Stepper Motors for Low Cost and Low Maintenance

Stepper motors are known for several advantages. This low cost and low maintenance device can produce high torques even during startup phase or at low speed. A typical step motor is able to operate in open loop control systems and in most types of environments, and is less likely to slip or stall. Its relatively simple construction and ruggedness makes maintenance cheap and easy, too. For applications where cost is a concern, a DC stepper motor can be used for motion control.

Stepper Motors Defined

Stepper motors are electromechanical devices that generate mechanical movements by converting electrical pulses. Digital pulses make them work instead of continuously applied voltage. Hence, unlike typical continuously rotating electric motors, stepper motors step or rotate in fixed angular increments. They are typically used for applications where costs are a major factor and position control is crucial, like in linear actuators, mirror mounts, goniometers, and rotation stages, as well as in commercial products like slot machines, plotters, printers, camera lenses, 3D printers, and CNC machines. A design that consists of a stepper motor, driver, and controller system ensures that the stepper motor will abide by digital instructions.

Stepper motors typically consist of a shaft, stator and rotor laminations, copper and lead wires, bearings, magnets, washers, and end and front covers. The shaft is usually made of stainless steel metal, and the rotor and stator laminations are made of silicon steel, which is known for superb electrical resistivity to lower core loss. Magnets are supplied in different types to suit various applications, but they are usually Nd-Fe-B bonded, ferrite sintered, or ferrite plastic magnets.

There are three basic types of stepper motors: permanent magnet, variable reluctance, and hybrid NEMA stepper motors. A variable reluctance stepper motor has multiple soft iron rotors and a wound stator, large step angles, and provides no detent torque. A permanent magnet stepper motor has a rotor that is made up of a permanent magnet. Hybrid NEMA stepper motors are a combination of VR and PM stepper motors and can be applied to a wider range of applications, including CNC equipment. These are the basic reasons why stepper motor are preferred over other traditional motors.

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