Tips on Selecting and Sizing Geared Stepper Motors

In this post, I’ll describe the process I use for sizing gearboxes and geared stepper motors.

To make the selection, I am using KEB’s software sizing program called KEB-DRIVE. KEB-DRIVE is free and easy to use. If interested to follow along, you can download a copy of the software.

gearmotor sizing

2. Select the correct gear technology for the application
Configurations in KEB-Drive start at the top left. On the left, you’ll see drop-downs to select different gear types and sizes.

3.Motor Selection (Size, voltage, frequency)
Working to the right, I then select the size of the motor I want. Options for both Induction motors and AC Servo motors are listed. Here is a comparison of the advantages between servo and induction motors.

4.Adjust the Torque/Speed selection
Is it a speed reducer? Or a torque Increaser? It’s both – higher gear ratios will provide lower output speeds and higher torques. Use the drop down to see all the different possible configurations with the selected gearbox/motor combo.

5. What is the gearing Service Factor and why is it important?
The gearing service factor (SF) is the ratio between the:
A SF of 1.0 means the gears will have a nominal output torque equal to that of their rating. Selecting a motor/gear configuration with a SF of less than 1.0 is not advised. This means the gears will be undersized when operated at the nominal point. This could also indicate that the motor selected is too large.

6.Select gearmotor options (mounting style)
This section allows a user to select how the geared motor will be mounted. The flexibility of mounting is one reason that the KEB integral gearmotor solution has been so popular. Users can select a unit with an output shaft. Or a shaft mounted unit with a hollow bore. Mounting feet and mounting flanges can also be selected.

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