FAQ Page
Category Other
Title 55. I’m preparing to choose a motor. If there is a selection tool or guide lines for choosing a motor, could you please send it to me?

If you want to select a motor properly, please contact our distributor or call our sales department(Tel. 032-234-6300), we will give you a detailed answer. Moreover, with our Motor Selection Tool you will be able to view all four applications and select your own motor through our website. (  


■ When you select a motor, Load's inertia Moment Ratio must be less than 30.
​   If it's not, the motor still can operate but a change in the motor's  operation behavior
   (vibration at Acc/Dec, overshoot and undershoot as the motor runs and stops, consequently settling time increase) can occur.


■ Motor Selection Tool Demonstration on FASTECH Website 
   (Application demonstration - Direct Drive Rotary Table)



(1) Fill in the yellow blanks with the basic data.
※ Precautions
The outer diameter of the table is the radius from the rotation center point to the farthest point of the work, and double the value.
Positioning time is the time including acceleration, deceleration and constant velocity time.
Acceleration / deceleration time means acceleration time and deceleration time. If acceleration time and deceleration time are the same, it is calculated as acceleration time and if it is different, it is calculated as short time.
The reduction gear efficiency can be calculated as 90% for 1st stage and 81% for 2nd stage for general planetary gear reducer.
The safety factor is 2 times the default, and if you are concerned about the safety, please put a larger value.

(1) Click the ‘Calculate’ button to check the motor speed and torque.
(2) Click ‘See Torque Curve of Selected
    Motor’ and choose a motor which has             
    an over running torque at the desired RPM.
(3)  Check Rotor Inertia Moment / Jo 



(4) Put Rotor Inertia Moment, Jo and click the ‘Calculate’ button.
(5) Check Load’s Inertia Moment Ratio / K.


■ If Ratio / K is over than 30, choose a bigger motor which has a higher inertia moment Or recalculate by increasing the ration of the reducer.
(Inertia Moment is reduced as 1/ration of reducer 2 when using a reducer.)

Files 200115_FAQ55_ENG.pdf