Engineering Notes by Oriental Motor

MOTOR CHALLENGE 5: 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 position 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.

There are a variety of stepper motors available in the market.  The most popular type of motor is the hybrid type, which includes the permanent magnet from the permanent magnet type, and the tooth construction from the variable reluctance 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.

So, when does it make sense to use a specific type of stepper motor?  
The answer is it depends on your application

APPLICATION: Performing quick indexing operations over short distances

SOLUTION: High torque 2-phase stepper motor 

High torque 2-phase stepper motors that deliver high torque at low speeds are suitable for applications such as indexing operations over short distances that require high acceleration and deceleration rates.  Stop accuracy of stepper motors is +/-3 arc min or (+/-0.05°).  The small error does not accumulate from step to step.

PKP Series 2-Phase Stepper Motor


PKP Series stepper motor

Indexing conveyor

 

PKP stepper motor speed torque curve

APPLICATION: Achieving high-speed reciprocating motions

SOLUTION: High torque 5-phase stepper motor

High torque 5-phase stepper motors with an improved high speed winding design are suitable for applications that require fast reciprocating motions.  Microstepping does not affects the stop accuracy of 5-phase motors.

PKP Series 5-Phase Stepper Motor

PKP 5-phase stepper motor

Reciprocating motion PKP 5-phase stepper motor speed torque curve

Because the basic step angle is small at 0.72° (0.36° for high-resolution type), the vibration and noise are 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 load

SOLUTION: Geared type stepper motor

A geared type stepper motor can rotate much higher inertial loads because of 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.  Our spur gears offers improved torque and backlash characteristics. 

PKP Series Geared Type Stepper Motor

PKP geared motor

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 

SOLUTION: High resolution type 2-phase stepper motor

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 PPR to 400 PPR,  and offers better stop accuracy (2 arc min or 0.034°).

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

APPLICATION: Performing vertical positioning operation with power-off braking

SOLUTION: Electromagnetic brake type stepper motor

An electromagnetic brake type stepper motor offers a power-off-activated electromagnetic brake which provides frictional torque for holding a load vertically.  When power is accidentally cut off due to a blackout or other unexpected events, the electromagnetic brake holds the load in position to prevent it from dropping or moving.  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

APPLICATION: Performing closed-loop positioning operation 

SOLUTION: Encoder type stepper motor 

An encoder type stepper motor offers a pre-assembled compact encoder that provides a pulse signal for a host controller to track its position.  Encoders are offered at either 200 PPR or 400 PPR to match the motor's basic step resolution.  Voltage (TTL) and line driver 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

Recap all the features for 2-phase and 5-phase stepper motors here.  Click on the motor type for specific features.

2-Phase Stepper Motors 5-Phase Stepper Motors

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Topics: Stepper Motors, Motor Selection, Position Control, 2-Phase, 5-Phase, Electromagnetic Brake, Encoder, High Resolution, Gearhead, Indexing Operation, Reciprocating Motion, Reducing Vibration

Johann Tang

Written by Johann Tang

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

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