What is the Optimal Stepper Motor Torque for Coupling with a Ball Screw?

[Ameya Joshi]

I have to select a stepper motor for the following specifications. I need to know the torque which will be sufficient for me to get the driving torque required.
Drive torque = 2.6 Nm
Gear ration used for coupling = 3:1 (Reduction)
Im to couple the motor with a ball screw.

 

[Baluncore]

Power is energy flow. The power is the same on both sides of the gearbox.
Power is torque multiplied by RPM. The torque must be transformed by the gear ratio.

The ball screw needs to be driven with a maximum torque of 2.6 Nm.
The ball screw is driven through a 3.0 : 1 reduction gear train by the stepper motor.
The stepper motor will therefore need a torque of 2.6 Nm / 3.0 = 0.867 Nm.