepper motor is equivalent to a 200-step motor (revolution).
Gearbox for Industrial Stepper Motors
To achieve high precision in positioning, gearboxes can be utilized. A gearbox with a 32:1 ratio applied to the output of an 8-step industrial stepper motor results in creating a 256-step industrial stepper motor. The gearbox also increases the torque of the stepper motor. Geared stepper motors are usually limited to low-speed applications. Another consideration is the issue of backlash in geared motors. When the stepper motor reverses direction, it must take up any slack present in the gearbox, which can affect positioning accuracy.
Shaft Types in Industrial Stepper Motors
Another aspect to consider is how the stepper motor interacts with the rest of the drive system.
Stepper motors are available with various types of shafts, as described below:
1. Stepper Motor with Round Shaft or “D” Shaft:
These shafts come in various standard diameters, and they are designed to accommodate pulleys, gears, and shaft couplings. “D” shafts have one flat side to prevent slipping. These features are desirable when high torques are present in stepper motors.
2. Gear Shaft Stepper Motor:
Some shafts have gear teeth precisely machined onto them. This type is typically designed for pairing with modular gear trains.
3. Lead Screw Shaft Stepper Motor:
Stepper motors with lead screw shafts are used to create linear actuators. Miniature versions of these are commonly seen as positioners in many disk drives.
Wiring of Industrial Stepper Motors
There are various wiring configurations for stepper motors. Typically, we encounter stepper motors that are powered by conventional drives. These stepper motors are permanent magnet or hybrid types, wired in two-phase, two-phase, or single-phase four-wire configurations.
Winding and Phases of Industrial Stepper Motors
The number of stages in a stepper motor may correspond to the number of windings. However, the windings are connected to each other in groups called phases. Also, all windings of a phase share the force together.
Industrial Stepper Motor Drive
A single-pole industrial stepper motor drive always receives power consistently, where one pole is always negative and the other pole is positive. A single-pole industrial stepper motor drive can be implemented using simple transistor circuits. The drawback is that less torque is available because only half of the windings can be powered simultaneously.
A two-pole stepper motor drive uses H-bridge circuits to effectively reverse the current through the stages. By energizing the phases with alternating polarity, all windings can be utilized to rotate the motor. A two-pole stepper motor has two winding groups in two phases.
A four-phase single-pole stepper motor has four winding wires. A two-phase, four-wire industrial stepper motor has two poles and four wires. Some stepper motors have flexible wiring options that allow you to use them in either bipolar or unipolar mode.
5-Wire Stepper Motor:
This style is common in smaller single-pole stepper motors. All common windings are tied together internally and emerge as a single wire known as the fifth wire. This industrial stepper motor can only be operated as a single-pole stepper motor.
6-Wire Stepper Motor:
This stepper motor only connects to the common wires of two paired phases. These two wires can be connected together to create a 5-wire single-pole stepper motor. Alternatively, they can be disregarded and the motor can behave like a two-pole stepper motor.
8-Wire Stepper Motor:
An 8-wire single-pole stepper motor is the most comprehensive and complete type of stepper motor.
There are several ways to drive an 8-wire single-pole industrial stepper motor:
1. 4-phase single-pole stepper motor: All common wires are connected together. (Similar to a 5-wire stepper motor)
2. 2-phase series two-pole stepper motor: The phases are connected in series. (Similar to a 6-wire stepper motor)
3. Parallel two-phase two-pole stepper motor: The phases are connected in parallel. This results in half the resistance and inductance. However, it requires twice the current for driving. The advantage of this wiring is higher torque and maximum speed.
Advantages of Using Stepper Motors:
1. Positioning: Stepper motors move in precise and repeatable steps, making them excellent for applications requiring precise positioning, such as 3D printers, CNC machines, camera systems, and X-Y plotters.
2. Speed Control: Industrial stepper motors also provide excellent speed control for process automation and robotics.
3. Low-Speed Torque: Conventional DC motors lack significant torque at low speeds. A stepper motor delivers maximum torque at low speeds, making it a good choice for high-speed and high-precision applications.
Limitations of Using Stepper Motors:
1. Low Efficiency: Unlike DC motors, the current consumption of stepper motors is not load-independent. Stepper motors draw maximum current when overloaded, leading to heat generation.
2. Limited Speed-Torque Range: Generally, stepper motors have less torque at high speeds compared to low speeds. While some stepper motors are optimized for better performance at high speeds, achieving such performance requires pairing the stepper motor with a suitable drive.
3. Lack of Feedback: Unlike servo motors, most stepper motors do not have integral feedback for position. However, high precision can be achieved by implementing an “open-loop” system. Switches or sensors are usually required for safety and establishing a reference position.
We appreciate your accompanying us until the end of the article on industrial stepper motors. For utilizing the expertise of our specialists and benefiting from their consultation, you can get in touch with Electroshield experts through the contact section.