Engineering Notes by Oriental Motor

    Choosing the Right Type of Stepper Motor for Your Application

    [fa icon="calendar"] Nov 12, 2018 8:30:00 AM / by Johann Tang

    Johann Tang

    Stepper motors are popular for their ability to stop accurately as well as their ease of use.  Both the amount of rotation and the speed are controlled easily with the same digital square wave pulse signal.  Unlike servo motors, stepper motors do not need an encoder to operate.  Example applications of stepper motors are CNC machines, index tables, robotics, scanners, and more recently, 3D printers.

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    There are a variety of stepper motors available in the market.  The most popular type of motor is the hybrid type, which combines the permanent magnet from the permanent magnet type, and the tooth construction from the variable reluctance type.  With the hybrid type, there are 2-phase, 5-phase, and high resolution designs.  Motors can also be pre-assembled with additional options for different purposes.  For example, there are motors with an electromagnetic brake, encoder, or gearhead.

      When does it make sense to use a specific type of stepper motor?  It depends on your application. 

    Application: Performing quick indexing operations over short distances
    Recommended: High torque 2-phase stepper motors

    High torque 2-phase stepper motors are the most common type used.  These motors offer high torque at low speeds and are ideal for general position control applications.  In linear motion applications, they are often combined with pulleys and belts for indexing conveyors, or ball screws for  linear actuators.  Although they are traditionally used for low speed applications, more designs are adopting bipolar-parallel winding type motors for better high speed performance.

    PKP Series 2-Phase Stepper Motor


    PKP Series stepper motor

    Indexing conveyor

     

    PKP stepper motor speed torque curve

     

    Application: Achieving a high-speed reciprocating motion with less vibration
    Recommended: High torque 5-phase stepper motors

    High torque 5-phase stepper motors with an improved high speed winding design are suitable for applications that require fast reciprocating motions.  Vibration is considerably lower than 2-phae stepper motors, and Oriental Motor's dedicated microstepping drivers do not affect the stop accuracy of 5-phase motors.  These motors are ideal for applications that are sensitive to noise or vibration.

    PKP Series 5-Phase Stepper Motor

    PKP 5-phase stepper motor

    Reciprocating motion PKP 5-phase stepper motor speed torque curve

    Since the basic step angle is small at 0.72° (0.36° for high-resolution type), the vibration and noise are considerably lower than 2-phase stepper motors with a basic step angle of 1.8°. 

    2-phase vs 5-phase vibration comparison


     

    Application: Performing indexing operations of large inertial loads
    Recommended: Geared stepper motors

    A geared type stepper motor can rotate a larger inertial load, such as a robotic arm, due to its ability to generate high torque and reduce the inertia ratio between the load and the motor.  Larger inertia ratios can cause overshooting and undershooting during starting and stopping, which can add missed steps or increase settling time.  The new CS centered style spur geared stepper motors offer improved torque and backlash characteristics.  Planetary and harmonic geared motors are also available.

    PKP Series CS Geared Type Stepper Motor

    PKP CS

    Challenge 3 inertia ratio
    Challenge 3 geared PKP and CVD driver Challenge 3 geared PKP motor FT curve

    For space-saving machine designs, a geared type motor can drive heavier loads while keeping the motor frame size compact.


     

    Application: Performing indexing operations with higher stop accuracy
    Recommended: High resolution type 2-phase stepper motors

    A high resolution type stepper motor has 100 rotor teeth instead of 50 rotor teeth.  The increase in rotor teeth doubles the basic step resolution of standard motors from 200 to 400 steps per revolution  and offers better stop accuracy (2 arc min or 0.034°).  These motors can be combined with microstepping drivers for smoothness and accuracy.

    PKP Series High Resolution Type Stepper Motor

    PKP Series stepper motor

    PKP high resolution motor rotor tooth comparison

    PKP high resolution motor stop accuracy comparison

    Watch How It Works


     

    Application: Performing vertical positioning operation with power-off braking
    Recommended: Electromagnetic brake type stepper motors

    An electromagnetic brake type stepper motor offers a built-in power-off-activated electromagnetic brake which uses friction to hold the motor shaft in place.  When power is accidentally cut off due to a blackout or other unexpected events, the electromagnetic brake can be used to hold a load in position to prevent it from dropping or moving, such as in a rack and pinion lift.  With an electromagnetic brake, the motor current can also be turned off at standstill to suppress heat or lower power consumption.

    PKP Series Electromagnetic Brake Type Stepper Motor

    PKP Series electromagnetic brake type stepper motor

    Elevator application with electromagnetic brake type motor

    Watch How It Works


     

    Application: Performing closed-loop positioning operation
    Recommended: Encoder type stepper motors

    An encoder type stepper motor offers a pre-assembled compact encoder that provides a pulse signal for a host controller to track its position.  These motors are used for applications where position tracking is critical.  For 2-phase stepper motors, encoders are offered at either 200 PPR or 400 PPR to match the motor's basic step resolution.  500 PPR or 1,000 PPR are offered for 5-phase stepper motors.  Voltage (TTL) and line driver output types are available with 3 channel output (A-phase, B-phase, and Z-phase).

    PKP Series Encoder Type Stepper Motor

    PKP Series electromagnetic brake type stepper motor

    PKP encoder map

    Watch How It Works


     

    Application: Positioning within a small space
    Recommended: Flat type stepper motors

    A flat type stepper motor is a thin type of motor designed to fit into tight spaces.  For applications such as index tables, small conveyors, or even robotics, flat type stepper motors can help save space.  A 42 mm frame size and a 60 mm frame size (including a harmonic gear type) are offered.  

    Flat type stepper motors

    Watch How It Works

     


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    Topics: Stepper Motors, Motor Sizing, VIDEOS, Application Examples

    Johann Tang

    Written by Johann Tang

    Johann Tang is a Product Specialist at Oriental Motor USA Corp. with over 15 years of knowledge and experience supporting applications of various types of electric motors, gearheads, actuators, drivers, and controllers.