I am trying to work out the maximum torque a motor puts out to do some stress analysis on a structure, and I have just been given the motor details from the manufacturer. They said it produces 20 Nm of torque, rotates at 1432 RPM and has a power output of 1.8 kW. I didn't pick up on this at first but later found some errors in my calcs, which pointed back to the motor specs not being in line with each other. From a mechanical standpoint, I've always gone with the Power[W] = Torque[Nm] X Angular Velocity[rad/s] to do any rotational calcs. In this case, if the power output and speed are correct, the torque would be 12 Nm not 20 Nm.
The manufacturer has come back and told me he confirmed the original figures he provided me and they are correct. I was wondering if anyone can tell me how this would work?
Best Answer
20 Nm of torque does not coincide with maximum RPM so you can't just multiply that torque and maximum (unloaded) radians per second because that would be nonesense.
The manufacturer is most likely telling you that the motor can produce a maximum torque of 20 Nm at a significantly lower speed.
Maximum torque will be when the motor is significantly loaded and turning at 859.4 RPM or 60.0% of full (unloaded) speed.