When selecting the model of planetary gearbox, the user needs to clarify three parameter values, motor power, reduction ratio, and precision requirements. Generally, if these three parameters are provided, the planetary gearbox manufacturer can know how to choose the right planetary gearbox model. So how to choose a suitable servo gearbox for your own servo motor or stepper motor? Here, MKD guides you on how to choose through the following steps.
Step 1: Confirm the motor power and input sizes
Users provide their own motor power so that the planetary gearbox manufacturer can determine the model of the planetary gearbox according to the motor power provided by the user. Generally, 100W and 200W servo motors match frame size 42 servo planetary gearbox. 200W and 400W configured with a servo planetary gearbox with a frame size of 60. 750W servo motor, you can choose a frame size of 90, and for a 1000W motor, you could select a planetary gearbox with a frame size of 120, and so on.
Then, you need to find out the accurate servo motor installation drawing and confirm the main dimensions of S, LB, LR, LE, LA, and LZ, from which we can know whether the input sizes of the gearbox you need are standard or non-standard. If non-standard products, need to be customized, thus the production time is longer than the standard ones, and the price cost is also about 10%-20% higher than the standard ones. The specific situation depends on the quantity of non-standard sizes.
Step 2: Confirm the reduction ratio
Professional users will directly tell us the reduction ratio he has calculated. Some users don’t know how to calculate the reduction ratio. They will consult the planetary gearbox manufacturer. Here we teach you how to calculate the reduction ratio of the planetary gearbox.
You can tell us the rated speed of your servo motor and the required output speed of the gearbox. Then use the following formula to calculate the ratio.
＊Reduction Ratio ( i) = motor speed / gearbox output speed
Step 3: Confirm the output torque of the planetary gearbox
Firstly, you can calculate the output torque of the motor based on the motor power and rated speed. secondly, use the output torque of the motor to multiply the reduction ratio to obtain the torque of the planetary gearbox. The value obtained should be less than the rated output torque of the selected model of the gearbox, and at the same time, the overload capacity of the drive motor and the actual required largest working torque should also be considered. The largest working torque is required to be less than 3 times the rated output torque, that is, the maximum output torque of the planetary gearbox which you can check in our catalogue parameter.
＊Motor output torque (N.M) = 9550x motor power (kw)/motor speed (rpm)
＊ 1 HP = 0.75kw
*The output torque of the reducer = the output torque of the motor x speed ratio
Finally, the final model is determined by the three comprehensive factors of the output torque of the planetary gearbox, motor power and motor input size.
Core Formula
Motor output torque×Ratio ＜ The torque that the gearbox can bear
Step 4：Other requirements of the user
After determining the above steps, choose the planetary gearbox with the smallest volume to reduce costs. If the installation space of the gearbox is not enough, you can use a right-angle gearbox, which can rotate 90 degrees. Regarding other requirements of the gearbox, such as whether the output end of the gearbox needs a flange, whether it needs a hollow output or a shaft output, what kind of accuracy or clearance, noise value, gearbox shape and other information, please inform our sales engineer for your specific needs, we will help you choose a suitable model as soon as possible. Generally, planetary gearboxes are divided into spur gear and helical gear. The backlash of straight teeth is larger than that of helical gears, and the cost is also lower. The accuracy of helical gears is higher than that of straight teeth, and the return clearance is smaller, so the precision is higher, and also the cost is higher. Users can choose a gearbox that can meet the accuracy requirements according to their own application. For more technical options, please contact us for a catalogue.
